MULTISPECTRAL IMAGING BASED ON COMPUTATIONAL IMAGING AND A NARROW-BAND ABSORPTIVE FILTER ARRAY

• US 20160245698A1
• Filed: 10/16/2014
• Published: 08/25/2016
• Est. Priority Date: 10/16/2013
• Status: Active Grant

• Current Assignee: Arizona Board of Regents (University of Arizona)
• Original Assignee: Arizona Board of Regents (University of Arizona)
• Inventors: Pau, Stanley, Ashok, Amit
• Granted Patent: US 9,823,128 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01J 2003/2806 Array and filter array
• CPC Class Codes: G01J 2003/2826 Multispectral imaging, e.g. filter imaging
• CPC Class Codes: G01J 3/28 Investigating the spectrum using colour filters G01J3/51
• CPC Class Codes: G01J 3/2803 using photoelectric array detector
• 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 3/513 having fixed filter-detector pairs

Abstract

Multispectral imaging systems are disclosed. An exemplary multispectral imager includes a narrow-band absorptive filter array and a sensor array comprising a plurality of pixels. The narrow-band absorptive filter array has a plurality of filter elements, each filter element being associated with a pixel of the sensor array. The filter elements are organized into groups of N filter elements, where N is greater than three. Each filter element absorbs one narrow band and transmits N−1 narrow bands. The group of N filter elements absorbs all N narrow bands.

Claims

1. A multispectral imager for sensing a multispectral image, comprising:

a light sensor array comprising a plurality of pixels; and

a filter array situated upstream of the light sensor array, the filter array comprising a plurality of narrow-band absorptive filter elements in which individual filter elements are associated with respective individual pixels of the light sensor array, the plurality of filter elements being organized into groups each comprising respective N filter elements, in which individual filter element i absorbs K_i respective narrow bands and transmits N−

K_i narrow bands of incident light, wherein the group of N filter elements absorbs the N narrow bands, N is greater than three, K_i is between 1 and N−

1, i is from 1 to N, and K_i is different for at least two individual filter elements.

2. The imager of claim 1, wherein respective absorption peaks of the N filter elements are within a range of 900 nanometers to 1700 nanometers.

3. The imager of claim 1, wherein at least one absorption peak of the N filter elements is within a visible spectrum.

4. The imager of claim 1, wherein at least one absorption peak of the N filter elements is within an ultraviolet spectrum

5. The imager of claim 1, wherein at least one absorption peak of the N filter elements is within an infrared spectrum.

6. The imager of claim 1, wherein one or more of the N filter elements includes an interference-type filter.

7. The imager of claim 1, wherein one or more of the N filter elements includes a color dye in a polymer matrix.

8. The imager of claim 1, wherein the group of N filter elements comprises a first and a second filter element, the first filter element including a color dye in a polymer matrix, and the second filter element including an interference-type filter.

9. A method for detecting a multispectral image, comprising:

directing light toward an array of filter elements and an array of light sensors, the array of filter elements being organized into a plurality of groups of filter elements, each group of filter elements comprising respective N filter elements in which individual filter elements are associated with a respective light sensor of the array of light sensors;

filtering the light entering the array of light sensors to an image spectrum comprising N narrow bands of spectra, N being greater than three;

at individual filter elements, absorbing one respective narrow band of the spectrum and transmitting N−

1 respective narrow bands of the spectrum such that the group of filter elements absorbs respective N narrow bands of the image spectrum; and

detecting respective intensity of light received at each light sensor.

10. The method of claim 9, wherein an overlap integral for the absorbed narrow bands of any two filter elements of the group of N filter elements is less than 0.1.

11. The method of claim 9, wherein an overlap integral for the absorbed narrow bands of any two filter elements of the group of N filter elements is less than 0.2.

12. The method of claim 9, wherein:

a respective absorption peak of each of the N filter elements is within a spectrum of interest; and

a sum of full widths at half maxima for the N filter elements is less than a range of the spectrum of interest.

13. The method of claim 12, wherein the N narrow bands corresponding to the full widths at half maxima for the respective N filter elements are non-overlapping.

14. The method of claim 9, further comprising calculating, using an interpolation algorithm, intensity of respective narrow bands of spectra reaching the light sensors associated with the groups of filter elements.

15. A camera for capturing a multispectral image, comprising:

a focusing system situated and configured to produce a focused image from light incident to the focusing system;

a light sensor array comprising a plurality of light-sensitive pixels; and

a filter array situated between the focusing system and the light sensor array, the filter array comprising a plurality of narrow-band absorptive filter elements in which individual filter elements are associated with respective individual pixels of the light sensor array, the plurality of filter elements being organized into groups comprising respective N filter elements, in which individual filter elements absorb K respective narrow bands and transmit N−

K narrow bands of incident light, the group of N filter elements absorbing all N narrow bands, wherein N is greater than three and K is between one and N−

2.

16. The camera of claim 15, wherein the group of N filter elements includes a first filter element that absorbs a first number of narrow bands and a second element that absorbs a second number of narrow bands.

17. The camera of claim 15, wherein respective absorption peaks of the N filter elements include at least one absorption peak within a visible spectrum and at least one absorption peak within an infrared spectrum.

18. The camera of claim 15, wherein respective absorption peaks of the N filter elements include at least one absorption peak within an ultraviolet spectrum.

19. The camera of claim 15, wherein each of the N narrow bands corresponding to the full widths at half maxima for the respective N filter elements is less than 2/N of a spectrum of interest.

20. The camera of claim 15, wherein the group of N filter elements comprises a first filter element including a color dye in a polymer matrix and a second filter element including an interference-type filter.