CN108897139A - Polarize regulation device, method and laser interference formula Structured Illumination microscopic system - Google Patents

Abstract

The invention discloses a polarization control device, a method and a laser interference structured light illumination microscope system. The polarization control device disclosed in the present invention comprises: two Pockels cells or two liquid crystal phase retarders, the incident light passes through the first Pockels cell, the second Pockels cell or the first liquid crystal phase retarder, the second A liquid crystal phase retarder, and two Pockels cells or two liquid crystal phase retarders are used to adjust the polarization state of incident light. In the laser interference type structured light illumination microscope system, the incident linearly polarized light (including 0-order and ±1-order diffracted light) of each direction angle is still linearly polarized after the polarization control device of the present invention is parallel to the polarization direction, which can ensure The two or three beams of light that interfere at the focal plane of the large numerical aperture objective lens are all s-polarized to obtain the best structured light modulation degree.

Description

Polarization control device, method and laser interference structured light illumination microscope system

The invention belongs to the field of microscopic imaging, and in particular relates to a polarization control device and method and a laser interference structured light illumination microscope system, in particular to a polarization control method suitable for the laser interference structured light illumination microscope system.

Background technique

SIM technology is the fastest imaging speed among all current super-resolution fluorescence microscopy techniques, and is the most suitable method for real-time imaging of live cells. For the laser interferometric SIM system, the polarization state of the interfering light and the numerical aperture of the objective lens are the main factors affecting the contrast of the interference fringes. In particular, almost all current SIM systems use large numerical aperture objectives for imaging. In order to ensure that the excitation light produces high-contrast structured light fringes on the focal plane of the objective lens, it is necessary to adjust the polarization state of the excitation light in real time to ensure that it is at the focal plane of the objective lens. s polarized light. At this stage, the polarization control methods used in the SIM system mainly include the following:

(1) The first type: a polarization control device composed of two ferroelectric liquid crystal phase retarders and a quarter-wave plate, which is characterized in that the liquid crystal phase retarder is a specially customized fast-axis variable wave plate. Afterwards, its fast axis can be rotated by 45°, and the phase delay is π/3; however, the control system is complicated, the effective energy utilization rate is low, and the cost is high, and the dispersion problem of the quarter-wave plate will cause multi-channel imaging. The modulated outgoing light is no longer linearly polarized, which reduces the contrast of the interference light fringes;

(2) The second type: a control system consisting of a quarter-wave plate and a specially customized pizza polarizer. The pizza polarizer uses 12 fan-shaped linear polarizers to form a large circular polarizer. , and ensure that the fast axes of the symmetrically distributed 6 pairs of sub-polarizers are parallel to the circumferential direction. The incident linearly polarized light is modulated into circularly polarized light after passing through a quarter-wave plate, and the outgoing light is linearly polarized after passing through a pizza polarizer, but the energy loss is more than 50%, and the processing technology of the pizza polarizer is complicated and expensive;

(3) The third method: using a control scheme of a zero-order vortex half-wave plate, using the characteristics of programmable control of the fast axis distribution of the zero-order vortex half-wave plate, the incident linearly polarized light is modulated by the wave plate and then the outgoing light The polarization direction is in the same direction at the spatially symmetrical position, which can ensure that the polarization direction of the ±1st-order interference light of the illumination is parallel to obtain the best fringe contrast; however, most zero-order vortex half-wave plates can only perform polarization accuracy for a single central wavelength. Modulation, which cannot meet the requirements of multi-channel SIM imaging;

The fourth type: A liquid crystal phase retarder and an achromatic quarter-wave plate are used to form a polarization control system. This solution is characterized by a simple structure and high energy utilization rate, and it is a polarization control method commonly used in current SIM systems. .

However, since the achromatic quarter-wave plate is not absolutely achromatic in the visible light band (400-700nm), the measured phase retardation after incident light of different wavelengths passes through the achromatic quarter-wave plate is no longer exactly equal to λ /4, but fluctuates up and down relative to λ/4, and eventually the outgoing light after the polarized light passes through the LCVR and the achromatic quarter-wave plate is not linearly polarized but elliptically polarized, and the ellipse varies with the excitation wavelength Rates are also different. The contrast of the interference fringes produced by the above-mentioned elliptically polarized light interference on the focal plane of the objective lens is usually worse than that of two linearly polarized light beams with the same s polarization; the SIM image reconstruction algorithm is used to process such low-modulation images, and it is easy to reconstruct the image. Generate artifacts.

Contents of the invention

In order to solve the above technical problems, the present invention proposes a polarization control device, method and laser interference structured light illumination microscope system.

In order to achieve the above object, technical scheme of the present invention is as follows:

Polarization control device, including: two Pockels cells or two liquid crystal phase retarders, incident light sequentially passes through the first Pockels cell, the second Pockels cell or the first liquid crystal phase retarder, the second liquid crystal phase retarder device, and two Pockels cells or two liquid crystal phase retarders are used to adjust the polarization state of the incident light, so that the outgoing light generated by it is in any target polarization state.

The polarization control device of the present invention has simple structure and convenient operation, can realize precise control of the polarization state of the excitation light in the laser interferometric SIM system, and ensure the best interference fringe contrast at the focal plane of the microscopic objective lens, resulting in unexpected beneficial effect.

In the laser interferometric structured illumination microsystem, the incident linearly polarized light (including 0-order and ±1-order diffracted light) of each orientation angle is still linearly polarized with parallel polarization directions after passing through the polarization control device of the present invention, which can Ensure that the two or three beams of light that interfere at the focal plane of the large numerical aperture objective lens are all s-polarized to obtain the best structured light modulation degree.

On the basis of the above-mentioned technical scheme, the following improvements can also be made:

As an optimal solution, the fast axis of the first Pockels cell is placed at 45 degrees to the polarization direction of the incident light.

By adopting the above preferred scheme, the control effect is better.

As a preferred solution, the fast axis of the second Pockels cell is placed parallel to the polarization direction of the incident light.

By adopting the above preferred scheme, the control effect is better.

As a preferred solution, the fast axis of the first liquid crystal phase retarder is placed at 45 degrees to the polarization direction of the incident light.

By adopting the above preferred scheme, the control effect is better.

As a preferred solution, the fast axis of the second liquid crystal phase retarder is placed parallel to the polarization direction of the incident light.

By adopting the above preferred scheme, the control effect is better.

The polarization control method uses a polarization control device to perform control, and specifically includes the following steps:

1) The incident light is linearly polarized light;

2) The fast axis of the first Pockels cell is placed at 45° to the polarization direction of the incident light;

3) The fast axis of the second Pockels cell is placed parallel to the polarization direction of the incident light;

4) By changing the magnitude of the voltage applied to the first Pockels cell and the second Pockels cell respectively, the polarization state of the incident light is adjusted, so that the output light produced by it is in any target polarization state.

Using the polarization regulation method disclosed in the present invention for regulation, the regulation effect is better.

The polarization control method uses a polarization control device to perform control, and specifically includes the following steps:

1) The incident light is linearly polarized light;

2) The fast axis of the first liquid crystal phase retarder is placed at 45° to the polarization direction of the incident light;

3) The fast axis of the second liquid crystal phase retarder is placed parallel to the polarization direction of the incident light;

4) Adjusting the polarization state of the incident light by changing the voltages applied to the first liquid crystal phase retarder and the second liquid crystal phase retarder respectively, so that the outgoing light generated by it is in any target polarization state.

Using the polarization regulation method disclosed in the present invention for regulation, the regulation effect is better.

Laser interferometric structured light illumination microscope system, including: laser source, reflector, dichroic mirror, acousto-optic modulator AOTF, doublet lens, half-wave plate HWP, spatial light modulator LCOS, microscope objective lens and camera, and Including polarization control device.

A laser interference type structured light illumination microscope system of the present invention can accurately realize the incident line polarized light (including 0-order and ±1-order diffracted light) of each direction angle after passing through the polarization control device, and the outgoing light is still linearly polarized in parallel to the polarization direction. It can ensure that the two or three beams of light that interfere at the focal plane of the large numerical aperture objective lens are all s-polarized to obtain the best structured light modulation degree.

It should be noted that the laser interference structured light illumination microscope system disclosed in the present invention can be a 3D-SIM system or a 2D-SIM system.

As a preferred solution, it also includes: a spatial filter MASK, the spatial filter MASK is arranged at the incident end of the polarization control device, and the spatial filter MASK is used to filter light of different orders;

The laser source emits laser light, which is coupled into a single-mode polarization-maintaining fiber after being gated by a mirror, a dichroic mirror, and an acousto-optic modulator (AOTF). On the LCOS, the diffracted light of all levels is filtered by the spatial filter MASK, and then enters the microscopic objective lens after passing through the polarization control device, doublet lens, and dichroic mirror and focuses on the focal plane.

By adopting the above preferred scheme, the control effect is better.

As an optimal solution, the spatial filter MASK only allows the ±1st-order diffracted light under the 2D-SIM system or the 0th-order and ±1st-order diffracted light under the 3D-SIM system to pass through.

By adopting the above preferred scheme, the control effect is better.

Description of drawings

Figure 1 is a schematic diagram of the SIM technology;

Figure 1(a) is the Moiré fringe diagram generated by the Moiré effect;

Figure 1(b) Spectrum range map of traditional wide-field imaging technology detection image;

Fig. 1(c) Spectrum range map of SIM image with unidirectional illumination;

Fig. 1(d) SIM spectral range map for three-direction angle illumination.

Fig. 2 shows nine sinusoidally distributed illumination structured light fringe images of three projection angles (0°, 60° and 120°) and three phases (0°, 120° and 240°).

Figure 3 is a graph showing the influence of large NA objective lens on the polarization state.

Fig. 4 is the combination control device of the liquid crystal phase retarder LCVR and the quarter QWP wave plate in the prior art.

Figure 5 is an actual measurement diagram of the phase retardation of a typical achromatic λ/4 wave plate.

Figure 6 shows the polarization state of the outgoing light after adjustment by the existing scheme;

Figure 6(a) direction angle 0°;

Figure 6(b) direction angle is 60°;

Figure 6(c) has a direction angle of 120°.

Fig. 7 is one of the structural schematic diagrams of the polarization regulating device provided by the embodiment of the present invention.

Fig. 8 shows the polarization state of the outgoing light after being regulated by the polarization regulating device of the present invention;

Figure 8(a) direction angle 0°;

Figure 8(b) direction angle is 60°;

Figure 8(c) has a direction angle of 120°.

Fig. 9 is a schematic structural diagram of a laser interference structured light illumination microscope system provided by an embodiment of the present invention.

FIG. 10 is the second structural schematic diagram of the polarization regulating device provided by the embodiment of the present invention.

Among them, 1 is the fast axis.

Detailed ways

Preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings.

In order to better illustrate the effect of the present invention, in a specific embodiment, the existing SIM system is briefly described first.

As a kind of optical microscope, fluorescence microscopy plays an important role in modern biomedical research. The resolution of fluorescence microscopy is determined by the wavelength of light and the numerical aperture (Numerical Aperture, NA) of the objective lens. According to Abbe's diffraction law, the limit lateral resolution of ordinary fluorescence microscope is about 200nm, which makes it difficult for the microscope to observe biological structures smaller than the wavelength characteristic scale. In recent years, driven by the demand for nanoscale imaging in biological research, along with the development of light sources, detectors, new fluorescent probes and new imaging theories, a variety of super-resolution fluorescence imaging techniques that can break through the "diffraction limit" have been proposed. And improve the resolution of fluorescence microscopy to one hundred nanometers or even less than 10 nanometers.

According to different imaging methods, super-resolution fluorescence microscopy can be divided into three categories: single-molecule localization microscopy (SMLM), including stochastic optical reconstruction microscopy (STORM) and light-activated localization microscopy. Microscopy (photoactivated localization microscopy, PALM), stimulated emission depletion microscopy (STED) microscopy, and structured-illumination microscopy (SIM). SMLM can achieve 20nm or even higher resolution, but the time resolution is low, and the total internal reflection fluorescence (TIRF) illumination method is usually used, resulting in a very shallow imaging depth (about the order of wavelength), up to several kW/cm2 The high excitation light power density also makes the sample highly susceptible to photobleaching. STED can obtain 40-70nm super-resolution images, but the STED optical power density up to GW/cm ² also has the problem of sample bleaching, which is not suitable for live cell imaging. SIM effectively overcomes the shortcomings of the above two types of super-resolution microscopes. Its non-specific fluorescent labeling and wide-field imaging characteristics make it have considerable advantages in time resolution and suppression of photobleaching, and it is regarded as the best for live cell observation. effective measures.

SIM technology utilizes intensity sinusoidally modulated structured light to illuminate the observed object to produce a "Moiré effect", encodes high-frequency information that does not propagate in the far-field space into low-frequency images, and decodes high-frequency components through image reconstruction algorithms to achieve resolution improve. From the imaging process of the optical system, the collected original image D(r) can be expressed as:

In the formula, S(r) is the observed object, I(r) is the illumination light field, PSF(r) is the point spread function of the imaging optical system, N(r) is the detector noise, Represents a convolution operation. For linear SIM technology, the emitted light field intensity is proportional to the illumination light field intensity, and the observed object is usually illuminated by a sinusoidally distributed structured light field:

I(r)＝I ₀ [1+m cos(2πk ₀ ·r+φ)] (2)

where k ₀ and φ are the spatial frequency and initial phase of the structured light, respectively. Put formula (2) into formula (1) and perform Fourier transform to get:

In the formula, is the fluorescence spectrum image, is the spectrum of the observed object, OTF(k) is the transfer function of the imaging optical system, and N(k) is the noise spectrum. The first term on the right represents the ordinary wide-field microscopic spectrum, and the other two terms are shifted by k ₀ relative to the first term, which is equivalent to encoding the high-frequency components greater than the cut-off frequency k _c into the low-frequency region of the optical transfer function. For simple analysis: Then there are:

in, is the original image spectrum, φ _i are different phase values. Usually, a total of 9 original images in three directions and three different phases are collected and brought into the above equations for simultaneous solution. The three harmonic terms ( and ) are separated; for two spectral items and Translate to decode high-frequency information and splicing into The high-frequency region, and finally the high-resolution image can be reconstructed based on nano-filtering.

Figure 1 shows a schematic diagram of the basic principle of the SIM technology. Figure 1a) shows the moiré fringe pattern generated by the moiré effect, showing that the moiré effect modulates to generate high-frequency information. Figure 1b) shows the spectrum range of images that can be detected by common wide-field imaging technology. Figures 1c)-d) are schematic diagrams of linear SIM spectrum expansion. Specifically, Figure 1c) shows the spectrum range of the SIM image illuminated in one direction, and Figure 2d) shows the spectrum range of the SIM image illuminated in three directions.

Figure 2 shows nine sinusoidally distributed illuminated structured light fringe images of three projection angles (0°, 60°, and 120°) and three phases (0°, 120°, and 240°).

At present, most laser interferometric SIM systems mostly adopt high NA objective lens for imaging, such as Olympus TIRF oil lens with 100x magnification and NA1.49 (UAPON 100XOTIRF). When using high NA objective lens to carry out SIM imaging, the polarization state modulation of excitation light is one of the key technical problems that need to be solved. If the two beams of p-polarized light emerge from the high NA objective lens and focus on the focal plane at a near-vertical angle, there will be almost no interference, and no structured light fringes will be generated. In order to ensure that the structured light fringes generated by the excitation light field on the focal plane of the objective lens have high contrast, the polarization state of the excitation light is usually adjusted in real time to make it perpendicular to the pupil plane of the objective lens (s-polarized light), as shown in Figure 3.

At present, among several polarization control methods used in the laser interferometric SIM system, the most commonly used control scheme is the combination of a liquid crystal phase retarder and an achromatic quarter-wave plate, as shown in Figure 4 . The principle of the modulation scheme is: the incident light is linearly polarized light with a vertical polarization direction, the angle between the fast axis 1 of the liquid crystal phase retarder LCVR and the polarization direction of the incident light is 45°, and the fast axis of the achromatic quarter-wave plate QWP 1 is parallel to the polarization direction of the incident light. Therefore, when the linearly polarized light is incident on the liquid crystal phase retarder, the outgoing light is circularly polarized light, and then the outgoing light becomes linearly polarized light after entering the quarter-wave plate; change the voltage applied to the liquid crystal phase retarder LCVR to control its The fast axis is rotated by 60° and 120° accordingly to ensure that each excitation light is strictly linearly polarized at 0°, 60° and 120° direction angles, so as to ensure the best interference fringe contrast at the focal plane of the objective lens.

However, the phase retardation of almost all achromatic quarter-wave plates in the visible light band (400-700nm) is not exactly equal to λ/4, but fluctuates around λ/4 with the change of wavelength, as shown in Figure 5 Show. This fluctuation finally causes the circularly polarized light emitted from the liquid crystal phase retarder LCVR to enter the achromatic quarter-wave plate, and the outgoing light is not linearly polarized but elliptically polarized, and the ellipticity is different with different excitation wavelengths. . The modulation degree of structured light produced by the interference of two beams of elliptically polarized light at the focal plane position of the objective lens is lower than the fringe modulation degree produced by the interference of two beams of s-polarized linearly polarized light, which seriously affects the image reconstruction effect of the SIM algorithm.

So up to this point, we can find the shortcomings of the existing technology: the achromatic quarter-wave plate cannot achieve absolute "achromatic" in the visible light band (400-700nm), resulting in the light emitted from the quarter-wave plate by the above control scheme It is not linearly polarized light but elliptically polarized light, and the ellipticity of the outgoing light corresponding to different excitation wavelengths is different, as shown in FIG. 6 . Figure 6a)-Figure 6c) respectively represent the polarization state distribution of the outgoing light after the illumination structured light is modulated at 0°, 60° and 120° direction angles, and the two symmetrically distributed black dots in the figure represent the ± In the center of the first-order spectrum, the three colors represent the wavelength of excitation light at 488/561/647nm respectively.

The present invention is described below. In order to achieve the purpose of the present invention, in some embodiments of the polarization control device, method and laser interference structured light illumination microscope system, as shown in FIG. 7, the polarization control device includes: two Pockels The incident light passes through the first Pockels cell V1 and the second Pockels cell V2 in turn, and the two Pockels cells are used to control the polarization state of the incident light so that the outgoing light generated by it is any target polarization state.

Wherein, the fast axis 1 of the first Pockels cell V1 (indicated by the solid arrow in the figure) is placed at 45 degrees to the polarization direction of the incident light (indicated by the dotted arrow in the figure). The fast axis 1 of the second Pockels cell V2 (indicated by the solid arrow in the figure) is placed parallel to the polarization direction of the incident light (indicated by the dotted arrow in the figure).

The polarization control device of the present invention has simple structure and convenient operation, can realize precise control of the polarization state of the excitation light in the laser interferometric SIM system, and ensure the best interference fringe contrast at the focal plane of the microscopic objective lens, resulting in unexpected beneficial effect.

In the laser interferometric structured illumination microsystem, the incident linearly polarized light (including 0-order and ±1-order diffracted light) of each orientation angle is still linearly polarized with parallel polarization directions after passing through the polarization control device of the present invention, which can Ensure that the two or three beams of light that interfere at the focal plane of the large numerical aperture objective lens are all s-polarized to obtain the best structured light modulation degree.

The polarization control method uses a polarization control device to perform control, and specifically includes the following steps:

1) The incident light is linearly polarized light, and the polarization direction is assumed to be vertical;

2) The fast axis of the first Pockels cell V1 is placed at 45° to the polarization direction of the incident light;

3) The fast axis of the second Pockels cell V2 is placed parallel to the polarization direction of the incident light;

4) Adjust the polarization state of the incident light by changing the voltages applied to the first Pockels cell V1 and the second Pockels cell V2 respectively, so that the outgoing light generated by it is in any target polarization state.

As shown in Figure 8, therefore, based on the above polarization control method, the two beams of ±1st-order interference light at 0°, 60° and 120° direction angles can be modulated into outgoing light with parallel polarization directions to ensure the best SIM fringe contrast . FIG. 8 is a diagram of a comparative experiment based on FIG. 6 . Figure 8a)-Figure 8c) respectively represent the polarization state distribution of the outgoing light after the illumination structured light is modulated at 0°, 60° and 120° direction angles, and the two symmetrically distributed black dots in the figure represent the ± In the center of the first-order spectrum, the three colors represent the wavelength of excitation light at 488/561/647nm respectively.

After two beams of linearly polarized illumination light at any direction angle pass through the polarization control device of this application, the outgoing light is still linearly polarized at this direction angle, and the polarization directions of the two beams of light are parallel, which can ensure the best structured light at the focal plane of the objective lens degree of modulation.

As shown in Figure 9, the present invention also discloses a laser interference structured light illumination microscope system, including: a laser source, a mirror, a dichroic mirror, an acousto-optic modulator AOTF, a doublet lens, a half-wave plate HWP, a space Light modulator LCOS, microscope objective lens, camera, polarization control device and spatial filter MASK.

A laser interference type structured light illumination microscope system of the present invention can accurately realize the incident line polarized light (including 0-order and ±1-order diffracted light) of each direction angle after passing through the polarization control device, and the outgoing light is still linearly polarized in parallel to the polarization direction. It can ensure that the two or three beams of light that interfere at the focal plane of the large numerical aperture objective lens are all s-polarized to obtain the best structured light modulation degree.

The laser source emits four-way lasers with wavelengths of 405/488/561/647nm, and the lasers are coupled into single-mode polarization-maintaining fibers after being gated by mirrors (M1-M5), dichroic mirrors (D1-D3), and acousto-optic modulator AOTF , after collimating and expanding the beam, it is vertically incident on the spatial light modulator LCOS through the half-wave plate HWP and PSB, and the diffracted light of each order (0 order, ±1 order and other high-order orders) is passed through the Fourier lens L2 in the It is focused at the focal plane, filtered by the spatial filter MASK to allow only the ±1st order (or 0th order and ±1st order) diffracted light to pass through, and enter the microscope objective lens OBJ through the polarization control device, the doublet lens group L3 and L4, and then After being reflected by the orthogonally placed dichroic mirrors D4 and D5, it enters the microscope objective lens OBJ and focuses on the focal plane. At this time, the structured light fringes generated by the interference excite the fluorescent sample under observation to produce fluorescence, and the fluorescence is collected by the camera after passing through the dichroic mirror D5, the emission sheet, and the Tube Lens to obtain the original SIM image.

Among them, the polarization control device is two Pockels cells, which are used to control the polarization state of the ±1st order (or 0th order and ±1st order) diffracted light, so that the two interferences of 0°, 60° and 120° spatial orientation angles The beams are all s-polarized at the objective focal plane to ensure optimum fringe contrast.

Among them, 405 is: 405nm laser source; 488 is: 488nm laser source; 561 is: 561nm laser source; 647 is: 647nm laser source;

M1-M5: mirror; D1-D5: dichroic mirror; AOTF: acousto-optic modulator; L1-L4: doublet lens; HWP: half-wave plate; OBJ: microscope objective.

The above-mentioned laser interference type structured light illumination microscope system disclosed in FIG. 9 is a 2D-SIM system, but it should be noted that it is only a certain embodiment. The 3D-SIM system also belongs to the protection scope of the present invention.

In order to further optimize the implementation effect of the present invention, in some other embodiments, the rest of the characteristic technologies are the same, the difference is that, as shown in Figure 10, the polarization control device may also include: two liquid crystal phase retarders, and the incident light is successively After passing through the first liquid crystal phase retarder LCVR1 and the second liquid crystal phase retarder LCVR2, the two liquid crystal phase retarders are used to adjust the polarization state of the incident light, so that the outgoing light generated by it is in any target polarization state.

Wherein, the fast axis 1 of the first liquid crystal phase retarder LCVR1 is placed at 45 degrees to the polarization direction of the incident light. The fast axis 1 of the second liquid crystal phase retarder LCVR2 is placed parallel to the polarization direction of the incident light.

The polarization control method uses a polarization control device to perform control, and specifically includes the following steps:

1) The incident light is linearly polarized light, and the polarization direction is assumed to be vertical;

2) The fast axis 1 of the first liquid crystal phase retarder LCVR1 is placed at 45° to the polarization direction of the incident light;

3) The fast axis 1 of the second liquid crystal phase retarder LCVR2 is placed parallel to the polarization direction of the incident light;

4) Adjust the polarization state of the incident light by changing the voltages applied to the first liquid crystal phase retarder LCVR1 and the second liquid crystal phase retarder LCVR2 respectively, so that the output light generated by it is in any target polarization state.

The invention aims at the "dispersion" problem in the control scheme composed of a liquid crystal phase retarder and an achromatic quarter-wave plate in the current laser interferometric SIM system, and proposes a method using two Pockels cells or two The control device for the combination of two liquid crystal phase retarders can ensure that the incident linearly polarized light is still in any specified polarization direction after the incident linearly polarized light passes through the control system by changing the voltage applied to each Pockels cell or liquid crystal phase retarder respectively. Linear Polarization. This method has simple optical-mechanical structure and high modulation precision, which can effectively make up for the deficiency of current modulation technology.

For the preferred embodiments of the present invention, it should be pointed out that for those of ordinary skill in the art, without departing from the inventive concept of the present invention, some modifications and improvements can also be made, and these all belong to the protection scope of the present invention.

Claims (10)

1. The polarization control device is characterized in that it comprises: two Pockels cells or two liquid crystal phase retarders, and the incident light passes through the first Pockels cell, the second Pockels cell or the first liquid crystal phase retarder successively . A second liquid crystal phase retarder, and the two Pockels cells or the two liquid crystal phase retarders are used to regulate the polarization state of the incident light, so that the outgoing light generated by it is in any target polarization state. 2 . The polarization control device according to claim 1 , wherein the fast axis of the first Pockels cell is placed at an angle of 45 degrees to the polarization direction of the incident light. 3 . 3. The polarization control device according to claim 2, wherein the fast axis of the second Pockels cell is placed parallel to the polarization direction of the incident light. 4. The polarization control device according to claim 1, wherein the fast axis of the first liquid crystal phase retarder is placed at 45 degrees to the polarization direction of the incident light. 5 . The polarization control device according to claim 4 , wherein the fast axis of the second liquid crystal phase retarder is placed parallel to the polarization direction of the incident light. 6. The polarization regulation method, characterized in that, the polarization regulation device according to any one of claims 1-3 is used for regulation, specifically comprising the following steps: 1) The incident light is linearly polarized light; 2) The fast axis of the first Pockels cell is placed at 45° to the polarization direction of the incident light; 3) The fast axis of the second Pockels cell is placed parallel to the polarization direction of the incident light; 4) Adjusting the polarization state of the incident light by changing the magnitudes of the voltages applied to the first Pockels cell and the second Pockels cell respectively, so that the outgoing light generated by it is in any target polarization state. 7. Polarization control method, is characterized in that, utilizes the polarization control device as claimed in claim 1,4-5 to carry out control, specifically comprises the following steps: 1) The incident light is linearly polarized light; 2) The fast axis of the first liquid crystal phase retarder is placed at 45° to the polarization direction of the incident light; 3) The fast axis of the second liquid crystal phase retarder is placed parallel to the polarization direction of the incident light; 4) Adjusting the polarization state of the incident light by changing the voltages applied to the first liquid crystal phase retarder and the second liquid crystal phase retarder respectively, so that the output light generated by it is in any target polarization state. 8. Laser interference structured light illumination microscope system, including: laser source, mirror, dichroic mirror, acousto-optic modulator AOTF, doublet lens, half-wave plate HWP, spatial light modulator LCOS, microscope objective lens and camera , characterized in that it further comprises the polarization regulating device according to any one of claims 1-5. 9. The laser interference type structured light illumination microscope system according to claim 8, further comprising: a spatial filter MASK, the spatial filter MASK is arranged at the incident end of the polarization control device, and the The spatial filter MASK is used to filter light of different orders; The laser source emits laser light, which is coupled into a single-mode polarization-maintaining fiber after being gated by the reflector, dichroic mirror, and acousto-optic modulator AOTF. After being collimated and expanded, the laser beam passes through the half-wave plate HWP and PSB vertically Incident to the spatial light modulator LCOS, the generated diffracted light of various levels is filtered by the spatial filter MASK, and enters the microscope after passing through the polarization control device, doublet lens and dichroic mirror. objective lens and focus on the focal plane. 10. The laser interference type structured light illumination microscope system according to claim 9, wherein the spatial filter MASK only allows ±1st-order diffracted light under the 2D-SIM system or 0 under the 3D-SIM system order, ±1 order diffracted light passes through.