Photodetection apparatus including optical filter and optical detector

• US 9,976,904 B2
• Filed: 07/09/2016
• Issued: 05/22/2018
• Est. Priority Date: 07/23/2015
• Status: Active Grant

• Current Assignee: Panasonic Intellectual Property Management Co., Ltd. (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Intellectual Property Management Co., Ltd. (Panasonic Holdings Corporation)
• Inventors: Nishiwaki, Seiji
• Primary Examiner(s): BOLOGNA, DOMINIC JOSEPH
• Application Number:
  US15/206,266
• Publication Number:
  US 20170023410A1
• Time in Patent Office: 682 Days
• CPC Class Codes: G01J 2003/102 Plural sources
• CPC Class Codes: G01J 2003/104 Monochromatic plural sources
• CPC Class Codes: G01J 2003/4538 Special processing
• 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 3/0229 using masks, aperture plates, spatial light modulators or spatial filters, e.g. reflective filters
• CPC Class Codes: G01J 3/10 Arrangements of light sources specially adapted for spectrometry or colorimetry
• CPC Class Codes: G01J 3/4531 Devices without moving parts

Abstract

In one aspect, an apparatus includes a first light source that applies first light having a first wavelength as a center wavelength to an object, a second light source that applies second light having a second wavelength as a center wavelength longer than the first wavelength to the object, an optical filter that includes first and second regions and that transmits third light produced by the first and second light each passed through or reflected by the object, first and second optical detectors that determine first and second amounts, respectively, of the third light passed through the first and second regions. The transmission ranges of spectral transmission curves of the first and second regions are located between the first wavelength and the second wavelength. The spectral transmission curve of the first region has a width at half maximum different from that of the spectral transmission curve of the second region.

Claims

1. A photodetection apparatus comprising:

a first light source configured to apply a first light beam having a first wavelength as a center wavelength to an object;

a second light source configured to apply a second light beam having a second wavelength as a center wavelength longer than the first wavelength to the object;

an optical filter that includes a first region and a second region and is configured to transmit a third light beam produced by the first light beam and the second light beam each passed through or reflected by the object;

a first optical detector configured to determine a first amount of a first part of the third light beam passed through the first region; and

a second optical detector configured to determine a second amount of a second part of the third light beam passed through the second region, wherein;

a spectral transmission curve of the first region has a first center wavelength, a first transmission range and a first width at half maximum;

a spectral transmission curve of the second region has a second center wavelength, a second transmission range and a second width at half maximum;

the first and second transmission ranges are located between the first wavelength and the second wavelength; and

the first width at half maximum is different from the second width at half maximum.

2. The photodetection apparatus according to claim 1, wherein the first center wavelength is equal to the second center wavelength.

3. The photodetection apparatus according to claim 1, wherein each of the first light beam and the second light beam is a pulsed light beam.

4. The photodetection apparatus according to claim 1, wherein the first light source is configured to apply the first light beam to a target surface of the object at a certain incident angle from one side of the target surface of the object, and

the second light source is configured to apply the second light beam to the target surface of the object at the certain incident angle from another side of the target surface.

5. The photodetection apparatus according to claim 1, wherein the third light beam is an interference light beam produced by interference between the first light beam and the second light beam.

6. The photodetection apparatus according to claim 1, wherein:

a plurality of first regions are provided in the optical filter, each of the plurality of first regions being the first region,

a plurality of second regions are provided in the optical filter, each of the plurality of second regions being the second region,

a plurality of first optical detectors are provided in the photodetection apparatus, each of the plurality of first optical detectors being the first optical detector,

a plurality of second optical detectors are provided in the photodetection apparatus, each of the plurality of second optical detectors being the second optical detector,

each of the plurality of first regions and each of the plurality of second regions are alternately arranged in plan view,

each of the plurality of first optical detectors and each of the plurality of second optical detectors are alternately arranged in plan view,

each of the plurality of first regions faces at least one of the plurality of first optical detectors in plan view, and

each of the plurality of second regions faces at least one of the plurality of second optical detectors in plan view.

7. The photodetection apparatus according to claim 6, wherein the plurality of first regions are arranged in a stripe pattern or a checker board pattern in plan view.

8. The photodetection apparatus according to claim 6, further comprising processing circuitry configured to calculate, for each of the plurality of first optical detectors, a ratio between the first amount and the second amount determined by one of the plurality of second optical detectors adjacent to a corresponding one of the plurality of first optical detectors, to produce an image indicating a distribution of ratios in plan view.

9. The photodetection apparatus according to claim 6, further comprising processing circuitry configured to calculate, for each of the plurality of first optical detectors, at least one selected from the group consisting of a first proportion of the first amount to a total of the first amount and the second amount determined by one of the plurality of second optical detectors adjacent to a corresponding one of the plurality of first optical detectors and a second proportion of the second amount to the total, to produce an image indicating a distribution of at least one selected from the group consisting of the first proportion and the second proportion.

10. The photodetection apparatus according to claim 1, further comprising processing circuitry configured to calculate a ratio between the first amount and the second amount.

11. The photodetection apparatus according to claim 1, further comprising processing circuitry configured to calculate at least one selected from the group consisting of a first proportion of the first amount to a total of the first amount and the second amount and a second proportion of the second amount to the total.

12. The photodetection apparatus according to claim 1, wherein

the first center wavelength is different from the first wavelength and the second wavelength,

the second center wavelength is different from the first wavelength and the second wavelength, and

the first center wavelength and the second center wavelength are positioned between the first wavelength and the second wavelength.

13. The photodetection apparatus according to claim 1, wherein

a wavelength of the third light beam is different from the first wavelength and the second wavelength, and

the wavelength of the third light beam is positioned between the first wavelength and the second wavelength.

14. The photodetection apparatus according to claim 1, wherein

short wavelength edges of the first and second transmission ranges are longer than the first wavelength, and

long wavelength edges of the first and second transmission ranges are shorter than the second wavelength.

15. The photodetection apparatus according to claim 1, wherein

at least one of the first light beam or the second light beam passes through the object from a different side thereof.

16. A photodetection apparatus comprising:

a first light source configured to apply a first light beam having a first wavelength as a center wavelength to an object;

a second light source configured to apply a second light beam having a second wavelength as a center wavelength longer than the first wavelength to the object;

an optical filter configured to receive and optically filter a third light beam produced by the first light beam and the second light beam each passed through or reflected by the object, the optical filter having a spectral transmission curve, of which range of transmission is longer than the first wavelength and shorter than the second wavelength;

an optical detector configured to determine an amount of the third light beam passed through the optical filter; and

controlling circuitry configured to control intensity of the first light beam and intensity of the second light beam.

17. The photodetection apparatus according to claim 16, wherein each of the first light beam and the second light beam is a pulsed light beam.

18. The photodetection apparatus according to claim 16, wherein the first light source is configured to apply the first light beam to a target surface of the object at a certain incident angle from one side of the target surface, and

the second light source is configured to apply the second light beam to the target surface at the certain incident angle from another side of the target surface.

19. The photodetection apparatus according to claim 16, wherein the third light beam is an interference light beam produced by interference between the first light beam and the second light beam.

20. The photodetection apparatus according to claim 16, further comprising processing circuitry configured to calculate a ratio between the intensity of the first light beam and the intensity of the second light beam to produce an image indicating a relationship between ratios and the amount of the third light beam.

21. The photodetection apparatus according to claim 16, further comprising processing circuitry configured to calculate at least one selected from the group consisting of a first proportion of the intensity of the first light beam to a total of the intensity of the first light beam and the intensity of the second light beam and a second proportion of the intensity of the second light beam to the total to produce an image indicating a relationship between the amount of the third light beam and at least one selected from the group consisting of the first proportion and the second proportion.

22. The photodetection apparatus according to claim 16, wherein

a center wavelength of the range of transmission is different from the first wavelength and the second wavelength, and

the center wavelength of the range of transmission is positioned between the first wavelength and the second wavelength.

23. The photodetection apparatus according to claim 16, wherein

a wavelength of the third light beam is different from the first wavelength and the second wavelength, and

the wavelength of the third light beam is positioned between the first wavelength and the second wavelength.

24. The photodetection apparatus according to claim 16, wherein

a short wavelength edge of the range of transmission is longer than the first wavelength, and

a long wavelength edge of the range of transmission is shorter than the second wavelength.

25. The photodetection apparatus according to claim 16, wherein

at least one of the first light beam or the second light beam passes through the object from a different side thereof.

26. An apparatus comprising:

a first light source for emitting a first light beam having a first wavelength as a center wavelength;

a second light source for emitting a second light beam having a second wavelength as a center wavelength;

an optical filter including a first region and a second region;

a first optical detector, provided for the first region, for determining a first amount of light passed through the first region; and

a second optical detector, provided for the second region, for determining a second amount of light passed through the second region, wherein;

a spectral transmission curve of the first region has a first center wavelength, a first transmission range and a first width at half maximum;

a spectral transmission curve of the second region has a second center wavelength, a second transmission range and a second width at half maximum;

the first and second transmission ranges are located between the first wavelength and the second wavelength; and

the first width at half maximum is different from the second width at half maximum.

27. The apparatus according to claim 26, wherein

the first center wavelength is different from the first wavelength and the second wavelength,

the second center wavelength is different from the first wavelength and the second wavelength, and

the first center wavelength and the second center wavelength are positioned between the first wavelength and the second wavelength.

28. The apparatus according to claim 26, wherein

short wavelength edges of the first and second transmission ranges are longer than the first wavelength, and

long wavelength edges of the first and second transmission ranges are shorter than the second wavelength.

29. The apparatus according to claim 26, wherein

at least one of the first light beam or the second light beam passes through the object from a different side thereof.