Spectral imaging system

• US 10,228,283 B2
• Filed: 08/14/2017
• Issued: 03/12/2019
• Est. Priority Date: 08/12/2016
• Status: Active Grant

• Current Assignee: Nicole Chin Spectral Insights Private Limited
• Original Assignee: Nicole Chin Spectral Insights Private Limited
• Inventors: Nath, Sumit, Das, Dipankar, Gerald, Suhash
• Primary Examiner(s): Decenzo, Shawn
• Application Number:
  US15/676,979
• Publication Number:
  US 20180045569A1
• Time in Patent Office: 575 Days
• 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 3/0208 using focussing or collimating elements, e.g. lenses or mirrors; performing aberration correction
• CPC Class Codes: G01J 3/14 using refracting elements, e.g. prisms G01J3/18, G01J3/26 take precedence prisms per se G02B5/04
• 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: G01J 3/45 Interferometric spectrometry
• CPC Class Codes: G01J 3/4531 Devices without moving parts

Abstract

A spectral imaging system includes a spectrometer and an optics imaging system. The spectrometer is operable for generating spectral signatures of objects from a scene. The optics imaging system is operable to generate six or more responses from the same scene. Each of the six or more responses represents different spectral content of the objects in the scene. The responses generated by the optics imaging system can be used to generate a hypercube using spectral reconstruction techniques. In an embodiment, the spectral imaging system could be implemented as part of a mobile phone.

Claims

1. An imaging system comprising:

an interferometer to generate an interference pattern from a first light beam emanating from a first scene; and

an optics sub-system to generate six or more responses from a second light beam formed by illumination of a second scene, wherein each of said six or more responses is a corresponding image of said second scene represented by different spectral content of said second light beam,

wherein said second light beam is a single beam formed by one illumination of said second scene,

wherein each response contains a respective magnitude of reflectance at a corresponding distinct wavelength band for each pixel representing said second scene,

wherein all of said six or more responses represent a same spatial area of said second scene.

2. The imaging system of claim 1, further comprising a processing block to process said interference pattern to generate a spectral signature of said first scene such that said spectral imaging system operates as a spectrometer,

said processing block to also process said reflectance magnitudes in said six or more responses to generate a hypercube by spectral reconstruction based on said six or more responses such that said spectral imaging system operates as a spectral camera,

wherein said hypercube contains, a plurality of values for each pixel of an image representing said second scene, wherein each value represents the magnitude of reflectance of the portion of the second scene corresponding to the pixel at a corresponding wavelength contained in said single illumination.

3. The imaging system of claim 2, wherein said optic sub-system comprises:

a filter to alter the intensity of one or more wavelengths from said second light beam to generate a filtered beam; and

a set of sensors to generate six responses from said filtered beam and said second light beam,

wherein some of said six responses are generated from said filtered beam, the rest of the six responses being generated from the second light beam.

4. The imaging system of claim 3, wherein said set of sensors comprise a first sensor and a second sensor,

wherein each of said first sensor and said second sensor is a RGB (red, green and blue) sensor that generates three signal streams, with the first, second and third signal streams respectively representing only red, green, and blue colors.

5. The imaging system of claim 4, further comprising:

a memory to store said spectral signature as representing a base characteristic of an object representing said first scene; and

wherein said processing block compares said spectral signature to characteristics represented by at least some of said plurality of values to determine whether said second scene deviates from said base characteristic.

6. The imaging system of claim 3, further comprising:

a beam splitter to split said second light beam from said scene into two beams, wherein a first beam of said two beams travels towards said first sensor; and

a prism to receive a second beam of said two beams and to deflect said second beam towards said second sensor.

7. The imaging system of claim 6, further comprising:

a first focusing lens disposed between said beam splitter and said first sensor to focus said first beam in a first direction on to said first sensor; and

a second focusing lens disposed between said prism and said second sensor to focus said deflected second beam in a second direction on to said second sensor,

wherein said first direction is parallel to said second direction,

wherein said first sensor and said second sensor are juxtaposed along a same plane.

10. The imaging system of claim 1, wherein said interferometer and said optics sub-system are implemented using at least one common optic component.

11. The imaging system of claim 1, wherein said spectrometer and said spectral camera are integrated into a mobile phone or a portable form factor.

8. The imaging system of 7, wherein said beam splitter is in the form of a cube, said cube containing a diagonal partially-reflecting plane to cause part of said beam of light to be reflected towards said prism in a third direction, wherein a pair of surfaces in the combination of said beam splitter and said prism are designed

to be partially reflecting surfaces to reflect at least respective portions of both of said first beam and said second beam,

wherein said respective portions are processed by said spectrometer to generate said spectral signature,

wherein other surfaces in said combination are designed not to be reflective surfaces.

9. The imaging system of claim 8, wherein said interferometer comprises:

a monochrome sensor to capture an interference pattern generated by said respective portions, wherein said processor processes said interference pattern to generate said spectral signature; and

a third focusing lens disposed between said beam splitter and said monochrome sensor to focus said respective portions onto said monochrome sensor.

12. A spectral camera system comprising:

an optics sub-system to form a plurality of beams of light from a single beam received by a single illumination of a scene, wherein each of said single beam and said plurality of beams represent said scene, wherein each of said plurality of beams contain different spectral content; and

a set of sensors, each sensor to receive a corresponding one of said plurality of beams and to generate a corresponding set of responses, said sets of responses together comprising six or more responses, wherein each response is a respective image of said scene in only a corresponding band of wavelengths, wherein each band of wavelengths is constituted of a plurality of wavelengths which are contiguous,

wherein each response contains a respective magnitude of reflectance at the corresponding band of wavelengths for each pixel representing said scene,

wherein all of said six or more responses represent a same spatial area of said scene.

13. The spectral camera system of claim 12, wherein said plurality of beams are parallel to each other, said spectral camera system further comprising a processor to generate a hypercube by spectral reconstruction based on said six or more responses,

wherein said hypercube contains a plurality of intensity values captured by each pixel of an image sensor representing said scene, wherein each value corresponds to a wavelength present in the illumination.

14. The spectral camera system of claim 13, wherein said set of sensors comprise two color sensors, each of said color sensor comprises an RGB sensor a first color sensor of said two color sensors generates a first set of three responses of band of wavelengths corresponding red (R), green (G) and blue (B) colors, and a second color sensor of said two color sensors generating a second set of three responses of band of wavelengths corresponding red (R′

), green (G′

) and blue (B′

) colors, such that the six responses are in band of wavelengths corresponding to R, G, B, R′

, G′

, B′

colors respectively,

wherein said processor processes said six responses formed by said two sensors together, said six responses being contained in said sets of responses.

15. The spectral camera system of claim 13, wherein said plurality of parallel beams contain two beams having same spectral content, wherein said optics sub-system comprises:

a beam splitter and a prism to form said two beams from said single beam;

a filter to alter the intensity of one or more wavelengths in one of said two beams to generate a filtered beam; and

a pair of focusing lenses to focus said filtered beam and the other one of said two beams on respective ones of said set of sensors.

16. The spectral camera system of claim 12, wherein a first beam of said plurality of beams is orthogonal to a second beam of said plurality of beams.

17. An imaging system comprising:

a processor;

a memory;

an interferometer to generate an interference pattern from a first light beam emanating from a first scene; and

an optics sub-system to generate six or more responses from a second light beam formed by a single illumination of a second scene, wherein each of said six or more responses is a corresponding image of said second scene represented by different spectral content of said second light beam,

wherein each response contains a respective magnitude of reflectance at a corresponding distinct wavelength band for each pixel representing said second scene,

wherein all of said six or more responses represent a same spatial area of said second scene

wherein said processing block is operable to process said interference pattern to generate a spectral signature of said first scene, said processing block operable to store, in said memory, said spectral signature as representing a base characteristic of an object representing said first scene,

wherein said processing block is operable to process said reflectance magnitudes in said six or more responses to generate a hypercube, said hypercube containing a plurality of values for each pixel of an image representing said second scene, wherein each value represents the magnitude of reflectance of the portion of the second scene corresponding to the pixel at a corresponding wavelength contained in said single illumination,

wherein said processing block compares said spectral signature to characteristics represented by at least some of said plurality of values to determine whether said second scene deviates from said base characteristic.

18. The imaging system of claim 17, wherein said optic sub-system comprises:

a filter to alter the intensity of one or more wavelengths from said second light beam to generate a filtered beam;

a set of sensors to generate six responses from said filtered beam and said second light beam.

19. The imaging system of claim 18, wherein said set of sensors comprise a first sensor and a second sensor,

wherein each of said first sensor and said second sensor is a RGB (red, green and blue) sensor that generates three signal streams, with the first, second and third signal streams respectively representing only red, green, and blue colors.

20. The imaging system of claim 19, wherein said optics sub-system further comprises:

a beam splitter to split said second light beam from said second scene into two beams, wherein a first beam of said two beams travels towards said first sensor; and

a prism to receive a second beam of said two beams and to deflect said second beam towards said second sensor.