U.S. patent application number 17/069719 was filed with the patent office on 2021-02-11 for tunable color-temperature white light source.
The applicant listed for this patent is Verily Life Sciences LLC. Invention is credited to Vidya Ganapati, Eden Rephaeli, Supriyo Sinha.
Application Number | 20210038054 17/069719 |
Document ID | / |
Family ID | 1000005181050 |
Filed Date | 2021-02-11 |
United States Patent
Application |
20210038054 |
Kind Code |
A1 |
Ganapati; Vidya ; et
al. |
February 11, 2021 |
TUNABLE COLOR-TEMPERATURE WHITE LIGHT SOURCE
Abstract
A system for medical diagnosis includes a fiber optic cable and
a plurality of light emitters optically coupled to a first end of
the fiber optic cable. Each light emitter in the plurality of light
emitters emits a distinct bandwidth of light. The system also
includes a controller electrically coupled to the plurality of
light emitters. The controller includes logic that when executed by
the controller causes the controller to perform operations
including: receiving instructions including an illumination mode,
and adjusting an intensity of the light emitted from each light
emitter in the plurality of light emitters to match the
illumination mode.
Inventors: |
Ganapati; Vidya; (Portland,
OR) ; Sinha; Supriyo; (Menlo Park, CA) ;
Rephaeli; Eden; (Oakland, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Verily Life Sciences LLC |
South San Francisco |
CA |
US |
|
|
Family ID: |
1000005181050 |
Appl. No.: |
17/069719 |
Filed: |
October 13, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15222471 |
Jul 28, 2016 |
10835102 |
|
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17069719 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61B 1/0684 20130101;
A61B 1/07 20130101; A61B 2090/309 20160201; G02B 23/2469 20130101;
A61B 1/00006 20130101; A61B 1/00039 20130101; A61B 1/063 20130101;
A61B 1/0638 20130101; A61B 1/0669 20130101 |
International
Class: |
A61B 1/00 20060101
A61B001/00; A61B 1/06 20060101 A61B001/06; A61B 1/07 20060101
A61B001/07; G02B 23/24 20060101 G02B023/24 |
Claims
1. A system for medical diagnosis, comprising: a fiber optic cable;
a plurality of light emitters optically coupled to a first end of
the fiber optic cable, wherein each light emitter in the plurality
of light emitters emits a distinct bandwidth of light; a user input
device; and a controller operatively coupled to the plurality of
light emitters and the user input device, the controller including
logic that, when executed by the controller, causes the system to
perform operations including: receiving, with the controller,
parameters of a custom emission spectrum from the user input
device; selecting a light emission mode from a plurality of light
emission modes based on the custom emission spectrum; and emitting
light from the plurality of light emitters in response to the light
emission mode selected, wherein each light emitter in the plurality
of light emitters emits a distinct bandwidth of the light, wherein
the light output from the plurality of light emitters mimics the
custom emission spectrum to a human eye.
2. The system of claim 1, wherein the custom emission spectrum is a
continuous custom emission spectrum.
3. The system of claim 1, wherein the user input device is
configured to receive user the parameters from a user.
4. The system of claim 1, further comprising: a reference
illuminant; and a camera; wherein the controller is operatively
coupled to the reference illuminant and the camera and further
includes logic that, when executed by the controller, causes the
system to perform operations including: generating reference image
data with the camera based on a scene under reference illumination
from the reference illuminant; generating light emission mode image
data based on the scene illuminated under the light emission mode;
and comparing the reference image data and the light emission mode
image data.
5. The system of claim 4, further comprising a color checker,
wherein selecting a light emission mode includes: determining a
color of the color checker under the reference illumination; and
generating the illumination mode to match the reference
illumination.
6. The system of claim 4, wherein the plurality of light emitters
includes a plurality of laser diodes with a bandwidth of 5 nm or
less.
7. A method of endoscopic illumination, comprising: receiving, with
a controller, parameters of a custom emission spectrum; selecting a
light emission mode from a plurality of light emission modes based
on the custom emission spectrum; and emitting light from a
plurality of light emitters in response to the light emission mode
selected, wherein each light emitter in the plurality of light
emitters emits a distinct bandwidth of the light, wherein the light
output from the plurality of light emitters mimics the custom
emission spectrum to a human eye.
8. The method of claim 7, wherein the custom emission spectrum is a
continuous custom emission spectrum.
9. The method of claim 7, wherein the light emission mode is
selected by a user by inputting parameters of a custom continuous
emission spectrum.
10. The method of claim 9, wherein the user inputs the parameters
of the custom continuous emission spectrum by drawing the emission
spectrum on a tablet.
11. The method of claim 9, wherein the user inputs the parameters
with a user input device.
12. The method of claim 7, wherein the method further comprises:
transporting the light through a fiber optic cable, wherein a first
end of the fiber optic cable is optically coupled to the plurality
of light emitters; and out-coupling the light from a second end of
the fiber optic cable.
13. The method of claim 7, wherein the plurality of light emitters
includes a plurality of laser diodes with a bandwidth of 5 nm or
less.
14. The method of claim 7, further comprising: generating reference
image data based on a scene under reference illumination from a
reference illuminant; generating light emission mode image data
based on the scene illuminated under the light emission mode; and
comparing the reference image data and the light emission mode
image data.
15. The method of claim 14, wherein selecting a light emission mode
includes: determining a color of a color checker under the
reference illumination; and generating the illumination mode to
match the reference illumination.
16. An endoscope, comprising: a fiber optic cable; a plurality of
light emitters optically coupled to a first end of the fiber optic
cable, wherein each light emitter in the plurality of light
emitters emits a distinct bandwidth of light; a user input device;
and a controller operatively coupled to the plurality of light
emitters and the user input device, the controller including logic
that, when executed by the controller, causes the endoscope to
perform operations including: receiving, with the controller,
parameters of a custom emission spectrum from the user input
device; selecting a light emission mode from a plurality of light
emission modes based on the custom emission spectrum; and emitting
light from a plurality of light emitters in response to the light
emission mode selected, wherein each light emitter in the plurality
of light emitters emits a distinct bandwidth of the light, wherein
the light output from the plurality of light emitters mimics the
custom emission spectrum to a human eye.
17. The endoscope of claim 16, wherein the user input device is
configured to receive user the parameters from a user.
18. The endoscope of claim 16, further comprising: a reference
illuminant; and a camera; wherein the controller is operatively
coupled to the reference illuminant and the camera and further
includes logic that, when executed by the controller, causes the
endoscope to perform operations including: generating reference
image data with the camera based on a scene under reference
illumination from the reference illuminant; generating light
emission mode image data based on the scene illuminated under the
light emission mode; and comparing the reference image data and the
light emission mode image data.
19. The endoscope of claim 16, wherein the custom emission spectrum
is a continuous custom emission spectrum.
20. The endoscope of claim 16, wherein the plurality of light
emitters includes a plurality of laser diodes with a bandwidth of 5
nm or less.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 15/222,471, filed Jul. 28, 2016, which is
incorporated herein by reference in its entirety.
TECHNICAL FIELD
[0002] This disclosure relates generally to white light sources,
and in particular but not exclusively, relates to endoscopic light
sources.
BACKGROUND INFORMATION
[0003] Endoscopy allows a physician to view organs and cavities
internal to a patient using an insertable instrument. This is a
valuable tool for making diagnoses without needing to guess or
perform exploratory surgery. The insertable instruments, sometimes
referred to as endoscopes or borescopes, have a portion, such as a
tube, that is inserted into the patient and positioned to be close
to an organ or cavity of interest.
[0004] Endoscopes first came into existence in the early 1800's,
and were used primarily for illuminating dark portions of the body
(since optical imaging was in its infancy). In the late 1950's, the
first fiber optic endoscope capable of capturing an image was
developed. A bundle of glass fibers was used to coherently transmit
image light from the distal end of the endoscope to a camera.
However, there were physical limits on the image quality this
seminal imaging endoscope was able to capture: namely, the number
of fibers limited the resolution of the image, and the fibers were
prone to breaking.
[0005] Now endoscopes are capable of capturing high-resolution
images, as endoscopes use various modern image processing
techniques to provide the physician with as natural a view as
possible. For example, the views provided by an endoscope may be
capable of mimicking a natural feeling field and depth of view to
emulate a physician seeing with her own eyes.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] Non-limiting and non-exhaustive embodiments of the invention
are described with reference to the following figures, wherein like
reference numerals refer to like parts throughout the various views
unless otherwise specified. Not all instances of an element are
necessarily labeled so as not to clutter the drawings where
appropriate. The drawings are not necessarily to scale, emphasis
instead being placed upon illustrating the principles being
described.
[0007] FIG. 1A is a block diagram of an endoscope system, in
accordance with an embodiment of the disclosure.
[0008] FIG. 1B shows an endoscope emission spectrum and a
corresponding blackbody emission spectrum, in accordance with an
embodiment of the disclosure.
[0009] FIG. 2 illustrates an endoscopic light emitter, in
accordance with an embodiment of the disclosure.
[0010] FIGS. 3A-3I illustrate black body emission spectra and
corresponding endoscopic emission spectra, in accordance with
several embodiments of the disclosure.
[0011] FIG. 4 illustrates a user creating an endoscope emission
spectrum, in accordance with an embodiment of the disclosure.
[0012] FIG. 5 illustrates method of endoscopic illumination, in
accordance with an embodiment of the disclosure.
DETAILED DESCRIPTION
[0013] Embodiments of a system and method for a tunable
color-temperature white light source are described herein. In the
following description numerous specific details are set forth to
provide a thorough understanding of the embodiments. One skilled in
the relevant art will recognize, however, that the techniques
described herein can be practiced without one or more of the
specific details, or with other methods, components, materials,
etc. In other instances, well-known structures, materials, or
operations are not shown or described in detail to avoid obscuring
certain aspects.
[0014] Reference throughout this specification to "one embodiment"
or "an embodiment" means that a particular feature, structure, or
characteristic described in connection with the embodiment is
included in at least one embodiment of the present invention. Thus,
the appearances of the phrases "in one embodiment" or "in an
embodiment" in various places throughout this specification are not
necessarily all referring to the same embodiment. Furthermore, the
particular features, structures, or characteristics may be combined
in any suitable manner in one or more embodiments.
[0015] Endoscopes are devices physicians use to view inside of
patients without the need to perform exploratory surgery. In
general, endoscopes are imaging devices with insertion tubes that
are inserted into a patient through (small) incisions. The imaging
device provides views from a tip ("distal end") of the insertion
tube and displays the view, for example, on a monitor for the
physician. The imaging system may provide a stereoscopic view of an
area of interest so that a more natural image is presented to the
viewer. To generate the stereoscopic view, endoscopes may include
multiple image sensors, where each image sensor provides an image
of the area of interest from a slightly different perspective. The
difference in perspective is intended to emulate the different
perspective of human eyes. To further enhance endoscope imaging and
aid physicians in diagnosis, the instant disclosure provides an
elegant solution to produce substantially white light (or another
operator-desired emission spectrum) at the distal end of the
endoscope.
[0016] The color of an object depends on the spectrum of the
illumination light source, as well as the object's own spectral
reflectance. When imaging with an endoscope inside a cavity, the
illumination source is located at the distal end. To make the
colors look "natural" and recognizable to the surgeon, a white
light source with a spectrum similar to daylight (e.g., a blackbody
emission spectrum at 6500.degree. K) is frequently preferred.
However, to get the light to the tip of the endoscope, the light
source needs to be well-coupled to a fiber optic cable so that the
cable can efficiently carry the light to the tip. A broadband lamp
or LED can be used as the light source, but coupling efficiency to
the fiber may, in some situations, be limited. A laser can couple
efficiently to a fiber optic cable; however, the monochromatic
laser source will likely produce colors that look unnatural. This
may impede the ability of the endoscope operator (e.g., surgeon)
from making an accurate diagnosis or properly identify tissue.
Additionally, in both the case of laser or broadband illumination,
the source emission spectrum is fixed; what looks like "natural"
coloring is subjective, so a tunable source is desirable.
[0017] As will be discussed in greater detail, a set of discrete
lasers are coupled into an illumination fiber bundle, with the
relative power of the lasers set by software. The user can set a
temperature (T) in the software, and the relative power of the
lasers is tuned by the software to illuminate the patient. Thus,
the patient looks as if he/she was illuminated by blackbody
radiation from an object with the temperature "T". Additionally, in
some embodiments, the user can input any source spectrum
characteristics, and the software will tune the lasers to match the
desired spectrum.
[0018] FIG. 1A is a block diagram of endoscope system 100, in
accordance with an embodiment of the disclosure. Endoscope system
100 includes: endoscope body 102; fiber optic cable 104; control
logic 108; light controller 110; light source 112; and computer
system 114 (including data input/output 116, and power input 118).
In endoscope system 100, light source 112 includes a plurality of
light emitters and is optically coupled to a first end of fiber
optic cable 104. Each light emitter in light source 112 emits a
distinct bandwidth of light--depicted as the five photons with five
different energies exiting the distal (second) end of fiber optic
cable 104. Control logic 108 is electrically coupled to the
plurality of light emitters to control an emission intensity of
each light emitter in the plurality of light emitters. As will be
discussed in FIG. 1B, the light output from a second end of fiber
optic cable 104 mimics a blackbody emission spectrum to the human
eye.
[0019] In the depicted embodiment, control logic 108 is coupled to
receive user input (from computer system 114) and, in response to
the user input, independently change the emission intensity of each
light emitter in the plurality of light emitters. However, in a
different embodiment, user instructions may be directly input into
the endoscope (not an attached computer system 114). Although the
illustrated embodiment shows endoscope body 102 hardwired to
computer system 114, in other embodiments endoscope body 102 may
have its own onboard computer system 114 and interface.
[0020] Although not depicted to avoid obscuring certain aspects,
endoscope system 100 may have a lens system for transmitting images
from an objective lens to the endoscope user (this may include a
relay lens system or a bundle of fiber optics). Endoscope system
100 may also have one or more mechanical actuators to guide
insertion of fiber optic cable 104, and maneuver fiber optic cable
104 through the body. Control logic 108 (e.g., a microcontroller)
is disposed in the system and electrically coupled to the plurality
of light emitters. The controller includes logic that when executed
by the controller causes the controller to perform a myriad of
operations. For example, in addition to controlling light output,
control logic 108 may be able to control any of the aforementioned
pieces of device architecture (e.g., lens system, image sensors,
mechanical actuators, etc.). Control logic 108 may be able to
precisely control the distances between lenses to focus an image
captured by the endoscope, or manipulate the body of fiber optic
cable 104 with the one or more mechanical actuators.
[0021] FIG. 1B shows an example endoscope emission spectrum 120 and
a corresponding user-observed blackbody emission spectrum 122, in
accordance with an embodiment of the disclosure. In the depicted
embodiment, endoscope emission spectrum 120 and user-observed
blackbody emission spectrum 122 have been superimposed on the same
graph; this is for comparison purposes only. Both spectra are not
drawn to scale.
[0022] As illustrated, endoscope emission spectrum 120 includes
five discrete emission peaks. To achieve the five peaks, five
lasers are directed into a fiber. By tuning the relative power of
the lasers, a scene with color that approximates user-observed
blackbody emission spectrum 122 can be rendered. The depicted
embodiment may contain, for example, five lasers, with center
wavelengths of 415 nm, 462 nm, 520 nm, 575 nm, and 635 nm. All
lasers may have a bandwidth of 1 nm. These five laser emission
peaks may resemble user-observed blackbody emission spectrum 122
(which is similar to a 6,500.degree. K blackbody emission
spectrum).
[0023] FIG. 2 illustrates an endoscopic light emitter 200, in
accordance with an embodiment of the disclosure. As shown,
endoscopic light emitter 200 includes: fiber optic cable 204, light
source 212 (including the plurality of light emitters 209), and
control logic 208. Plurality of light emitters 209 includes five
lasers: laser 231, laser 233, laser 235, laser 237, and laser 239.
Each of the plurality of light emitters 209 is optically coupled to
fiber optic cable 204, and individually electrically coupled to
control logic 208. Plurality of light emitters 209 each emit a
discrete wavelength of light. Laser 231 emits the shortest
wavelength of light, laser 233 emits the second shortest wavelength
of light, laser 235 emits a longer wavelength of light than laser
233, laser 237 emits the second longest wavelength of light, and
laser 239 emits the longest wavelength of light. The emission
intensity or duty cycle (ratio of on-time to off-time) may be
varied to output different emission spectra. For example, the
relative intensity (or on time) of laser 231 may be greater when
emulating higher temperature (blue-shifted) blackbody emission
spectra. Conversely, the relative intensity (or on time) of laser
239 may be greater when emulating lower temperature (red-shifted)
blackbody emission spectra.
[0024] Although the embodiment depicted in FIG. 2 shows five
lasers, in other embodiments plurality of light emitters 209 may
have any number of light sources including lasers and/or light
emitting diodes. Further, the lasers depicted in FIG. 2 emit
relatively monochromatic light (e.g., light with a bandwidth of
less than 1 nm). However, in other embodiments, the bandwidth of
plurality of light emitters 209 may be larger (on the order of 5 nm
or more). In some embodiments, fiber optic cable 204 may include
cladding to promote total internal reflection (e.g., the cladding
may include a reflective metal, or a material with a lower index of
refraction than the bulk of fiber optic cable 204) or contain
multiple fibers. An image sensor may be coupled to the distal end
of the fiber optic cable 204, or an image sensor may be contained
in the body of the endoscope, and the fiber optic cable 204 may be
used to relay image light back to the image sensor.
[0025] FIGS. 3A-3I illustrate black body emission spectra (left)
and corresponding endoscopic emission spectra (right) ranging from
1,500 to 10,000.degree. K, in accordance with several embodiments
of the disclosure. Each spectrum depicted is merely one example of
many possible emission spectra. All of the endoscopic emission
spectra depicted here include five separate light sources (e.g.,
laser diodes, light emitting diodes, gas lasers, etc.). In all of
these embodiments, a user may input a temperature of blackbody
emission, and the endoscope will output an endoscopic emission
spectrum that resembles the blackbody emission spectrum (to the
human eye). In other words, the endoscope's discrete emission peaks
can be tuned to trick the human eye into seeing a blackbody
emission spectrum or other continuous spectrum, such as a phosphor
spectrum.
[0026] FIG. 3A shows a 1,500.degree. K blackbody emission spectrum
301, and the corresponding endoscopic emission spectrum 303. The
relatively low-temperature blackbody spectrum is red-shifted.
Accordingly, only three low-energy endoscopic emission peaks are
used to approximate blackbody emission spectrum 301. The intensity
of these peaks increase monotonically in order of decreasing
wavelength.
[0027] FIG. 3B shows a 2,000.degree. K blackbody emission spectrum
305, and the corresponding endoscopic emission spectrum 307.
Similarly to FIG. 3A, the relatively low-temperature blackbody
spectrum is red-shifted. Thus, only four low-energy endoscopic
emission peaks are used to approximate blackbody emission spectrum
307. The intensity of these peaks increase monotonically in order
of decreasing wavelength.
[0028] FIG. 3C shows a 2,500.degree. K blackbody emission spectrum
309, and the corresponding endoscopic emission spectrum 311. At
2,500.degree. K blackbody emission spectrum 309 starts to
blue-shift but is still red-dominant. Accordingly, the lowest
energy peak still has the largest intensity, the second lowest
energy peak has the second largest intensity, and the middle peak
has a lower intensity than the second lowest energy peak. The
second highest energy peak has the lowest intensity, and the
highest energy peak has the fourth largest intensity.
[0029] FIG. 3D shows a 3,000.degree. K blackbody emission spectrum
313, and the corresponding endoscopic emission spectrum 315. Here,
despite the blackbody emission spectrum 313 blue-shifting relative
to the 2,500.degree. K spectrum, only four of the five lasers are
used to form the corresponding endoscopic emission spectrum 315. As
shown, the four lowest energy lasers are used to emit the spectrum,
and the intensity of each emission peak increases monotonically in
order of decreasing wavelength.
[0030] FIG. 3E shows a 4,000.degree. K blackbody emission spectrum
317, and the corresponding endoscopic emission spectrum 319.
Blackbody emission spectrum 317 continues to blue-shift, but is
still red dominant. Accordingly, endoscopic emission spectrum 319
includes all five laser emission peaks. The highest energy peak has
the second lowest intensity, the second highest energy peak has the
lowest intensity, the middle energy peak has the third largest
intensity, the second lowest energy peak has the second largest
intensity, and the lowest energy peak has the largest
intensity.
[0031] FIG. 3F shows a 6,000.degree. K blackbody emission spectrum
321, and the corresponding endoscopic emission spectrum 323. At
6000.degree. K, blackbody emission spectrum 321 shows a dramatic
blue-shift. To match this shift, the highest energy (lowest
wavelength) endoscopic emission peak intensity is at least two
times larger than the other peaks. However, the second highest
energy peak intensity has a lower intensity than all other peaks.
The three lowest energy peak intensities are roughly the same size,
but the middle peak (second to lowest energy) is slightly smaller
than the other two peaks.
[0032] FIG. 3G shows a 6,500.degree. K blackbody emission spectrum
325, and the corresponding endoscopic emission spectrum 327. At
6,500.degree. K blackbody emission spectrum 325 resembles the solar
spectrum. It is prominently blue-shifted. The highest energy peak
intensity is the largest, the second highest energy peak has the
smallest peak intensity, the middle energy peak intensity is larger
than the second highest energy peak intensity, and the second
lowest energy peak has roughly the same peak intensity as the
second highest energy peak intensity. Lastly, the lowest energy
peak has roughly the same peak intensity as the middle energy
peak.
[0033] FIG. 3H shows an 8,000.degree. K blackbody emission spectrum
329, and the corresponding endoscopic emission spectrum 331. At
8,000.degree. K, the blackbody emission spectrum 329 is greatly
blue-shifted. Endoscopic emission spectrum 331 is also
blue-shifted, with the highest energy peak having the greatest
intensity, the second highest energy peak having a lower intensity
then the highest energy peak, the third highest energy peak having
roughly the same intensity as the second highest energy peak, the
second lowest energy peak having the lowest intensity, and the
lowest energy peak having the second lowest intensity.
[0034] FIG. 3I shows a 10,000.degree. K blackbody emission spectrum
333, and the corresponding endoscopic emission spectrum 335.
Blackbody emission spectrum 333 is the most blue-shifted spectrum
depicted. Thus, endoscopic emission spectrum 335 is also highly
blue-shifted. The highest energy peak is approximately twice as
large as every other peak. The next two highest energy peaks are
approximately half the size of the highest energy peak, and the two
lowest energy peaks are approximately the same size and have a
lower intensity than the previous two peaks.
[0035] One skilled in the art will observe several trends
associated with the above blackbody emission spectra, and their
corresponding endoscopic emission spectra: (1) when the temperature
of the blackbody emission spectrum is less than 2,500.degree. K the
plurality of light emitters emit a monotonically increasing
spectrum of light (where the light emitter in the plurality of
light emitters with the shortest wavelength emission spectrum has
the smallest amplitude, and the light emitter in the plurality of
light emitters with the longest wavelength emission spectrum has a
largest amplitude); (2) when the temperature of the blackbody
emission spectrum is less than 4,000.degree. K, the light emitter
in the plurality of light emitters with the longest wavelength
emission spectrum has the largest amplitude; and (3) when the
temperature of the blackbody emission spectrum is greater than
4,000.degree. K, the light emitter in the plurality of light
emitters with the shortest wavelength emission spectrum has the
largest amplitude.
[0036] FIG. 4 illustrates a user creating an endoscope emission
spectrum, in accordance with an embodiment of the disclosure. As
shown, the light emission mode is selected by the user via
inputting parameters of a custom continuous emission spectrum into
a tablet (or other electronic device). In the depicted embodiment,
the user draws the emission spectrum on the screen of a tablet with
his/her finger. The tablet wirelessly communicates to endoscope
400, and endoscope 400 adjusts its emission spectra to match the
spectra drawn on the tablet. One skilled in the art will appreciate
that while the illustrated embodiment involves a person drawing the
desired spectra on a tablet, any number of other methods for
defining a continuous emission spectra may be used. For example,
emission parameters may simply be entered into a table, or the
relative peak intensity may be increased/decreased with toggles.
Alternatively, a picture may be taken of a scene under a certain
kind of illumination, and the tablet may analyze the spectra and
adjust the output of endoscope 400 accordingly. Further, any
computer system (not just a tablet) may be used to communicate with
endoscope 400 either wirelessly, by wire, or other electronic
communication method.
[0037] Also shown in FIG. 4 is a color checker (a series of squares
with idealized colors) which, in some embodiments, may be a
"Macbeth" color checker. The color checker includes colors that are
meant to represent a range of colors seen in photographs. In one
embodiment, selecting a light emission mode may include determining
the colors in a color checker under a desired illumination, and
generating endoscopic spectral output to match the desired
illumination mode. The color checker can be imaged under a
reference illuminant (such as a blackbody at 6500.degree. K), and
then imaged again under a custom light source. The colors under the
custom light source can be compared with the colors under the
reference source to see how close the output of the custom source
is to the reference. By doing this, endoscope 400 can simulate the
desired custom illumination mode. In one embodiment, imaging the
color checker may be accomplished with a camera in the tablet (or
any other camera device such as a cell phone camera, computer
camera, or the like). Alternatively, rather than using a color
checker to set the desired spectral output, the endoscope operator
could also set the emitted spectrum to enhance the color of a
particular organ. This may make diagnosis and treatment easier. For
example, a tumor may look different from healthy tissue under
different types of light; the endoscope user could adjust the
spectra to emit predominantly this diagnostic wavelength of
light.
[0038] To perform the calculations discussed above, and determine
the color of an object (or square in the color checker) the tablet
or other computer must calculate the color of an object in XYZ
space. The illuminance spectrum ("I(.lamda.)") first has to be
multiplied by the color-specific reflectivity spectrum
("R(.lamda.), G(.lamda.), B(.lamda.)") of the object. This spectrum
is multiplied by the appropriate curve (x(.lamda.) for the X value
of the color, y(.lamda.) for the Y value of the color, and
z(.lamda.) for the Z value of the color), and then integrated (see
equations 1, 2, and 3).
X=.intg.I(.lamda.)R(.lamda.)x(.lamda.)d.lamda. Equation 1
Y=.intg.I(.lamda.)G(.lamda.)y(.lamda.)d.lamda. Equation 2
Z=.intg.I(.lamda.)B(.lamda.)z(.lamda.)d.lamda. Equation 3
[0039] In the representation of color, there are two primary
concepts: "colorfulness" (i.e., the amount of color) and
"luminosity" (i.e., the brightness of the color). It takes two
terms to represent the colorfulness and one term to represent the
luminosity. "Colorfulness" may be determined by calculating u' and
v' using X, Y, and Z (see equations 4 and 5).
u'=4X/(X+15Y+3Z) Equation 4
v'=9Y/(X+15Y+3Z) Equation 5
[0040] When comparing the color to a reference illuminant, we can
calculate .DELTA.(u'v') (see equation 6).
.DELTA.(u'v')= ((u'-u'.sub.ref).sup.2+(v'-v'.sub.ref).sup.2)
Equation 6
[0041] Ideally .DELTA.(u'v').ltoreq.0.030. In this range, the human
eye has difficulty perceiving the difference between the colors. In
other words, the optimization seeks to minimize the sum (or some
other linear combination) of the difference between the color of a
tile (or other color reference) under broadband normal illumination
(e.g., blackbody illumination at 6500.degree. K) and the color of
that same tile under illumination from the set of lasers described
here.
[0042] FIG. 5 illustrates method 500 of endoscopic illumination, in
accordance with an embodiment of the disclosure. The order in which
some or all of process blocks 501-507 appear in method 500 should
not be deemed limiting. Rather, one of ordinary skill in the art
having the benefit of the present disclosure will understand that
some of method 500 may be executed in a variety of orders not
illustrated, or even in parallel.
[0043] Block 501 shows selecting a light emission mode from a
plurality of light emission modes. In one embodiment, the light
emission mode is any one of the endoscopic emission spectrums
corresponding to a blackbody emission spectrum depicted in FIGS.
3A-3I. In other embodiments, the user may select, trace, or input a
custom emission spectrum (see e.g., FIG. 4).
[0044] Block 503 illustrates emitting light from a plurality of
light emitters in response to the light emission mode selected. In
one embodiment, each light emitter in the plurality of light
emitters emits a distinct bandwidth of the light. The bandwidth of
light emitted by most light emitters in the plurality of light
emitters may be less than 5 nm. In other embodiments, the bandwidth
may be appreciably smaller, such as 1 nm or less.
[0045] Block 505 depicts transporting the light through a fiber
optic cable; a first end of the fiber optic cable is optically
coupled to the plurality of light emitters. In some embodiments,
using lasers as the light source provides for extremely efficient
light coupling to the fiber optic cable (relative to other white
light sources).
[0046] Block 507 shows out-coupling the light from a second end of
the fiber optic cable, and the light output from the second end of
the fiber optic cable mimics a continuous emission spectrum to the
human eye. In one embodiment, the light output from the second end
of the fiber optic cable mimics a blackbody emission spectrum by
having a .DELTA.(u'v').ltoreq.0.030 from the blackbody emission
spectrum, in a CIELUV color space.
[0047] The above description of illustrated embodiments of the
invention, including what is described in the Abstract, is not
intended to be exhaustive or to limit the invention to the precise
forms disclosed. While specific embodiments of, and examples for,
the invention are described herein for illustrative purposes,
various modifications are possible within the scope of the
invention, as those skilled in the relevant art will recognize.
[0048] These modifications can be made to the invention in light of
the above detailed description. The terms used in the following
claims should not be construed to limit the invention to the
specific embodiments disclosed in the specification. Rather, the
scope of the invention is to be determined entirely by the
following claims, which are to be construed in accordance with
established doctrines of claim interpretation.
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