# US 12,216,264 B2 · Dark-field confocal microscopic measurement apparatus and method based on vortex dichroism

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- Number: US 12,216,264 B2
- Document ID: US12216264B2
- Status: Granted
- Kind: B2
- Application number: 18/739,866
- Filed: 2024-06-11
- Published: 2024-10-03
- Granted: 2025-02-04
- Earliest claimed: 2023-03-16
- Assignees: Harbin Institute of Technology
- Applicants: Harbin Institute of Technology
- Inventors: Jian Liu; Chenguang Liu; Zijie Hua
- Web page: https://patentgrep.com/patent/US12216264B2

## CPC

- G02B 21/0032: {Optical details of illumination, e.g. light-sources, pinholes, beam splitters, slits, fibers (G02B21/0036 - G02B21/008; means for illumination of specimens in general G02B21/06)}
- G01N 21/8806: {Specially adapted optical and illumination features}
- G02B 21/26: Stages; Adjusting means therefor
- G01N 2021/8822: {Dark field detection}
- G01N 2021/8848: {Polarisation of light}
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)

## Abstract

Disclosed are a dark-field confocal microscopic measurement apparatus and method based on vortex dichroism. The apparatus includes an array vortex light generation module, an array vortex light illumination module and an array dark-field confocal detection module; an array vortex wave plate of the array vortex light generation module generates vortex light to illuminate a sample of the array vortex light illumination module; and the array dark-field confocal detection module extracts scattering signals, and identifies differences between scattering signals collected under the illumination of opposite-order vortex light. Three-dimensional distribution information of defects, such as subsurface scratches, abrasion, subsurface cracks, and bubbles, can be extracted by directly analyzing the scattering signals under the 1-order vortex illumination; and chirality information of the micro-nano material can be obtained by analyzing difference values of the scattering signals under the illumination of the opposite-order vortex light.

## Claims

### Claim 1

An apparatus, comprising an array vortex light generation module, an array vortex light illumination module and an array dark-field confocal detection module;
wherein the array vortex light generation module comprises, along a direction of light propagation, a laser, a half-wave plate, a quarter-wave plate, a one-dimensional scanning galvanometer, a scanning lens, a tube lens and an array vortex wave plate;
wherein the array vortex light illumination module comprises, along the direction of light propagation, a non-polarizing beam splitter, an objective lens, a three-dimensional moving stage configured to support a sample,
wherein the objective lens is configured to focus vortex illumination light beams onto the sample, and is configured to collect light from the sample;
wherein the non-polarizing beam splitter is configured to direct the light from the sample into the array dark-field confocal detection module; and
wherein the array dark-field confocal detection module comprises, along the direction of light propagation, an aperture diaphragm array, a focusing lens, a single-mode optical fiber and a photomultiplier tube (PMT) detector.

### Claim 2 (depends on 1)

The apparatus according to claim 1, wherein the laser is configured to emit a linearly polarized laser beam, and the half-wave plate and the quarter-wave plate collectively are configured to transform the linearly polarized laser beam into a circularly polarized laser beam.

### Claim 3 (depends on 2)

The apparatus according to claim 2, wherein the one-dimensional scanning galvanometer is configured to direct the circularly polarized laser beam to the array vortex wave plate through the scanning lens and the tube lens,
wherein the array vortex wave plate comprises a vortex phased array configured to generate the vortex illumination light beams from the circularly polarized laser beam, wherein the vortex illumination light beams comprise ±m-order vortex illumination light beams respectively incident at centers of ±m-order vortex phase diagrams, wherein m=0, 1, 2, . . . , and 10.

### Claim 4 (depends on 3)

The apparatus according to claim 3, wherein the objective lens is configured to focus the vortex illumination light beams on a same focal point on the sample, and wherein the aperture diaphragm array is configured to refract the light from the sample.

### Claim 5 (depends on 3)

The apparatus according to claim 3, wherein a center of each aperture in the aperture diaphragm array corresponds to a center of a vortex phase of the array vortex wave plate and a size of each aperture in the aperture diaphragm array and a size of the vortex phase of the array vortex wave plate corresponding thereto are a size of a central dark spot of an annular vortex light reflected by the sample illuminated by the 1-order vortex illumination light beam.

### Claim 6 (depends on 4)

The apparatus according to claim 4, wherein the focusing lens is configured to couple the light from the sample into the single-mode optical fiber, and the PMT detector is configured to measure a magnitude of the light from the sample.

### Claim 7 (depends on 6)

The apparatus according to claim 6, configured to obtain vortex dichroic scattering signals based on differences between the light from the sample caused by illumination of the +m-order vortex illumination light beams and the light from the sample caused by the −m-order vortex illumination light beam.

### Claim 8 (depends on 1)

A method using the apparatus according to claim 1, comprising:
emitting a linearly polarized laser beam from the laser, and transforming the linearly polarized laser beam into a circularly polarized laser beam;
directing the circularly polarized laser beam to the array vortex wave plate;
focusing the vortex illumination light beams onto the same focal point on the sample;
filtering out random-order vortex light from the light from the sample using the aperture diaphragm array;
coupling the light into the single-mode optical fiber using the focusing lens, and collecting the light from the single-mode optical fiber using the PMT detector;
obtaining vortex dichroic scattering signals based on differences between the light from the sample caused by illumination of the +m-order vortex illumination light beam and the light from the sample caused by the −m-order vortex illumination light beam; and
moving the sample using the three-dimensional moving stage.