Digital holographic imaging apparatus and illumination apparatus

Patent metadata

Field	Value
Publication number	US-10649405-B2
Application number	US-201715843881-A
Country	US
Kind code	B2
Filing date	Dec 15, 2017
Priority date	Jul 7, 2015
Publication date	May 12, 2020
Grant date	May 12, 2020

Abstract

Provided is a digital holographic imaging apparatus, comprising: an illumination portion ( 10 ) having an illumination light emission surface ( 32 i ) for emitting coherent light of a specific wavelength as illumination light toward an object ( 1 ) side relative to the illumination light emission surface ( 32 i ), and a reference light emission surface ( 32 r ) for emitting the coherent light, as reference light, in a direction opposite to the illumination light; and an image sensor ( 50 ) located on the reference light emission surface ( 32 r ) side of the illumination portion ( 10 ) and imaging an interference pattern between object light having been modulated by the object ( 1 ) and passed through the illumination portion ( 10 ) and the reference light of the illumination light, the image sensor ( 50 ) having a pixel array ( 51 ) comprising two-dimensionally aligned pixels.

First claim

The invention claimed is:

1. A digital holographic imaging apparatus, comprising:
an illumination portion comprising: an illumination light emission surface for emitting, as illumination light, coherent light of a specific wavelength toward an object side; and a reference light emission surface located on the opposite side to the object side relative to the illumination light emission surface, the reference light emission surface emitting, as reference light, the coherent light in a direction opposite to the illumination light; and
an image sensor located on a reference light emission surface side of the illumination portion, the image sensor imaging an interference pattern between object light and the reference light, the object light being part of the illumination light having been modulated by the object and passed through the illumination portion, and the image sensor having a pixel array including two-dimensionally arranged pixels,
wherein:
the illumination portion further includes:
a light source portion that emits the coherent light; and
a plane optical waveguide portion that propagates the coherent light from the light source portion, wherein the plane optical waveguide portion includes a first material having a first refractive index and a second material having a second refractive index, wherein the first refractive index and the second refractive index are different from a refractive index of air,

the plane optical waveguide portion includes:
a plane optical waveguide having a plane serving as the illumination light emission surface and a plane serving as the reference light emission surface,

the plane optical waveguide includes:
a grating part formed by an interface between the first material and the second material, wherein the interface is located between the illumination light emission surface and the reference light emission surface, the plane optical waveguide diffracting, while propagating, the coherent light by the grating part so as to emit the coherent light as the illumination light from the illumination light emission surface, and also emit the coherent light diffracted by the grating part as the reference light from the reference light emission surface,

the illumination portion further includes:
a phase adjuster that adjusts a phase of the coherent light from the light source portion; and
a light-adjusting plane optical waveguide that is located between the image sensor and the object, in tandem in a direction to be layered on the plane optical waveguide, and propagates the coherent light adjusted in phase by the phase adjuster, and

the light-adjusting plane optical waveguide has a plane serving as the illumination light emission surface and a plane serving as the reference light emission surface, and emits the coherent light, as the illumination light, from the illumination light emission surface and also emits the coherent light, as the reference light, from the reference light emission surface.

2. The digital holographic imaging apparatus according to claim 1 , further comprising:
an illumination light angle changer that changes an irradiation angle of the illumination light emitted from the illumination light emission surface to be irradiated onto the object.

3. The digital holographic imaging apparatus according to claim 1 , further comprising a phase changer disposed on the object side of the illumination portion, the phase changer changing a phase of the illumination light emitted from the illumination light emission surface to be irradiated onto the object.

4. The digital holographic imaging apparatus according to claim 1 , wherein:
the plane optical waveguide portion includes:
at least three of the plane optical waveguides located in tandem in a direction of being layered between the image sensor and the object, the at least three of the plane optical waveguides satisfying the following condition when either two thereof are combined:
0<mod( D ,λ)<λ,

where:
λ represents the specific wavelength,
D represents an air conversion length of a distance between the gratings of the two plane optical waveguides combined, and
mod(D,λ) represents a remainder after a division of D by λ.

5. The digital holographic imaging apparatus according to claim 1 , further comprising:
a first quarter-wave plate disposed on the object side of the illumination portion;
a second quarter-wave plate disposed in an optical path between the illumination portion and the image sensor; and
an analyzer array disposed between the image sensor and the second quarter-wave plate, the analyzer array comprising a plurality of analyzers having different polarization transmission direction and disposed side by side for every one or more pixels of the image sensor.

6. The digital holographic imaging apparatus according to claim 1 , wherein:
the light-adjusting plane optical waveguide has a grating part located between the illumination light emission surface and the reference light emission surface, and diffracts the coherent light by the grating part while propagating the coherent light and emits the coherent light as the illumination light from the illumination light emission surface, and also emits, as the reference light, the diffracted coherent light from the reference light emission surface.

7. The digital holographic imaging apparatus according to claim 1 , wherein:
the pixel array of the image sensor is aligned in tandem along a plane substantially parallel to at least one of the illumination light emission surface and the reference light emission surface of the illumination portion.

8. The digital holographic imaging apparatus according to claim 1 , further comprising an object holder that holds the object.

9. The digital holographic imaging apparatus according to claim 8 , satisfying the following conditional expressions:
Z 10 2 /S <4,
0.0000001 <Z 20 2 /S <4,
where:
Z 10 represents a distance from the illumination light emission plane of the illumination portion to an object contact surface of the object holder,
Z 20 represents a distance from the object contact surface to the pixel array of the image sensor, and
S represents an area of the illumination light emission surface of the illumination portion.

10. The digital holographic imaging apparatus according to claim 9 , satisfying 0.25<Z 10 /Z 20 <4.

11. The digital holographic imaging apparatus according to claim 1 , satisfying the following conditional expression:
0.0000001 <Z 2 /S <16,
where:
S represents an area of the illumination light emission surface of the illumination portion; and
Z represents a distance from the illumination light emission surface of the illumination light to the pixel array of the image sensor.

12. An illumination apparatus, comprising:
a light source portion that emits coherent light of a specific wavelength;
a plane optical waveguide having a first light emission plane for emitting, while propagating, the coherent light from the light source portion in a first direction, and a second light emission plane for emitting the coherent light in a second direction opposite to the first direction;
a phase adjuster that adjusts a phase of the coherent light from the light source portion; and
a light-adjusting plane optical waveguide located in tandem in a direction to be layered on the plane optical waveguide, the light-adjusting plane optical waveguide having a third light emission plane for emitting the coherent light in the first direction, and a fourth light emission plane for emitting the coherent light in the second direction, while propagating the coherent light adjusted in phase by the phase adjuster.

Assignees

• Olympus Corp

Inventors

• Watanabe Satoshi

Classifications

• G03H2223/23

  Diffractive element · CPC title

• G03H1/0402 Primary

  Recording geometries or arrangements (G03H1/0443, G03H1/0476, G03H1/16 take precedence) · CPC title

• G03H2225/32

  Phase only · CPC title

• G03H2222/31

  Polarised light · CPC title

• G03H2001/0447

  In-line recording arrangement · CPC title