Optical imaging system and imaging method regulated based on spatial coherence structure

Patent metadata

Field	Value
Publication number	US-12025429-B2
Application number	US-202117764266-A
Country	US
Kind code	B2
Filing date	Feb 20, 2021
Priority date	Dec 21, 2020
Publication date	Jul 2, 2024
Grant date	Jul 2, 2024

Abstract

The invention discloses an optical imaging system and an imaging method regulated based on a spatial coherence structure, including the steps of: building a 4f imaging system; detecting, by a first optical detector, the shape of the spectrum domain obstacle in the 4f imaging system; designing a spatial coherence structure of the incident beam based on the shape of the spectrum domain obstacle, so that all the modes of the incident beam can pass through the opening in the obstacle; and placing an object to be detected in the optical path and detecting, by the second optical detector, the optical imaging information of the object to be detected. According to the present invention, in the case where the frequency plane of the 4f optical imaging system is partially occluded, imaging without speckles is enabled, utilization of the systematic light is substantially improved, and the signal-to-noise ratio in imaging is improved.

First claim

What is claimed is:

1. An optical imaging system regulated based on a spatial coherence structure, comprising:
a light source assembly including a laser and a first beam split element, the first beam split element splitting a beam emitted from the laser into a first beam and a second beam;
an obstacle optical assembly including a first lens and a second lens, the first lens being positioned at a front side of an obstacle and the second lens being positioned at a back side of the obstacle, in which the first lens and the second lens form a 4f imaging system;
an adjustable optical assembly positioned at a front side of an object to be detected, the adjustable optical assembly including a first shading element and a spatial light modulator that are sequentially arranged, the first beam passing through the first shading element and the spatial light modulator and then entering the obstacle optical assembly;
a front optical assembly including a second shading element and a third lens, the second beam passing sequentially through the second shading element and the third lens, and then entering the obstacle optical assembly, the third lens and the first lens forming a 4f imaging system;
a first optical detection assembly configured to detect optical imaging information of the obstacle and positioned in an image space of the obstacle optical assembly, the first optical detection assembly including a fourth lens and a first optical detector, the fourth lens being positioned at a front side of the first optical detector, the second lens and the fourth lens forming a 4f imaging system;
a second optical detection assembly configured to detect optical imaging information of the object to be detected and positioned in an image space of the obstacle optical assembly, the second optical detection assembly including a second optical detector; and
a computer connected to the first optical detector and the spatial light modulator, the first optical detector sending the optical information of the obstacle to the computer which, based on the optical information of the obstacle, adjusts the spatial light modulator to allow the second beam to pass through an opening in the obstacle.

2. The optical imaging system regulated based on a spatial coherence structure of claim 1 , wherein the first optical detector and/or the second optical detector is a beam profiler.

3. The optical imaging system regulated based on a spatial coherence structure of claim 1 , wherein the first shading element and/or the second shading element is a light diaphragm.

4. The optical imaging system regulated based on a spatial coherence structure of claim 1 , wherein the light source assembly further includes a beam expander positioned between the laser and the first beam split element.

5. The optical imaging system regulated based on a spatial coherence structure of claim 1 , wherein the first beam split element is a first beam splitter.

6. The optical imaging system regulated based on a spatial coherence structure of claim 1 , wherein the optical imaging system further comprises a second beam splitter positioned between the object to be detected and the first lens, a beam exiting the third lens is reflected by the second beam splitter and enters the obstacle optical assembly.

7. The optical imaging system regulated based on a spatial coherence structure of claim 1 , wherein a third beam splitter is provided at a rear end of the second lens, the second optical detector being positioned on a first illuminating surface of the third beam splitter and the fourth lens being positioned on a second illuminating surface of the third beam splitter.

8. The optical imaging system regulated based on a spatial coherence structure of claim 1 , wherein the light emitted from the laser is completely coherent linearly polarized light.

9. An optical imaging method regulated based on a spatial coherence structure, using the optical imaging system of claim 1 , comprising steps of:
S1: allowing the first shading element in a shading status and the second shading element in an opened status, and detecting, by the first optical detector, the light intensity image distribution I(ι 2 ) of the spectrum domain obstacle, where ι 2 is the coordinate of any point in the output plane;
S2: acquiring the light intensity image distribution I(ι 2 ) of the spectrum domain obstacle and designing a spatial distribution in a function p(v), which is Fourier transform relationship, of the incident light spatial coherence structure by the computer; in which the shape of an opening in the obstacle is obtained based on the light intensity image distribution I(ι 2 ) of the spectrum domain obstacle, and the function p(v) is modified based on the shape of the opening in the obstacle so that all modes of the incident beam can pass through the opening in the obstacle, p(V) being a non-negative function of any vector V≡(v x , v y );
S3: obtaining a cross spectral density W(r 1 , r 2 ) of the incident light based on the function p(V) and consequently obtaining a light field T mn (r, φ) loaded by the spatial light modulator, where r≡(x, y) represents any position vector in the source plane, r 1 ≡(x 1 , y 1 ) and r 2 ≡(x 2 , y 2 ) are the position vectors of any two points in the source plane, and φ represents a random phase having a value in the range of [0, 2π]; and
S4: allowing the second shading element in a shading status and the first shading element in an opened status, and acquiring, by the second optical detector, the light intensity image distribution information of the object to be detected.

10. An optical imaging method regulated based on a spatial coherence structure, comprising steps of:
building a 4f imaging system, in which an obstacle is positioned on a spectrum plane of the 4f imaging system so that the spectrum plane of the 4f imaging system is partially occluded, an opening being provided in the obstacle and extending through the obstacle;
detecting, by a first optical detector, the shape of the spectrum domain obstacle in the 4f imaging system;
designing a spatial coherence structure of the incident beam based on the shape of the spectrum domain obstacle in the 4f imaging system, so that all the modes of the incident beam can pass through the opening of the obstacle; and
placing an object to be detected in the optical path, and detecting, by the second optical detector, the optical imaging information of the object to be detected.

Assignees

• Univ Soochow

Inventors

• Chen Yahong
• Peng Deming
• Shen Yuechen
• Sun Hu
• Wang Fei
• Cai Yangjian

Classifications

• G02B27/48

  Laser speckle optics · CPC title

• G02B27/50

  Optics for phase object visualisation · CPC title

• G02B26/06

  for controlling the phase of light (G02B26/08 takes precedence {, measuring optical phase difference G01J9/00}) · CPC title

• G02B27/0025 Primary

  for optical correction, e.g. distorsion, aberration · CPC title

• G01B11/24 Primary

  for measuring contours or curvatures · CPC title