1. Patterned liquid crystal photo-alignment device with continuously adjustable polarization period angle, comprising:

the light source assembly is used for providing a light source and generating collimated linearly polarized light with adjustable polarization angle;

the focal length servo assembly is used for correcting the defocusing phenomenon generated by movement;

the motion control component is used for adjusting the spatial position of the workbench loaded with the light polarization sensitive material so as to realize light field splicing;

it is characterized by also comprising:

polarization grating, light source assembly emittingThe linearly polarized light passes through the polarization grating to form a periodic polarization grating pattern, and the period of the newly generated polarization grating pattern isWherein: lambda is the wavelength of linearly polarized light, when the linearly polarized light vertically enters the polarization grating, a beam of left-handed circularly polarized light and a beam of right-handed circularly polarized light are respectively generated in the positive first-order diffraction angle and the negative first-order diffraction angle, the two beams of circularly polarized light can interfere, and the included angle of the two beams of circularly polarized light is 2 beta;

and the field diaphragm is used for selecting the shape and the size of the periodic polarization grating patterns and combining the periodic polarization grating patterns into any designable pattern.

2. The patterned liquid crystal photoalignment device of claim 1, further comprising: a first Fourier lens and a second Fourier lens, the first Fourier lens, polarization grating, and second Fourier lens forming a Fourier transform system;

linearly polarized light of the light source assembly sequentially passes through the first Fourier lens, the polarization grating and the second Fourier lens, the Fourier transformation system is used for realizing output of a continuously adjustable polarization grating pattern, the polarization grating pattern with a continuously adjustable and controllable period is generated by adjusting the distance from the polarization grating to the first Fourier lens, and the period of the newly generated polarization grating pattern is

Wherein: p is the period of the polarization grating, f is the focal length of the Fourier transform system, and d is the distance between the polarization grating and the first Fourier lens.

3. The patterned liquid crystal photo-alignment device with continuously adjustable polarization period angle of claim 2, wherein the space frequency of the polarization grating in the Fourier transform system is 251p/mm to 33331p/mm, and the corresponding period is 40 μm to 0.3 μm.

4. The patterned liquid crystal photo-alignment device of claim 2, wherein the polarization grating of the fourier transform system is connected to the motion control unit, and the distance between the polarization grating and the first fourier lens and the angle between the polarization grating and the horizontal direction can be changed according to the setting;

wherein the distance adjusting range is 0-f, the minimum adjusting quantity is 0.5 μm, the angle adjusting range is 0-pi degrees, and the minimum adjusting quantity is 0.05 pi.

5. The patterned liquid crystal photoalignment device of claim 2, wherein the spatial frequency of the light field after passing through the fourier transform system is further increased after passing through a subsequent micro imaging system, and the spatial frequency of the newly generated polarization grating pattern is

Wherein: setting the micro multiple of a micro imaging system as M, setting F as the space frequency of a polarization grating in a Fourier transform system, setting the space frequency as 1 mm/period, and setting the space frequency range of a new grating pattern obtained by changing the distance between the polarization grating and a first Fourier lens as [0, 2FM ]1 p/mm;

space frequency change delta F of grating pattern on surface of polarization sensitive material brought by polarization grating translation delta d₁＝|2*Δd*F*M/f|。

6. The patterned liquid crystal photo-alignment device with continuously adjustable polarization cycle angle of claim 2, wherein the light source of the light source module can be a pulsed light source or a continuous light source, and the light beam generated by the light source has a cumulative energy density on the surface of the polarization grating in the fourier transform system lower than the damage threshold of the polarization grating and a cumulative energy density on the surface of the sample higher than the threshold energy of the light polarization sensitive material after passing through the imaging micro-reduction system.

7. The patterned liquid crystal photoalignment device of any of claims 1 to 6, wherein the polarization grating is capable of changing the orientation of the newly generated polarization grating pattern angularly by an equal angle around the rotation angle of the optical axis.

8. The patterned liquid crystal photoalignment device of any of claims 1 to 6, wherein the light source module comprises: a linearly polarized light source and a beam shaping and expanding system; or, comprising: a non-polarized light source, a beam shaping and expanding system and a polarizer.

9. The patterned liquid crystal photo-alignment method with the continuously adjustable polarization period angle is characterized by comprising the following steps of:

s1, providing a light source and generating collimated linearly polarized light with adjustable polarization angle by a light source component;

s2, making the linear polarized light vertically incident to the polarization grating, generating a left-handed circular polarized light and a right-handed circular polarized light respectively in the positive and negative first-order diffraction angle directions, interfering the two circular polarized lights to generate a new polarization grating pattern, and periodically generating the new polarization gratingWherein: lambda is the wavelength of linearly polarized light, and 2 beta is the included angle of two beams of circularly polarized light;

s3, enabling the polarization grating patterns to pass through a field diaphragm, wherein the field diaphragm selects the shape and size of the polarization grating patterns and can combine the shapes and sizes into any designable graph;

s4, reflecting the light spot reflected by the surface of the light polarization sensitive material to a focus servo assembly through an imaging objective lens assembly, performing focus negative feedback adjustment, and adjusting the distance between the imaging objective lens assembly and the surface of the light polarization sensitive material through the focus servo assembly to ensure that the focal plane of the imaging objective lens assembly is always kept on the surface of the light polarization sensitive material, and the space frequency of the newly generated polarization grating pattern is further improved through a subsequent miniature imaging system;

s5, recording the written light polarization orientation information on the light polarization sensitive material;

s6, the motion control part moves the work table carrying the light polarization sensitive material to the next appointed position for the next pattern light field recording or can control the exposure and moving parameters to carry out continuous exposure when the platform moves.

And S7, splicing each orientation unit together to form the optical orientation structure with large-area polarization light pattern on the optical polarization sensitive material.

10. The patterned liquid crystal photo-alignment method with the continuously adjustable polarization period angle is characterized by comprising the following steps of:

s1, providing a light source and generating collimated linearly polarized light with adjustable polarization angle by a light source component;

s2, vertically irradiating the linearly polarized light to the first Fourier lens, the polarization grating and the second Fourier lens of the Fourier transform system, when the linearly polarized light is vertically irradiated to the polarization grating, respectively generating a left-handed circularly polarized light beam and a right-handed circularly polarized light beam in the positive and negative first-order diffraction angle directions, interfering the two circularly polarized light beams to generate a new polarization grating pattern, and periodically irradiating the newly generated polarization grating pattern with the new polarization grating pattern Wherein: p is the period of the polarization grating, f is the focal length of the Fourier transform system, and d is the distance between the polarization grating and the first Fourier lens;

s3, enabling the polarization grating patterns to pass through a field diaphragm, wherein the field diaphragm selects the shape and size of the polarization grating patterns and can combine the shapes and sizes into any designable graph;

s4, reflecting the light spot reflected by the surface of the light polarization sensitive material to the focus servo assembly via the imaging objective lens assembly for performing focus negative feedback adjustment, adjusting the distance between the imaging objective lens assembly and the surface of the light polarization sensitive material via the focus servo assembly to maintain the focal plane of the imaging objective lens assembly on the surface of the light polarization sensitive material, and further increasing the space frequency of the newly generated polarization grating pattern via the subsequent micro imaging systemWherein: setting the micro multiple of a micro imaging system as M, F as the space frequency of a polarization grating in a Fourier transform system, the space frequency being 1 mm/period, and the space frequency range of a new grating pattern obtained by changing the distance between the polarization grating and a first Fourier lens is [0, 2FM [ ]]1p/mm, space frequency change delta F of grating pattern on surface of polarization sensitive material brought by polarization grating translation delta d₁＝|2*Δd*F*M/f|；

S5, recording the written light polarization orientation information on the light polarization sensitive material;

s6, connecting the polarization grating in Fourier transform system with motion control part, changing the distance between the polarization grating and the first Fourier lens and the angle between the polarization grating and the horizontal direction according to the setting, the distance adjusting range is 0-f₁The minimum regulating quantity is 0.5 mu m, the angle regulating range is 0-pi DEG, and the minimum regulating quantity is 0.05 pi.

S7, the motion control part moves the work table carrying the light polarization sensitive material to the next appointed position for the next pattern light field recording or can control the exposure and moving parameters to carry out continuous exposure when the platform moves.

And S8, splicing each orientation unit together to form the optical orientation structure with large-area polarization light pattern on the optical polarization sensitive material.

Background

Liquid crystals have wide applications in the fields of information display, optics, photonic devices, and the like. Many of these applications require that the liquid crystal be aligned according to the designed alignment to achieve the modulation of the amplitude, phase and polarization of light, so the alignment control of the liquid crystal is a research hotspot in academic and industrial production. In recent years, with the development of photosensitive materials, the concept of photoalignment has been proposed, which utilizes the photosensitive materials to generate molecular orientation perpendicular to the direction of linearly polarized light under the irradiation of ultraviolet polarized light, and the molecular orientation generates anchoring force similar to that brought by grooves, thereby inducing the alignment of liquid crystal molecules.

The method for realizing the photo-alignment mainly comprises two major types at present, one type is required to be masked, and the other type is contact type mask exposure, projection type mask exposure and projection type dynamic mask exposure, wherein the contact type mask exposure and the projection type mask exposure are required to manufacture corresponding masks aiming at different patterns, so that the method has the defects of high production cost, low efficiency and the like, and the reported projection type dynamic mask exposure accuracy based on the DMD of the spatial light modulator cannot realize that different selected areas form different liquid crystal alignment patterns under single exposure, cannot realize continuous change exposure of small polarization angle, needs multiple exposure, and also has the problems of low resolution, difficult alignment and the like; the other is holographic interference without mask, which can only generate liquid crystal orientation arrangement pattern with non-adjustable one-dimensional or two-dimensional period and single orientation, and is difficult to prepare complex pattern.

Disclosure of Invention

In order to solve the technical problems, the invention provides a patterned liquid crystal photo-alignment device and a method with continuously adjustable polarization period angle.

In order to achieve the purpose, the technical scheme of the invention is as follows:

patterned liquid crystal photo-alignment device with continuously adjustable polarization period angle, comprising:

the light source assembly is used for providing a light source and generating collimated linearly polarized light with adjustable polarization angle;

the focal length servo assembly is used for correcting the defocusing phenomenon generated by movement;

the motion control component is used for adjusting the spatial position of the workbench loaded with the light polarization sensitive material so as to realize light field splicing;

the linearly polarized light emitted by the light source component passes through the polarization grating to form a periodic polarization grating pattern, and the period of the newly generated polarization grating pattern isWherein: lambda is the wavelength of linearly polarized light, when the linearly polarized light vertically enters the polarization grating, a beam of left-handed circularly polarized light and a beam of right-handed circularly polarized light are respectively generated in the positive first-order diffraction angle and the negative first-order diffraction angle, the two beams of circularly polarized light can interfere, and the included angle of the two beams of circularly polarized light is 2 beta;

and the field diaphragm is used for selecting the shape and the size of the periodic polarization grating pattern and combining the periodic polarization grating pattern into any designable pattern.

On the basis of the technical scheme, the following improvements can be made:

preferably, the method further comprises the following steps: the first Fourier lens, the polarization grating and the second Fourier lens form a Fourier transform system;

linearly polarized light of the light source component sequentially passes through the first Fourier lens, the polarization grating and the second Fourier lens, the Fourier transformation system is used for realizing the output of the continuously adjustable polarization grating pattern, the polarization grating pattern with the continuously adjustable and controllable period is generated by adjusting the distance from the polarization grating to the first Fourier lens, and the newly generated polarization grating pattern has the period ofWherein: p is the period of the polarization grating, f is the focal length of the Fourier transform system, and d is the distance between the polarization grating and the first Fourier lens.

Preferably, the space frequency of the polarization grating in the Fourier transform system is 25lp/mm to 3333lp/mm, and the corresponding period is 40 μm to 0.3 μm.

As a preferable scheme, a polarization grating in the fourier transform system is connected with the motion control part, and the distance between the polarization grating and the first fourier lens and the angle between the polarization grating and the horizontal direction can be changed according to setting;

wherein the distance adjusting range is 0-f, the minimum adjusting quantity is 0.5 μm, the angle adjusting range is 0-pi degrees, and the minimum adjusting quantity is 0.05 pi.

Preferably, the spatial frequency of the light field after the fourier transform system is further increased after the subsequent micro-imaging system, and the spatial frequency of the newly generated polarization grating pattern is

Wherein: setting the micro multiple of a micro imaging system as M, setting F as the space frequency of a polarization grating in a Fourier transform system, setting the space frequency as 1 mm/period, and setting the space frequency range of a new grating pattern obtained by changing the distance between the polarization grating and a first Fourier lens as [0, 2FM ] lp/mm;

space frequency change delta F of grating pattern on surface of polarization sensitive material brought by polarization grating translation delta d₁＝|2*Δd*F*M/f|。

Preferably, the light source of the light source assembly can be a pulse light source or a continuous light source, the accumulated energy density of the light beam generated by the light source on the surface of the polarization grating in the fourier transform system is lower than the damage threshold of the polarization grating, and after passing through the imaging micro-reduction system, the accumulated energy density on the surface of the sample is higher than the threshold energy of the light polarization sensitive material.

Preferably, the polarization grating is angularly equidistant from the newly generated polarization grating pattern orientation by an angle of rotation about the optical axis.

As a preferred aspect, the light source assembly may include: a linearly polarized light source and a beam shaping and expanding system; or, comprising: a non-polarized light source, a beam shaping and expanding system and a polarizer.

The invention also discloses a patterned liquid crystal photo-alignment method with continuously adjustable polarization period angle, which specifically comprises the following steps:

s1, providing a light source and generating collimated linearly polarized light with adjustable polarization angle by a light source component;

s2, making the linear polarized light vertically incident to the polarization grating, generating a left-handed circular polarized light and a right-handed circular polarized light respectively in the positive and negative first-order diffraction angle directions, interfering the two circular polarized lights to generate a new polarization grating pattern, and periodically generating the new polarization gratingWherein: lambda is the wavelength of linearly polarized light, and 2 beta is the included angle of two beams of circularly polarized light;

s3, enabling the polarization grating patterns to pass through a field diaphragm, wherein the field diaphragm selects the shape and size of the polarization grating patterns and can combine the shapes and sizes into any designable graph;

s4, reflecting the light spot reflected by the surface of the light polarization sensitive material to a focus servo assembly through an imaging objective lens assembly, performing focus negative feedback adjustment, and adjusting the distance between the imaging objective lens assembly and the surface of the light polarization sensitive material through the focus servo assembly to ensure that the focal plane of the imaging objective lens assembly is always kept on the surface of the light polarization sensitive material, and the space frequency of the newly generated polarization grating pattern is further improved through a subsequent miniature imaging system;

s5, recording the written light polarization orientation information on the light polarization sensitive material;

s6, the motion control part moves the work table carrying the light polarization sensitive material to the next appointed position for the next pattern light field recording or can control the exposure and moving parameters to carry out continuous exposure when the platform moves.

And S7, splicing each orientation unit together to form the optical orientation structure with large-area polarization light pattern on the optical polarization sensitive material.

The invention also discloses a patterned liquid crystal photo-alignment method with continuously adjustable polarization period angle, which specifically comprises the following steps:

s1, providing a light source and generating collimated linearly polarized light with adjustable polarization angle by a light source component;

s2, vertically inputting linearly polarized light to the first Fourier lens, the polarization grating and the second Fourier lens of the Fourier transform systemWhen linearly polarized light vertically enters the polarization grating, a left-handed circularly polarized light beam and a right-handed circularly polarized light beam are respectively generated in the positive first-order diffraction angle direction and the negative first-order diffraction angle direction, the two circularly polarized light beams interfere to generate a new polarization grating pattern, and the period of the newly generated polarization grating isWherein: p is the period of the polarization grating, f is the focal length of the Fourier transform system, and d is the distance between the polarization grating and the first Fourier lens;

s3, enabling the polarization grating patterns to pass through a field diaphragm, wherein the field diaphragm selects the shape and size of the polarization grating patterns and can combine the shapes and sizes into any designable graph;

s4, reflecting the light spot reflected by the surface of the light polarization sensitive material to the focus servo assembly via the imaging objective lens assembly for performing focus negative feedback adjustment, adjusting the distance between the imaging objective lens assembly and the surface of the light polarization sensitive material via the focus servo assembly to maintain the focal plane of the imaging objective lens assembly on the surface of the light polarization sensitive material, and further increasing the space frequency of the newly generated polarization grating pattern via the subsequent micro imaging systemWherein: setting the micro multiple of the micro imaging system as M, F as the space frequency of the polarization grating in the Fourier transform system, the space frequency as 1 mm/period, and the space frequency range of the new grating pattern obtained by changing the distance between the polarization grating and the first Fourier lens as [0, 2 FM-]lp/mm, space frequency change Delta F of grating pattern on the surface of polarization sensitive material brought by polarization grating translation Delta d₁＝|2*Δd*F*M/f|；

S5, recording the written light polarization orientation information on the light polarization sensitive material;

s6, connecting the polarization grating in Fourier transform system with motion control part, changing the distance between the polarization grating and the first Fourier lens and the angle between the polarization grating and the horizontal direction according to the setting, the distance adjusting range is 0-f₁The minimum regulating quantity is 0.5 mu m, the angle regulating range is 0-pi degree,the minimum adjustment amount is 0.05 pi.

S7, the motion control part moves the work table carrying the light polarization sensitive material to the next appointed position for the next pattern light field recording or can control the exposure and moving parameters to carry out continuous exposure when the platform moves.

And S8, splicing each orientation unit together to form the optical orientation structure with large-area polarization light pattern on the optical polarization sensitive material.

The invention provides a patterned liquid crystal photo-alignment technology with continuously adjustable polarization period, which adopts a polarization grating or a polarization grating combined with a Fourier transform system, can prepare a periodic grating structure with adjustable period from ten micrometers to millimeter level and size from hundreds of nanometers to tens of micrometers, the shape and size of the periodic structure can be selected according to a field diaphragm and can be combined into any designable graph, wherein the polarization angle and the period of each small periodic grating structure are freely available, and a large-area high-freedom polarized photoetching pattern can be realized.

Drawings

Fig. 1 is a schematic structural diagram of a patterned liquid crystal photo-alignment device according to an embodiment of the present invention.

FIG. 2 is a second schematic structural diagram of a patterned liquid crystal photo-alignment device according to an embodiment of the present invention.

Fig. 3 is a schematic diagram of a fourier transform system according to an embodiment of the present invention.

Wherein: 1-light source assembly, 2-Fourier transform system, 201-first Fourier lens, 202-polarization grating, 202-second Fourier lens, 3-field diaphragm, 4-imaging detection assembly, 5-depolarization beam splitter, 6-depolarization beam splitter, 7-focal length servo assembly, 8-motion control assembly, 9-imaging objective lens set and 10-workbench.

Detailed Description

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

To achieve the objects of the present invention, in some embodiments of patterned liquid crystal photo-alignment devices and methods in which the polarization period angle is continuously adjustable,

as shown in fig. 1, the patterned liquid crystal photo-alignment device with continuously adjustable polarization period angle comprises:

the light source assembly 1 is used for providing a light source and generating collimated linearly polarized light with adjustable polarization angle;

the focal length servo assembly 7 is used for correcting the defocusing phenomenon generated by movement;

the motion control component 8 is used for adjusting the spatial position of the workbench 10 loaded with the light polarization sensitive material so as to realize light field splicing;

the linearly polarized light emitted by the light source component 1 passes through the polarization grating 202 to form a periodic polarization grating pattern, and the period of the newly generated polarization grating pattern isWherein: lambda is the wavelength of linearly polarized light, when the linearly polarized light vertically enters the polarization grating 202, a beam of left-handed circularly polarized light and a beam of right-handed circularly polarized light are respectively generated in the positive and negative first-order diffraction angle directions, the two beams of circularly polarized light can interfere, wherein the included angle of the two beams of circularly polarized light is 2 beta;

the field diaphragm 3 is used for selecting the shape and the size of the periodic polarization grating pattern, and the periodic polarization grating pattern can be combined into any designable pattern.

The invention also discloses a patterned liquid crystal photo-alignment method with continuously adjustable polarization period angle, which specifically comprises the following steps:

s1, providing a light source and generating collimated linearly polarized light with adjustable polarization angle by the light source component 1;

s2, making the linearly polarized light vertically incident to the polarization grating 202, respectively generating a left circularly polarized light beam and a right circularly polarized light beam in the positive and negative first-order diffraction angle directions, interfering the two circularly polarized light beams to generate a new polarization grating pattern, and periodically generating the polarization grating 202 Wherein: lambda is the wavelength of linearly polarized light, and 2 beta is the included angle of two beams of circularly polarized light;

s3, enabling the polarization grating patterns to pass through a field diaphragm 3, wherein the field diaphragm 3 selects the shape and size of the polarization grating patterns and can combine the shapes and sizes into any designable graph;

s4, reflecting the light spot reflected by the surface of the light polarization sensitive material to a focal length servo assembly 7 through an imaging objective lens assembly 9, performing focal length negative feedback adjustment, and adjusting the distance between the imaging objective lens assembly 9 and the surface of the light polarization sensitive material by the focal length servo assembly 7 so that the focal plane of the imaging objective lens assembly 9 is always kept at the surface of the light polarization sensitive material, and the space frequency of the newly generated polarization grating pattern is further improved through a subsequent miniature imaging system;

s5, recording the written light polarization orientation information on the light polarization sensitive material;

s6, the motion control unit 8 moves the stage 10 carrying the light polarization sensitive material to the next designated position for the next pattern light field recording or may control the exposure and movement parameters to perform successive exposures as the stage moves.

And S7, splicing each orientation unit together to form the optical orientation structure with large-area polarization light pattern on the optical polarization sensitive material.

Further, the polarization grating 202 may change the orientation of the newly generated polarization grating pattern angularly by an equal angle about the optical axis rotation angle. If the polarization grating 202 is rotated clockwise by pi/6, then the newly generated grating pattern also has a polarization angle of pi/6 from vertical.

Further, the light source assembly 1 may include: a linearly polarized light source and a beam shaping and expanding system; or, comprising: a non-polarized light source, a beam shaping and expanding system and a polarizer.

As shown in fig. 2, in order to further optimize the implementation effect of the present invention, in other embodiments, the remaining features are the same, except that: a first fourier lens 201 and a second fourier lens 202, the first fourier lens 201, the polarization grating 202 and the second fourier lens 202 forming a fourier transform system 2;

linearly polarized light of the light source assembly 1 sequentially passes through the first fourier lens 201, the polarization grating 202 and the second fourier lens 202, the fourier transform system 2 is used for outputting a continuously adjustable polarization grating pattern, a polarization grating pattern with a continuously adjustable period is generated by adjusting the distance from the polarization grating 202 to the first fourier lens 201, and the newly generated polarization grating pattern has the period ofWherein: p is the period of the polarization grating 202, f is the focal length of the fourier transform system 2, and d is the distance between the polarization grating 202 and the first fourier lens 201.

As shown in fig. 3, the specific derivation process is as follows:

the angle between the positive and negative first-order diffraction light generated by the linearly polarized light after passing through the first Fourier lens 201 and entering the polarization grating 202 and the optical axis is alpha, the angle between the positive and negative first-order diffraction light and the optical axis after passing through the second Fourier lens 202 is beta, wherein the period of the polarization grating 202 is P, and the period of the grating pattern obtained by the interference of the positive and negative first-order circularly polarized diffraction light in the optical field of the output plane is P₁The focal length of the fourier transform system 2 is f, the distance between the polarization grating 202 and the first fourier lens 201 is d, the illumination light is incident perpendicular to the focal plane, and h is the offset in the direction perpendicular to the optical axis when the first-order diffracted light is transmitted to the focal plane;

the above parameters have the following relationships:

P*sinα＝λ.

the period of the newly generated raster pattern is:

using paraxial approximation: alpha is approximately equal to sin alpha, beta is approximately equal to sin beta, and tan beta;

then there are:

i.e. a grating pattern with a continuously controllable period can be generated by adjusting the distance of the polarization grating 202 to the first fourier lens 201.

By adopting the idea and the optical path of the polarization grating 202 combined with the Fourier transform system 2, the polarization grating 202 with continuously adjustable period and randomly changed angle can be realized, and can be spliced into any large-width pattern, and the polarization angle and the period of any area in the pattern can be freely set

Further, the space frequency of the polarization grating 202 in the Fourier transform system 2 may be 25lp/mm to 3333lp/mm, with a corresponding period of 40 μm to 0.3 μm.

Further, the polarization grating 202 in the fourier transform system 2 is connected to the motion control unit 8, and the distance between the polarization grating 202 and the first fourier lens 201 and the angle between the polarization grating 202 and the horizontal direction can be changed according to the setting;

wherein the distance adjusting range is 0-f, the minimum adjusting quantity is 0.5 μm, the angle adjusting range is 0-pi degrees, and the minimum adjusting quantity is 0.05 pi.

Further, after the light field after passing through the Fourier transform system 2 passes through a subsequent micro imaging system, the space frequency is further improved, and the space frequency of the newly generated polarization grating pattern is

Wherein: setting the micro multiple of the micro imaging system as M, F as the space frequency of the polarization grating 202 in the fourier transform system 2, where the space frequency is 1 mm/period, and the space frequency range of the new grating pattern obtained by changing the distance between the polarization grating 202 and the first fourier lens 201 is [0, 2FM ] lp/mm;

spatial frequency change Δ F of grating pattern on the surface of the polarization sensitive material caused by Δ d translation of the polarization grating 202₁＝|2*Δd*F*M/f|。

Further, the light source of the light source module 1 may be a pulse light source or a continuous light source, the accumulated energy density of the light beam generated by the light source on the surface of the polarization grating 202 in the fourier transform system 2 is lower than the damage threshold of the polarization grating 202, and after passing through the imaging micro-shrinking system, the accumulated energy density on the surface of the sample is higher than the threshold energy of the light polarization sensitive material.

The light source of the light source assembly 1 can be, but is not limited to, a laser and an LED light source, and the wavelength of the light source can be from ultraviolet to visible light.

Further, the polarization grating 202 may change the orientation of the newly generated polarization grating pattern angularly by an equal angle about the optical axis rotation angle. If the polarization grating 202 is rotated clockwise by pi/6, then the newly generated grating pattern also has a polarization angle of pi/6 from vertical.

Further, the light source assembly 1 may include: a linearly polarized light source and a beam shaping and expanding system; or, comprising: a non-polarized light source, a beam shaping and expanding system and a polarizer.

The invention also discloses a patterned liquid crystal photo-alignment method with continuously adjustable polarization period angle, which specifically comprises the following steps:

s1, providing a light source and generating collimated linearly polarized light with adjustable polarization angle by the light source component 1;

s2, vertically irradiating the linearly polarized light to the first Fourier lens 201, the polarization grating 202 and the second Fourier lens 202 of the Fourier transform system 2, when the linearly polarized light is vertically irradiated to the polarization grating 202, respectively generating a left circularly polarized light beam and a right circularly polarized light beam in the positive and negative first-order diffraction angle directions, interfering the two circularly polarized light beams to generate a new polarization grating pattern, and periodically irradiating the newly generated polarization grating 202 to the second Fourier lens 202Wherein: p is the period of the polarization grating 202, f is the focal length of the fourier transform system 2, and d is the distance between the polarization grating 202 and the first fourier lens 201;

s3, enabling the polarization grating patterns to pass through a field diaphragm 3, wherein the field diaphragm 3 selects the shape and size of the polarization grating patterns and can combine the shapes and sizes into any designable graph;

s4, reflecting the light spot reflected by the light polarization sensitive material surface to the focus servo assembly 7 through the imaging objective lens assembly 9 for focus negative feedback adjustment, adjusting the distance between the imaging objective lens assembly 9 and the light polarization sensitive material surface by the focus servo assembly 7 to keep the focal plane of the imaging objective lens assembly 9 at the light polarization sensitive material surface all the time, further improving the space frequency of the newly generated polarization grating pattern through the subsequent micro imaging system, and generating the newly generated grating pattern with the space frequency ofWherein: assuming that the reduction factor of the miniature imaging system is M, F is the space frequency of the polarization grating 202 in the fourier transform system 2, the space frequency is 1 mm/period, and the space frequency range of the new grating pattern obtained by changing the distance between the polarization grating 202 and the first fourier lens 201 is [0, 2FM [ ]]lp/mm, space frequency change Δ F of grating pattern on the surface of the polarization sensitive material caused by Δ d translation of the polarization grating 202₁＝|2*Δd*F*M/f|；

S5, recording the written light polarization orientation information on the light polarization sensitive material;

s6, the polarization grating 202 in the Fourier transform system 2 is connected with the motion control component 8, the distance between the polarization grating 202 and the first Fourier lens 201 and the angle between the polarization grating 202 and the horizontal direction are changed according to the setting, and the distance adjusting range is 0-f₁The minimum regulating quantity is 0.5 mu m, the angle regulating range is 0-pi DEG, and the minimum regulating quantity is 0.05 pi.

S7, the motion control unit 8 moves the stage 10 carrying the light polarization sensitive material to the next designated position for the next pattern light field recording or may control the exposure and movement parameters to perform successive exposures as the stage moves.

And S8, splicing each orientation unit together to form the optical orientation structure with large-area polarization light pattern on the optical polarization sensitive material.

In order to further optimize the effect of the present invention, in other embodiments, the rest features are the same, except that the focus servo assembly 7 sequentially comprises: the detection light source, the second lens, the second light splitting sheet, the imaging objective lens group 9, the second imaging CCD and the motor;

the detection light source is positioned on the front focal plane of the second lens;

the second light splitting sheet is positioned on the back focal plane of the second lens;

the imaging surface of the second imaging CCD is positioned on the front focal plane of the second lens;

the main axis direction of the optical path of the imaging objective lens group 9 is perpendicular to the workbench 10 carrying the light polarization sensitive material, and the motor is used for driving the imaging objective lens group 9 to vertically move up and down, so that a focusing plane is formed on the workbench 10.

Further, on the basis of the above embodiment, the value of the wavelength of light emitted from the light source outside the polarization photosensitive absorption wavelength region is detected;

the second lens is used for reflecting the light spots projected to the light polarization sensitive material surface to the second imaging CCD;

the second imaging CCD is used for mapping the Z-axis servo focusing position through the light spot diameter;

and the motor is used for adjusting the vertical height of the Z-axis lens, so that the diameter of a light spot in the second imaging CCD can be always kept to be R, and whether the light polarization sensitive material surface is on the focus surface of the objective lens or not is judged by detecting the size of the light spot projected on the light polarization sensitive material surface through the second imaging CCD.

The detection light source may be, but is not limited to, a laser or an LED.

Further, on the basis of the above embodiment, the working table 10 is disposed below the imaging objective lens group 9 and has a two-dimensional motion track, and the light polarization sensitive material is driven by the motion control component 8 to move in a two-dimensional plane, so as to implement light field splicing.

Further, on the basis of the above embodiment, the focal length servo assembly 7 is connected to the imaging detection assembly 4, and shares the imaging objective lens group 9 and the worktable 10;

the imaging detection assembly 4 comprises a first light splitter, a tube lens, an imaging objective lens group 9, a polarizing film, a first lens and a first imaging CCD which are sequentially connected; the front focal plane of the imaging objective group 9 is located near the back focal plane of the barrel mirror; the imaging surface of the first imaging CCD is positioned on the front focal surface of the first lens; the back focal plane of the first lens is positioned on the front focal plane of the tube mirror; the imaging detection component 4 is used for detecting the imaging of the generated liquid crystal photo-alignment pattern, the tube lens and the imaging objective lens group 9 form a double telecentric optical system, and the position of a focus plane is adjusted by finely adjusting the distance between the tube lens and the imaging objective lens group 9.

The light beam passes through the beam splitter, the transmitted light enters the imaging lens group, and the imaging lens group can shrink the femtosecond laser spot and balance the writing precision and efficiency. The beam splitter adopts a depolarization beam splitter 6, and the polarization states of the transmitted light and the reflected light cannot be changed.

Specific examples are as follows:

the light source adopts a linear polarization laser, the wavelength of the laser corresponds to the wavelength of the light polarization sensitive material, the laser is incident to the Fourier transform system 2 after beam expanding and collimating, and the accumulated energy density is lower than the damage threshold of the polarization grating 202 on the surface of the polarization grating 202 in the Fourier transform system 2; after the subsequent imaging and shrinking steps, the accumulated energy density is higher than the threshold energy of the light polarization sensitive material on the surface of the sample, the left circularly polarized light and the right circularly polarized light generated by the linearly polarized light irradiating the polarization grating 202 interfere with each other, the interference light field is focused by the cylindrical lens and the micro objective lens to generate another group of polarization grating patterns on the surface of the polarization sensitive material, and the motion control part 8 adjusts the position and deflection angle of the polarization grating 202 in the Fourier transform system 2 in real time according to the design to regulate the period and the polarization angle of the newly generated polarization grating patterns.

In this embodiment, the polarization grating 202F is 100lp/mm, and in the fourier transform system 2, the focal length of the first fourier lens 201 and the second fourier lens 202 is 200mm, and the objective lens reduction factor is 20 times, so that the space frequency of the interference pattern that can be generated is [0, 4000] lp/mm.

The imaging detection assembly 4 determines whether the focal plane of the objective lens is on the surface of the photosensitive material by receiving the contrast of the profile of the imaging light spot reflected from the surface of the light polarization sensitive material.

Light spots reflected by the surface of the light polarization sensitive material are reflected to the focal length servo assembly 7 through the imaging objective lens assembly 9 to carry out focal length negative feedback adjustment, so that focusing errors caused by uneven coating or mechanical movement of the sensitive material are avoided. The motion control unit 8 is used to adjust the spatial position of the stage 10 carrying the light polarization sensitive material and to stitch the patterned light field. The motion control part 8 can also rotate the orientation of the Fourier polarized light according to the design, and a series of liquid crystal devices with high resolution can be prepared by matching with the subsequent box manufacturing and liquid crystal perfusion.

The invention provides a patterned liquid crystal photo-alignment technology with continuously adjustable polarization period, which adopts a polarization grating 202, or the polarization grating 202 is combined with a Fourier transformation system 2, so that a periodic grating structure with adjustable period from ten micrometers to millimeter level and size from hundreds of nanometers to tens of micrometers can be prepared, the shape and size of the periodic structure can be selected according to a field diaphragm 3 and can be combined into any designable graph, wherein the polarization angle and the period of each small periodic grating structure are freely selectable, and a large-area high-freedom polarized photo-etching pattern can be realized.

The various embodiments above may be implemented in cross-parallel.

With respect to the preferred embodiments of the present invention, it should be noted that, for those skilled in the art, various changes and modifications can be made without departing from the inventive concept of the present invention, and these changes and modifications are within the scope of the present invention.