COMPACT LIGHT SENSOR

• US 20190149749A1
• Filed: 12/19/2018
• Published: 05/16/2019
• Est. Priority Date: 03/21/2014
• Status: Active Grant

• Current Assignee: Hypermed Imaging Incorporated
• Original Assignee: Hypermed Imaging Incorporated
• Inventors: Darty, Mark Anthony, Tilleman, Michael, Meenen, Peter, Yudovsky, Dmitry
• Granted Patent: US 10,652,481 B2
• Time in Patent Office: Days
• CPC Class Codes: G01J 2003/106 the two sources being alternating or selectable, e.g. in two ranges or line:continuum
• CPC Class Codes: G01J 2003/1213 Filters in general, e.g. dichroic, band
• CPC Class Codes: G01J 2003/2826 Multispectral imaging, e.g. filter imaging
• CPC Class Codes: G01J 3/0205 Optical elements not provided otherwise, e.g. optical manifolds, diffusers, windows
• CPC Class Codes: G01J 3/0208 using focussing or collimating elements, e.g. lenses or mirrors; performing aberration correction
• CPC Class Codes: G01J 3/0272 Handheld
• CPC Class Codes: G01J 3/0278 Control or determination of height or angle information for sensors or receivers
• CPC Class Codes: G01J 3/0283 using a charging unit
• CPC Class Codes: G01J 3/0289 Field-of-view determination; Aiming or pointing of a spectrometer; Adjusting alignment; Encoding angular position; Size of measurement area; Position tracking
• CPC Class Codes: G01J 3/0291 Housings; Spectrometer accessories; Spatial arrangement of elements, e.g. folded path arrangements
• CPC Class Codes: G01J 3/0294 Multi-channel spectroscopy
• CPC Class Codes: G01J 3/10 Arrangements of light sources specially adapted for spectrometry or colorimetry
• CPC Class Codes: G01J 3/108 for measurement in the infrared range
• CPC Class Codes: G01J 3/2823 Imaging spectrometer
• CPC Class Codes: G01J 3/36 Investigating two or more bands of a spectrum by separate detectors
• CPC Class Codes: G06T 2207/10016 Video; Image sequence
• CPC Class Codes: H04N 23/11 for generating image signals from visible and infrared light wavelengths
• CPC Class Codes: H04N 23/55 Optical parts specially adapted for electronic image sensors; Mounting thereof
• CPC Class Codes: H04N 23/56 provided with illuminating means
• CPC Class Codes: H04N 23/74 by influencing the scene brightness using illuminating means

Abstract

Provided are methods and systems for concurrent imaging at multiple wavelengths. In one aspect, a hyperspectral/multispectral imaging device includes a lens configured to receive light backscattered by an object, a plurality of photo-sensors, a plurality of bandpass filters covering respective photo-sensors, where each bandpass filter is configured to allow a different respective spectral band to pass through the filter, and a plurality of beam splitters in optical communication with the lens and the photo-sensors, where each beam splitter splits the light received by the lens into a plurality of optical paths, each path configured to direct light to a corresponding photo-sensor through the bandpass filter corresponding to the respective photo-sensor.

Claims

1. An imaging device, comprising:

a lens disposed along an optical axis and configured to receive light;

a plurality of photo-sensors;

an optical path assembly comprising a plurality of beam splitters in optical communication with the lens and the plurality of photo-sensors; and

a plurality of multi-bandpass filters, wherein each respective multi-bandpass filter in the plurality of multi-bandpass filters covers a corresponding photo-sensor in the plurality of photo-sensors thereby selectively allowing a different corresponding spectral band of light, from the light received by the lens and split by the plurality of beam splitters, to pass through to the corresponding photo-sensor;

wherein

each respective beam splitter in the plurality of beam splitters is configured to split the light received by the lens into at least two optical paths,

a first beam splitter in the plurality of beam splitters is in direct optical communication with the lens and a second beam splitter in the plurality of beam splitters is in indirect optical communication with the lens through the first beam splitter, and

the plurality of beam splitters collectively split light received by the lens into a plurality of optical paths, wherein each respective optical path in the plurality of optical paths is configured to direct light to a corresponding photo-sensor in the plurality of photo-sensors through the respective multi-bandpass filter covering the corresponding photo-sensor.

2. The imaging device of claim 1, wherein the plurality of multi-bandpass filters are dual bandpass filters.

3. The imaging device of claim 1, further comprising a first light source and a second light source, wherein the first light source and the second light source are configured to shine light so that a portion of the light is backscattered by the object and received by the lens.

4. The imaging device of claim 3, wherein

the first light source emits light that is substantially limited to a first spectral range, and

the second light source emits light that is substantially limited to a second spectral range.

5. The imaging device of claim 4, wherein

the first light source is a first multi-spectral light source covered by a first bandpass filter, wherein the first bandpass filter substantially blocks all light emitted by the first light source other than the first spectral range, and

the second light source is a second multi-spectral light source covered by a second bandpass filter, wherein the second bandpass filter substantially blocks all light emitted by the second light source other than the second spectral range.

6. The imaging device of claim 5, wherein the first multi-spectral light source is a first white light emitting diode and the second multi-spectral light source is a second white light emitting diode.

7. The imaging device of claim 4, wherein each respective multi-bandpass filter in the plurality of multi-bandpass filters is configured to selectively allow light corresponding to either of two discrete spectral bands to pass through to the corresponding photo-sensor.

8. The imaging device of claim 7, wherein:

a first of the two discrete spectral bands corresponds to a first spectral band that is represented in the first spectral range and not in the second spectral range; and

a second of the two discrete spectral bands corresponds to a second spectral band that is represented in the second spectral range and not in the first spectral range.

9. The imaging device of claim 4, wherein the first spectral range is substantially non-overlapping with the second spectral range.

10. The imaging device of claim 4, wherein the first spectral range is substantially contiguous with the second spectral range.

11. The imaging device of claim 4, wherein

the first spectral range comprises 520 nm, 540 nm, 560 nm and 640 nm wavelength light and does not include 580 nm, 590 nm, 610 nm and 620 nm wavelength light, and

the second spectral range comprises 580 nm, 590 nm, 610 nm and 620 nm wavelength light and does not include 520 nm, 540 nm, 560 nm and 640 nm wavelength light.

12. The imaging device of claim 1, further comprising a plurality of beam steering elements, each respective beam steering element configured to direct light in a respective optical path to a respective photo-sensor, of the plurality of photo-sensors, corresponding to the respective optical path.

13. The imaging device of claim 12, wherein each one of a first subset of the plurality of beam steering elements is configured to direct light in a first direction that is perpendicular to the optical axis, and each one of a second subset of the plurality of beam steering elements is configured to direct light in a second direction that is perpendicular to the optical axis and opposite to the first direction.

14. The imaging device of claim 4, further comprising a controller configured to capture a plurality of images from the plurality of photo-sensors by performing a method including:

(A) illuminating the object a first time using the first light source;

(B) capturing a first set of images with the plurality of photo-sensors during the illuminating (A), wherein the first set of images includes, for each respective photo-sensor in the plurality of photo-sensors, an image corresponding to a first spectral band transmitted by the corresponding multi-bandpass filter, wherein the light falling within the first spectral range includes light falling within the first spectral band of each multi-bandpass filter in the plurality of multi-bandpass filters;

(C) extinguishing the first light source;

(D) illuminating the object a second time using the second light source; and

(E) capturing a second set of images with the plurality of photo-sensors during the illuminating (D), wherein the second set of images includes, for each respective photo-sensor in the plurality of photo-sensors, an image corresponding to a second spectral band transmitted by the corresponding multi-bandpass filter, wherein the light falling within the second spectral range includes light falling within the second spectral band of each multi-bandpass filter in the plurality of multi-bandpass filters.

15. The imaging device of claim 14, wherein

each respective photo-sensor in the plurality of photo-sensors is a pixel array that is controlled by a corresponding shutter mechanism that determines an image integration time for the respective photo-sensor, and

a first photo-sensor in the plurality of photo-sensors is independently associated with a first integration time for use during the capturing (B) and a second integration time for use during the capturing (E), wherein the first integration time is independent of the second integration time.

16. The imaging device of claim 14, wherein

each respective photo-sensor in the plurality of photo-sensors is a pixel array that is controlled by a corresponding shutter mechanism that determines an image integration time for the respective photo-sensor,

a duration of the illuminating (A) is determined by a first maximum integration time associated with the plurality of photo-sensors during the capturing (B), wherein an integration time of a first photo-sensor in the plurality of photo-sensors is different than an integration time of a second photo-sensor in the plurality of photo-sensors during the capturing (B),

a duration of the illuminating (D) is determined by a second maximum integration time associated with the plurality of photo-sensors during the capturing (E), wherein an integration time of the first photo-sensor is different than an integration time of the second photo-sensor during the capturing (E), and

the first maximum integration time is different than the second maximum integration time.

17. The imaging device of claim 1, wherein each beam splitter in the plurality of beam splitters exhibits a ratio of light transmission to light reflection of about 50:

50.

18. The imaging device of claim 17, wherein the beam splitters are wavelength-independent beam splitters.

19. The imaging device of claim 3, wherein the first light source is in a first lighting assembly and the second light source is in a second lighting assembly separate from the first lighting assembly.

20. The imaging device of claim 14, wherein each image in the plurality of images is a multi-pixel image of a location on the object, the method further comprising:

(F) combining each image in the plurality of images, on a pixel by pixel basis, to form a composite image.

21. The imaging device of claim 14, wherein,

the imaging device is portable and powered independent of a power grid during the illuminating (A) and the illuminating (D),

the first light source provides at least 80 watts of illuminating power during the illuminating (A),

the second light source provides at least 80 watts of illuminating power during the illuminating (D), and

the imaging device further comprises a capacitor bank in electrical communication with the first light source and the second light source, wherein a capacitor in the capacitor bank has a voltage rating of at least 2 volts and a capacitance rating of at least 80 farads.

22. The imaging device of claim 7, wherein the two discrete bands of a multi-bandpass filter in the plurality of multi-bandpass filters are separated by at least 60 nm.

23. The imaging device of claim 14, wherein the imaging device is portable and electrically independent of a power grid during the illuminating (A) and the illuminating (D), and wherein the illuminating (A) occurs for less than 300 milliseconds and the illuminating (D) occurs for less than 300 milliseconds.

24. The imaging device of claim 1, further comprising:

a first circuit board positioned on a first side of the optical path assembly, wherein a first photo-sensor and a third photo-sensor in the plurality of photo-sensors are coupled to the first circuit board; and

a second circuit board positioned on a second side of the optical path assembly opposite to the first side, wherein the second circuit board is substantially parallel with the first circuit board, wherein a second photo-sensor and a fourth photo-sensor in the plurality of photo-sensors are coupled to the second circuit board, and

wherein;

the first beam splitter is configured to split light received from the lens into a first optical path and a second optical path, wherein the first optical path is substantially collinear with the optical axis, and the second optical path is substantially perpendicular to the optical axis,

the second beam splitter is configured split light from the first optical path into a third optical path and a fourth optical path, wherein the third optical path is substantially collinear with the first optical path, and the fourth optical path is substantially perpendicular to the optical axis,

a third beam splitter in the plurality of beam splitters is configured to split light from the second optical path into a fifth optical path and a sixth optical path, wherein the fifth optical path is substantially collinear with the second optical path, and the sixth optical path is substantially perpendicular to the second optical path, and wherein

the optical path assembly further comprises;

a first beam steering element configured to deflect light from the third optical path perpendicular to the third optical path and onto the first photo-sensor coupled to the first circuit board,

a second beam steering element configured to deflect light from the fourth optical path perpendicular to the fourth optical path and onto the second photo-sensor coupled to the second circuit board,

a third beam steering element configured to deflect light from the fifth optical path perpendicular to the fifth optical path and onto the third photo-sensor coupled to the first circuit board, and

a fourth beam steering element configured to deflect light from the sixth optical path perpendicular to the sixth optical path and onto the fourth photo-sensor coupled to the second circuit board.

25. The imaging device of claim 24, wherein

a first multi-bandpass filter in the plurality of multi-bandpass filters is positioned in the third optical path between the first beam splitter and the first photo-sensor,

a second multi-bandpass filter in the plurality of multi-bandpass filters is positioned in the fourth optical path between the second beam splitter and the second photo-sensor,

a third multi-bandpass filter in the plurality of multi-bandpass filters is positioned in the fifth optical path between the third beam splitter and the third photo-sensor, and

a fourth multi-bandpass filter in the plurality of multi-bandpass filters is positioned in the sixth optical path between the fourth beam splitter and the fourth photo-sensor.

26. The imaging device of claim 24, further comprising a polarizing filter disposed along the optical axis.

27. The imaging device of claim 26, wherein the polarizing filter is adjacent to the lens and before the first beam splitter along the optical axis.

28. The imaging device of claim 24, wherein the first beam steering element is a folding prism.

29. The imaging device of claim 24, wherein each respective beam splitter and each respective beam steering element is oriented along substantially the same plane.

30. The imaging device of claim 24, wherein the first beam splitter, the second beam splitter, and the third beam splitter each exhibits a ratio of light transmission to light reflection of about 50:

50.