Spectral image acquisition apparatus and light reception wavelength acquisition method

Patent metadata

Field	Value
Publication number	US-9857221-B2
Application number	US-201514813472-A
Country	US
Kind code	B2
Filing date	Jul 30, 2015
Priority date	Jul 31, 2014
Publication date	Jan 2, 2018
Grant date	Jan 2, 2018

Abstract

A spectral camera includes a wavelength variable interference filter, an imaging unit having a plurality of light receiving elements arranged in a two-dimensional array configuration, and a wavelength acquisition unit which acquires center wavelengths of light beams received by the light receiving elements in accordance with signal values output from the light receiving elements when reference light is received by the imaging unit. Light amounts of the reference light corresponding to different wavelength components in a certain wavelength range are uniform in a plane, and different signal values are acquired when light beams of the different wavelength components are received by the light receiving elements.

First claim

What is claimed is:

1. A spectral image acquisition apparatus comprising:
a light source that is configured to emit a reference light having a plurality of wavelengths, light amounts of the reference light being substantially uniform in a plane which intersects with a light axis of the reference light;
a spectral filter that is configured to receive the reference light so as to transmit a transmitted light having of the plurality of wavelengths of the reference light in a predetermined wavelength range, the spectral filter having a pair of reflection films, the pair of reflection films having in-plane variation therebetween;
an image sensor that is configured with a plurality of light receiving elements and that is configured to receive the transmitted light, the image sensor configured to output different signals having different signal values; and
a processor that is configured to acquire a center wavelength of the transmitted light individually incident on each of the plurality of light receiving elements in accordance with the different signal values output from the plurality of light receiving elements,
wherein when each of the plurality of light receiving elements of the image sensor receives each of the plurality of wavelengths of the reference light in the predetermined wavelength range, respectively, the plurality of light receiving elements of the image sensor output the different signals having the different signal values corresponding to different wavelength components of the plurality of wavelengths, and
the different signal values include values corresponding to the in-plane variation of the pair of reflection films.

2. The spectral image acquisition apparatus according to claim 1 , further comprising:
a fixed filter that is in an upstream side to the spectral filter, that is disposed on a light path of light incident on the image sensor, and that is configured to have different light transmittances according to the plurality of wavelengths in the predetermined wavelength range.

3. The spectral image acquisition apparatus according to claim 1 ,
wherein the light source is configured to emit the reference light having the plurality of wavelengths, the plurality of wavelengths have different light amounts depending on the different wavelength components in the predetermined wavelength range.

4. The spectral image acquisition apparatus according to claim 1 ,
wherein the plurality of light receiving elements in the image sensor have different sensitivities from each other for the different wavelength components.

5. The spectral image acquisition apparatus according to claim 1 ,
wherein when a wavelength of the transmitted light is changes, a value of the different signal values monotonically changes relative to the wavelength of the transmitted light.

6. The spectral image acquisition apparatus according to claim 5 , further comprising:
a fixed filter that is in an upstream side to the spectral filter, that is disposed on a light path of light incident on the image sensor, and that is formed by laminating Ag and Al 2 O 3 on a glass substrate thereof.

7. The spectral image acquisition apparatus according to claim 1 ,
wherein the processor is configured to change a wavelength of the transmitted light from the spectral filter,
the processor is configured to generate, in accordance with light amounts of the transmitted light in which the plurality of wavelengths have substantially same wavelengths received by the plurality of light receiving elements, a spectral image corresponding to substantially the same wavelengths, and
wherein the spectral filter is configured to change the wavelength of the transmitted light.

8. The spectral image acquisition apparatus according to claim 7 ,
wherein the processor is configured to measure spectral spectra of the transmitted light received by the plurality of light receiving elements.

9. The spectral image acquisition apparatus according to claim 8 ,
wherein the processor is configured to acquire the light amounts of the transmitted light in which the plurality of wavelengths have substantially the same wavelengths received by the plurality of light receiving elements in accordance with the spectral spectra of the transmitted light received by the plurality of light receiving elements, and the processor is configured to generate the spectral image corresponding to substantially the same wavelengths.

10. The spectral image acquisition apparatus according to claim 1 ,
wherein the processor is configured to acquire incident angles of the transmitted light individually incident on each of the plurality of light receiving elements in accordance with the center wavelength of the transmitted light individually received by each of the plurality of light receiving elements.

11. The spectral image acquisition apparatus according to claim 1 ,
wherein the spectral filter is a wavelength variable interference filter including a pair of reflection films which face and is spaced apart to each other with an air gap and an actuator that is configured to change a gap distance between the pair of reflection films.

12. A light reception wavelength acquisition method employed in a spectral image acquisition apparatus, the light spectral image acquisition apparatus including:
a light source that is configured to emit a reference light having a plurality of wavelengths, light amounts of the reference light being substantially uniform in a plane which intersects with a light axis of the reference light;
a spectral filter that is configured to receive the reference light so as to transmit a transmitted light having a predetermined wavelength selected from the plurality of wavelengths of the reference light and that is configured to change the predetermined wavelength, the spectral filter having a pair of reflection films, the pair of reflection films having in-plane variation therebetween; and
an image sensor that is configured with a plurality of light receiving elements and that is configured to receive the transmitted light which is spectrally dispersed by the spectral filter, the light reception wavelength acquisition method comprising:

causing the image sensor to receive the transmitted light from the spectral filter;
providing a plurality of signals output by the plurality of light receiving elements when the image sensor receives the transmitted light; and
acquiring a center wavelength of the transmitted light individually incident on each of the plurality of light receiving elements in accordance with different signal values of the plurality of signals output from the plurality of light receiving elements,
wherein when each of the plurality of light receiving elements of the image sensor receives each of the plurality of wavelengths of the reference light in a predetermined wavelength range, respectively, the plurality of light receiving elements of the image sensor output the plurality of signals having the different signal values corresponding to different wavelength components of the plurality of wavelengths, and
the different signal values include values corresponding to the in-plane variation of the pair of reflection films.

13. A spectral image acquisition apparatus comprising:
a light source that is configured to emit a reference light having a plurality of wavelengths, light amounts of the reference light being substantially uniform in a plane which intersects with a light axis of the reference light;
a spectral filter that is configured to receive the reference light so as to transmit a transmitted light having of the plurality of wavelengths of the referenc

Assignees

• Seiko Epson Corp

Inventors

• Matsushita Tomonori

Classifications

• G01J3/0256

  Compact construction · CPC title

• G01J3/0213 Primary

  using attenuators · CPC title

• G01J2003/2826

  Multispectral imaging, e.g. filter imaging · CPC title

• G01J3/26

  using multiple reflection, e.g. Fabry-Perot interferometer, variable interference filters · CPC title

• G01J2003/2813

  2D-array · CPC title