U.S. patent number RE48,042 [Application Number 15/919,479] was granted by the patent office on 2020-06-09 for devices and methods for a lidar platform with a shared transmit/receive path.
This patent grant is currently assigned to Waymo LLC. The grantee listed for this patent is Waymo LLC. Invention is credited to Pierre-Yves Droz, Daniel Gruver, Anthony Levandowski, Zachary Morriss, Gaetan Pennecot, Drew Eugene Ulrich.
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United States Patent |
RE48,042 |
Pennecot , et al. |
June 9, 2020 |
Devices and methods for a LIDAR platform with a shared
transmit/receive path
Abstract
A LIDAR device may transmit light pulses originating from one or
more light sources and may receive reflected light pulses that are
then detected by one or more detectors. The LIDAR device may
include a lens that both (i) collimates the light from the one or
more light sources to provide collimated light for transmission
into an environment of the LIDAR device and (ii) focuses the
reflected light onto the one or more detectors. The lens may define
a curved focal surface in a transmit path of the light from the one
or more light sources and a curved focal surface in a receive path
of the one or more detectors. The one or more light sources may be
arranged along the curved focal surface in the transmit path. The
one or more detectors may be arranged along the curved focal
surface in the receive path.
Inventors: |
Pennecot; Gaetan (San
Francisco, CA), Droz; Pierre-Yves (Los Altos, CA),
Ulrich; Drew Eugene (San Francisco, CA), Gruver; Daniel
(San Francisco, CA), Morriss; Zachary (San Francisco,
CA), Levandowski; Anthony (Berkeley, CA) |
Applicant: |
Name |
City |
State |
Country |
Type |
Waymo LLC |
Mountain View |
CA |
US |
|
|
Assignee: |
Waymo LLC (Mountain View,
CA)
|
Family
ID: |
1000004248183 |
Appl.
No.: |
15/919,479 |
Filed: |
March 13, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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13971606 |
Sep 16, 2014 |
8836922 |
|
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Reissue of: |
14462075 |
Aug 18, 2014 |
9285464 |
Mar 15, 2016 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G01S
17/42 (20130101); G01S 7/4817 (20130101); G01S
17/89 (20130101); G01S 7/4812 (20130101); G01S
17/89 (20130101); G01S 7/4813 (20130101); G01S
7/4816 (20130101); G01S 7/4815 (20130101); G01S
7/4813 (20130101); G01S 7/4816 (20130101); G01S
7/4815 (20130101); G01S 17/931 (20200101) |
Current International
Class: |
G01C
3/08 (20060101); G01S 7/481 (20060101); G01S
17/89 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
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2410358 |
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Jan 2012 |
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EP |
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H01-240884 |
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Sep 1989 |
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JP |
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H06-214027 |
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Aug 1994 |
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JP |
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|
Primary Examiner: Jastrzab; Jeffrey R
Attorney, Agent or Firm: McDonnell Boehnen Hulbert &
Berghoff LLP
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATION
The present application is a continuation of U.S. patent
application Ser. No. 13/971,606, filed Aug. 20, 2013, which
application is incorporated herein by reference
Claims
What is claimed is:
1. A light detection and ranging (LIDAR) device, comprising: a lens
mounted to a housing, wherein the housing .[.is configured to
rotate about an axis and.]. has an interior space that includes a
transmit block, a receive block, a transmit path, and a receive
path, wherein the transmit block has an exit aperture, wherein the
receive block has an entrance aperture, wherein the transmit path
extends from the exit aperture to the lens, wherein the receive
path extends from the lens to the entrance aperture, and wherein
the transmit path at least partially overlaps the receive path in
the interior space between the transmit block and the receive
block; a plurality of light sources in the transmit block, wherein
the plurality of light sources are configured to emit a plurality
of light beams through the exit aperture in a plurality of
different directions.[., the light beams comprising light having
wavelengths in a wavelength range.].; a plurality of detectors in
the receive block, wherein the plurality of detectors are
configured to detect light .[.having wavelengths in the wavelength
range.].; and wherein the lens is configured to receive the light
beams via the transmit path, collimate the light beams for
transmission into an environment of the LIDAR device, collect light
comprising light from one or more of the collimated light beams
reflected by one or more objects in the environment of the LIDAR
device, and focus the collected light onto the detectors via the
receive path.
2. The LIDAR device of claim 1, wherein each detector in the
plurality of detectors is associated with a corresponding light
source in the plurality of light sources, and wherein the lens is
configured to focus onto each detector a respective portion of the
collected light that comprises light from the detector's
corresponding light source.
3. The LIDAR device of claim 1, wherein the exit aperture is in a
wall that comprises a reflective surface.
4. The LIDAR device of claim 3, wherein the receive path extends
from the lens to the entrance aperture via the reflective
surface.
5. The LIDAR device of claim 3, wherein the wall comprises a
transparent material, the reflective surface covers a portion of
the transparent material, and the exit aperture corresponds to a
portion of the transparent material that is not covered by the
reflective surface.
6. The LIDAR device of claim 1, wherein the lens defines a curved
focal surface in the transmit block and a curved focal surface in
the receive block.
7. The LIDAR device of claim 6, wherein the light sources in the
plurality of light sources are arranged in a pattern substantially
corresponding to the curved focal surface in the transmit block,
and wherein the detectors in the plurality of detectors are
arranged in a pattern substantially corresponding to the curved
focal surface in the receive block.
8. The LIDAR device of claim 1, wherein the lens has an aspheric
surface and a toroidal surface.
9. The LIDAR device of claim 8, wherein the toroidal surface is in
the interior space within the housing and the aspheric surface is
outside of the housing.
10. The LIDAR device of claim 1, wherein the .[.axis is
substantially vertical.]. .Iadd.housing is configured to rotate
about an axis.Iaddend..
11. The LIDAR device of claim 1, further comprising a mirror in the
transmit block, wherein the mirror is configured to reflect the
light beams toward the exit aperture.
12. The LIDAR device of claim 1, wherein the receive block
comprises a sealed environment containing an inert gas.
13. The LIDAR device of claim 1, wherein the entrance aperture
comprises a .[.material that passes light having wavelengths in the
wavelength range and attenuates light having other wavelengths.].
.Iadd.filtering window.Iaddend..
14. The LIDAR device of claim 1, wherein each light source in the
plurality of light sources comprises a respective laser diode.
15. The LIDAR device of claim 1, wherein each detector in the
plurality of detectors comprises a respective avalanche
photodiode.
16. A method comprising: .[.rotating a housing of.].
.Iadd.operating .Iaddend.a light detection and ranging (LIDAR)
device .[.about an axis.]. .Iadd.comprising a housing.Iaddend.,
wherein the housing mounts a lens and has an interior space that
includes a transmit block, a receive block, a transmit path, and a
receive path, wherein the transmit block has an exit aperture,
wherein the receive block has an entrance aperture, wherein the
transmit path extends from the exit aperture to the lens, wherein
the receive path extends from the lens to the entrance aperture,
and wherein the transmit path at least partially overlaps the
receive path in the interior space between the transmit block and
the receive block.[.;.]..Iadd., wherein operating the LIDAR device
comprises: .Iaddend. emitting, by a plurality of light sources in
the transmit block, a plurality of light beams through the exit
aperture in a plurality of different directions.[., the light beams
comprising light having wavelengths in a wavelength range.].;
receiving, by the lens, the light beams via the transmit path;
collimating, by the lens, the light beams for transmission into an
environment of the LIDAR device; collecting, by the lens, light
from one or more of the collimated light beams reflected by one or
more objects in the environment of the LIDAR device; focusing, by
the lens, the collected light onto a plurality of detectors in the
receive block via the receive path; and detecting, by the plurality
of detectors in the receive block, light from the focused light
.[.having wavelengths in the wavelength range.]..
17. The method of claim 16, wherein each detector in the plurality
of detectors is associated with a corresponding light source in the
plurality of light sources, .[.the method further comprising.].
.Iadd.wherein operating the LIDAR device further
comprises.Iaddend.: focusing onto each detector, by the lens, a
respective portion of the collected light that comprises light from
the detector's corresponding light source.
18. The method of claim 16, wherein the exit aperture is in a wall
that comprises a reflective surface, and wherein the receive path
extends from the lens to the entrance aperture via the reflective
surface, .[.further comprising.]. .Iadd.wherein operating the LIDAR
device further comprises.Iaddend.: reflecting, by the reflective
surface, the collected light that is focused by the lens onto the
plurality of detectors in the receive block via the receive
path.
19. The method of claim 16, .[.further comprising.]. .Iadd.wherein
operating the LIDAR device further comrpises.Iaddend.: reflecting,
by a mirror in the transmit block, the emitted light beams toward
the exit aperture.
.Iadd.20. The LIDAR device of claim 10, wherein the axis is
substantially vertical. .Iaddend.
Description
BACKGROUND
Unless otherwise indicated herein, the materials described in this
section are not prior art to the claims in this application and are
not admitted to be prior art by inclusion in this section.
Vehicles can be configured to operate in an autonomous mode in
which the vehicle navigates through an environment with little or
no input from a driver. Such autonomous vehicles can include one or
more sensors that are configured to detect information about the
environment in which the vehicle operates.
One such sensor is a light detection and ranging (LIDAR) device. A
LIDAR can estimates distance to environmental features while
scanning through a scene to assemble a "point cloud" indicative of
reflective surfaces in the environment. Individual points in the
point cloud can be determined by transmitting a laser pulse and
detecting a returning pulse, if any, reflected from an object in
the environment, and determining the distance to the object
according to the time delay between the transmitted pulse and the
reception of the reflected pulse. A laser, or set of lasers, can be
rapidly and repeatedly scanned across a scene to provide continuous
real-time information on distances to reflective objects in the
scene. Combining the measured distances and the orientation of the
laser(s) while measuring each distance allows for associating a
three-dimensional position with each returning pulse. In this way,
a three-dimensional map of points indicative of locations of
reflective features in the environment can be generated for the
entire scanning zone.
SUMMARY
In one example, a light detection and ranging (LIDAR) device is
provided that includes a housing configured to rotate about an
axis. The housing has an interior space that includes a transmit
block, a receive block, and a shared space. The transmit block has
an exit aperture and the receive block has an entrance aperture.
The LIDAR device also includes a plurality of light sources in the
transmit block. The plurality of light sources is configured to
emit a plurality of light beams that enter the shared space through
the exit aperture and traverse the shared space via a transmit
path. The light beams include light having wavelengths in a
wavelength range. The LIDAR device also includes a plurality of
detectors in the receive block. The plurality of detectors is
configured to detect light having wavelengths in the wavelength
range. The LIDAR device also includes a lens mounted to the
housing. The lens is configured to (i) receive the light beams via
the transmit path, (ii) collimate the light beams for transmission
into an environment of the LIDAR device, (iii) collect light that
includes light from one or more of the collimated light beams
reflected by one or more objects in the environment of the LIDAR
device, and (iv) focus the collected light onto the detectors via a
receive path that extends through the shared space and the entrance
aperture of the receive block.
In another example, a method is provided that involves rotating a
housing of a light detection and ranging (LIDAR) device about an
axis. The housing has an interior space that includes a transmit
block, a receive block, and a shared space. The transmit block has
an exit aperture and the receive block has an entrance aperture.
The method further involves emitting a plurality of light beams by
a plurality of light sources in the transmit block. The plurality
of light beams enter the shared space via a transmit path. The
light beams include light having wavelengths in a wavelength range.
The method further involves receiving the light beams at a lens
mounted to the housing along the transmit path. The method further
involves collimating, by the lens, the light beams for transmission
into an environment of the LIDAR device. The method further
involves collecting, by the lens, light from one or more of the
collimated light beams reflected by one or more objects in the
environment of the LIDAR device. The method further involves
focusing, by the lens, the collected light onto a plurality of
detectors in the receive block via a receive path that extends
through the shared space and the entrance aperture of the receive
block. The method further involves detecting, by the plurality of
detectors in the receive block, light from the focused light having
wavelengths in the wavelength range.
These as well as other aspects, advantages, and alternatives, will
become apparent to those of ordinary skill in the art by reading
the following detailed description, with reference where
appropriate to the accompanying figures.
BRIEF DESCRIPTION OF THE FIGURES
FIG. 1 is a block diagram of an example LIDAR device.
FIG. 2 is a cross-section view of an example LIDAR device.
FIG. 3A is a perspective view of an example LIDAR device fitted
with various components, in accordance with at least some
embodiments described herein
FIG. 3B is a perspective view of the example LIDAR device shown in
FIG. 3A with the various components removed to illustrate interior
space of the housing.
FIG. 4 illustrates an example transmit block, in accordance with at
least some embodiments described herein.
FIG. 5A is a view of an example light source, in accordance with an
example embodiment.
FIG. 5B is a view of the light source of FIG. 5A in combination
with a cylindrical lens, in accordance with an example
embodiment.
FIG. 5C is another view of the light source and cylindrical lens
combination of FIG. 5B, in accordance with an example
embodiment.
FIG. 6A illustrates an example receive block, in accordance with at
least some embodiments described herein.
FIG. 6B illustrates a side view of three detectors included in the
receive block of FIG. 6A.
FIG. 7A illustrates an example lens with an aspheric surface and a
toroidal surface, in accordance with at least some embodiments
described herein.
FIG. 7B illustrates a cross-section view of the example lens 750
shown in FIG. 7A.
FIG. 8A illustrates an example LIDAR device mounted on a vehicle,
in accordance with at least some embodiments described herein.
FIG. 8B illustrates a scenario where the LIDAR device shown in FIG.
8A is scanning an environment that includes one or more objects, in
accordance with at least some embodiments described herein.
FIG. 9 is a flowchart of a method, in accordance with at least some
embodiments described herein.
DETAILED DESCRIPTION
The following detailed description describes various features and
functions of the disclosed systems, devices and methods with
reference to the accompanying figures. In the figures, similar
symbols identify similar components, unless context dictates
otherwise. The illustrative system, device and method embodiments
described herein are not meant to be limiting. It may be readily
understood by those skilled in the art that certain aspects of the
disclosed systems, devices and methods can be arranged and combined
in a wide variety of different configurations, all of which are
contemplated herein.
A light detection and ranging (LIDAR) device may transmit light
pulses originating from a plurality of light sources and may
receive reflected light pulses that are then detected by a
plurality of detectors. Within examples described herein, a LIDAR
device is provided that includes a transmit/receive lens that both
collimates the light from the plurality of light sources and
focuses the reflected light onto the plurality of detectors. By
using a transmit/receive lens that performs both of these
functions, instead of a transmit lens for collimating and a receive
lens for focusing, advantages with respect to size, cost, and/or
complexity can be provided.
The LIDAR device comprises a housing that is configured to rotate
about an axis. In some examples, the axis is substantially
vertical. The housing may have an interior space that includes
various components such as a transmit block that includes the
plurality of light sources, a receive block that includes the
plurality of detectors, a shared space where emitted light
traverses from the transmit block to the transmit/receive lens and
reflected light traverses from the transmit/receive lens to the
receive block, and the transmit/receive lens that collimates the
emitted light and focuses the reflected light. By rotating the
housing that includes the various components, in some examples, a
three-dimensional map of a 360-degree field of view of an
environment of the LIDAR device can be determined without frequent
recalibration of the arrangement of the various components.
In some examples, the housing may include radio frequency (RF) and
optical shielding between the transmit block and the receive block.
For example, the housing can be formed from and/or coated by a
metal, metallic ink, or metallic foam to provide the RF shielding.
Metals used for shielding can include, for example, copper or
nickel.
The plurality of light sources included in the transmit block can
include, for example, laser diodes. In one example, the light
sources emit light with wavelengths of approximately 905 nm. In
some examples, a transmit path through which the transmit/receive
lens receives the light emitted by the light sources may include a
reflective element, such as a mirror or prism. By including the
reflective element, the transmit path can be folded to provide a
smaller size of the transmit block and, hence, a smaller housing of
the LIDAR device. Additionally, the transmit path includes an exit
aperture of the transmit block through which the emitted light
enters the shared space and traverses to the transmit/receive
lens.
In some examples, each light source of the plurality of light
sources includes a respective lens, such as a cylindrical or
acylindrical lens. The light source may emit an uncollimated light
beam that diverges more in a first direction than in a second
direction. In these examples, the light source's respective lens
may pre-collimate the uncollimated light beam in the first
direction to provide a partially collimated light beam, thereby
reducing the divergence in the first direction. In some examples,
the partially collimated light beam diverges less in the first
direction than in the second direction. The transmit/receive lens
receives the partially collimated light beams from the one or more
light sources via an exit aperture of the transmit block and the
transmit/receive lens collimates the partially collimated light
beams to provide collimated light beams that are transmitted into
the environment of the LIDAR device. In this example, the light
emitted by the light sources may have a greater divergence in the
second direction than in the first direction, and the exit aperture
can accommodate vertical and horizontal extents of the beams of
light from the light sources.
The housing mounts the transmit/receive lens through which light
from the plurality of light sources can exit the housing, and
reflected light can enter the housing to reach the receive block.
The transmit/receive lens can have an optical power that is
sufficient to collimate the light emitted by the plurality of light
sources and to focus the reflected light onto the plurality of
detectors in the receive block. In one example, the
transmit/receive lens has a surface with an aspheric shape that is
at the outside of the housing, a surface with a toroidal shape that
is inside the housing, and a focal length of approximately 120
mm.
The plurality of detectors included in the receive block can
include, for example, avalanche photodiodes in a sealed environment
that is filled with an inert gas, such as nitrogen. The receive
block can include an entrance aperture through which focused light
from the transmit/receive lens traverses towards the detectors. In
some examples, the entrance aperture can include a filtering window
that passes light having wavelengths within the wavelength range
emitted by the plurality of light sources and attenuates light
having other wavelengths.
The collimated light transmitted from the LIDAR device into the
environment may reflect from one or more objects in the environment
to provide object-reflected light. The transmit/receive lens may
collect the object-reflected light and focus the object-reflected
light through a focusing path ("receive path") onto the plurality
of detectors. In some examples, the receive path may include a
reflective surface that directs the focused light to the plurality
of detectors. Additionally or alternatively, the reflective surface
can fold the focused light towards the receive block and thus
provide space savings for the shared space and the housing of the
LIDAR device.
In some examples, the reflective surface may define a wall that
includes the exit aperture between the transmit block and the
shared space. In this case, the exit aperture of the transmit block
corresponds to a transparent and/or non-reflective portion of the
reflective surface. The transparent portion can be a hole or
cut-away portion of the reflective surface. Alternatively, the
reflective surface can be formed by forming a layer of reflective
material on a transparent substrate (e.g., glass) and the
transparent portion can be a portion of the substrate that is not
coated with the reflective material. Thus, the shared space can be
used for both the transmit path and the receive path. In some
examples, the transmit path at least partially overlaps the receive
path in the shared space.
The vertical and horizontal extents of the exit aperture are
sufficient to accommodate the beam widths of the emitted light
beams from the light sources. However, the non-reflective nature of
the exit aperture prevents a portion of the collected and focused
light in the receive path from reflecting, at the reflective
surface, towards the detectors in the receive block. Thus, reducing
the beam widths of the emitted light beams from the transmit blocks
is desirable to minimize the size of the exit aperture and reduce
the lost portion of the collected light. In some examples noted
above, the reduction of the beam widths traversing through the exit
aperture can be achieved by partially collimating the emitted light
beams by including a respective lens, such as a cylindrical or
acylindrical lens, adjacent to each light source.
Additionally or alternatively, to reduce the beam widths of the
emitted light beams, in some examples, the transmit/receive lens
can be configured to define a focal surface that has a substantial
curvature in a vertical plane and/or a horizontal plane. For
example, the transmit/receive lens can be configured to have the
aspheric surface and the toroidal surface described above that
provides the curved focal surface along the vertical plane and/or
the horizontal plane. In this configuration, the light sources in
the transmit block can be arranged along the transmit/receive lens'
curved focal surface in the transmit block, and the detectors in
the receive block can be arranged on the transmit/receive lens'
curved focal surface in the receive block. Thus, the emitted light
beams from the light sources arranged along the curved focal
surface can converge into the exit aperture having a smaller size
than an aperture for light beams that are substantially parallel
and/or diverging.
To facilitate such curved arrangement of the light sources, in some
examples, the light sources can be mounted on a curved edge of one
or more vertically-oriented printed circuit boards (PCBs), such
that the curved edge of the PCB substantially matches the curvature
of the focal surface in the vertical plane of the PCB. In this
example, the one or more PCBs can be mounted in the transmit block
along a horizontal curvature that substantially matches the
curvature of the focal surface in the horizontal plane of the one
or more PCBs. For example, the transmit block can include four
PCBs, with each PCB mounting sixteen light sources, so as to
provide 64 light sources along the curved focal plane of the
transmit/receive lens in the transmit block. In this example, the
64 light sources are arranged in a pattern substantially
corresponding to the curved focal surface defined by the
transmit/receive lens such that the emitted light beams converge
towards the exit aperture of the transmit block.
For the receive block, in some examples, the plurality of detectors
can be disposed on a flexible PCB that is mounted to the receive
block to conform with the shape of the transmit/receive lens' focal
surface. For example, the flexible PCB may be held between two
clamping pieces that have surfaces corresponding to the shape of
the focal surface. Additionally, in this example, each of the
plurality of detectors can be arranged on the flexible PCB so as to
receive focused light from the transmit/receive lens that
corresponds to a respective light source of the plurality of light
sources. In this example, the detectors can be arranged in a
pattern substantially corresponding to the curved focal surface of
the transmit/receive lens in the receive block. Thus, in this
example, the transmit/receive lens can be configured to focus onto
each detector of the plurality of detectors a respective portion of
the collected light that comprises light from the detector's
corresponding light source.
Some embodiments of the present disclosure therefore provide
systems and methods for a LIDAR device that uses a shared
transmit/receive lens. In some examples, such LIDAR device can
include the shared lens configured to provide a curved focal plane
for transmitting light sources and receiving detectors such that
light from the light sources passes through a small exit aperture
included in a reflective surface that reflects collected light
towards the detectors.
FIG. 1 is a block diagram of an example LIDAR device 100. The LIDAR
device 100 comprises a housing 110 that houses an arrangement of
various components included in the LIDAR device 100 such as a
transmit block 120, a receive block 130, a shared space 140, and a
lens 150. The LIDAR device 100 includes the arrangement of the
various components that provide emitted light beams 102 from the
transmit block 120 that are collimated by the lens 150 and
transmitted to an environment of the LIDAR device 100 as collimated
light beams 104, and collect reflected light 106 from one or more
objects in the environment of the LIDAR device 100 by the lens 150
for focusing towards the receive block 130 as focused light 108.
The reflected light 106 comprises light from the collimated light
beams 104 that was reflected by the one or more objects in the
environment of the LIDAR device 100. The emitted light beams 102
and the focused light 108 traverse in the shared space 140 also
included in the housing 110. In some examples, the emitted light
beams 102 are propagating in a transmit path through the shared
space 140 and the focused light 108 are propagating in a receive
path through the shared space 140. In some examples, the transmit
path at least partially overlaps the receive path in the shared
space 140. The LIDAR device 100 can determine an aspect of the one
or more objects (e.g., location, shape, etc.) in the environment of
the LIDAR device 100 by processing the focused light 108 received
by the receive block 130. For example, the LIDAR device 100 can
compare a time when pulses included in the emitted light beams 102
were emitted by the transmit block 120 with a time when
corresponding pulses included in the focused light 108 were
received by the receive block 130 and determine the distance
between the one or more objects and the LIDAR device 100 based on
the comparison.
The housing 110 included in the LIDAR device 100 can provide a
platform for mounting the various components included in the LIDAR
device 100. The housing 110 can be formed from any material capable
of supporting the various components of the LIDAR device 100
included in an interior space of the housing 110. For example, the
housing 110 may be formed from a structural material such as
plastic or metal.
In some examples, the housing 110 can be configured for optical
shielding to reduce ambient light and/or unintentional transmission
of the emitted light beams 102 from the transmit block 120 to the
receive block 130. Optical shielding from ambient light of the
environment of the LIDAR device 100 can be achieved by forming
and/or coating the outer surface of the housing 110 with a material
that blocks the ambient light from the environment. Additionally,
inner surfaces of the housing 110 can include and/or be coated with
the material described above to optically isolate the transmit
block 120 from the receive block 130 to prevent the receive block
130 from receiving the emitted light beams 102 before the emitted
light beams 102 reach the lens 150.
In some examples, the housing 110 can be configured for
electromagnetic shielding to reduce electromagnetic noise (e.g.,
Radio Frequency (RF) Noise, etc.) from ambient environment of the
LIDAR device 110 and/or electromagnetic noise between the transmit
block 120 and the receive block 130. Electromagnetic shielding can
improve quality of the emitted light beams 102 emitted by the
transmit block 120 and reduce noise in signals received and/or
provided by the receive block 130. Electromagnetic shielding can be
achieved by forming and/or coating the housing 110 with a material
that absorbs electromagnetic radiation such as a metal, metallic
ink, metallic foam, carbon foam, or any other material configured
to absorb electromagnetic radiation. Metals that can be used for
the electromagnetic shielding can include for example, copper or
nickel.
In some examples, the housing 110 can be configured to have a
substantially cylindrical shape and to rotate about an axis of the
LIDAR device 100. For example, the housing 110 can have the
substantially cylindrical shape with a diameter of approximately 10
centimeters. In some examples, the axis is substantially vertical.
By rotating the housing 110 that includes the various components,
in some examples, a three-dimensional map of a 360 degree view of
the environment of the LIDAR device 100 can be determined without
frequent recalibration of the arrangement of the various components
of the LIDAR device 100. Additionally or alternatively, the LIDAR
device 100 can be configured to tilt the axis of rotation of the
housing 110 to control the field of view of the LIDAR device
100.
Although not illustrated in FIG. 1, the LIDAR device 100 can
optionally include a mounting structure for the housing 110. The
mounting structure can include a motor or other means for rotating
the housing 110 about the axis of the LIDAR device 100.
Alternatively, the mounting structure can be included in a device
and/or system other than the LIDAR device 100.
In some examples, the various components of the LIDAR device 100
such as the transmit block 120, receive block 130, and the lens 150
can be removably mounted to the housing 110 in predetermined
positions to reduce burden of calibrating the arrangement of each
component and/or subcomponents included in each component. Thus,
the housing 110 provides the platform for the various components of
the LIDAR device 100 for ease of assembly, maintenance,
calibration, and manufacture of the LIDAR device 100.
The transmit block 120 includes a plurality of light sources 122
that can be configured to emit the plurality of emitted light beams
102 via an exit aperture 124. In some examples, each of the
plurality of emitted light beams 102 corresponds to one of the
plurality of light sources 122. The transmit block 120 can
optionally include a mirror 126 along the transmit path of the
emitted light beams 102 between the light sources 122 and the exit
aperture 124.
The light sources 122 can include laser diodes, light emitting
diodes (LED), vertical cavity surface emitting lasers (VCSEL),
organic light emitting diodes (OLED), polymer light emitting diodes
(PLED), light emitting polymers (LEP), liquid crystal displays
(LCD), microelectromechanical systems (MEMS), or any other device
configured to selectively transmit, reflect, and/or emit light to
provide the plurality of emitted light beams 102. In some examples,
the light sources 122 can be configured to emit the emitted light
beams 102 in a wavelength range that can be detected by detectors
132 included in the receive block 130. The wavelength range could,
for example, be in the ultraviolet, visible, and/or infrared
portions of the electromagnetic spectrum. In some examples, the
wavelength range can be a narrow wavelength range, such as provided
by lasers. In one example, the wavelength range includes
wavelengths that are approximately 905 nm. Additionally, the light
sources 122 can be configured to emit the emitted light beams 102
in the form of pulses. In some examples, the plurality of light
sources 122 can be disposed on one or more substrates (e.g.,
printed circuit boards (PCB), flexible PCBs, etc.) and arranged to
emit the plurality of light beams 102 towards the exit aperture
124.
In some examples, the plurality of light sources 122 can be
configured to emit uncollimated light beams included in the emitted
light beams 102. For example, the emitted light beams 102 can
diverge in one or more directions along the transmit path due to
the uncollimated light beams emitted by the plurality of light
sources 122. In some examples, vertical and horizontal extents of
the emitted light beams 102 at any position along the transmit path
can be based on an extent of the divergence of the uncollimated
light beams emitted by the plurality of light sources 122.
The exit aperture 124 arranged along the transmit path of the
emitted light beams 102 can be configured to accommodate the
vertical and horizontal extents of the plurality of light beams 102
emitted by the plurality of light sources 122 at the exit aperture
124. It is noted that the block diagram shown in FIG. 1 is
described in connection with functional modules for convenience in
description. However, the functional modules in the block diagram
of FIG. 1 can be physically implemented in other locations. For
example, although illustrated that the exit aperture 124 is
included in the transmit block 120, the exit aperture 124 can be
physically included in both the transmit block 120 and the shared
space 140. For example, the transmit block 120 and the shared space
140 can be separated by a wall that includes the exit aperture 124.
In this case, the exit aperture 124 can correspond to a transparent
portion of the wall. In one example, the transparent portion can be
a hole or cut-away portion of the wall. In another example, the
wall can be formed from a transparent substrate (e.g., glass)
coated with a non-transparent material, and the exit aperture 124
can be a portion of the substrate that is not coated with the
non-transparent material.
In some examples of the LIDAR device 100, it may be desirable to
minimize size of the exit aperture 124 while accommodating the
vertical and horizontal extents of the plurality of light beams
102. For example, minimizing the size of the exit aperture 124 can
improve the optical shielding of the light sources 122 described
above in the functions of the housing 110. Additionally or
alternatively, the wall separating the transmit block 120 and the
shared space 140 can be arranged along the receive path of the
focused light 108, and thus, the exit aperture 124 can be minimized
to allow a larger portion of the focused light 108 to reach the
wall. For example, the wall can be coated with a reflective
material (e.g., reflective surface 142 in shared space 140) and the
receive path can include reflecting the focused light 108 by the
reflective material towards the receive block 130. In this case,
minimizing the size of the exit aperture 124 can allow a larger
portion of the focused light 108 to reflect off the reflective
material that the wall is coated with.
To minimize the size of the exit aperture 124, in some examples,
the divergence of the emitted light beams 102 can be reduced by
partially collimating the uncollimated light beams emitted by the
light sources 122 to minimize the vertical and horizontal extents
of the emitted light beams 102 and thus minimize the size of the
exit aperture 124. For example, each light source of the plurality
of light sources 122 can include a cylindrical lens arranged
adjacent to the light source. The light source may emit a
corresponding uncollimated light beam that diverges more in a first
direction than in a second direction. The cylindrical lens may
pre-collimate the uncollimated light beam in the first direction to
provide a partially collimated light beam, thereby reducing the
divergence in the first direction. In some examples, the partially
collimated light beam diverges less in the first direction than in
the second direction. Similarly, uncollimated light beams from
other light sources of the plurality of light sources 122 can have
a reduced beam width in the first direction and thus the emitted
light beams 102 can have a smaller divergence due to the partially
collimated light beams. In this example, at least one of the
vertical and horizontal extents of the exit aperture 124 can be
reduced due to partially collimating the light beams 102.
Additionally or alternatively, to minimize the size of the exit
aperture 124, in some examples, the light sources 122 can be
arranged along a substantially curved surface defined by the
transmit block 120. The curved surface can be configured such that
the emitted light beams 102 converge towards the exit aperture 124,
and thus the vertical and horizontal extents of the emitted light
beams 102 at the exit aperture 124 can be reduced due to the
arrangement of the light sources 122 along the curved surface of
the transmit block 120. In some examples, the curved surface of the
transmit block 120 can include a curvature along the first
direction of divergence of the emitted light beams 102 and a
curvature along the second direction of divergence of the emitted
light beams 102, such that the plurality of light beams 102
converge towards a central area in front of the plurality of light
sources 122 along the transmit path.
To facilitate such curved arrangement of the light sources 122, in
some examples, the light sources 122 can be disposed on a flexible
substrate (e.g., flexible PCB) having a curvature along one or more
directions. For example, the curved flexible substrate can be
curved along the first direction of divergence of the emitted light
beams 102 and the second direction of divergence of the emitted
light beams 102. Additionally or alternatively, to facilitate such
curved arrangement of the light sources 122, in some examples, the
light sources 122 can be disposed on a curved edge of one or more
vertically-oriented printed circuit boards (PCBs), such that the
curved edge of the PCB substantially matches the curvature of the
first direction (e.g., the vertical plane of the PCB). In this
example, the one or more PCBs can be mounted in the transmit block
120 along a horizontal curvature that substantially matches the
curvature of the second direction (e.g., the horizontal plane of
the one or more PCBs). For example, the transmit block 120 can
include four PCBs, with each PCB mounting sixteen light sources, so
as to provide 64 light sources along the curved surface of the
transmit block 120. In this example, the 64 light sources are
arranged in a pattern such that the emitted light beams 102
converge towards the exit aperture 124 of the transmit block
120.
The transmit block 120 can optionally include the mirror 126 along
the transmit path of the emitted light beams 102 between the light
sources 122 and the exit aperture 124. By including the mirror 126
in the transmit block 120, the transmit path of the emitted light
beams 102 can be folded to provide a smaller size of the transmit
block 120 and the housing 110 of the LIDAR device 100 than a size
of another transmit block where the transmit path that is not
folded.
The receive block 130 includes a plurality of detectors 132 that
can be configured to receive the focused light 108 via an entrance
aperture 134. In some examples, each of the plurality of detectors
132 is configured and arranged to receive a portion of the focused
light 108 corresponding to a light beam emitted by a corresponding
light source of the plurality of light sources 122 and reflected of
the one or more objects in the environment of the LIDAR device 100.
The receive block 130 can optionally include the detectors 132 in a
sealed environment having an inert gas 136.
The detectors 132 may comprise photodiodes, avalanche photodiodes,
phototransistors, cameras, active pixel sensors (APS), charge
coupled devices (CCD), cryogenic detectors, or any other sensor of
light configured to receive focused light 108 having wavelengths in
the wavelength range of the emitted light beams 102.
To facilitate receiving, by each of the detectors 132, the portion
of the focused light 108 from the corresponding light source of the
plurality of light sources 122, the detectors 132 can be disposed
on one or more substrates and arranged accordingly. For example,
the light sources 122 can be arranged along a curved surface of the
transmit block 120, and the detectors 132 can also be arranged
along a curved surface of the receive block 130. The curved surface
of the receive block 130 can similarly be curved along one or more
axes of the curved surface of the receive block 130. Thus, each of
the detectors 132 are configured to receive light that was
originally emitted by a corresponding light source of the plurality
of light sources 122.
To provide the curved surface of the receive block 130, the
detectors 132 can be disposed on the one or more substrates
similarly to the light sources 122 disposed in the transmit block
120. For example, the detectors 132 can be disposed on a flexible
substrate (e.g., flexible PCB) and arranged along the curved
surface of the flexible substrate to each receive focused light
originating from a corresponding light source of the light sources
122. In this example, the flexible substrate may be held between
two clamping pieces that have surfaces corresponding to the shape
of the curved surface of the receive block 130. Thus, in this
example, assembly of the receive block 130 can be simplified by
sliding the flexible substrate onto the receive block 130 and using
the two clamping pieces to hold it at the correct curvature.
The focused light 108 traversing along the receive path can be
received by the detectors 132 via the entrance aperture 134. In
some examples, the entrance aperture 134 can include a filtering
window that passes light having wavelengths within the wavelength
range emitted by the plurality of light sources 122 and attenuates
light having other wavelengths. In this example, the detectors 132
receive the focused light 108 substantially comprising light having
the wavelengths within the wavelength range.
In some examples, the plurality of detectors 132 included in the
receive block 130 can include, for example, avalanche photodiodes
in a sealed environment that is filled with the inert gas 136. The
inert gas 136 may comprise, for example, nitrogen.
The shared space 140 includes the transmit path for the emitted
light beams 102 from the transmit block 120 to the lens 150, and
includes the receive path for the focused light 108 from the lens
150 to the receive block 130. In some examples, the transmit path
at least partially overlaps with the receive path in the shared
space 140. By including the transmit path and the receive path in
the shared space 140, advantages with respect to size, cost, and/or
complexity of assembly, manufacture, and/or maintenance of the
LIDAR device 100 can be provided.
In some examples, the shared space 140 can include a reflective
surface 142. The reflective surface 142 can be arranged along the
receive path and configured to reflect the focused light 108
towards the entrance aperture 134 and onto the detectors 132. The
reflective surface 142 may comprise a prism, mirror or any other
optical element configured to reflect the focused light 108 towards
the entrance aperture 134 in the receive block 130. In some
examples where a wall separates the shared space 140 from the
transmit block 120. In these examples, the wall may comprise a
transparent substrate (e.g., glass) and the reflective surface 142
may comprise a reflective coating on the wall with an uncoated
portion for the exit aperture 124.
In embodiments including the reflective surface 142, the reflective
surface 142 can reduce size of the shared space 140 by folding the
receive path similarly to the mirror 126 in the transmit block 120.
Additionally or alternatively, in some examples, the reflective
surface 142 can direct the focused light 103 to the receive block
130 further providing flexibility to the placement of the receive
block 130 in the housing 110. For example, varying the tilt of the
reflective surface 142 can cause the focused light 108 to be
reflected to various portions of the interior space of the housing
110, and thus the receive block 130 can be placed in a
corresponding position in the housing 110. Additionally or
alternatively, in this example, the LIDAR device 100 can be
calibrated by varying the tilt of the reflective surface 142.
The lens 150 mounted to the housing 110 can have an optical power
to both collimate the emitted light beams 102 from the light
sources 122 in the transmit block 120, and focus the reflected
light 106 from the one or more objects in the environment of the
LIDAR device 100 onto the detectors 132 in the receive block 130.
In one example, the lens 150 has a focal length of approximately
120 mm. By using the same lens 150 to perform both of these
functions, instead of a transmit lens for collimating and a receive
lens for focusing, advantages with respect to size, cost, and/or
complexity can be provided. In some examples, collimating the
emitted light beams 102 to provide the collimated light beams 104
allows determining the distance travelled by the collimated light
beams 104 to the one or more objects in the environment of the
LIDAR device 100.
In an example scenario, the emitted light beams 102 from the light
sources 122 traversing along the transmit path can be collimated by
the lens 150 to provide the collimated light beams 104 to the
environment of the LIDAR device 100. The collimated light beams 104
may then reflect off the one or more objects in the environment of
the LIDAR device 100 and return to the lens 150 as the reflected
light 106. The lens 150 may then collect and focus the reflected
light 106 as the focused light 108 onto the detectors 132 included
in the receive block 130. In some examples, aspects of the one or
more objects in the environment of the LIDAR device 100 can be
determined by comparing the emitted light beams 102 with the
focused light beams 108. The aspects can include, for example,
distance, shape, color, and/or material of the one or more objects.
Additionally, in some examples, rotating the housing 110, a three
dimensional map of the surroundings of the LIDAR device 100 can be
determined.
In some examples where the plurality of light sources 122 are
arranged along the curved surface of the transmit block 120, the
lens 150 can be configured to have a focal surface corresponding to
the curved surface of the transmit block 120. For example, the lens
150 can include an aspheric surface outside the housing 110 and a
toroidal surface inside the housing 110 facing the shared space
140. In this example, the shape of the lens 150 allows the lens 150
to both collimate the emitted light beams 102 and focus the
reflected light 106. Additionally, in this example, the shape of
the lens 150 allows the lens 150 to have the focal surface
corresponding to the curved surface of the transmit block 120. In
some examples, the focal surface provided by the lens 150
substantially matches the curved shape of the transmit block 120.
Additionally, in some examples, the detectors 132 can be arranged
similarly in the curved shape of the receive block 130 to receive
the focused light 108 along the curved focal surface provided by
the lens 150. Thus, in some examples, the curved surface of the
receive block 130 may also substantially match the curved focal
surface provided by the lens 150.
FIG. 2 is a cross-section view of an example LIDAR device 200. In
this example, the LIDAR device 200 includes a housing 210 that
houses a transmit block 220, a receive block 230, a shared space
240, and a lens 250. For purposes of illustration, FIG. 2 shows an
x-y-z axis, in which the z-axis is in a substantially vertical
direction and the x-axis and y-axis define a substantially
horizontal plane.
The structure, function, and operation of various components
included in the LIDAR device 200 are similar to corresponding
components included in the LIDAR device 100 described in FIG. 1.
For example, the housing 210, the transmit block 220, the receive
block 230, the shared space 240, and the lens 250 are similar,
respectively, to the housing 110, the transmit block 120, the
receive block 130, and the shared space 140 described in FIG.
1.
The transmit block 220 includes a plurality of light sources 222a-c
arranged along a curved focal surface 228 defined by the lens 250.
The plurality of light sources 222a-c can be configured to emit,
respectively, the plurality of light beams 202a-c having
wavelengths within a wavelength range. For example, the plurality
of light sources 222a-c may comprise laser diodes that emit the
plurality of light beams 202a-c having the wavelengths within the
wavelength range. The plurality of light beams 202a-c are reflected
by mirror 224 through an exit aperture 226 into the shared space
240 and towards the lens 250. The structure, function, and
operation of the plurality of light sources 222a-c, the mirror 224,
and the exit aperture 226 can be similar, respectively, to the
plurality of light sources 122, the mirror 124, and the exit
aperture 226 discussed in the description of the LIDAR device 100
of FIG. 1.
Although FIG. 2 shows that the curved focal surface 228 is curved
in the x-y plane (horizontal plane), additionally or alternatively,
the plurality of light sources 222a-c may be arranged along a focal
surface that is curved in a vertical plane. For example, the curved
focal surface 228 can have a curvature in a vertical plane, and the
plurality of light sources 222a-c can include additional light
sources arranged vertically along the curved focal surface 228 and
configured to emit light beams directed at the mirror 224 and
reflected through the exit aperture 226.
Due to the arrangement of the plurality of light sources 222a-c
along the curved focal surface 228, the plurality of light beams
202a-c, in some examples, may converge towards the exit aperture
226. Thus, in these examples, the exit aperture 226 may be
minimally sized while being capable of accommodating vertical and
horizontal extents of the plurality of light beams 202a-c.
Additionally, in some examples, the curved focal surface 228 can be
defined by the lens 250. For example, the curved focal surface 228
may correspond to a focal surface of the lens 250 due to shape and
composition of the lens 250. In this example, the plurality of
light sources 222a-c can be arranged along the focal surface
defined by the lens 250 at the transmit block.
The plurality of light beams 202a-c propagate in a transmit path
that extends through the transmit block 220, the exit aperture 226,
and the shared space 240 towards the lens 250. The lens 250
collimates the plurality of light beams 202a-c to provide
collimated light beams 204a-c into an environment of the LIDAR
device 200. The collimated light beams 204a-c correspond,
respectively, to the plurality of light beams 202a-c. In some
examples, the collimated light beams 204a-c reflect off one or more
objects in the environment of the LIDAR device 200 as reflected
light 206. The reflected light 206 may be focused by the lens 250
into the shared space 240 as focused light 208 traveling along a
receive path that extends through the shared space 240 onto the
receive block 230. For example, the focused light 208 may be
reflected by the reflective surface 242 as focused light 208a-c
propagating towards the receive block 230.
The lens 250 may be capable of both collimating the plurality of
light beams 202a-c and focusing the reflected light 206 along the
receive path 208 towards the receive block 230 due to shape and
composition of the lens 250. For example, the lens 250 can have an
aspheric surface 252 facing outside of the housing 210 and a
toroidal surface 254 facing the shared space 240. By using the same
lens 250 to perform both of these functions, instead of a transmit
lens for collimating and a receive lens for focusing, advantages
with respect to size, cost, and/or complexity can be provided.
The exit aperture 226 is included in a wall 244 that separates the
transmit block 220 from the shared space 240. In some examples, the
wall 244 can be formed from a transparent material (e.g., glass)
that is coated with a reflective material 242. In this example, the
exit aperture 226 may correspond to the portion of the wall 244
that is not coated by the reflective material 242. Additionally or
alternatively, the exit aperture 226 may comprise a hole or
cut-away in the wall 244.
The focused light 208 is reflected by the reflective surface 242
and directed towards an entrance aperture 234 of the receive block
230. In some examples, the entrance aperture 234 may comprise a
filtering window configured to allow wavelengths in the wavelength
range of the plurality of light beams 202a-c emitted by the
plurality of light sources 222a-c and attenuate other wavelengths.
The focused light 208a-c reflected by the reflective surface 242
from the focused light 208 propagates, respectively, onto a
plurality of detectors 232a-c. The structure, function, and
operation of the entrance aperture 234 and the plurality of
detectors 232a-c is similar, respectively, to the entrance aperture
134 and the plurality of detectors 132 included in the LIDAR device
100 described in FIG. 1.
The plurality of detectors 232a-c can be arranged along a curved
focal surface 238 of the receive block 230. Although FIG. 2 shows
that the curved focal surface 238 is curved along the x-y plane
(horizontal plane), additionally or alternatively, the curved focal
surface 238 can be curved in a vertical plane. The curvature of the
focal surface 238 is also defined by the lens 250. For example, the
curved focal surface 238 may correspond to a focal surface of the
light projected by the lens 250 along the receive path at the
receive block 230.
Each of the focused light 208a-c corresponds, respectively, to the
emitted light beams 202a-c and is directed onto, respectively, the
plurality of detectors 232a-c. For example, the detector 232a is
configured and arranged to received focused light 208a that
corresponds to collimated light beam 204a reflected of the one or
more objects in the environment of the LIDAR device 200. In this
example, the collimated light beam 204a corresponds to the light
beam 202a emitted by the light source 222a. Thus, the detector 232a
receives light that was emitted by the light source 222a, the
detector 232b receives light that was emitted by the light source
222b, and the detector 232c receives light that was emitted by the
light source 222c.
By comparing the received light 208a-c with the emitted light beams
202a-c, at least one aspect of the one or more object in the
environment of the LIDAR device 200 may be determined. For example,
by comparing a time when the plurality of light beams 202a-c were
emitted by the plurality of light sources 222a-c and a time when
the plurality of detectors 232a-c received the focused light
208a-c, a distance between the LIDAR device 200 and the one or more
object in the environment of the LIDAR device 200 may be
determined. In some examples, other aspects such as shape, color,
material, etc. may also be determined.
In some examples, the LIDAR device 200 may be rotated about an axis
to determine a three-dimensional map of the surroundings of the
LIDAR device 200. For example, the LIDAR device 200 may be rotated
about a substantially vertical axis as illustrated by arrow 290.
Although illustrated that the LIDAR device 200 is rotated counter
clock-wise about the axis as illustrated by the arrow 290,
additionally or alternatively, the LIDAR device 200 may be rotated
in the clockwise direction. In some examples, the LIDAR device 200
may be rotated 360 degrees about the axis. In other examples, the
LIDAR device 200 may be rotated back and forth along a portion of
the 360 degree view of the LIDAR device 200. For example, the LIDAR
device 200 may be mounted on a platform that wobbles back and forth
about the axis without making a complete rotation.
FIG. 3A is a perspective view of an example LIDAR device 300 fitted
with various components, in accordance with at least some
embodiments described herein. FIG. 3B is a perspective view of the
example LIDAR device 300 shown in FIG. 3A with the various
components removed to illustrate interior space of the housing 310.
The structure, function, and operation of the LIDAR device 300 is
similar to the LIDAR devices 100 and 200 described, respectively,
in FIGS. 1 and 2. For example, the LIDAR device 300 includes a
housing 310 that houses a transmit block 320, a receive block 330,
and a lens 350 that are similar, respectively, to the housing 110,
the transmit block 120, the receive block 130, and the lens 150
described in FIG. 1. Additionally, collimated light beams 304
propagate from the lens 350 toward an environment of the LIDAR
device 300 and reflect of one or more objects in the environment as
reflected light 306, similarly to the collimated light beams 104
and reflected light 106 described in FIG. 1.
The LIDAR device 300 can be mounted on a mounting structure 360 and
rotated about an axis to provide a 360 degree view of the
environment surrounding the LIDAR device 300. In some examples, the
mounting structure 360 may comprise a movable platform that may
tilt in one or more directions to change the axis of rotation of
the LIDAR device 300.
As illustrated in FIG. 3B, the various components of the LIDAR
device 300 can be removably mounted to the housing 310. For
example, the transmit block 320 may comprise one or more printed
circuit boards (PCBs) that are fitted in the portion of the housing
310 where the transmit block 320 can be mounted. Additionally, the
receive block 330 may comprise a plurality of detectors 332 mounted
to a flexible substrate and can be removably mounted to the housing
310 as a block that includes the plurality of detectors. Similarly,
the lens 350 can be mounted to another side of the housing 310.
A plurality of light beams 302 can be transmitted by the transmit
block 320 into the shared space 340 and towards the lens 350 to be
collimated into the collimated light beams 304. Similarly, the
received light 306 can be focused by the lens 350 and directed
through the shared space 340 onto the receive block 330.
FIG. 4 illustrates an example transmit block 420, in accordance
with at least some embodiments described herein. Transmit block 420
can correspond to the transmit blocks 120, 220, and 320 described
in FIGS. 1-3. For example, the transmit block 420 includes a
plurality of light sources 422a-c similar to the plurality of light
sources 222a-c included in the transmit block 220 of FIG. 2.
Additionally, the light sources 422a-c are arranged along a focal
surface 428, which is curved in a vertical plane. The light sources
422a-c are configured to emit a plurality of light beams 402a-c
that converge and propagate through an exit aperture 426 in a wall
444.
Although the plurality of light sources 422a-c can be arranged
along a focal surface 428 that is curved in a vertical plane,
additionally or alternatively, the plurality of light sources
422a-c can be arranged along a focal surface that is curved in a
horizontal plane or a focal surface that is curved both vertically
and horizontally. For example, the plurality of light sources
422a-c can be arranged in a curved three dimensional grid pattern.
For example, the transmit block 420 may comprise a plurality of
printed circuit board (PCB) vertically mounted such that a column
of light sources such as the plurality of light sources 422a-c are
along the vertical axis of each PCB and each of the plurality of
PCBs can be arranged adjacent to other vertically mounted PCBs
along a horizontally curved plane to provide the three dimensional
grid pattern.
As shown in FIG. 4, the light beams 402a-c converge towards the
exit aperture 426 which allows the size of the exit aperture 426 to
be minimized while accommodating vertical and horizontal extents of
the light beams 402a-c similarly to the exit aperture 226 described
in FIG. 2.
As noted above in the description of FIG. 1, the light from light
sources 122 could be partially collimated to fit through the exit
aperture 124. FIGS. 5A, 5B, and 5C illustrate an example of how
such partial collimation could be achieved. In this example, a
light source 500 is made up of a laser diode 502 and a cylindrical
lens 504. As shown in FIG. 5A, laser diode 502 has an aperture 506
with a shorter dimension corresponding to a fast axis 508 and a
longer dimension corresponding to a slow axis 510. FIGS. 5B and 5C
show an uncollimated laser beam 512 being emitted from laser diode
502. Laser beam 512 diverges in two directions, one direction
defined by fast axis 508 and another, generally orthogonal
direction defined by slow axis 510. FIG. 5B shows the divergence of
laser beam 512 along fast axis 508, whereas FIG. 5C shows the
divergence of laser beam 512 along slow axis 510. Laser beam 512
diverges more quickly along fast axis 508 than along slow axis
510.
In one specific example, laser diode 502 is an Osram SPL DL90_3
nanostack pulsed laser diode that emits pulses of light with a
range of wavelengths from about 896 nm to about 910 nm (a nominal
wavelength of 905 nm). In this specific example, the aperture has a
shorter dimension of about 10 microns, corresponding to its fast
axis, and a longer dimension of about 200 microns, corresponding to
its slow axis. The divergence of the laser beam in this specific
example is about 25 degrees along the fast axis and about 11
degrees along the slow axis. It is to be understood that this
specific example is illustrative only. Laser diode 502 could have a
different configuration, different aperture sizes, different beam
divergences, and/or emit different wavelengths.
As shown in FIGS. 5B and 5C, cylindrical lens 504 may be positioned
in front of aperture 506 with its cylinder axis 514 generally
parallel to slow axis 510 and perpendicular to fast axis 508. In
this arrangement, cylindrical lens 504 can pre-collimate laser beam
512 along fast axis 508, resulting in partially collimated laser
beam 516. In some examples, this pre-collimation may reduce the
divergence along fast axis 508 to about one degree or less.
Nonetheless, laser beam 516 is only partially collimated because
the divergence along slow axis 510 may be largely unchanged by
cylindrical lens 504. Thus, whereas uncollimated laser beam 512
emitted by laser diode has a higher divergence along fast axis 508
than along slow axis 510, partially collimated laser beam 516
provided by cylindrical lens 504 may have a higher divergence along
slow axis 510 than along fast axis 508. Further, the divergences
along slow axis 510 in uncollimated laser beam 512 and in partially
collimated laser beam 516 may be substantially equal.
In one example, cylindrical lens 504 is a microrod lens with a
diameter of about 600 microns that is placed about 250 microns in
front of aperture 506. The material of the microrod lens could be,
for example, fused silica or a borosilicate crown glass, such as
Schott BK7. Alternatively, the microrod lens could be a molded
plastic cylinder or acylinder. Cylindrical lens 504 could also be
used to provide magnification along fast axis 508. For example, if
the dimensions of aperture 506 are 10 microns by 200 microns, as
previously described, and cylindrical lens 504 is a microrod lens
as described above, then cylindrical lens 504 may magnify the
shorter dimension (corresponding to fast axis 508) by about 20
times. This magnification effectively stretches out the shorter
dimension of aperture 506 to about the same as the longer
dimension. As a result, when light from laser beam 516 is focused,
for example, focused onto a detector, the focused spot could have a
substantially square shape instead of the rectangular slit shape of
aperture 506.
FIG. 6A illustrates an example receive block 630, in accordance
with at least some embodiments described herein. FIG. 6B
illustrates a side view of three detectors 632a-c included in the
receive block 630 of FIG. 6A. Receive block 630 can correspond to
the receive blocks 130, 230, and 330 described in FIGS. 1-3. For
example, the receive block 630 includes a plurality of detectors
632a-c arranged along a curved surface 638 defined by a lens 650
similarly to the receive block 230, the detectors 232 and the
curved plane 238 described in FIG. 2. Focused light 608a-c from
lens 650 propagates along a receive path that includes a reflective
surface 642 onto the detectors 632a-c similar, respectively, to the
focused light 208a-c, the lens 250, the reflective surface 242, and
the detectors 232a-c described in FIG. 2.
The receive block 630 comprises a flexible substrate 680 on which
the plurality of detectors 632a-c are arranged along the curved
surface 638. The flexible substrate 680 conforms to the curved
surface 638 by being mounted to a receive block housing 690 having
the curved surface 638. As illustrated in FIG. 6, the curved
surface 638 includes the arrangement of the detectors 632a-c curved
along a vertical and horizontal axis of the receive block 630.
FIGS. 7A and 7B illustrate an example lens 750 with an aspheric
surface 752 and a toroidal surface 754, in accordance with at least
some embodiments described herein. FIG. 7B illustrates a
cross-section view of the example lens 750 shown in FIG. 7A. The
lens 750 can correspond to lens 150, 250, and 350 included in FIGS.
1-3. For example, the lens 750 can be configured to both collimate
light incident on the toroidal surface 754 from a light source into
collimated light propagating out of the aspheric surface 752, and
focus reflected light entering from the aspheric surface 752 onto a
detector. The structure of the lens 750 including the aspheric
surface 752 and the toroidal surface 754 allows the lens 750 to
perform both functions of collimating and focusing described in the
example above.
In some examples, the lens 750 defines a focal surface of the light
propagating through the lens 750 due to the aspheric surface 752
and the toroidal surface 754. In these examples, the light sources
providing the light entering the toroidal surface 754 can be
arranged along the defined focal surface, and the detectors
receiving the light focused from the light entering the aspheric
surface 752 can also be arranged along the defined focal
surface.
By using the lens 750 that performs both of these functions
(collimating transmitted light and focusing received light),
instead of a transmit lens for collimating and a receive lens for
focusing, advantages with respect to size, cost, and/or complexity
can be provided.
FIG. 8A illustrates an example LIDAR device 810 mounted on a
vehicle 800, in accordance with at least some embodiments described
herein. FIG. 8A shows a Right Side View, Front View, Back View, and
Top View of the vehicle 800. Although vehicle 800 is illustrated in
FIG. 8 as a car, other examples are possible. For instance, the
vehicle 800 could represent a truck, a van, a semi-trailer truck, a
motorcycle, a golf cart, an off-road vehicle, or a farm vehicle,
among other examples.
The structure, function, and operation of the LIDAR device 810
shown in FIG. 8A is similar to the example LIDAR devices 100, 200,
and 300 shown in FIGS. 1-3. For example, the LIDAR device 810 can
be configured to rotate about an axis and determine a
three-dimensional map of a surrounding environment of the LIDAR
device 810. To facilitate the rotation, the LIDAR device 810 can be
mounted on a platform 802. In some examples, the platform 802 may
comprise a movable mount that allows the vehicle 800 to control the
axis of rotation of the LIDAR device 810.
While the LIDAR device 810 is shown to be mounted in a particular
location on the vehicle 800, in some examples, the LIDAR device 810
may be mounted elsewhere on the vehicle 800. For example, the LIDAR
device 810 may be mounted anywhere on top of the vehicle 800, on a
side of the vehicle 800, under the vehicle 800, on a hood of the
vehicle 800, and/or on a trunk of the vehicle 800.
The LIDAR device 810 includes a lens 812 through which collimated
light is transmitted from the LIDAR device 810 to the surrounding
environment of the LIDAR device 810, similarly to the lens 150,
250, and 350 described in FIGS. 1-3. Similarly, the lens 812 can
also be configured to receive reflected light from the surrounding
environment of the LIDAR device 810 that were reflected off one or
more objects in the surrounding environment.
FIG. 8B illustrates a scenario where the LIDAR device 810 shown in
FIG. 8A and scanning an environment 830 that includes one or more
objects, in accordance with at least some embodiments described
herein. In this example scenario, vehicle 800 can be traveling on a
road 822 in the environment 830. By rotating the LIDAR device 810
about the axis defined by the platform 802, the LIDAR device 810
may be able to determine aspects of objects in the surrounding
environment 830, such as lane lines 824a-b, other vehicles 826a-c,
and/or street sign 828. Thus, the LIDAR device 810 can provide the
vehicle 800 with information about the objects in the surrounding
environment 830, including distance, shape, color, and/or material
type of the objects.
FIG. 9 is a flowchart of a method 900 of operating a LIDAR device,
in accordance with at least some embodiments described herein.
Method 900 shown in FIG. 9 presents an embodiment of a method that
could be used with the LIDAR devices 100, 200, and 300, for
example. Method 900 may include one or more operations, functions,
or actions as illustrated by one or more of blocks 902-912.
Although the blocks are illustrated in a sequential order, these
blocks may in some instances be performed in parallel, and/or in a
different order than those described herein. Also, the various
blocks may be combined into fewer blocks, divided into additional
blocks, and/or removed based upon the desired implementation.
In addition, for the method 900 and other processes and methods
disclosed herein, the flowchart shows functionality and operation
of one possible implementation of present embodiments. In this
regard, each block may represent a module, a segment, or a portion
of a manufacturing or operation process.
At block 902, the method 900 includes rotating a housing of a light
detection and ranging (LIDAR) device about an axis, wherein the
housing has an interior space that includes a transmit block, a
receive block, and a shared space, wherein the transmit block has
an exit aperture, and wherein the receive block has an entrance
aperture.
At block 904, the method 900 includes emitting, by a plurality of
light sources in the transmit block, a plurality of light beams
that enter the shared space via a transmit path, the light beams
comprising light having wavelengths in a wavelength range.
At block 906, the method 900 includes receiving the light beams at
a lens mounted to the housing along the transmit path.
At block 908, the method 900 includes collimating, by the lens, the
light beams for transmission into an environment of the LIDAR
device.
At block 910, the method 900 includes focusing, by the lens, the
collected light onto a plurality of detectors in the receive block
via a receive path that extends through the shared space and the
entrance aperture of the receive block.
At block 912, the method 900 includes detecting, by the plurality
of detectors in the receive block, light from the focused light
having wavelengths in the wavelength range.
For example, a LIDAR device such as the LIDAR device 200 can be
rotated about an axis (block 902). A transmit block, such as the
transmit block 220, can include a plurality of light sources that
emit light beams having wavelengths in a wavelength range, through
an exit aperture and a shared space to a lens (block 904). The
light beams can be received by the lens (block 906) and collimated
for transmission to an environment of the LIDAR device (block 908).
The collimated light may then reflect off one or more objects in
the environment of the LIDAR device and return as reflected light
collected by the lens. The lens may then focus the collected light
onto a plurality of detectors in the receive block via a receive
path that extends through the shared space and an entrance aperture
of the receive block (block 910). The plurality of detectors in the
receive block may then detect light from the focused light having
wavelengths in the wavelength range of the emitted light beams from
the light sources (block 912).
Within examples, devices and operation methods described include a
LIDAR device rotated about an axis and configured to transmit
collimated light and focus reflected light. The collimation and
focusing can be performed by a shared lens. By using a shared lens
that performs both of these functions, instead of a transmit lens
for collimating and a receive lens for focusing, advantages with
respect to size, cost, and/or complexity can be provided.
Additionally, in some examples, the shared lens can define a curved
focal surface. In these examples, the light sources emitting light
through the shared lens and the detectors receiving light focused
by the shared lens can be arranged along the curved focal surface
defined by the shared lens.
It should be understood that arrangements described herein are for
purposes of example only. As such, those skilled in the art will
appreciate that other arrangements and other elements (e.g.
machines, interfaces, functions, orders, and groupings of
functions, etc.) can be used instead, and some elements may be
omitted altogether according to the desired results. Further, many
of the elements that are described are functional entities that may
be implemented as discrete or distributed components or in
conjunction with other components, in any suitable combination and
location, or other structural elements described as independent
structures may be combined.
While various aspects and embodiments have been disclosed herein,
other aspects and embodiments will be apparent to those skilled in
the art. The various aspects and embodiments disclosed herein are
for purposes of illustration and are not intended to be limiting,
with the true scope being indicated by the following claims, along
with the full scope of equivalents to which such claims are
entitled. It is also to be understood that the terminology used
herein is for the purpose of describing particular embodiments
only, and is not intended to be limiting.
* * * * *
References