KR20220105264A - Microscope system for quantifying birefringence of sample - Google Patents

Abstract

According to one embodiment of the present invention, a microscopy system for quantifying optical anisotropy of a sample, which provides quantitative information about optical anisotropy of a sample, comprises: a light source unit emitting light; a polarization modulation unit modulating a form of polarized light emitted from the light source unit; a polarized light obtaining unit radiating the light modulated by the polarized light modulation unit to the sample and detecting the light by dividing the light reflected or penetrated by the sample according to a polarization direction; and an image generation unit generating an image visualizing the quantitative information about the optical anisotropy of the sample through the light detected by the polarized light obtaining unit.

Description

MICROSCOPE SYSTEM FOR QUANTIFYING BIREFRINGENCE OF SAMPLE

The present invention relates to a microscope system for quantifying the optical anisotropy of a sample, and more particularly, by irradiating a sample with light modulated in a constant polarization state and calculating an image obtained by separating the light reflected or transmitted from the sample along the polarization axis. A microscopy system for quantifying the optical anisotropy of a sample.

Arithmetic microscope is an imaging technology that simplifies the complex optical system of a conventional microscope by using an arithmetic operation technique based on an optical numerical model, and restores and provides information that cannot be provided by a general microscope such as phase information as well as light intensity information of a sample. Representatively, there are differential phase-contrast imaging technology and Fourier ptychography technology. Differential phase contrast microscopy is an imaging technology that restores quantitative phase information of a transparent sample using multiple light intensity images acquired with two or more complementary light irradiation patterns. It is a technology to reconstruct a large-area, high-resolution image by superimposing the acquired image in Fourier space.

Birefringence is a phenomenon in which the refractive index is different in one medium according to the polarization state of the light and thus the light is separated into two refracted lights. Semiconductor materials, composite materials, and biological samples have optical anisotropy.

An image of optical anisotropy is used to observe the crystal structure to determine the mechanical properties, biodegradability, biocompatibility, etc. of the internal crystal structure of composite and semiconductor materials. In particular, in the silicon wafer and EUV mask required for the semiconductor process, defects can be found at an early stage through optical anisotropy measurement, and unnecessary processes can be minimized.

In addition, biological tissues such as chromosomes, muscle tissue, and microtubules have optical anisotropy, so that the internal structure can be observed through the optical anisotropy characteristic image. Therefore, the optical anisotropy characteristic image of a biological sample is used in biological and medical fields, and is more useful in that it does not require a pretreatment process such as dyeing.

Optical anisotropy measurement techniques include a polarization microscope and an interferometer-based technique. A polarizing microscope has a disadvantage in that stability and repeatability of image collection are low because an image is acquired while physically rotating the polarizing plate by providing a polarizing plate between the irradiation part and the measuring part. In order to solve this problem, it is necessary to use an expensive electric variable retarder, but since it is an electric device, calibration is required according to the conditions of use. Since the interferometer-based optical anisotropy measurement technique uses an interferometer, it requires a complex optical system configuration and has disadvantages in that it is vulnerable to disturbance.

The present invention modulates the polarization of light irradiated to a sample, acquires an image in which the light reflected or transmitted from the sample is separated along the polarization axis, and calculates the acquired image using a numerical model-based algorithm to quantify the optical anisotropy of the sample. provides

According to an embodiment of the present invention, there is provided a microscope system for quantifying optical anisotropy of a sample, comprising: a light source unit emitting light; a polarization modulator for modulating a polarization shape of the light emitted from the light source; a polarization acquisition unit for irradiating the light modulated by the polarization modulator to the sample and detecting the light reflected or transmitted from the sample according to the polarization direction; and an image generation unit generating an image for visualizing quantitative information on the optical anisotropy of the sample through the light detected by the polarization acquisition unit.

In addition, the optical anisotropy of the sample includes an optical axis direction and a phase retardation value of the sample.

In addition, the light source unit includes an LED array or a laser.

In addition, the polarization acquisition unit includes a plurality of condensing lenses and a polarization camera for classifying the light reflected or transmitted from the sample according to the polarization direction and detecting the respective intensity of the divided light.

In addition, the polarization acquisition unit, a plurality of condensing lenses, a Wollaston prism separating the light reflected or transmitted from the sample at a predetermined angle according to the orthogonal polarization direction, and the separated light according to the orthogonal polarization direction. and a camera including an image sensor.

In addition, the polarization acquisition unit further includes a field stop positioned between the plurality of condensing lenses.

In addition, the polarization acquisition unit includes a plurality of condensing lenses, a polarization beam splitter that reflects or transmits light reflected or transmitted from the sample in a polarization direction orthogonal to a polarization direction, and a first light that is reflected by the polarization beam splitter is detected. a camera, and a second camera configured to detect a second light that has passed through the polarizing beam splitter.

The microscope system for quantifying the optical anisotropy of a sample according to the present invention obtains an image of light reflected or transmitted through a sample using an optical system having a simple structure, and quantifies the optical anisotropy by arithmetic processing the light intensity of the image with a numerical model algorithm You can get one video.

The effects obtainable in the present invention are not limited to the above-mentioned effects, and other effects not mentioned may be clearly understood by those of ordinary skill in the art to which the present invention belongs from the following description. will be.

1 is a schematic configuration diagram of a microscope system for quantifying optical anisotropy of a sample according to an embodiment of the present invention.
2A is an example of a polarization acquisition unit of a microscope system for quantifying optical anisotropy of a sample according to an embodiment of the present invention.
2B is another example of a polarization acquisition unit of a microscope system for quantifying optical anisotropy of a sample according to an embodiment of the present invention.
2C is another example of a polarization acquisition unit of a microscope system for quantifying optical anisotropy of a sample according to an embodiment of the present invention.
3 is a diagram illustrating the visualization of quantitative information on the optical anisotropy of a sample according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The terms used in this specification are terms defined in consideration of the functions of the present invention, which may vary according to the intention or custom of the user or operator. Therefore, definitions of these terms should be made based on the content throughout this specification.

In addition, the embodiments disclosed below do not limit the scope of the present invention, but are merely exemplary matters of the components presented in the claims of the present invention, and are included in the technical spirit throughout the specification of the present invention and the scope of the claims. Embodiments including substitutable components as equivalents in components may be included in the scope of the present invention.

And in the embodiments disclosed below, terms such as “first”, “second”, “one side”, and “other side” are used to distinguish one component from other components, and the component is the term are not limited by Hereinafter, in describing the present invention, detailed description of known techniques that may obscure the gist of the present invention will be omitted.

1 is a schematic configuration diagram of a microscope system for quantifying optical anisotropy of a sample according to an embodiment of the present invention.

Referring to FIG. 1 , a microscope system 1000 for quantifying optical anisotropy of a sample according to an embodiment of the present invention includes a light source unit 100 , a polarization modulator 200 , a polarization acquisition unit 300 , and an image generator. (400).

The light source unit 100 emits light to the sample, and a light source such as an LED or a laser may be used. For example, the light source unit 100 uses an LED array as a light source, and in the LED array, light emitting diodes are arranged at a constant pitch in a matrix structure.

The polarization modulator 200 modulates the light emitted from the light source unit 100 into a constant polarization form. The light emitted from the light source unit 100 may have unpolarized light in which the vibration of the electric field does not have a constant direction or a constant polarization form. The present invention irradiates irradiated light polarized in a predetermined direction in advance to a sample, detects the sample according to the polarization direction orthogonal to the reflected or transmitted light, and determines the transfer function of the detection light reflecting the characteristics of the sample. By numerically comparing with , the optical anisotropy properties of the sample are extracted. Accordingly, the polarization modulator 200 modulates the light emitted from the light source unit 100 in a polarization form previously intended to simplify the arithmetic expression used by the image generator 400 to extract the optical anisotropy. According to an embodiment, the polarization modulator 200 modulates the emitted light so that circularly polarized light, particularly left circularly polarized light, is irradiated to the sample. In the polarization modulator 200 , various combinations of optical devices are possible to modulate the polarization form into an intended polarization form according to the polarization state of the light emitted from the light source unit.

The polarization modulator 200 may include, for example, a wave plate or a retarder for modulating a predetermined polarization form into circularly polarized light when the light source of the light source unit is a laser, or a spatial light modulator (SLM). Light Modulator).

In addition, as another example, when the light source of the light source unit emits unpolarized light, the polarization modulator 200 includes a linear polarizer and a wave plate or retarder to modulate the unpolarized light into circularly polarized light, or includes a circular polarizer. can do.

The polarization acquisition unit 300 detects the light reflected or transmitted from the sample according to the polarization direction, converts the intensity of the separated light according to the polarization direction into an electrical signal, and transmits it to the image generation unit. The irradiated light having a desired constant polarization shape is irradiated to the sample, and the light reflected or transmitted from the sample is changed without maintaining the polarization shape of the irradiated light due to the optical anisotropy of the sample. In an embodiment, the circularly polarized light is irradiated to the sample, and the reflected or transmitted light reflecting the optical anisotropy of the sample in the process of reflecting or transmitting the sample may be elliptically polarized light. The polarization acquisition unit 300 may include an optical device that separates the light reflected or transmitted from the sample according to the polarization direction or a camera including an image sensor that detects the intensity of each separated light according to the orthogonal polarization direction as an electrical signal. have.

2A to 2C show an example, another example, and another example of a polarization acquisition unit of a microscope system for quantifying optical anisotropy of a sample according to an embodiment of the present invention.

Referring to FIG. 2A , in one example, the polarization acquisition unit 300 includes a polarization camera 321 for classifying the light reflected or transmitted from the plurality of condensing lenses and the sample according to the polarization direction and detecting the intensity of the divided light. do. The polarization acquisition unit 300 includes a first lens 311 for modulating the light passing through the sample 10 into parallel light and a second lens 312 for condensing the parallel light so that the polarization camera 321 is photosensitive. It includes a plurality of condensing lenses. The polarization camera 321 classifies and detects the photosensitized light into intensities according to the components of the polarization direction of 0 degree, 45 degree, 90 degree, and 135 degree axis, respectively, and reconstructs the light intensity image. Referring to FIG. 2B , in another example, the polarization acquisition unit 300 is a Wollaston prism that separates light reflected or transmitted from a plurality of condensing lenses and samples at a predetermined angle according to the orthogonal polarization direction. ) 322 , and a camera 332 including an image sensor that detects light according to the separated orthogonal polarization directions.

The polarization acquisition unit 300 receives the light separated according to the polarization direction by the first lens 311 and the Wollaston prism 322 that modulates the light passing through the sample 10 into parallel light, respectively, of the camera 332 . and a plurality of condensing lenses including a second lens 312 condensing light so as to be sensitive to the image sensor. The Wollaston prism 322 separates the reflected light or transmitted light reflecting the optical anisotropy characteristic of the sample into two linearly polarized lights having an oscillation plane orthogonal to each other to be spaced apart at a predetermined angle. The light separated by the Wollaston prism 322 is simultaneously exposed in different regions in the image sensor of the camera 332, so that the light reflected or transmitted through the sample is classified and detected by intensity according to the components in the orthogonal polarization direction. .

In this example, the polarization acquisition unit 300 includes a third lens (not shown) disposed between the first lens 311 and the Wollaston prism 322 in addition to the first lens 311 and the second lens 312 . It further includes, and further includes a field stop (not shown) positioned between the first lens 311 and the third lens. The placement position and aperture size of the field stop are adjusted so that the light separated by the Wollaston prism is absorbed into the image sensor and the separated light is prevented from overlapping within the image sensor.

Referring to FIG. 2C , in another example, the polarization acquisition unit 300 includes a polarization beam splitter (PBS) that reflects or transmits light reflected or transmitted from a plurality of condensing lenses and the sample 10 according to a polarization direction orthogonal to each other. 323 , a first camera 333 that detects the first light reflected from the polarizing beam splitter 323 and a second camera 334 that detects the second light transmitted through the polarizing beam splitter 323 . .

The polarization acquisition unit 300 includes a first lens 311 for modulating the light passing through the sample 10 into parallel light and a second lens 312 for condensing the parallel light so that the parallel light passes through a polarization beam splitter and is sensitive to the image sensor. It includes a plurality of condensing lenses comprising a. The polarization beam splitter 323 separates the reflected light or transmitted light reflecting the optically anisotropic characteristic of the sample into two linearly polarized first light and second light having an oscillation plane orthogonal to each other. Since the light separated by the polarization beam splitter 323 travels in directions orthogonal to each other, two cameras for detecting the separated light are required in this example. Light reflected or transmitted through the sample by each image sensor included in the first camera and the second camera is detected with an intensity according to a component in an orthogonal polarization direction, respectively.

The image generating unit 400 generates an image for visualizing quantitative information on the optical anisotropy of a sample through the light detected by the polarization acquiring unit 300 . The polarization acquisition unit 300 converts the intensity of each light separated according to the polarization direction into an electrical signal and transmits it to the image generation unit 400 , and the image generation unit 400 that transmits this converts it to a pre-stored numerical model-based algorithm. The quantitative optical anisotropy characteristic information of the sample is extracted through the calculation. Here, the optical anisotropy of the sample includes an optical axis direction and a phase retardation value of the sample.

The image generator 400 may be a computing device capable of processing an electrical signal transmitted from the polarization acquisition unit 300 .

The image generator 400 may use different numerical model-based algorithms according to the characteristics of the sample or the method of the polarization acquisition unit. For example, Fourier Ptychographic Microscopy (FPM), which irradiates light from various angles and superimposes the acquired light information in Fourier space to restore large-area, high-resolution light absorption and optical phase images, and PTF (Phase Transfer Function) according to the irradiation light pattern There is an algorithm that can be applied to DPC (Differential Phase Contrast)-based QPI (Quantitative Phase Imaging), which reconstructs a high-sensitivity optical phase image using

In an embodiment, the image generating unit 400 irradiates circularly polarized light to the sample and separates the reflected or transmitted light according to a polarization direction orthogonal to the sample to detect each light intensity of the separated light, That is, in the case of the embodiment shown in FIGS. 2B and 2C , optical anisotropy information of the sample, ie, the optical axis direction and phase delay value of the sample, can be quantitatively extracted using the following equations.

The electric field of each separated light obtained by irradiating circularly polarized light to the sample and separating the light reflected or transmitted from the sample along the orthogonal polarization direction is the same as in Equation (1).

Equation 1

,

,

, 및

는 직교하는 편광 방향에 따라 분리된 광 각각의 전기장의 진폭 및 위상이고,

는 광학적 이방성 시료를 모델링한 Jones 매트릭스이다. here,

,

,

, and

is the amplitude and phase of the electric field of each light separated according to the orthogonal polarization direction,

is the Jones matrix modeling the optically anisotropic sample.

In order to extract the optical axis direction and phase delay, which are the optical anisotropy of the sample, Equation 1 is converted to the Stokes parameter, that is, Equation 2.

Equation 2

) 및 위상 지연(

)의 공간적 분포는 수학식 3과 같이 추출된다. The optical axis direction of the sample (

) and phase delay (

) is extracted as in Equation 3.

Equation 3

In the above, it has been described that the quantitative optical anisotropy characteristics of the sample are extracted using the Jones matrix, but when obtaining light intensity images according to more polarization directions and calculating using a Mueller matrix, dichroism Additional optically anisotropic properties can be obtained, such as

In an embodiment, the image generating unit 400 irradiates circularly polarized light to the sample, and separates and separates the light reflected or transmitted through the sample according to the polarization directions of 0 degrees, 45 degrees, 90 degrees, and 135 degrees polarization axes. In the case of detecting each light intensity of the emitted light, that is, in the case of the embodiment shown in FIG. 2A, the optical anisotropy information of the sample, that is, the optical axis direction and the phase delay value of the sample, can be quantitatively extracted using the following equations. can

Equation 4

는 X 편광 축의 방향으로 분리된 광세기 영상이고,

는 시료의 광축 방향이고,

는 위상 지연이다. 시료의 광축 방향(

) 및 위상 지연(

)은 수학식 5과 같이 얻을 수 있다. in Equation 4

is the light intensity image separated in the direction of the X polarization axis,

is the optical axis direction of the sample,

is the phase delay. The optical axis direction of the sample (

) and phase delay (

) can be obtained as in Equation 5.

Equation 5

3 is a diagram illustrating the visualization of quantitative information on the optical anisotropy of a sample according to an embodiment of the present invention.

Referring to FIG. 3 , FIGS. 3A to 3C are images obtained by averaging the intensity of each light separated according to a polarization direction orthogonal to the reflected or transmitted light of the transparent sample. 3 (d) to (f) provide the optical anisotropy of the sample extracted by the microscope system according to an embodiment of the present invention, that is, the optical axis direction and the phase delay value in the form of a two-dimensional map. Here, the optical axis direction is shown by mixing color and the phase delay value in dark. Accordingly, it can be confirmed that the characteristics of the sample having the optical anisotropy can be quantified and visualized by the microscope system for quantifying the optical anisotropy of the sample according to the present invention.

Figures 3 (a) to (d) are UAD (uric acid dihydrate) as a sample, Figure 3 (b) to (e) is UA (anhydrous uric acid) as a sample, Figure 3 (c) to (f) are samples of a mixture of UAD and UA.

Claims (7)

In the microscope system for providing quantitative information about the optical anisotropy of a sample,
a light source emitting light;
a polarization modulator for modulating a polarization shape of the light emitted from the light source;
a polarization acquisition unit irradiating the light modulated by the polarization modulator to the sample and detecting the light reflected or transmitted from the sample by dividing the light according to the polarization direction; and
A microscope system for quantifying the optical anisotropy of a sample, comprising an image generator for generating an image for visualizing quantitative information on the optical anisotropy of the sample through the light detected by the polarization acquisition unit.
The method according to claim 1,
The optical anisotropy of the sample is a microscope system for quantifying the optical anisotropy of the sample, including an optical axis direction and a phase delay value of the sample.
The method according to claim 1,
The light source unit includes an LED array or a laser microscope system for quantifying the optical anisotropy of the sample.
The method according to claim 1,
The polarization acquisition unit,
A microscope system for quantifying optical anisotropy of a sample, comprising: a plurality of condensing lenses; and a polarization camera for classifying light reflected or transmitted from the sample according to a polarization direction and detecting each intensity of the divided light.
The method according to claim 1,
The polarization acquisition unit,
a plurality of condensing lenses,
A Wollaston prism that separates the light reflected or transmitted from the sample at a predetermined angle according to the orthogonal polarization direction, and
A microscope system for quantifying optical anisotropy of a sample, including a camera including an image sensor for detecting light according to the separated orthogonal polarization directions.
6. The method of claim 5,
The polarization acquisition unit,
A microscope system for quantifying optical anisotropy of a sample, further comprising a field stop positioned between the plurality of condensing lenses.
The method according to claim 1,
The polarization acquisition unit,
a plurality of condensing lenses,
A polarizing beam splitter that reflects or transmits light reflected or transmitted from the sample in a polarization direction orthogonal to it;
a first camera for detecting the first light reflected from the polarizing beam splitter, and
A microscope system for quantifying optical anisotropy of a sample, comprising a second camera for detecting a second light that has passed through the polarizing beam splitter.

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