阅读说明：本技术 一种可快速改变剪切方向和大小的微分干涉成像系统 (Differential interference imaging system capable of quickly changing shearing direction and size ) 是由 吕晓旭 周成鑫 钟丽云 宁钦文 刘胜德 于 2020-03-26 设计创作，主要内容包括：本发明涉及一种可快速改变剪切方向和大小的微分干涉成像系统,包括：光源、滤光片、起偏器、样品台、无限远成像显微物镜、镜筒透镜、剪切组件、检偏器、图像传感器。光源发出的线偏振光经过滤光片调整光强和起偏器调整偏振方向后,再经过置于样品台上的透明样品后被无限远成像显微物镜收集并通过镜筒透镜成像,成像光束被剪切组件分为两束偏振方向相互垂直、具有微小剪切量的线偏振光场,再由检偏器合成后成为干涉光场,最终在图像传感器中形成微分干涉图像。本发明提供的微分干涉成像系统可以灵活地装配到常规光学显微镜上,结构简单,易于实现,能够通过对非染色样品进行高质量的定量相位测量来研究样品的形态与结构。(The invention relates to a differential interference imaging system capable of rapidly changing shearing direction and size, comprising: the device comprises a light source, an optical filter, a polarizer, a sample stage, an infinite imaging microscope objective, a tube lens, a shearing assembly, an analyzer and an image sensor. Linearly polarized light emitted by a light source passes through a light filter to adjust light intensity and a polarizer to adjust polarization direction, then passes through a transparent sample arranged on a sample stage, is collected by an infinite imaging microscope objective and is imaged through a tube lens, an imaging light beam is divided into two linearly polarized light fields with mutually vertical polarization directions and small shearing amount by a shearing assembly, the two linearly polarized light fields are synthesized by an analyzer to form an interference light field, and finally a differential interference image is formed in an image sensor. The differential interference imaging system provided by the invention can be flexibly assembled on a conventional optical microscope, has a simple structure, is easy to realize, and can be used for researching the form and structure of a sample by carrying out high-quality quantitative phase measurement on a non-dyed sample.)

1. A differential interferometric imaging system that can rapidly change the direction and magnitude of shear, comprising: the device comprises a light source, an optical filter, a polarizer, a sample stage, an infinite imaging microscope objective, a tube lens, a shearing assembly, a polarization analyzer and an image sensor, wherein linearly polarized light emitted by the light source passes through the optical filter to adjust the light intensity and the polarizer to adjust the polarization direction, passes through a transparent sample arranged on the sample stage, is collected by the infinite imaging microscope objective and is imaged through the tube lens, the imaging light beam is divided into two linearly polarized light fields with mutually perpendicular polarization directions and small shearing amount by the shearing assembly, and the two linearly polarized light fields are synthesized by the polarization analyzer to form an interference light field, and finally a differential interference image is formed in the image sensor.

2. The differential interference imaging system of claim 1, wherein the shearing module comprises a first liquid crystal variable retarder, a first half wave plate, a second liquid crystal variable retarder, a third liquid crystal variable retarder, a second half wave plate, and a fourth liquid crystal variable retarder, and the shearing module can rapidly and accurately change the shearing direction and obtain the shearing amount of any magnitude by adjusting the control voltages of the first liquid crystal variable retarder, the second liquid crystal variable retarder, the third liquid crystal variable retarder, and the fourth liquid crystal variable retarder.

3. The differential interference imaging system capable of rapidly changing the shearing direction and the shearing size as claimed in claim 2, wherein a spatial rectangular coordinate system is established, a main optical axis of a light path of the differential interference imaging system is taken as a z-axis, a polarization direction of linearly polarized light emitted by the light source is taken as an x-axis, a slow axis direction of the polarizer is in an xy plane and forms an included angle of 45 degrees with the x-axis, a slow axis direction of the first liquid crystal variable retarder is taken as the x-axis direction, a slow axis direction of the first one-half wave plate is in the xy plane and forms an included angle of 45 degrees with the x-axis, a slow axis direction of the second liquid crystal variable retarder is taken as the x-axis direction and is axially symmetrically arranged with the first liquid crystal variable retarder, a slow axis direction of the third liquid crystal variable retarder is taken as the y-axis direction, a slow axis direction of the second one-half wave plate is in the xy plane and forms an included angle of 45 degrees with the x-axis, the slow axis direction of the fourth liquid crystal variable retarder is the y axis direction, the fourth liquid crystal variable retarder and the third liquid crystal variable retarder 110 are arranged in axial symmetry, the included angle between the slow axis of the analyzer and the x axis is 45 degrees, and the image sensor is arranged at the equivalent air focal length of the tube lens.

4. The differential interference imaging system capable of rapidly changing the shearing direction and magnitude according to claim 1, wherein the shearing module is composed of a first convex lens, a first liquid crystal variable retarder, a second liquid crystal variable retarder, a half wave plate, a third liquid crystal variable retarder, a fourth liquid crystal variable retarder and a second convex lens, and the shearing direction can be rapidly and accurately changed and the shearing amount of any magnitude can be obtained by adjusting the control voltages of the first liquid crystal variable retarder, the second liquid crystal variable retarder, the third liquid crystal variable retarder and the fourth liquid crystal variable retarder.

5. The differential interference imaging system capable of rapidly changing the shearing direction and the shearing size as claimed in claim 4, wherein a spatial rectangular coordinate system is established, a main optical axis of a light path of the differential interference imaging system is taken as a z-axis, a polarization direction of linearly polarized light emitted by the light source is taken as an x-axis, a slow axis direction of the polarizer is in an xy plane, and an included angle with the x-axis is 45 degrees, the first convex lens and the second convex lens jointly form a 4f system, a slow axis direction of the first liquid crystal variable retarder is taken as the x-axis direction, a slow axis direction of the second liquid crystal variable retarder is taken as the y-axis direction, a slow axis direction of the half wave plate is in the xy plane, and an included angle with the x-axis is 45 degrees, a slow axis direction of the third liquid crystal variable retarder is taken as the y-axis direction, and the third liquid crystal variable retarder is placed in axial symmetry with the second liquid crystal variable retarder, a slow axis direction of the fourth liquid crystal variable retarder is taken as the x-axis, and is axisymmetrically arranged with the first liquid crystal variable retarder 208, the included angle between the slow axis of the analyzer and the x axis is 45 degrees, and the image sensor is arranged at the equivalent air focal length of the 4f system.

6. A differential interference imaging system capable of rapidly changing the shearing direction and magnitude according to claim 1, wherein the shearing module comprises a beam splitter, a first liquid crystal variable retarder, a second liquid crystal variable retarder, a quarter-wave plate and a mirror, and the shearing direction can be rapidly and accurately changed and the shearing amount of any magnitude can be obtained by adjusting the control voltages of the first liquid crystal variable retarder and the second liquid crystal variable retarder.

7. The differential interference imaging system capable of rapidly changing the shearing direction and the shearing size as claimed in claim 6, wherein a spatial rectangular coordinate system is established, a main optical axis of a light path of the differential interference imaging system is taken as a z-axis, a polarization direction of linearly polarized light emitted by the light source is taken as an x-axis, then an included angle between a slow axis direction of the polarizer and the x-axis is 45 degrees, a slow axis direction of the first liquid crystal variable retarder is taken as the x-axis direction, a slow axis direction of the second liquid crystal variable retarder is taken as the y-axis direction, an included angle between a slow axis of the analyzer and the x-axis is 45 degrees, and the image sensor is placed at an equivalent air focal length of the tube lens.

8. A differential interferometric imaging system in which the direction and magnitude of shear can be varied rapidly according to claim 1, characterized in that the amount of micro-shear is in the range of 0-7.6 μm.

9. A differential interference imaging system capable of rapidly changing the shearing direction and size is characterized in that a combination of a liquid crystal variable retarder and a wave plate is included in an optical path for realizing interference imaging.

10. A differential interference imaging method capable of rapidly changing the shearing direction and size is characterized in that a combination of a liquid crystal variable retarder and a wave plate is used in the optical path of interference imaging, and the orientation of liquid crystal molecules is changed by adjusting the control voltage of the liquid crystal variable retarder, so that the shearing direction and the shearing amount of an imaging light beam to be interfered are rapidly changed.

Technical Field

The invention relates to the technical field of optics, in particular to a differential interference imaging system capable of quickly changing the shearing direction and size.

Background

The differential interference imaging system is widely applied to the detection and imaging of transparent samples. For example, a differential interference phase contrast microscope mainly cuts an interference imaging light beam at a certain distance in the transverse direction, converts the optical path difference of the two light beams in different characteristic regions of a sample into intensity change, and generates a visual pseudo-3D (relief) effect, so that the detailed information of the transparent sample can be observed obviously. Compared with other types of microscopic techniques, the method has the advantages of outstanding phase contrast, high spatial resolution, optical sectioning capability, no need of fluorescence labeling and dyeing and the like, so that in-situ observation and measurement of the sample can be realized.

Conventional differential interference imaging systems, which typically employ a Nomarski prism to achieve shearing of the object beam in the transverse direction, have some significant disadvantages: firstly, a special prism is needed, and the processing and debugging of the prism are quite complicated; secondly, when a differential interference imaging system is used for observing a sample, due to different sample properties and the fact that the shearing amount needs to be changed after the objective lens with different magnification is replaced, a better observation effect is achieved, and the traditional method is to replace a different Normarski prism, so that the complexity of operation is increased; thirdly, the shearing direction of the shearing prism is not easy to adjust, so that the use is greatly limited; and fourthly, the quantitative measurement of the sample cannot be realized, and the requirement of data analysis is difficult to meet.

Disclosure of Invention

In view of the above, it is desirable to provide a differential interference imaging technique based on the shearing of a liquid crystal variable retarder. The method utilizes the electric control birefringence effect of the liquid crystal to realize differential shearing interference in the common optical path, can quickly and accurately change the shearing direction and the magnitude of any shearing amount through the combination of the liquid crystal variable retarder and the wave plate, avoids complicated mechanical movement, and is easy to realize.

A differential interferometric imaging system that can rapidly change the direction and magnitude of shear, comprising: the device comprises a light source, an optical filter, a polarizer, a sample stage, an infinite imaging microscope objective, a tube lens, a shearing assembly, a polarization analyzer and an image sensor, wherein linearly polarized light emitted by the light source passes through the optical filter to adjust the light intensity and the polarizer to adjust the polarization direction, passes through a transparent sample arranged on the sample stage, is collected by the infinite imaging microscope objective and is imaged through the tube lens, the imaging light beam is divided into two linearly polarized light fields with mutually perpendicular polarization directions and small shearing amount by the shearing assembly, and the two linearly polarized light fields are synthesized by the polarization analyzer to form an interference light field, and finally a differential interference image is formed in the image sensor.

Preferably, the shearing assembly comprises a first liquid crystal variable retarder, a first half wave plate, a second liquid crystal variable retarder, a third liquid crystal variable retarder, a second half wave plate and a fourth liquid crystal variable retarder, and the shearing direction can be changed rapidly and accurately and the shearing amount of any size can be obtained by adjusting the control voltages of the first liquid crystal variable retarder, the second liquid crystal variable retarder, the third liquid crystal variable retarder and the fourth liquid crystal variable retarder.

Preferably, a spatial rectangular coordinate system is established, a main optical axis of a light path of the differential interference imaging system is taken as a z axis, a polarization direction of linearly polarized light emitted by the light source is taken as an x axis, a slow axis direction of the polarizer is in an xy plane and an included angle with the x axis is 45 degrees, a slow axis direction of the first liquid crystal variable retarder is taken as the x axis direction, a slow axis direction of the first one-half wave plate is in the xy plane and an included angle with the x axis is 45 degrees, a slow axis direction of the second liquid crystal variable retarder is taken as the x axis direction and is arranged in axial symmetry with the first liquid crystal variable retarder, a slow axis direction of the third liquid crystal variable retarder is taken as the y axis direction, a slow axis direction of the second one-half wave plate is in the xy plane and an included angle with the x axis is 45 degrees, a slow axis direction of the fourth liquid crystal variable retarder is taken as the y axis direction and is arranged in axial symmetry with the third liquid crystal variable retarder, the included angle between the slow axis of the analyzer and the x axis is 45 degrees, and the image sensor is placed at the equivalent air focal length of the lens barrel.

Preferably, the shearing assembly is composed of a first convex lens, a first liquid crystal variable retarder, a second liquid crystal variable retarder, a half-wave plate, a third liquid crystal variable retarder, a fourth liquid crystal variable retarder and a second convex lens, and the shearing direction can be changed rapidly and accurately and the shearing amount of any size can be obtained by adjusting the control voltages of the first liquid crystal variable retarder, the second liquid crystal variable retarder, the third liquid crystal variable retarder and the fourth liquid crystal variable retarder.

Preferably, a spatial rectangular coordinate system is established, a main optical axis of a light path of the differential interference imaging system is taken as a z axis, a polarization direction of linearly polarized light emitted by the light source is taken as an x axis, a slow axis direction of the polarizer is in an xy plane, an included angle between the slow axis direction of the polarizer and the x axis is 45 degrees, the first convex lens and the second convex lens jointly form a 4f system, a slow axis direction of the first liquid crystal variable retarder is taken as the x axis direction, a slow axis direction of the second liquid crystal variable retarder is taken as the y axis direction, a slow axis direction of the half wave plate is in the xy plane, an included angle between the slow axis direction of the half wave plate and the x axis is 45 degrees, a slow axis direction of the third liquid crystal variable retarder is taken as the y axis direction and is placed in axial symmetry with the second liquid crystal variable retarder, a slow axis direction of the fourth liquid crystal variable retarder is taken as the x axis direction and is placed in axial symmetry with the first liquid crystal variable retarder, the included angle between the slow axis of the analyzer and the x axis is 45 degrees, and the image sensor is placed at the equivalent air focal length of the 4f system.

Preferably, the shearing assembly comprises a beam splitter, a first liquid crystal variable retarder, a second liquid crystal variable retarder, a quarter-wave plate and a reflecting mirror, and the shearing direction can be changed rapidly and accurately and the shearing amount with any size can be obtained by adjusting the control voltage of the first liquid crystal variable retarder and the second liquid crystal variable retarder.

Preferably, a spatial rectangular coordinate system is established, a main optical axis of a light path of the differential interference imaging system is taken as a z axis, a polarization direction of linearly polarized light emitted by the light source is taken as an x axis, a slow axis direction of the polarizer is in an xy plane, an included angle between the slow axis direction of the polarizer and the x axis is 45 degrees, a slow axis direction of the first liquid crystal variable retarder is taken as an x axis direction, a slow axis direction of the second liquid crystal variable retarder is taken as a y axis direction, an included angle between a slow axis of the analyzer and the x axis is 45 degrees, and the image sensor is placed at an equivalent air focal length of the tube lens.

Preferably, the range of the micro-shearing amount is 0 to 7.6 μm.

A differential interference imaging system capable of rapidly changing the shearing direction and size comprises a liquid crystal variable retarder and a wave plate combination in an optical path for realizing interference imaging.

The invention also provides a differential interference imaging method, which uses the combination of the liquid crystal variable retarder and the wave plate in the optical path of the interference imaging, and changes the orientation of liquid crystal molecules by adjusting the control voltage of the liquid crystal variable retarder, thereby quickly changing the shearing direction and the shearing amount of the imaging light beam to be interfered.

The differential interference imaging system provided by the invention can be flexibly assembled on a conventional optical microscope, has a simple structure, is easy to realize, and can be used for researching the form and structure of a sample by carrying out high-quality quantitative phase measurement on a non-dyed sample. The shearing assembly adopted by the invention has a simple structure, does not have a mechanical adjusting device and is very easy to adjust. By adjusting the driving voltage of the nematic liquid crystal device, the shearing amount can be flexibly changed, and any shearing direction can be obtained, so that the optimal shearing direction can be selected according to different properties of the sample, and the optimal phase contrast effect of the measured sample can be obtained. In addition, the response time of the liquid crystal is only millisecond order, so that an image in any shearing direction can be rapidly obtained, and the timeliness and convenience of measurement are enhanced.

Drawings

FIG. 1 is a schematic structural diagram of a transmission type differential interference imaging system according to an embodiment of the present invention;

FIG. 2 is a schematic structural diagram of a symmetric transmissive micro-interference imaging system according to a second embodiment of the present invention;

FIG. 3 is a schematic structural diagram of a reflective differential interference imaging system according to a third embodiment of the present invention;

fig. 4 is a bright-field image of polystyrene beads acquired by using the differential interference imaging system according to the first embodiment of the present invention;

FIG. 5 is a differential image of polystyrene beads acquired during transverse shearing by using the differential interference imaging system according to the first embodiment of the present invention;

FIG. 6 is a differential image of polystyrene beads acquired after the transverse shear rate of the differential interference imaging system provided by the first embodiment of the present invention is increased;

FIG. 7 is a differential image of polystyrene beads acquired during longitudinal shearing by using the differential interference imaging system according to the first embodiment of the present invention;

FIG. 8 is a differential image of polystyrene beads acquired after the longitudinal shear rate of the differential interference imaging system provided by the first embodiment of the present invention is increased;

fig. 9 is a differential image of polystyrene spheres obtained by oblique shearing acquisition using the differential interference imaging system according to the first embodiment of the present invention.

Detailed Description

For a better understanding of the present invention, reference will now be made in detail to the present embodiments of the invention, examples of which are illustrated in the accompanying drawings. It should be noted that the embodiments described herein are only for illustrating and explaining the present invention, and are not to be construed as limiting the present invention.