U.S. patent application number 15/939256 was filed with the patent office on 2018-08-02 for three dimensional imaging utilizing stacked imager devices and associated methods.
The applicant listed for this patent is SiOnyx, LLC. Invention is credited to Chen Feng, Leonard Forbes, Homayoon Haddad.
Application Number | 20180216928 15/939256 |
Document ID | / |
Family ID | 51580881 |
Filed Date | 2018-08-02 |
United States Patent
Application |
20180216928 |
Kind Code |
A1 |
Haddad; Homayoon ; et
al. |
August 2, 2018 |
THREE DIMENSIONAL IMAGING UTILIZING STACKED IMAGER DEVICES AND
ASSOCIATED METHODS
Abstract
Stacked imager devices that can determine distance and generate
three dimensional representations of a subject and associated
methods are provided. In one aspect, an imaging system can include
a first imager array having a first light incident surface and a
second imager array having a second light incident surface. The
second imager array can be coupled to the first imager array at a
surface that is opposite the first light incident surface, with the
second light incident surface being oriented toward the first
imager array and at least substantially uniformly spaced. The
system can also include a system lens positioned to direct incident
light along an optical pathway onto the first light incident
surface. The first imager array is operable to detect a first
portion of the light passing along the optical pathway and to pass
through a second portion of the light, where the second imager
array is operable to detect at least a part of the second portion
of light.
Inventors: |
Haddad; Homayoon;
(Beaverton, OR) ; Feng; Chen; (Snohomish, WA)
; Forbes; Leonard; (Corvallis, OR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SiOnyx, LLC |
Beverly |
MA |
US |
|
|
Family ID: |
51580881 |
Appl. No.: |
15/939256 |
Filed: |
March 28, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
14206890 |
Mar 12, 2014 |
9939251 |
|
|
15939256 |
|
|
|
|
61798805 |
Mar 15, 2013 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G06T 7/571 20170101;
G06T 2207/10148 20130101; G06T 7/557 20170101; G01B 11/026
20130101; H04N 13/271 20180501; H04N 13/236 20180501 |
International
Class: |
G01B 11/02 20060101
G01B011/02; G06T 7/571 20060101 G06T007/571; G06T 7/557 20060101
G06T007/557 |
Claims
1-24. (canceled)
25. An imaging system capable of deriving three dimensional
information from a three dimensional subject, comprising: an active
illumination source capable of emitting pulsed infrared light; a
first imager capable of detecting visible and infrared light; a
second imager capable of detecting infrared light, wherein the
active illumination source, first imager, and the second imager are
pulsed at a frequency and duty cycle such that the pulsed infrared
light is detected by the first imager and the second imager when
the active illumination is on.
26. The imaging system of claim 25, wherein the first imager is
operable to detect visible light when the active illumination
source is in an off state.
Description
PRIORITY DATA
[0001] This application claims the benefit of priority as a
continuation application to U.S. patent application Ser. No.
14/206,890, filed on Mar. 12, 2014, which claims the benefit of
U.S. Provisional Patent Application Ser. No. 61/798,805, filed on
Mar. 15, 2013, each of which is incorporated herein by reference in
their entireties.
BACKGROUND
[0002] Active pixel sensors (APS) are image sensors including
integrated circuit containing an array of pixel sensors, each pixel
containing a photodetector and an active amplifier. Such an image
sensor is typically produced by a complementary
metal-oxide-semiconductor (CMOS) process. CMOS APS can be used in
web cams, high speed and motion capture cameras, digital
radiography, endoscopy cameras, DSLRs, cell phone cameras, and the
like. Other advances in image sensor technology have been
implemented, such as the use of an intra-pixel charge transfer
along with an in-pixel amplifier to achieve true correlated double
sampling (CDS) and low temporal noise operation, and on-chip
circuits for fixed-pattern noise reduction.
[0003] Some CMOS APS imagers have utilized backside illuminated
(BSI) technology. BSI imager technology includes a semiconductor
wafer bonded to a permanent carrier on the front side and then
thinned from the backside. Passivation layers, anti-reflecting
layers, color filters and micro-lens can be positioned on the
backside, and the resulting device can be backside illuminated.
Through-Silicon Vias (TSV) can be used to provide electrical
connections from the front side to backside output pads. BSI CMOS
APS imagers are becoming useful technology for many types of
visible imagers in cell phones and digital cameras.
[0004] More generally, electromagnetic radiation can be present
across a broad wavelength range, including visible range
wavelengths (approximately 350 nm to 800 nm) and non-visible
wavelengths (longer than about 800 nm or shorter than 350 nm). The
infrared spectrum is often described as including a near infrared
portion of the spectrum including wavelengths of approximately 800
to 1300 nm, a short wave infrared portion of the spectrum including
wavelengths of approximately 1300 nm to 3 micrometers, and a mid to
long range wave infrared (or thermal infrared) portion of the
spectrum including wavelengths greater than about 3 micrometers up
to about 20 micrometers. These are generally and collectively
referred to herein as infrared portions of the electromagnetic
spectrum unless otherwise noted.
[0005] Traditional silicon photodetecting imagers have limited
light absorption/detection properties. For example, such silicon
based detectors are mostly transparent to infrared light. While
other mostly opaque materials (e.g. InGaAs) can be used to detect
infrared electromagnetic radiation having wavelengths greater that
about 1000 nm, silicon is still commonly used because it is
relatively cheap to manufacture and can be used to detect
wavelengths in the visible spectrum (i.e. visible light, 350 nm-800
nm). Traditional silicon materials require substantial path lengths
and absorption depths to detect photons having wavelengths longer
than approximately 700 nm. While visible light can be absorbed at
relatively shallow depths in silicon, absorption of longer
wavelengths (e.g. 900 nm) in silicon of a standard wafer depth
(e.g. approximately 750 .mu.m) is poor if at all.
SUMMARY
[0006] The present disclosure provides various systems and devices
having a unique architecture that can determine distance and
generate three dimensional representations of a subject, including
associated methods thereof. In one aspect, for example, an imaging
system capable of deriving three dimensional information from a
three dimensional subject is provided. Such a system can include a
first imager array having a first light incident surface and a
second imager array having a second light incident surface. The
second imager array can be coupled to the first imager array at a
surface that is opposite the first light incident surface, with the
second light incident surface being oriented toward the first
imager array and at least substantially uniformly spaced at a
distance of from about 2 microns to about 150 microns from the
first light incident surface. The system can also include a system
lens positioned to direct incident light along an optical pathway
onto the first light incident surface of the first imager. The
first imager array is operable to detect a first portion of the
light passing along the optical pathway and to pass through a
second portion of the light, where the second imager array is
operable to detect at least a part of the second portion of light.
In one aspect, the first imager and the second imager are detecting
and comparing light having substantially the same wavelength in
order to calculate distance to a subject or to generate a three
dimensional representation of the subject. Regarding the
frequencies of light that can be utilized by the present imager
arrays, the first portion of light and the second portion of light
can have at least one wavelength of from about 500 nm to about 1100
nm. In another aspect, the first portion of light and the second
portion of light can have at least one wavelength of from about 750
nm to about 1100 nm. Additionally, in some aspects such a system
can further include an active light emitter configured to emit
active light radiation at least substantially toward the three
dimensional subject, where the active light radiation has a center
wavelength of from about 750 nm to about 1100 nm. In another
aspect, the active light radiation has a center frequency of 850
nm, 940 nm, or 1064 nm.
[0007] In another aspect, the system can also include a computation
module operable to calculate distance data from the imaging system
to the three dimensional subject using first image data collected
by the first imager array from the first portion of light and
second image data collected by the second imager array from the
second portion of light. In another aspect, the computation module
is operable to generate a three dimensional representation of the
three dimensional subject from the distance data. Furthermore, in
some aspects the imaging system can be incorporated into a
computing system operable to alter computation based on variations
in distance data derived from movements of a subject.
[0008] Additionally, a variety of system configurations are
contemplated, which are considered to be non-limiting. In one
aspect, the first imager array includes a plurality of pixels
architecturally configured as front-side illuminated (FSI) pixels.
In another aspect, the second imager array includes a plurality of
pixels architecturally configured as FSI pixels or backside
illuminated (BSI) pixels.
[0009] Furthermore, various structures can be utilized to redirect
or otherwise reflect light that passes through the system back into
the system. In one aspect, a textured region can be coupled to the
second imager array on a side opposite the first imager array, such
that the textured region is positioned to redirect light passing
through the second imager array back into the second imager array.
In another aspect, the system can include a reflector coupled to
the second imager array on a side opposite the first imager array,
such that the reflector is positioned to reflect light passing
through the second imager array back into the second imager
array.
[0010] The present disclosure additionally provides a method of
determining distance to a subject. Such a method can include
focusing incident light along an optical pathway onto a first light
incident surface of a first imaging array, wherein the first
imaging array captures a first portion of the light having at least
one wavelength of from about 500 nm to about 1100 nm to generate a
first data set and passes through a second portion of the light
along the optical pathway. The method can also include receiving
the second portion of the light onto a second light incident
surface of a second imaging array, wherein the second imaging array
captures the second portion of the light having at least one
wavelength of from about 500 nm to about 1100 nm to generate a
second data set. In another aspect, the first portion of the light
has at least one wavelength of from about 750 nm to about 1100 nm
and the second portion of the light has at least one wavelength of
from about 750 nm to about 1100 nm. Additionally, the distance to
the subject can then be derived from variations between the first
data set and the second data set. In some aspects, at least part of
the second portion of light that passes through the second imaging
array can be redirected back into the second imaging array.
[0011] The distance between the first imaging array and the second
imaging array can vary depending on the wavelengths of light being
utilized and the distances to which three dimensional detection is
desired. In one aspect, however, the distance between the first
light incident surface and the second light incident surface is
from about 2 microns to about 150 microns.
[0012] In some aspects the method can further include emitting
active light radiation toward the subject such that at least a
portion of the incident light focused along the optical pathway
includes the active light radiation. In one aspect, the active
light radiation can be IR light radiation. In another aspect, the
active light radiation can have a center frequency selected from
850 nm, 940 nm, and 1064 nm.
[0013] In yet another aspect the method can further include
generating a three dimensional representation of the subject. In
one specific aspect, generating the three dimensional
representation can include determining a plurality of distances
from the first light incident surface to a surface of the subject
at a plurality of locations across the surface of the subject, and
using the distances to generate the three dimensional
representation.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] For a fuller understanding of the nature and advantage of
the present disclosure, reference is being made to the following
detailed description of various embodiments and in connection with
the accompanying drawings, in which:
[0015] FIG. 1 shows a cross sectional view of a stacked imager in
accordance with an aspect of the present disclosure.
[0016] FIG. 2 shows a schematic diagram of the effects of changing
distance to a subject on a stacked imager system in accordance with
another aspect of the present disclosure.
[0017] FIG. 3A shows a schematic diagram of the effects of changing
distance to a subject on a stacked imager system in accordance with
another aspect of the present disclosure.
[0018] FIG. 3B shows a schematic diagram of the effects of changing
distance to a subject on a stacked imager system in accordance with
another aspect of the present disclosure.
[0019] FIG. 3C shows a schematic diagram of the effects of changing
distance to a subject on a stacked imager system in accordance with
another aspect of the present disclosure.
[0020] FIG. 4 shows a cross sectional view of a stacked imager
system in accordance with an aspect of the present disclosure.
[0021] FIG. 5 shows a cross sectional view of a stacked imager
system in accordance with an aspect of the present disclosure.
[0022] FIG. 6A shows a cross sectional view of various steps in the
manufacture of a stacked imager in accordance with another aspect
of the present disclosure.
[0023] FIG. 6B shows a cross sectional view of various steps in the
manufacture of a stacked imager in accordance with another aspect
of the present disclosure.
[0024] FIG. 6C shows a cross sectional view of various steps in the
manufacture of a stacked imager in accordance with another aspect
of the present disclosure.
[0025] FIG. 6D shows a cross sectional view of various steps in the
manufacture of a stacked imager in accordance with another aspect
of the present disclosure.
[0026] FIG. 6E shows a cross sectional view of various steps in the
manufacture of a stacked imager in accordance with another aspect
of the present disclosure.
[0027] FIG. 7A shows a cross sectional view of various steps in the
manufacture of a stacked imager in accordance with another aspect
of the present disclosure.
[0028] FIG. 7B shows a cross sectional view of various steps in the
manufacture of a stacked imager in accordance with another aspect
of the present disclosure.
[0029] FIG. 7C shows a cross sectional view of various steps in the
manufacture of a stacked imager in accordance with another aspect
of the present disclosure.
[0030] FIG. 7D shows a cross sectional view of various steps in the
manufacture of a stacked imager in accordance with another aspect
of the present disclosure.
[0031] FIG. 7E shows a cross sectional view of various steps in the
manufacture of a stacked imager in accordance with another aspect
of the present disclosure.
DETAILED DESCRIPTION
[0032] Before the present disclosure is described herein, it is to
be understood that this disclosure is not limited to the particular
structures, process steps, or materials disclosed herein, but is
extended to equivalents thereof as would be recognized by those
ordinarily skilled in the relevant arts. It should also be
understood that terminology employed herein is used for the purpose
of describing particular embodiments only and is not intended to be
limiting.
[0033] Definitions
[0034] The following terminology will be used in accordance with
the definitions set forth below.
[0035] It should be noted that, as used in this specification and
the appended claims, the singular forms "a," and, "the" include
plural referents unless the context clearly dictates otherwise.
Thus, for example, reference to "a dopant" includes one or more of
such dopants and reference to "the layer" includes reference to one
or more of such layers.
[0036] As used herein, the terms "textured region" and "textured
surface" can be used interchangeably, and refer to a surface having
a topology with nano- to micron-sized surface variations formed by
a texturing technique, a few examples of which are discussed
herein. While the characteristics of such a surface can be variable
depending on the materials and techniques employed, in one aspect
such a surface can be several hundred nanometers thick and made up
of nanocrystallites (e.g. from about 10 to about 50 nanometers) and
nanopores. In another aspect, such a surface can include
micron-sized structures (e.g. about 2 .mu.m to about 10 .mu.m). In
yet another aspect, the surface can include nano-sized and/or
micron-sized structures from about 5 nm and about 10 .mu.m. In yet
another aspect the surface features can be from about 100 nm to
about 1 .mu.m.
[0037] As used herein, the terms "surface modifying" and "surface
modification" refer to the altering of a surface of a semiconductor
material to form a textured surface using a variety of surface
modification techniques. Non-limiting examples of such techniques
include plasma etching, reactive ion etching, porous silicon
etching, lasing, chemical etching (e.g. anisotropic etching,
isotropic etching), nanoimprinting, material deposition, selective
epitaxial growth, shallow trench isolation techniques, and the
like, including combinations thereof.
[0038] As used herein, the term "subject" refers to any object,
living or non-living, that has a three dimensional structure or
that can be imaged to determine distance. Non-limiting examples can
include humans, animals, vehicles, buildings and building
structures such as doors, windows, and the like, plants, animal
enclosures, geological structures, and the like.
[0039] As used herein, the term "backside illumination" (BSI)
refers to a device architecture design whereby electromagnetic
radiation is incident on a surface of a semiconductor material that
is opposite a surface containing the device circuitry. In other
words, electromagnetic radiation is incident upon and passes
through a semiconductor material prior to contacting the device
circuitry.
[0040] As used herein, the term "front side illumination" (FSI)
refers to a device architecture design whereby electromagnetic
radiation is incident on a surface of a semiconductor material
containing the device circuitry. In some cases a lens can be used
to focus incident light onto an active absorbing region of the
device while reducing the amount of light that impinges the device
circuitry.
[0041] As used herein, the term "light incident surface" refers to
a surface of an active semiconductor layer in an imager that is
first struck by light entering the imager. As such, other materials
that make up an imager or a device containing an imager that are
positioned between the incoming light and the active layer should
not be considered to be light incident surfaces unless the context
clearly indicates otherwise. In the case of multiple imagers
stacked upon one another, each imager will have a light incident
surface. Distances described herein between light incident surfaces
of stacked imagers, for example, represent the distances between
the active layer surfaces of each imager that is first struck by
incident light on an initial pass through each imager.
[0042] In this application, "comprises," "comprising," "containing"
and "having" and the like can have the meaning ascribed to them in
U.S. Patent law and can mean "includes," "including," and the like,
and are generally interpreted to be open ended terms. The terms
"consisting of" or "consists of" are closed terms, and include only
the components, structures, steps, or the like specifically listed
in conjunction with such terms, as well as that which is in
accordance with U.S. Patent law. "Consisting essentially of" or
"consists essentially of" have the meaning generally ascribed to
them by U.S. Patent law. In particular, such terms are generally
closed terms, with the exception of allowing inclusion of
additional items, materials, components, steps, or elements, that
do not materially affect the basic and novel characteristics or
function of the item(s) used in connection therewith. For example,
trace elements present in a composition, but not affecting the
composition's nature or characteristics would be permissible if
present under the "consisting essentially of" language, even though
not expressly recited in a list of items following such
terminology. When using an open ended term, like "comprising" or
"including," it is understood that direct support should be
afforded also to "consisting essentially of" language as well as
"consisting of" language as if stated explicitly, and vice versa.
Further, it is to be understood that the listing of components,
species, or the like in a group is done for the sake of convenience
and that such groups should be interpreted not only in their
entirety, but also as though each individual member of the group
has been articulated separately and individually without the other
members of the group unless the context dictates otherwise. This is
true of groups contained both in the specification and claims of
this application. Additionally, no individual member of a group
should be construed as a de facto equivalent of any other member of
the same group solely based on their presentation in a common group
without indications to the contrary.
[0043] As used herein, the term "substantially" refers to the
complete or nearly complete extent or degree of an action,
characteristic, property, state, structure, item, or result. For
example, an object that is "substantially" enclosed would mean that
the object is either completely enclosed or nearly completely
enclosed. The exact allowable degree of deviation from absolute
completeness may in some cases depend on the specific context.
However, generally speaking the nearness of completion will be so
as to have the same overall result as if absolute and total
completion were obtained. The use of "substantially" is equally
applicable when used in a negative connotation to refer to the
complete or near complete lack of an action, characteristic,
property, state, structure, item, or result. For example, a
composition that is "substantially free of" particles would either
completely lack particles, or so nearly completely lack particles
that the effect would be the same as if it completely lacked
particles. In other words, a composition that is "substantially
free of" an ingredient or element may still actually contain such
item as long as there is no measurable effect thereof.
[0044] As used herein, the term "about" is used to provide
flexibility to a numerical range endpoint by providing that a given
value may be "a little above" or "a little below" the endpoint.
[0045] As used herein, a plurality of items, structural elements,
compositional elements, and/or materials may be presented in a
common list for convenience. However, these lists should be
construed as though each member of the list is individually
identified as a separate and unique member. Thus, no individual
member of such list should be construed as a de facto equivalent of
any other member of the same list solely based on their
presentation in a common group without indications to the
contrary.
[0046] Concentrations, amounts, and other numerical data may be
expressed or presented herein in a range format. It is to be
understood that such a range format is used merely for convenience
and brevity and thus should be interpreted flexibly to include not
only the numerical values explicitly recited as the limits of the
range, but also to include all the individual numerical values or
sub-ranges encompassed within that range as if each numerical value
and sub-range is explicitly recited. As an illustration, a
numerical range of "about 1 to about 5" should be interpreted to
include not only the explicitly recited values of about 1 to about
5, but also include individual values and sub-ranges within the
indicated range. Thus, included in this numerical range are
individual values such as 2, 3, and 4 and sub-ranges such as from
1-3, from 2-4, and from 3-5, etc., as well as 1, 2, 3, 4, and 5,
individually.
[0047] This same principle applies to ranges reciting only one
numerical value as a minimum or a maximum. Furthermore, such an
interpretation should apply regardless of the breadth of the range
or the characteristics being described.
[0048] The Disclosure
[0049] The present disclosure provides devices, systems, and
methods for obtaining 3D information from an object. For example,
in one aspect two imager arrays can be positioned in a stacked
configurations along an optical axis, such that light passes
through the first imager sensor having an array of pixels before
contacting the second imager sensor having an array of pixels. Such
an arrangement is shown schematically in FIG. 1. A first imager
array 102 is positioned in a stacked configuration with a second
imager array 104. The first imager array 102 captures a first
portion of the incident light 106, while the second imager array
104 captures a second portion of the incident light 108 that passes
through the first imaging array. It is noted that, while the
portions of light are shown as distinct lines in FIG. 1 for
clarity, these lines are intended to represent the portion of the
overall incident light that is absorbed by each imager array. Thus,
light from an object that is being imaged is captured on both
imager arrays and will create different image patterns on each
imager array that is a function of the distance from each imager
array to the object. Differences in these image patterns can thus
be utilized to obtain distance and/or 3D information about the
object. In some cases a "light field" can be computed giving, for
example, the light wavelength, intensity, and direction of light
rays passing through the imager. Computations can then performed,
in some cases in real time, by an on-chip processing unit or in a
system processing unit to provide a variety of data, including
visible image, IR image, range or distance to the object, 3D
information, and the like. The object distance information
collected can also be used to create a three dimensional image of
the object.
[0050] FIG. 2 shows a side view schematic diagram of such three
dimensional imaging at different distances, represented by rows
1-5. The imaging device can include a first imager array 202, a
second imager array 204, and a system lens 206 for focusing
incident light 208 onto the first and second imager arrays. A
subject 210 is shown at a given distance for each of rows 1-5 from
the imaging arrays. The boxes shown to the right of the imager
arrays represent the imaging surface of each of the arrays, with
the imaging surface for the first imaging array 202 being on the
left and the imaging surface for the second imaging array 204 being
on the right. The circle shown in each of the imaging surfaces
represents the image patterns formed on each imaging surface of the
subject 208 for a given distance. As is shown in FIG. 2, as the
subject moves closer to the imager arrays, the dimensions of the
image patterns on the imaging surfaces change as a function of the
distance to each imager array. As such, the differences between the
image patterns for a given distance can be utilized to calculate
the distance to the subject. As the image pattern differences
change, the change in distance to the subject can be repeatedly
calculated. Furthermore, three dimensional representations can be
obtained of subjects, including for subjects with complex surface
contours or structures. In such cases, the three dimensional nature
of a subject is reflected in the image pattern created on each of
the imager arrays. The differences between image patterns from each
array can be utilized to create a three dimensional representation.
Such a representation can include three dimensional measurements of
the subject, as well as three dimensional images.
[0051] These concepts are further illustrated in FIGS. 3A-C where
incident light 302 is shown passing through a first imager array
304 and a second imager array 306. The incident light 302 contacts
the first imager array 304 with a first image pattern 308 that is
related, at least in part, to the distance to the subject and the
characteristics and distance of the system lens (not shown) from
the first imager array 302. Due to the greater distance of the
subject and the system lens from the second imager array 306, the
second image pattern 310 is different from the first image pattern
308. For example, the patterns will often differ in size between
the two arrays, and the pixels that detect the pattern will be
different between the two imager arrays. It is noted, however, that
in some limited situations the patterns on both imager arrays will
be the same size. As the subject moves closer to the imager arrays
(FIGS. 3B and 3C), the first and second image patterns
concomitantly vary.
[0052] The following are exemplary descriptions of techniques that
can be utilized to perform such stacked imager array calculations.
It should be understood that these techniques are non-limiting, and
that the scope of the present disclosure includes any technique for
performing such calculations. Accordingly, the distance to a
subject can be calculated based on the image feature difference
between the first image pattern and the second image pattern of the
stacked imager array, with known imager stack structure and system
lens data.
[0053] In one aspect, distance to a subject with a point or
near-point source as well as image features can be calculated
directly. Such point or near-point sources will generally produce
simple image patters on each imager array. First, the effective
image pattern radii of the first image pattern and the second image
pattern can be determined as r1 and r2, respectively. The effective
feature radii of a defocussed image can be calculated from the
total volume of the image pixel values according to Equations I and
II:
r1=sqrt(sum(pixel_value_image1)/(pi*max(pixel_value_image1) I
r2=sqrt(sum(pixel_value_image2)/(pi*max(pixel_value_image2) II
where r1 and r2 are the image radii of the first image pattern and
the second image pattern. Pixel values are in the sampling kernels
of 5.times.5 to 10.times.10 pixels. Optically, with generic imaging
system optics, focused images occur at a single plane with the best
focal distance relative to the optics for specific subject. At this
best focused location, the image is the sharpest with the smallest
feature size for any image contents. At any other location, image
will be defocused (a blurred image), with feature sizes that are
bigger for the same image content at focused location.
[0054] Next, the smallest image size location from the first image
based on the feature radii of the first image pattern and the
second image pattern is calculated by Equation III:
d=r1*t/(r1+r2) III
where d is the distance from the first image, r1 and r2 are the
effective feature radii of the first image and second image, and t
is the separation between the first light incident surface and
second light incident surface. The smallest image feature size
location is at the best focus location, where image is focused with
minimum blur. Depending on the design of the system, for some
aspects including a mix of front side illuminated and back side
illuminated imagers, an offset may be introduced to compensate for
the difference in the distance from the front of the image array to
the effective image plane.
[0055] The subject distance can then be calculated using the lens
imaging Equation IV:
D=1/(1/f-1/(s+d)) IV
where D is the distance from the subject to the lens' principle
plane, f is the focal length of the imaging lens, s is the distance
from lens principle plane to the first image, and d is the distance
from the first image to the smallest image location. In some
aspects the actual distance calculation can consider the image
stack layer material refractive index because the actual distance
in the non-air material will be, according to Equation V:
(Distance in material)=(distance in air)*(material refractive
index) V
[0056] Furthermore, the x and y position of an image feature in an
imager array used in distance calculation can be calculated using a
centroid, as is shown by Equations VI and VII:
xc=sum(x*(pixel value))/sum(pixel value) VI
yc=sum(y*(pixel value))/sum(pixel value) VII
It is noted that the centroid xc and yc position is not limited by
the pixel resolution, as x and y are pixel coordinates. Sub-pixel
result can be used to achieve required calculation precision. The
precision of the position can be sensor signal-to-noise ratio
limited.
[0057] For a non-point object source, image feature size can be
determined by cross correlation between the inverse scaled first
image and second image. First, the inverse scaled cross correlation
is calculated according to Equation VIII:
C=sum((Inverse scaled first image pixel values)*(second image pixel
value)) VIII
where C is the result of the inverse scaled correlation. The
inverse scaled first image is processed by applying the inverse
scale factor k to the image size (similar to a digital zoom).
Again, the scaling is not pixel resolution limited, and sub-pixel
scaling process is used to find the best correlated scale factor k
with the highest correction result C.
[0058] The best correlated scale factor k can then be used to
describe the relationship between the first image and the second
image. The image distance from the first image than can be
calculated as according to Equation IX:
d=r1*t/(r1+r2)32 r1*t/(r1+k*r1)=t/(1+k) IX
where d is the image distance from first image to the smallest
image size location, t is the separation between first light
incident surface and second light incident surface, and k is the
scale factor applied to the first image in cross correlation.
Depending on the design of the system, for some aspects including a
mix of front side illuminated and back side illuminated imagers, an
offset may be introduced to compensate for the difference in the
distance from the front of the image array to the effective image
plane.
[0059] The distance to the subject can then be calculated according
to Equation X:
D=1/(1/f-1/(s+d)) X
where D is the distance from the subject to the lens principle
plane, f is the focal length of the imaging lens, s is the distance
from lens principle plane to the first image, and d is the distance
from first image to the smallest image location. Again,
compensation can be made for the refractive index of the imager
array material.
[0060] A variety of configurations are contemplated for carrying
out the calculations utilized to derive distance and/or three
dimensional information from a subject. For example, in one aspect
the calculations or at least a portion of the calculations can be
performed on-chip with the imager arrays. In another aspect, a
dedicated image processing unit can be utilized for the
calculations or at least a portion of the calculations. In other
aspects, the calculations or at least a portion of the calculations
can be performed in a computing device.
[0061] Turning to various physical configurations of the system, in
one aspect an imaging system capable of deriving three dimensional
information from a three dimensional subject can, as is shown in
FIG. 4, include a first imager array 402 having a first light
incident surface 404 and a second imager array 406 having a second
light incident surface 408. The second imager array 406 is coupled
to the first imager array 402 at a surface that is opposite the
first light incident surface 404. It is noted that in one aspect
the first imager array can be physically coupled to the second
imager array. In another aspect, the first imager array can be
optically coupled to the second imager array. Furthermore, the
second light incident surface 408 is oriented toward the first
imager array 402 and at least substantially uniformly spaced at a
distance of from about 2 microns to about 150 microns from the
first light incident surface. The system can additionally include a
system lens 410 positioned to direct incident light 412 along an
optical pathway 414 onto the first light incident surface 404. In
some aspects, the system lens 410 can have a focal point 416
located in between the first light incident surface 404 and the
second light incident surface 408, and/or in between the first
imager array 402 and the second imager array 406. The first imager
array 402 is operable to detect a first portion of the light
passing along the optical pathway 414 and to pass through a second
portion of the light, and the second imager array 406 is operable
to detect at least a part of the second portion of light. In some
aspects the first portion of light and the second portion of light
have at least one wavelength of from about 500 nm to about 1100 nm.
In another aspect, the first portion of light and the second
portion of light have at least one wavelength of from about 750 nm
to about 1100 nm. In another aspect, the second portion of light
includes at least substantially all wavelengths of light of from
about 750 nm to about 1100 nm. In a further aspect, the first
portion of light and the second portion of light have a center
wavelength frequency between about 500 nm and about 1100 nm. In
another aspect, the first portion of light and the second portion
of light have a center wavelength frequency between about 750 nm
and about 1100 nm.
[0062] The wavelengths of light utilized by the stacked imager
system can vary depending on, among other things, the design of the
system and the intended application. In some aspects the same or
substantially the same light wavelengths can be utilized by both
the first imager array and the second imager array to derive
distance and/or three dimensional information from the subject. In
other aspects, different light wavelengths can be utilized by the
first imager array than by the second imager array. While in many
aspects IR light wavelengths are used to calculate three
dimensional information about a subject, in some aspects visible
light can be used to make such calculations. For example, assuming
crystalline silicon imagers are utilized for the imager arrays,
light in the visible spectrum of from about 500 nm to about 700 nm
can be used, provided the first imaging array is sufficiently thin
to allow a second portion of the visible light to pass there
through. Furthermore, in some cases different wavelengths of light
can be utilized differently in the system. For example, infrared
light can be used by both the first imager array and the second
imager array to generate a three dimensional representation or
three dimensional image, while visible light can be captured by the
first imager array in order to generate a visible image of the
subject. When the two representations are combined, a resulting
three dimensional visible image of the subject can be achieved.
[0063] In another aspect, system can include an active illumination
source, a first imager capable of detecting visible and infrared
(IR) light and a second imager capable of detecting IR light. The
system can further include an active illumination source capable of
emitting IR light. The active illumination source, first imager and
the second imager can pulsed at the same frequency such that the
pulsed IR light is detected during the pulse window. When the IR
illumination source is off (i.e. in between pulses), the first
image sensor is detecting and reading out visible light data.
[0064] Additionally, in some aspects the one or more of the first
and second imager arrays can include light filters that are capable
of filtering out specific wavelengths of light or ranges of
wavelengths of light. As such, light having a certain wavelength or
wavelength range can be concentrated by a structure such as a
system lens on a specific imager array or even a portion of an
imager array. In one aspect, an IR cut filter (moveable) or notch
filter can be employed in front one or more pixels of the first
imager array. Such a filter can pass infrared light that will be
used in range or distance determination and filter out light in the
visible range. In some cases a long-pass filter can pass both
infrared and visible red light. Similarly, a long-pass filter can
be utilized that passes green, red, and infrared light. In other
aspects, a band-pass filter can be used that passes visible light
and specific wavelengths of IR light, such as, for example, 850 nm,
940 nm, and/or 1064 nm light, while blocking all other
wavelengths.
[0065] It is additionally contemplated that in one aspect the
system can include a focusing system for altering the focal
plane(s) of the imaging system. While various techniques are
contemplated, in one aspect the distance of the first imager array
from the second imager array can be varied by, for example,
piezoelectric materials.
[0066] In some aspects, the system can additionally include an
active light emitter configured to emit active light radiation at
least substantially toward the subject. While any light can be
utilized as an active light source, in one aspect the active light
source can emit light having a center wavelength in the infrared
range. In another aspect, the emitted light can have a center
wavelength of from about 750 nm to about 1100 nm. In yet another
aspect, the active light radiation can have a center frequency
selected from 850 nm, 940 nm, 1064 nm, or a combination
thereof.
[0067] As has been described, in some aspects the system can
include a computational module that is operable to calculate
distance data from the imaging system to the three dimensional
subject using first image data collected by the first imager array
from the first portion of light and second image data collected by
the second imager array from the second portion of light.
Computational modules are well known, and can include various
processing units, data storage, memory, I/O functionality, and the
like. In one aspect the computation module is capable of generating
a three dimensional representation of the subject from the distance
data. In another aspect the computational module can generate a
three dimensional image from the data derived from the first imager
array and the second imager array. In other aspects, the imaging
system can be incorporated into a computing system operable to
alter computation based on variations in distance data derived from
movements of a subject. For example, in the case of a human
subject, motions made by the subject can be captured by the imaging
system and used by the computing system to alter the computation of
the computing system. In the case of non-living subjects,
computation of the computing system can be varied according to the
motion of an oncoming vehicle or other moving subject.
[0068] Returning to the imager system configuration, in one aspect
the distance from the first light incident surface to the second
light incident surface is from about 1 microns to about 150
microns. In another aspect, aspect the distance from the first
light incident surface to the second light incident surface is from
about 10 microns to about 100 microns. In a further aspect, the
distance from the first light incident surface to the second light
incident surface is from about 1 micron to about 50 microns.
Furthermore, each of the first and second imager array is made up
of a plurality of pixels. The pixels can be architecturally
configured as front-side illuminated pixels or back-side
illuminated pixels. For example, in one aspect all of the first
imager array pixels and the second imager array pixels can be
front-side illuminated pixels. In another aspect, all of the first
imager array pixels can be front-side illuminated and all of the
second imager array pixels can be backside illuminated pixels.
Additionally, it is contemplated that in some aspects either of the
first or second imager arrays can be front-side illuminated while
the other imager array can be backside illuminated.
[0069] Furthermore, as is shown in FIG. 5, in some aspects a system
can include a texture region 502 coupled to the second imager array
406 on a side opposite the first imager array 402. In this case,
the textured region 502 is positioned to redirect light passing
through the second imager array 406 back into the second imager
array 406. The light passing through the second imager array is
shown at 504, and the light redirected back into the imager array
is shown at 506. It is noted that the textured region 502 can be
formed across all or substantially all of the back surface of the
second imager array 406, or the textured region 502 can be formed
on a portion thereof. Additionally, in some aspects the textured
region can be formed at the level of the pixels that make up the
imager array, and as such, can be formed on a portion of the pixel
surface, substantially all of the pixel surface, or all of the
pixel surface. Also, it is noted that callout numbers used in FIG.
5 from previous figures denote the same or similar structures as
the previous figure. Furthermore, in some aspects a textured region
is explicitly disclaimed from being applied to the first imager
array, while in other aspects such a textured region can be
utilized.
[0070] The textured region can function to diffuse electromagnetic
radiation, to redirect electromagnetic radiation, and/or to absorb
electromagnetic radiation, thus increasing the efficiency of the
second imager array. The textured region can include surface
features to thus increase the optical path length of the second
imager array. Such surface features can be micron-sized and/or
nano-sized, and can be any shape or configurations. Non-limiting
examples of such shapes and configurations include cones, pillars,
pyramids, micolenses, quantum dots, inverted features, gratings,
protrusions, and the like, including combinations thereof.
Additionally, factors such as manipulating the feature sizes,
dimensions, material type, dopant profiles, texture location, etc.
can allow the diffusing region to be tunable for a specific
wavelength or wavelength range. Thus in one aspect, tuning the
device can allow specific wavelengths or ranges of wavelengths to
be absorbed.
[0071] As has been described, textured regions according to aspects
of the present disclosure can also allow an imager array to
experience multiple passes of incident electromagnetic radiation
within the device, particularly at longer wavelengths (i.e.
infrared). Such internal reflection increases the optical path
length to be greater than the thickness of the semiconductor. This
increase in the optical path length increases the quantum
efficiency of the device, leading to an improved signal to noise
ratio.
[0072] The textured region can be formed by various techniques,
including plasma etching, reactive ion etching, porous silicon
etching, lasing, chemical etching (e.g. anisotropic etching,
isotropic etching), nanoimprinting, material deposition, selective
epitaxial growth, shallow trench isolation, and the like. One
effective method of producing a textured region is through laser
processing. Such laser processing allows discrete locations of the
imager array or other substrate to be textured. A variety of
techniques of laser processing to form a textured region are
contemplated, and any technique capable of forming such a region
should be considered to be within the present scope. Examples of
such processing have been described in further detail in U.S. Pat.
Nos. 7,057,256, 7,354,792 and 7,442,629, which are incorporated
herein by reference in their entireties. Briefly, a surface of a
substrate material is irradiated with laser radiation to form a
textured or surface modified region.
[0073] The type of laser radiation used to surface modify a
material can vary depending on the material and the intended
modification. Any laser radiation known in the art can be used with
the devices and methods of the present disclosure. There are a
number of laser characteristics, however, that can affect the
texturing process and/or the resulting product including, but not
limited to the wavelength of the laser radiation, pulse width,
pulse fluence, pulse frequency, polarization, laser propagation
direction relative to the semiconductor material, etc. In one
aspect, a laser can be configured to provide pulsatile lasing of a
material. A short-pulsed laser is one capable of producing
femtosecond, picosecond and/or nanosecond pulse durations. Laser
pulses can have a central wavelength in a range of about from about
10 nm to about 8 .mu.m, and more specifically from about 200 nm to
about 1200 nm. The pulse width of the laser radiation can be in a
range of from about tens of femtoseconds to about hundreds of
nanoseconds. In one aspect, laser pulse widths can be in the range
of from about 50 femtoseconds to about 50 picoseconds. In another
aspect, laser pulse widths can be in the range of from about 50
picoseconds to 100 nanoseconds. In another aspect, laser pulse
widths are in the range of from about 50 to 500 femtoseconds. In
another aspect, laser pulse widths are in the range of from about
10 femtoseconds to about 500 picoseconds.
[0074] The number of laser pulses irradiating a target region can
be in a range of from about 1 to about 2000. In one aspect, the
number of laser pulses irradiating a target region can be from
about 2 to about 1000. Further, the repetition rate or frequency of
the pulses can be selected to be in a range of from about 10 Hz to
about 10 .mu.Hz, or in a range of from about 1 kHz to about 1 MHz,
or in a range from about 10 Hz to about 1 kHz. Moreover, the
fluence of each laser pulse can be in a range of from about 1
kJ/m.sup.2 to about 20 kJ/m.sup.2, or in a range of from about 3
kJ/m.sup.2 to about 8 kJ/m.sup.2.
[0075] In another aspect of the present disclosure, an imaging
system can further include a reflector coupled to the second imager
array on a side opposite the first imager array. The reflector can
be positioned to reflect light passing through the second imager
array back into the second imager array. Numerous reflector
materials are contemplated, and can include any material or
composite of materials that can function to reflect light.
Non-limiting examples of such materials can include metals, metal
alloys, ceramics, polymers, glass, quartz, Bragg-type reflectors,
and the like.
[0076] FIGS. 6A-E show various steps in the non-limiting
manufacture of a stacked imager structure according to one aspect
of the present disclosure. As is shown in FIG. 6A, for example,
first imager array 602 is formed on the front side of a
semiconductor layer 604. The first imager array 602 can include any
form of imager array that can be incorporated into an imager
system, and any such device is considered to be within the present
scope. A variety of semiconductor materials are contemplated for
use as the semiconductor layer of the devices and methods according
to aspects of the present disclosure. As such, any semiconductor
material that can be used in a stacked imager device is considered
to be within the present scope. Non-limiting examples of such
semiconductor materials can include group IV materials, compounds
and alloys comprised of materials from groups II and VI, compounds
and alloys comprised of materials from groups III and V, and
combinations thereof. More specifically, exemplary group IV
materials can include silicon, carbon (e.g. diamond), germanium,
and combinations thereof. Various exemplary combinations of group
IV materials can include silicon carbide (SiC) and silicon
germanium (SiGe). In one specific aspect, the semiconductor
material can be silicon. In another specific aspect, the
semiconductor layer can be a silicon wafer. The silicon
wafer/material can be monocrystalline, multicrystalline,
microcrystalline, amorphous, and the like. In one specific aspect,
the silicon material can be a monocrystalline silicon wafer.
[0077] Turning to FIG. 6B, a carrier substrate (or handle) 606 can
be bonded to the first imager array 602. Note that in FIG. 6B, the
device has been flipped or rotated 180.degree. as compared to FIG.
6A. The carrier substrate can include a variety of materials.
Because in many aspects the carrier substrate 606 is a temporary
substrate to be removed at a later processing step, the material
can be chosen based on its usefulness as a temporary substrate. It
can also be beneficial for the carrier substrate 606 to be capable
of adequately holding the first imager array 602 during processing
of the semiconductor layer 604 and yet be capable of easy removal.
Non-limiting examples of potential carrier substrate materials can
include glass, ceramics, semiconductors, and the like, including
combinations thereof.
[0078] Various bonding techniques are contemplated for attaching
the carrier substrate 606 to the first imager array 602, and any
such bonding technique useful in making a stacked imager device is
considered to be within the present scope. One such process can
include a liquid UV curable adhesive process that utilizes solids
acrylic adhesives designed for temporary bonding of semiconductor
wafers to a glass carrier substrate. This technique provides a
rigid, uniform support surface that minimizes stress on the wafer
during the subsequent processing steps, resulting in less warpage,
cracking, edge chipping and higher yields. Other exemplary methods
can include bonding and detaching a temporary carrier used for
handling a wafer during the fabrication of semiconductor devices,
includes bonding the wafer onto the carrier through an adhesive
layer. After detaching the carrier from the wafer, the first
adhesive layer remaining on the wafer is removed. In another
method, bonding at low or room temperature can include surface
cleaning and activation by cleaning or etching, followed by
polishing the surfaces to be bonded to a high degree of smoothness
and planarity. Reactive ion etching or wet etching is used to
slightly etch the surfaces being bonded. The etched surfaces may be
rinsed in solutions such as ammonium hydroxide or ammonium fluoride
to promote the formation of desired bonding species on the
surfaces.
[0079] In one aspect, the first imager array 602 and the carrier
substrate 606 can be bonded at room temperature and a thermal
treatment can be applied to consolidate the bonding interface. The
parameters of the consolidation annealing can be controlled to
provide a bonding energy high enough for the heterostructure to
withstand post-bonding conventional process steps (e.g. CMOS
processing). In one specific aspect, the bonding technique can
include various oxide-oxide, oxide-silicon, or metal-metal bonding
methods.
[0080] Some bonding processes can achieve a bond strength of at
least 1 J/m.sup.2 at room temperature. For even higher bond
strengths, a bake cycle at 100.degree.-300.degree. C. can be
utilized. Some of these oxide-oxide bonding process have been
described in U.S. Pat. No. 7,871,898 and U.S. Pat. No. 5,843,832,
which are incorporated by reference in their entireties. One method
of direct bonding a silicon wafer onto an insulated wafer in order
to obtain a stacked imager device is similar to the bonding of two
silicon wafers together, with the exception that before bonding a
thin thermal oxide layer (e.g. about 1 micron) is grown on one of
the wafers.
[0081] Release of the carrier substrate from the device layer can
vary depending on the attachment process. Acrylic adhesives, for
example, can be released by exposure to UV light. More permanent
bonds, such as silicon-oxide bonds may require the removal of the
carrier substrate by mechanical grinding and/or chemical etching to
expose the device layer.
[0082] Turning to FIG. 6C, the semiconductor layer 604 (FIG. 6B) is
at least partially removed (e.g. polished and thinned) to expose
the backside of the first imager array 602 or, in other words, to
form a processed surface 608 at the backside of the first imager
array 602. Thus, the resulting structure is comprised of the first
substrate 606 coupled to the first imager array 602. At this point,
any necessary or beneficial backside processing can be performed on
the processed surface 608 of the first imager array 602. Such
beneficial backside processing can include, without limitation,
shallow or deep trench formation, via formation, annealing,
implantation, and the like.
[0083] In one aspect, backside processing can also include exposing
contact pads associated with the first imager array. By opening the
backside of the device layer (i.e. at the processed surface), such
electrical contacts can be exposed for bonding and providing
electrical contact to subsequent structures, such as the second
imager array (see below). Opening the backside can occur by any
known technique, including the thinning and processing methods
described. In one specific aspect, opening the backside can be
accomplished via plasma etching.
[0084] Any technique useful for removing the semiconductor layer
604 is considered to be within the present scope. Non-limiting
examples can include ion implantation/separation processes, laser
ablation, laser splitting, CMP processing, dry etching, wet etching
and the like, including combinations thereof. In one specific
aspect, the semiconductor layer is removed by CMP techniques to
expose the device layer 602.
[0085] Following removal or thinning of the semiconductor layer
604, a second imager array 610 is bonded to the backside of the
first imager array 602, as is shown in FIG. 6D. Note that in FIG.
6D, the device has been flipped or rotated by 180.degree. compared
to FIG. 6C. Any bonding technique can be utilized to bond the
second imager array 210 to the first imager array 202, as was
described for the bonding of the first substrate 206 to the first
imager array 202 (FIG. 6B), provided the process is compatible with
both structures. It is noted that any spacing that exists between
the first and second imager arrays can be filled with a light
transparent material such as amorphous silicon, an oxide, nitride,
or the like. In some aspects an air gap can be maintained between
the first and second imager arrays. Such a gap can be filled with
actual air, an inert gas, a vacuum, etc.
[0086] Additionally, it is noted that the first imager array and
the second imager array can be electrically coupled to, and thus
can function in conjunction with, one another. Such electrical
coupling can be accomplished by vias formed through the processed
surface that connect the two imager arrays.
[0087] Turning to FIG. 6E, in some aspects the carrier substrate
606 (FIG. 6D) can be removed from the first imager array 602
following bonding of the second imager array 610. Thus, the
resulting stacked imager structure shown in FIG. 6E includes a
second imager array 610 bonded to a first imager array 602.
[0088] In another aspect, FIGS. 7A-E show various steps in the
manufacture of a stacked imager device using an embedded oxide
layer to facilitate thinning and creating a space between the
imager arrays. As is shown in FIG. 7A, for example, first imager
array 702 can be formed on the front side of a semiconductor layer
704. The first imager array 702 can include any form of imager
array that can be incorporated into a stacked imager device, as has
been described. A thin oxide layer 703 can be embedded within the
semiconductor layer 704, either before or after the formation of
the first imager array 702. The thin oxide layer can be of any
shape and thickness useful for the particular device design. In
some aspects, however, the thin oxide layer can be from about 4000
angstroms to about 1.5 microns thick. It is also noted that
commercial SOI substrates can be used that are manufactured having
such a thin oxide layer embedded. Turning to FIG. 7B, a carrier
substrate 706 can be bonded to the first imager array 702. Note
that in FIG. 7B, the device has been flipped or rotated 180.degree.
as compared to FIG. 7A. The carrier substrate can include a variety
of materials. Because in most aspects the carrier substrate 706 is
a temporary substrate to be removed at a later processing step, the
material can be chosen based on its usefulness as a temporary
substrate.
[0089] Turning to FIG. 7C, the semiconductor layer 704 (FIG. 7B) is
at least partially removed to form a processed surface 708 near the
backside of the first imager array 702. In one aspect, the
semiconductor layer 704 can be removed at least to the thin oxide
layer 703. In some aspects at least a portion of the thin oxide
layer can remain, while in other aspects the thin oxide layer can
be completely removed from the semiconductor layer. This material
can be removed by any known method, such as, for example, laser
splitting, polishing, thinning, etching, lapping or grinding, CMP
processing, or a combination thereof.
[0090] Thus, the resulting structure is comprised of the carrier
substrate 706 coupled to the first imager array 702. A portion of
the semiconductor layer 704 can remain coupled to the first imager
array 702 opposite the carrier substrate 706. At this point, any
necessary or beneficial backside processing can be performed on the
first imager array 702. In one specific aspect, processing the
semiconductor layer on the backside can include implant and/or
laser anneal conditions to reduce surface defects.
[0091] Following thinning of the semiconductor layer 704, a second
imager array 710 can be bonded to the semiconductor layer 704 at
backside of the first imager array 702, as is shown in FIG. 7D.
Note that in FIG. 7D, the device has been flipped or rotated
180.degree. compared to FIG. 7C. Any bonding technique can be
utilized to bond the second imager array 710 to the semiconductor
layer 704, as has been described.
[0092] Turning to FIG. 7E, in some aspects the carrier substrate
706 (FIG. 7D) can be removed from the first imager array 702
following bonding of the second imager array 710. Thus, the
resulting stacked imager structure shown in FIG. 7E includes a
second imager array 710 bonded to the semiconductor layer 704,
which is bonded to the first imager array 702. It is noted that the
distance between the imagers can be varied during manufacture by
varying the thickness of the semiconductor layer 704 that remains
and is bonded between the imager arrays.
[0093] The present disclosure additionally provides methods of
determining distance to a subject. In one aspect, for example, such
a method can include focusing incident light along an optical
pathway onto a first light incident surface of a first imaging
array, where the first imaging array captures a first portion of
the light having at least one wavelength of from about 500 nm to
about 1100 nm to generate a first data set and passes through a
second portion of the light along the optical pathway. The method
can also include receiving the second portion of the light onto a
second light incident surface of a second imaging array, where the
second imaging array captures the second portion of the light
having at least one wavelength of from about 500 nm to about 1100
nm to generate a second data set. Furthermore, the distance to the
subject can be derived from variations between the first data set
and the second data set. In another aspect the method can also
include redirecting at least part of the second portion of the
light that passes through the second imaging array back into the
second imaging array.
[0094] In another aspect, the present disclosure provides an
imaging system capable of deriving three dimensional information
from a three dimensional subject. Such a system can include an
active illumination source capable of emitting pulsed infrared
light, a first imager capable of detecting visible and infrared
light, and a second imager capable of detecting infrared light. The
active illumination source, first imager, and the second imager can
be pulsed at a frequency and duty cycle such that the pulsed
infrared light is detected by the first imager and the second
imager when the active illumination is on. In one aspect the first
imager is operable to detect visible light when the active
illumination source is in an off state.
[0095] It is to be understood that the above-described arrangements
are only illustrative of the application of the principles of the
present disclosure. Numerous modifications and alternative
arrangements may be devised by those skilled in the art without
departing from the spirit and scope of the present disclosure and
the appended claims are intended to cover such modifications and
arrangements. Thus, while the present disclosure has been described
above with particularity and detail in connection with what is
presently deemed to be the most practical embodiments of the
disclosure, it will be apparent to those of ordinary skill in the
art that numerous modifications, including, but not limited to,
variations in size, materials, shape, form, function and manner of
operation, assembly and use may be made without departing from the
principles and concepts set forth herein.
* * * * *