CN112946960A - Large-breadth randomly-distributed optical orientation device and method based on digital micro-reflector - Google Patents
Large-breadth randomly-distributed optical orientation device and method based on digital micro-reflector Download PDFInfo
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- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/1333—Constructional arrangements; Manufacturing methods
- G02F1/1337—Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers
- G02F1/13378—Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers by treatment of the surface, e.g. embossing, rubbing or light irradiation
- G02F1/133788—Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers by treatment of the surface, e.g. embossing, rubbing or light irradiation by light irradiation, e.g. linearly polarised light photo-polymerisation
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Abstract
The invention discloses a large-area patterned liquid crystal photo-alignment device based on a digital micro-reflector, which comprises a light source component, a dynamic mask generating component, an imaging detection component, a focal length servo system and a motion control component which are sequentially arranged; the dynamic mask generating assembly comprises a numerical control micro-mirror DMD, an electrically adjustable polaroid and a computer control system and is used for dynamically adjusting and controlling the polarization state of incident light; and the image signal of the computer control system is input to the signal input end of the digital control micro-mirror DMD. The invention integrates the optical system, the motion control system and the detection system, and can realize the advantages of high precision, arbitrary controllability and high efficiency of the light orientation and polarization patterns of large-area complex patterns.
Description
Technical Field
The invention relates to the field of liquid crystal display, in particular to a large-breadth randomly-distributed optical orientation device and method based on a digital micro-reflector.
Background
Liquid crystals have wide applications in the fields of information display, optics, photonics devices, and the like; the liquid crystal can further realize the modulation of amplitude, phase and polarization of light according to the designed orientation arrangement, and plays an important role in the applications, so the orientation arrangement control mode of the liquid crystal becomes a research hotspot of academic and industrial production, and the prior art disclosed at present mainly comprises a rubbing orientation technology and a photo-orientation technology:
the rubbing alignment is to rub an alignment film of a liquid crystal display with materials such as nylon fibers or cotton linters in a certain direction to change the surface condition of the film and generate uniform anchoring effect on liquid crystal molecules, so that the liquid crystal molecules are uniformly arranged in a certain area between two glass plates of the liquid crystal display at a certain pretilt angle. However, there are the following problems: static electricity is easily generated in the friction process, which can cause the breakdown of the thin film transistor, and because fluff dust is generated in the friction process, cleaning and drying processes must be added after friction, so that the production efficiency is reduced.
Photoalignment is a newly developed non-contact liquid crystal aligning method, which utilizes photosensitive materials to perform oriented photocrosslinking, isomerization or photocleavage reaction under ultraviolet or blue light polarized light irradiation to obtain the required arrangement, and the current photoalignment technologies are divided into four types: mask overlay polarization patterning techniques, periodic liquid crystal alignment techniques obtained by holographic interference methods, dynamic mask photo-alignment techniques based on DMDs, and also polarization alignment techniques based on spatial modulators.
The mask overlay polarization pattern technology has the following problems: the alignment difficulty is too high, and the efficiency is low; the precision is low; the large breadth is difficult to manufacture; the mask is in contact with the photoresist layer on the wafer causing damage.
The periodic liquid crystal orientation technology obtained by the holographic interference method can only realize specific periodic polarization patterns and cannot realize the writing of any polarization patterns.
The polarization orientation technology based on the liquid crystal spatial modulator is a programmable control device capable of modulating the phase and amplitude of incident light, pattern recording of different orientation arrangements of liquid crystals in different selected areas can be realized by single projection orientation, but if an imaging system is an amplification system, the sample size is large, the pixel unit size is also large, and a high-precision polarization pattern cannot be output.
The dynamic mask photo-alignment technology based on the DMD can quickly generate a required mask plate pattern by refreshing an intensity distribution diagram on the DMD, does not need to physically produce a new mask plate, is easier to realize alignment distribution of various shapes, but still uses a method of mechanically rotating a linear polarization film to control the polarization direction of light, so that multiple exposures are still needed to complete photo-alignment of complex patterns.
Therefore, a new device and method for outputting polarization pattern with high precision and large width in the field of liquid crystal display is needed.
Disclosure of Invention
In order to solve the problems in the prior art, on one hand, the invention discloses a large-area patterned liquid crystal photo-alignment device based on a digital micro-reflector, which comprises a light source assembly, a dynamic mask generation assembly, an imaging detection assembly, a focal length servo system and a motion control component which are sequentially arranged;
the light source component comprises an ultraviolet or blue light source, a collimation and beam expansion system and a polarizer which are sequentially connected, wherein the polarizer is connected with the collimation and beam expansion system and used for controlling the initial polarization direction of light and generating a surface light source with any polarization direction within the range of 0-179 ℃;
the dynamic mask generating assembly comprises a numerical control micro-mirror DMD, an electric adjustable polaroid and a computer control system and is used for dynamically adjusting and controlling the polarization state of incident light; the image signal of the computer control system is input to the signal input end of the numerical control micro-mirror DMD;
the imaging detection component is used for detecting the generated pattern imaging; the focal length servo system comprises a normally open light source insensitive to light polarization sensitive materials and a vertical direction correction assembly, and is used for correcting the defocusing phenomenon generated by movement;
the motion control component is used for adjusting the spatial position of the platform carrying the light polarization sensitive material so as to realize light field splicing.
As a further improvement of the embodiment of the present invention, the imaging detection assembly further comprises a miniature imaging component;
the miniature imaging component is used for miniature the polarization pattern output by the polarization pattern generating component and writing the polarization pattern into the light polarization sensitive material;
the miniature imaging component comprises an imaging objective lens group, the main shaft direction of the optical path of the imaging objective lens group is vertical to the platform, and a motor drives the imaging objective lens group to vertically move up and down to form a focusing surface on the platform;
the imaging objective lens group comprises a tubular lens and a microscope objective lens; the digital micromirror DMD is arranged in front of the tubular lens.
As a further improvement of the embodiment of the present invention, the miniature imaging component is connected to the electrically adjustable polarizer and the splitting prism, and the electrically adjustable polarizer and the splitting prism are disposed on a horizontal central axis of the digital micromirror DMD; the beam splitting prism is used for transmitting the light with polarization information to the imaging detection assembly.
As a further improvement of an embodiment of the invention, the apparatus further comprises a platform for carrying the light polarization sensitive material; the platform is arranged below the imaging objective lens group and is provided with a two-dimensional motion track which is used for bearing a light polarization sensitive material and driving the light polarization sensitive material to move on a two-dimensional plane under the driving of the motion control part, so that the surface of the light polarization sensitive material is always kept on the focal plane of the imaging objective lens group;
and the motion control component is connected with the miniature imaging component and is used for splicing the miniature polarization pattern light field.
As a further improvement of the embodiment of the present invention, the imaging detection assembly includes a first light splitter, a tube lens, an imaging objective lens group, a polarizer, a first lens, and a first imaging CCD, which are connected in sequence;
the front focal plane of the imaging objective group is positioned near the rear focal plane of the tube mirror; the imaging surface of the first imaging CCD is positioned on the front focal plane of the first lens; the back focal plane of the first lens is positioned on the front focal plane of the tube mirror.
As a further improvement of the embodiment of the present invention, the focal length servo system includes a detection light source, a second lens, a second light splitting plate, an imaging objective lens group, a second imaging CCD, and a motor, which are connected in sequence;
the detection light source is positioned on the front focal plane of the second lens; the second light splitter 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 motor drives the imaging objective lens group;
the first imaging CCD receives the reflected image projected to the light polarization sensitive material surface, and the first imaging CCD forms a conjugate image with the generated polarization pattern.
As a further improvement of the embodiments of the present invention, the light source is a pulsed light source or a continuous light source with a controllable light barrier system; the pulse width of the pulse laser generated by the light source is in the picosecond to second level, and the wavelength of the pulse laser is 340nm to 600 nm.
On the other hand, the embodiment of the invention discloses a large-breadth randomly-distributed optical orientation method based on a digital micro-reflector, which comprises the following steps:
s1, adjusting light emitted by the light source into a collimated light beam through the collimation and beam expansion system;
s2, uniformly irradiating the collimated light beam to the surface of the DMD panel of the numerical control micro-mirror array at a preset angle;
s3, the computer outputs a graphic signal to control each micromirror of the DMD to present different reflection states to realize a mask, and the DMD panel refreshes an exposure graphic;
and S4, after the light beam forming the exposure pattern is micro-scaled by a micro objective lens, projecting the light beam to a liquid crystal substrate coated with a photo-alignment material on the surface through a polaroid, controlling the light intensity and time to complete exposure, and reorienting the liquid crystal in the exposure pattern area.
As a further improvement of the embodiment of the present invention, the step S4 specifically includes:
s401, refreshing the graph according to the DMD, and rotating the polaroid to a corresponding polarization angle to enable the light passing through the polaroid to be polarized light with a preset fixed polarization angle;
s402, the polarized light on the horizontal central axis is reflected by a beam splitter prism to form vertically downward polarized light, and the vertically downward polarized light sequentially passes through a tubular lens and a miniature objective lens to irradiate the surface of the light polarization sensitive material, and the beam splitter prism transmits the light with polarization information to an imaging detection assembly.
As a further improvement of the embodiment of the present invention, in the step S4, the miniature imaging component forms a fixed miniature magnification ratio according to the focal length ratio of the tube lens and the miniature objective lens, and miniature the polarization pattern, so as to output the polarization pattern light field.
As a further improvement of the embodiment of the present invention, after the step S4, the method further includes:
s5, detecting and adjusting the distance between the miniature objective lens and the light polarization sensitive material surface by the imaging detection part, so that the focus surface of the miniature objective lens is always kept on the light polarization sensitive material surface;
s6, recording a single polarized light pattern on the light polarization sensitive material;
and S7, equally dividing any patterned polarization information into a plurality of different polarized light patterns, and performing pattern refreshing and polarization control for a plurality of times to form a pattern recording process.
As a further improvement of the embodiment of the present invention, after the step S7, the method further includes:
s8, moving the platform carrying the light polarization sensitive material to the next appointed view field position for the next pattern light field recording;
the polarization pattern of one splicing unit is formed by a plurality of different polarization patterns, wherein in a single polarization pattern, all polarization states are fixed.
As a further improvement of the embodiment of the present invention, the step S1 of collimating the light source includes using an LED light source, forming collimated light through a set of collimating lenses, or using a laser light source, expanding the laser light source through an objective lens, and forming collimated light through a lens.
As a further improvement of the embodiment of the present invention, in the step S3, the different reflection states are that the DMD panel divides the incident collimated light into two paths for reflection, including forming on-state reflected light in the area where the exposure pattern is formed and forming off-state reflected light in the area where the exposure pattern is not formed;
the on-state reflected light is perpendicular to the DMD panel and is located on a horizontal central axis.
As a further improvement of the embodiment of the present invention, the step S402 specifically includes:
after an image reflected from the surface of the light polarization sensitive material sequentially passes through the microscope objective, the tubular lens, the specified waveband reflection flat plate and the first light splitter, the image enters the first imaging CCD through the first lens, and a generated polarization pattern and the first imaging CCD are positioned on the front focal plane of the tubular lens and form a conjugate relation; adjusting the definition of an image in the first imaging CCD by controlling the up-and-down movement of a lens of the microscope objective, judging whether the focal plane of the microscope objective is on the light polarization sensitive material surface, calibrating the laser spot size in the second imaging CCD, and carrying out focusing monitoring on subsequent splicing; and judging whether the focal plane of the objective lens is on the surface of the light polarization sensitive material or not through the contrast of the outline of the imaging light spot projected to the light polarization sensitive material.
As a further improvement of the embodiment of the present invention, the step S5 specifically includes:
detecting any value between 550nm and 650nm of wavelength of light emitted by a light source;
the second lens reflects the light spots projected to the light polarization sensitive material surface to the second imaging CCD, the Z-axis servo focusing position is mapped through the light spot diameter, the vertical height of the Z-axis lens is adjusted, the light spot diameter in the second imaging CCD can be always kept to be R, and whether the light polarization sensitive material surface is on the focusing surface of the objective lens or not is judged by detecting the size of the light spots projected to the light polarization sensitive material surface through the second imaging CCD.
As a further improvement of the embodiment of the present invention, in step S8, the single exposure area can be spliced into a complete pattern light field by the stepping movement of the motion control component control platform, so as to form a large-format high-precision exposure pattern;
when the single polarization pattern is recorded on the light polarization sensitive material in the step S6, the motion control unit moves the platform carrying the light polarization sensitive material to the next designated position for the next light orientation, which is implemented by the following steps:
the computer control system transmits the position data to the motion control part, the motion control part converts the received data into a control signal and transmits the control signal to the motor driver, the motor driver controls the motion of the motor according to the received control signal, and the detection device is responsible for monitoring the motion of the motor in real time and transmitting the motion position and the motion speed of the motor to the motion control part; and then the motion control part feeds back the current positions and the current speeds of the focusing platform and the sample carrying platform to the computer control system.
Compared with the prior art, the invention has the following beneficial effects:
1. the light source of the invention adopts ultraviolet or blue light after beam expansion collimation, adjusts the light field by the generated polarization pattern, can generate different polarization phases, and then combines with an imaging system for micro-shrinkage, finally realizes the polarization modulation in any direction in unit pixels, and effectively overcomes the problems of single polarization orientation, low flexibility and low processing efficiency;
2. the invention adopts the assistance of a focusing servo system to control the objective lens to move up and down, focus in real time and improve the resolution;
3. the invention adopts the high-precision platform to accurately control the sample to do two-dimensional plane movement, thereby providing favorable conditions for realizing large-format writing;
4. because the light energy is not concentrated, the invention proposes that the abutted seams between each light-operated orientation view field are eliminated and the resolution is improved by controlling the relation between the size of a single view field and the single translation distance;
5. the invention has the advantages of high precision, arbitrary controllability, large-area writing and high efficiency of exposure polarization patterns, and has important significance for designing and manufacturing large-size, high-precision and multifunctional liquid crystal optical devices.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
Fig. 1 is a schematic structural diagram of a large-area patterned liquid crystal photo-alignment device based on a digital micro-mirror according to an embodiment of the present invention;
FIG. 2 is a schematic structural diagram of an imaging detection assembly provided by an embodiment of the invention;
FIG. 3 is a schematic diagram of a focus servo system according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of the path of incident collimated light according to an embodiment of the present invention;
FIG. 5 is a schematic diagram of gray scale levels and polarization angles according to an embodiment of the present invention;
fig. 6 is a light orientation generation example according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The embodiment of the invention provides a large-area patterned liquid crystal photo-alignment device based on a digital micro-reflector, which comprises a light source assembly, a dynamic mask generation assembly, an imaging detection assembly, a focal length servo system and a motion control assembly which are sequentially arranged, as shown in figure 1;
the light source assembly comprises an ultraviolet or blue light source, a collimation and beam expansion system and a polarizer which are sequentially connected, wherein the polarizer is connected with the collimation and beam expansion system and used for controlling the initial polarization direction of light and generating a surface light source with any polarization direction within the range of 0-179 ℃;
the dynamic mask generating assembly comprises a numerical control micro-mirror DMD, an electrically adjustable polaroid and a computer control system and is used for dynamically adjusting and controlling the polarization state of incident light; wherein, the image signal of the computer control system is input to the signal input end of the digital control micro-mirror DMD;
an imaging detection component for detecting the generated pattern imaging;
the focal length servo system comprises a normally open light source insensitive to light polarization sensitive materials and a vertical direction correction assembly, and is used for correcting the defocusing phenomenon generated by movement;
and the motion control component is used for adjusting the spatial position of the platform carrying the light polarization sensitive material so as to realize light field splicing.
In some embodiments, the imaging detection assembly further comprises a miniature imaging component for miniature polarization patterns output by the polarization pattern generation component and writing into the light polarization sensitive material;
the miniature imaging component comprises an imaging objective lens group, the main shaft direction of the optical path of the imaging objective lens group is vertical to the platform, and the motor drives the imaging objective lens group to vertically move up and down to form a focusing surface on the platform;
the imaging objective lens group comprises a tubular lens and a microscope objective lens; the digital micromirror DMD is arranged in front of the tubular lens.
Specifically, the miniature imaging component is connected with an electrically adjustable polarizing film and a beam splitter prism, and the electrically adjustable polarizing film and the beam splitter prism are arranged on a horizontal central axis of the digital controlled micromirror DMD; the beam splitting prism is used for transmitting the light with polarization information to the imaging detection assembly.
The device further comprises a platform for carrying the light polarization sensitive material; the platform is arranged below the imaging objective lens group and is provided with a two-dimensional motion track which is used for bearing the light polarization sensitive material and driving the light polarization sensitive material to move on a two-dimensional plane under the drive of the motion control component, so that the surface of the light polarization sensitive material is always kept on the focus plane of the imaging objective lens group;
the motion control component is connected with the miniature imaging component and is used for splicing the miniature polarization pattern light field.
As shown in fig. 2, the imaging detection assembly includes a first light splitter, a tube lens, an imaging objective lens group, a polarizer, a first lens, and a first imaging CCD, which are connected in sequence;
specifically, the front focal plane of the imaging objective lens group 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.
As shown in fig. 3, the focal length servo system includes a detection light source, a second lens, a second dichroic plate, an imaging objective lens group, a second imaging CCD, and a motor, which are connected in sequence;
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; a motor-driven imaging objective lens group;
the first imaging CCD receives the reflected image projected to the light polarization sensitive material surface, and the first imaging CCD forms a conjugate image with the generated polarization pattern.
In the embodiment of the invention, the light source is a pulse light source or a continuous light source with a controllable light barrier system; the pulse width of the pulse laser generated by the light source is in picosecond to second level, and the wavelength of the pulse laser is 340nm to 600 nm.
On the other hand, the embodiment of the invention discloses a large-breadth randomly-distributed optical orientation method based on a digital micro-reflector, which comprises the following steps:
s1, adjusting light emitted by the light source into a collimated light beam through the collimation and beam expansion system;
s2, uniformly irradiating the collimated light beam to the surface of the DMD panel of the numerical control micro-mirror array at a preset angle;
s3, the computer outputs a graphic signal to control each micromirror of the DMD to present different reflection states to realize a mask, and the DMD panel refreshes an exposure graphic;
and S4, after the light beam forming the exposure pattern is micro-scaled by a micro objective lens, projecting the light beam to a liquid crystal substrate coated with a photo-alignment material on the surface through a polaroid, controlling the light intensity and time to complete exposure, and reorienting the liquid crystal in the exposure pattern area.
Wherein, step S4 specifically includes:
s401, refreshing the graph according to the DMD, and rotating the polaroid to a corresponding polarization angle to enable the light passing through the polaroid to be polarized light with a preset fixed polarization angle;
s402, the polarized light on the horizontal central axis is reflected by a beam splitter prism to form vertically downward polarized light, and the vertically downward polarized light sequentially passes through a tubular lens and a miniature objective lens to irradiate the surface of the light polarization sensitive material, and the beam splitter prism transmits the light with polarization information to an imaging detection assembly.
Specifically, in step S4, the miniature imaging component forms a fixed miniature magnification ratio by the focal length ratio of the tube lens and the miniature objective lens, and miniature the polarization pattern, thereby outputting the polarization pattern light field.
Further, step S402 specifically includes:
after an image reflected from the surface of the light polarization sensitive material sequentially passes through the microscope objective, the tubular lens, the specified waveband reflection flat plate and the first light splitter, the image enters the first imaging CCD through the first lens, and a generated polarization pattern and the first imaging CCD are positioned on the front focal plane of the tubular lens and form a conjugate relation; adjusting the definition of an image in the first imaging CCD by controlling the up-and-down movement of a lens of the microscope objective, judging whether the focal plane of the microscope objective is on the light polarization sensitive material surface, calibrating the laser spot size in the second imaging CCD, and carrying out focusing monitoring on subsequent splicing; and judging whether the focal plane of the objective lens is on the surface of the light polarization sensitive material or not through the contrast of the outline of the imaging light spot projected to the light polarization sensitive material.
Further, step S4 is followed by:
s5, detecting and adjusting the distance between the miniature objective lens and the light polarization sensitive material surface by the imaging detection part, so that the focus surface of the miniature objective lens is always kept on the light polarization sensitive material surface; specifically, step S5 specifically includes:
detecting any value between 550nm and 650nm of wavelength of light emitted by a light source;
the second lens reflects the light spots projected to the light polarization sensitive material surface to the second imaging CCD, the Z-axis servo focusing position is mapped through the light spot diameter, the vertical height of the Z-axis lens is adjusted, the light spot diameter in the second imaging CCD can be always kept to be R, and whether the light polarization sensitive material surface is on the focusing surface of the objective lens or not is judged by detecting the size of the light spots projected to the light polarization sensitive material surface through the second imaging CCD.
S6, recording a single polarized light pattern on the light polarization sensitive material;
and S7, equally dividing any patterned polarization information into a plurality of different polarized light patterns, and performing pattern refreshing and polarization control for a plurality of times to form a pattern recording process.
As a further improvement of the embodiment of the present invention, after the step S7, the method further includes:
s8, moving the platform carrying the light polarization sensitive material to the next appointed view field position for the next pattern light field recording;
the polarization pattern of one splicing unit is formed by a plurality of different polarization patterns, wherein in a single polarization pattern, all polarization states are fixed.
In this embodiment of the present invention, the light source collimation manner in step S1 includes using an LED light source, forming collimated light through a set of collimating lenses, or using a laser light source, expanding the laser light source through an objective lens, and forming collimated light through a lens.
Further, as shown in fig. 4, in step S3, the different reflection states are that the DMD panel splits incident collimated light into two paths for reflection, including forming on-state reflected light in the area where the exposure pattern is formed and forming off-state reflected light in the area where the exposure pattern is not formed;
the on-state reflected light is vertical to the DMD panel and is positioned on a horizontal central axis; collimated light is incident on the DMD panel after passing through the reflecting lens; the incident angle was 12 degrees.
In step S8, the single exposure area can be spliced into a complete pattern light field through the stepping movement of the platform controlled by the motion control part, and a large-format high-precision exposure pattern is formed;
further, the movement control part moves the platform carrying the light polarization sensitive material to the next designated position for the next light orientation after the single polarization pattern is recorded on the light polarization sensitive material in step S6 is realized by the following steps:
the computer control system transmits the position data to the motion control part, the motion control part converts the received data into a control signal and transmits the control signal to the motor driver, the motor driver controls the motion of the motor according to the received control signal, and the detection device is responsible for monitoring the motion of the motor in real time and transmitting the motion position and the motion speed of the motor to the motion control part; and then the motion control part feeds back the current positions and the current speeds of the focusing platform and the sample carrying platform to the computer control system.
The invention also comprises a set of data processing and motion control method, which establishes a mapping function relation between the gray level and the polarization angle: and a is (255-g) 180/256, wherein g is the gray scale value of the image pixel point position and a is the corresponding polarization angle. And decomposing the gray image according to gray values. As shown in fig. 5, one gray scale map includes 3 gray scales, the original image is decomposed into 3 monochrome bitmaps for each gray scale value, each monochrome bitmap has two values of 0 and 1, 1 represents white, and 0 represents black, and the gray scale value represented by 1 in the monochrome bitmap and the gray scale value represented by the monochrome bitmap are at the same position in the original image as the gray scale value, but the pixel values at the positions other than the gray scale value are all 0. Each monochromatic bitmap corresponds to a polarization angle, the 255 gray scale corresponds to the polarization angle of 0 degree, the 128 gray scale corresponds to the polarization angle of 90 degrees, and the 0 gray scale corresponds to the polarization angle of 180 degrees. The pixel value of the monochrome bitmap corresponding to the gray value position is 1, and the rest positions are 0. After the 3 monochromatic bitmaps are uploaded to the DMD control board card in sequence, the control system controls the DMD panel to refresh the 3 monochromatic bitmaps in sequence according to a fixed time interval, and when one monochromatic bitmap is brushed, the control system rotates the polaroid to a specified angle by controlling the rotating motor. In the monochrome bitmap refreshed by the DMD panel, the position with the pixel value of 1 is in the on state, and the position with the pixel value of 0 is in the off state. After passing through the polarizer with the adjusted angle, the light at the on-state position is projected on a photosensitive material to form primary fixed-orientation exposure. Keeping the position of the two-dimensional motion platform unchanged, refreshing 3 monochromatic bitmaps by the DMD, and rotating the polarizing plate for 3 times by the polarization angle to form exposure with 3 orientations, as shown in FIG. 6.
Compared with the prior art, the invention has the following beneficial effects:
1. the light source of the invention adopts ultraviolet or blue light after beam expansion collimation, adjusts the light field by the generated polarization pattern, can generate different polarization phases, and then combines with an imaging system for micro-shrinkage, finally realizes the polarization modulation in any direction in unit pixels, and effectively overcomes the problems of single polarization orientation, low flexibility and low processing efficiency;
2. the invention adopts the assistance of a focusing servo system to control the objective lens to move up and down, focus in real time and improve the resolution;
3. the invention adopts the high-precision platform to accurately control the sample to do two-dimensional plane movement, thereby providing favorable conditions for realizing large-format writing;
4. because the light energy is not concentrated, the invention proposes that the abutted seams between each light-operated orientation view field are eliminated and the resolution is improved by controlling the relation between the size of a single view field and the single translation distance;
5. the invention has the advantages of high precision, arbitrary controllability, large-area writing and high efficiency of exposure polarization patterns, and has important significance for designing and manufacturing large-size, high-precision and multifunctional liquid crystal optical devices.
All the above-mentioned optional technical solutions can be combined arbitrarily to form the optional embodiments of the present invention, and are not described herein again.
It should be noted that: in the foregoing embodiment, when the optical alignment apparatus with large-format and arbitrary distribution based on the digital micro-mirror is used to perform an optical alignment method with large-format and arbitrary distribution based on the digital micro-mirror, the above-mentioned division of the functional modules is only used as an example, and in practical applications, the above-mentioned function distribution can be completed by different functional modules according to needs, that is, the internal structure of the system is divided into different functional modules, so as to complete all or part of the above-mentioned functions. In addition, the embodiments of the optical orientation device and the optical orientation method based on the large-format random distribution of the digital micro-mirror provided by the embodiments belong to the same concept, and specific implementation processes thereof are described in the embodiments of the method and are not described herein again.
It will be understood by those skilled in the art that all or part of the steps for implementing the above embodiments may be implemented by hardware, or may be implemented by a program instructing relevant hardware, where the program may be stored in a computer-readable storage medium, and the above-mentioned storage medium may be a read-only memory, a magnetic disk or an optical disk, etc.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
Claims (17)
1. A large-area patterned liquid crystal photo-alignment device based on a digital micro-reflector is characterized by comprising a light source assembly, a dynamic mask generation assembly, an imaging detection assembly, a focal length servo system and a motion control component which are sequentially arranged;
the light source component comprises an ultraviolet or blue light source, a collimation and beam expansion system and a polarizer which are sequentially connected, wherein the polarizer is connected with the collimation and beam expansion system and used for controlling the initial polarization direction of light and generating a surface light source with any polarization direction within the range of 0-179 ℃;
the dynamic mask generating assembly comprises a numerical control micro-mirror DMD, an electric adjustable polaroid and a computer control system and is used for dynamically adjusting and controlling the polarization state of incident light; the image signal of the computer control system is input to the signal input end of the numerical control micro-mirror DMD;
the imaging detection component is used for detecting the generated pattern imaging; the focal length servo system comprises a normally open light source insensitive to light polarization sensitive materials and a vertical direction correction assembly, and is used for correcting the defocusing phenomenon generated by movement;
the motion control component is used for adjusting the spatial position of the platform carrying the light polarization sensitive material so as to realize light field splicing.
2. The large format random distribution light orientation device based on digital micro-mirrors of claim 1, wherein the imaging detection assembly further comprises a micro-imaging component;
the miniature imaging component is used for miniature the polarization pattern output by the polarization pattern generating component and writing the polarization pattern into the light polarization sensitive material;
the miniature imaging component comprises an imaging objective lens group, the main shaft direction of the optical path of the imaging objective lens group is vertical to the platform, and a motor drives the imaging objective lens group to vertically move up and down to form a focusing surface on the platform;
the imaging objective lens group comprises a tubular lens and a microscope objective lens; the digital micromirror DMD is arranged in front of the tubular lens.
3. The large-breadth random distribution light orientation device based on the digital micro-mirror of claim 2, characterized in that the miniature imaging component is connected with the electrically adjustable polarizer and the beam splitter prism, and the electrically adjustable polarizer and the beam splitter prism are arranged on a horizontal central axis of the digital micromirror DMD; the beam splitting prism is used for transmitting the light with polarization information to the imaging detection assembly.
4. The large format random distribution light orientation device based on digital micro-mirrors of claim 3, further comprising a platform for carrying light polarization sensitive material; the platform is arranged below the imaging objective lens group and is provided with a two-dimensional motion track which is used for bearing a light polarization sensitive material and driving the light polarization sensitive material to move on a two-dimensional plane under the driving of the motion control part, so that the surface of the light polarization sensitive material is always kept on the focal plane of the imaging objective lens group;
and the motion control component is connected with the miniature imaging component and is used for splicing the miniature polarization pattern light field.
5. The large-breadth arbitrary-distribution light orientation device based on the digital micro-reflector of claim 1, wherein the imaging detection assembly comprises a first light splitter, a tube mirror, an imaging objective lens group, a polarizer, a first lens, and a first imaging CCD, which are connected in sequence;
the front focal plane of the imaging objective group is positioned near the rear focal plane of the tube mirror; the imaging surface of the first imaging CCD is positioned on the front focal plane of the first lens; the back focal plane of the first lens is positioned on the front focal plane of the tube mirror.
6. The large-breadth randomly-distributed light orientation device based on the digital micro-reflector of claim 1, wherein the focal length servo system comprises a detection light source, a second lens, a second light splitter, an imaging objective lens group, a second imaging CCD and a motor which are connected in sequence;
the detection light source is positioned on the front focal plane of the second lens; the second light splitter 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 motor drives the imaging objective lens group;
the first imaging CCD receives the reflected image projected to the light polarization sensitive material surface, and the first imaging CCD forms a conjugate image with the generated polarization pattern.
7. The large-format arbitrary-distribution light-orientation device based on digital micro-mirrors according to claim 1, characterized in that the light source is a pulsed light source or a continuous light source with a controllable light barrier system; the pulse width of the pulse laser generated by the light source is in the picosecond to second level, and the wavelength of the pulse laser is 340nm to 600 nm.
8. A large-breadth randomly distributed light orientation method based on a digital micro-reflector is characterized by comprising the following steps:
s1, adjusting light emitted by the light source into a collimated light beam through the collimation and beam expansion system;
s2, uniformly irradiating the collimated light beam to the surface of the DMD panel of the numerical control micro-mirror array at a preset angle;
s3, the computer outputs a graphic signal to control each micromirror of the DMD to present different reflection states to realize a mask, and the DMD panel refreshes an exposure graphic;
and S4, after the light beam forming the exposure pattern is micro-scaled by a micro objective lens, projecting the light beam to a liquid crystal substrate coated with a photo-alignment material on the surface through a polaroid, controlling the light intensity and time to complete exposure, and reorienting the liquid crystal in the exposure pattern area.
9. The method according to claim 8, wherein the step S4 specifically comprises:
s401, refreshing the graph according to the DMD, and rotating the polaroid to a corresponding polarization angle to enable the light passing through the polaroid to be polarized light with a preset fixed polarization angle;
s402, the polarized light on the horizontal central axis is reflected by a beam splitter prism to form vertically downward polarized light, and the vertically downward polarized light sequentially passes through a tubular lens and a miniature objective lens to irradiate the surface of the light polarization sensitive material, and the beam splitter prism transmits the light with polarization information to an imaging detection assembly.
10. The method as claimed in claim 8, wherein the step S4 is performed by the miniature imaging component forming a fixed miniature magnification ratio according to the focal length ratio of the tube lens and the miniature objective lens, and miniature the polarization pattern to output the polarization pattern light field.
11. The method according to claim 8, further comprising the step of, after the step S4:
s5, detecting and adjusting the distance between the miniature objective lens and the light polarization sensitive material surface by the imaging detection part, so that the focus surface of the miniature objective lens is always kept on the light polarization sensitive material surface;
s6, recording a single polarized light pattern on the light polarization sensitive material;
and S7, equally dividing any patterned polarization information into a plurality of different polarized light patterns, and performing pattern refreshing and polarization control for a plurality of times to form a pattern recording process.
12. The method according to claim 11, further comprising after the step S7:
and S8, moving the platform carrying the light polarization sensitive material to the next appointed view field position for the next pattern light field recording.
13. The method according to claim 8, wherein the step S1 of collimating the light source comprises using an LED light source, forming collimated light by a set of collimating lenses, or using a laser light source, expanding the laser light source by an objective lens, and forming collimated light by a lens.
14. The method according to claim 8, wherein the different reflection states of step S3 are that the DMD panel splits incident collimated light into two paths for reflection, including on-state reflected light in the areas where the exposure patterns are formed and off-state reflected light in the areas where the exposure patterns are not formed;
the on-state reflected light is perpendicular to the DMD panel and is located on a horizontal central axis.
15. The method according to claim 9, wherein the step S402 specifically comprises:
after an image reflected from the surface of the light polarization sensitive material sequentially passes through the microscope objective, the tubular lens, the specified waveband reflection flat plate and the first light splitter, the image enters the first imaging CCD through the first lens, and a generated polarization pattern and the first imaging CCD are positioned on the front focal plane of the tubular lens and form a conjugate relation; adjusting the definition of an image in the first imaging CCD by controlling the up-and-down movement of a lens of the microscope objective, judging whether the focal plane of the microscope objective is on the light polarization sensitive material surface, calibrating the laser spot size in the second imaging CCD, and carrying out focusing monitoring on subsequent splicing; and judging whether the focal plane of the objective lens is on the surface of the light polarization sensitive material or not through the contrast of the outline of the imaging light spot projected to the light polarization sensitive material.
16. The high-speed exposure patterned liquid crystal photoalignment method according to claim 8, wherein the step S5 specifically comprises:
detecting any value between 550nm and 650nm of wavelength of light emitted by a light source;
the second lens reflects the light spots projected to the light polarization sensitive material surface to the second imaging CCD, the Z-axis servo focusing position is mapped through the light spot diameter, the vertical height of the Z-axis lens is adjusted, the light spot diameter in the second imaging CCD can be always kept to be R, and whether the light polarization sensitive material surface is on the focusing surface of the objective lens or not is judged by detecting the size of the light spots projected to the light polarization sensitive material surface through the second imaging CCD.
17. The method according to claim 12, wherein the single exposure field in step S8 can be spliced into a complete pattern light field by controlling the stepping movement of the stage by the motion control unit to form a large-format high-precision exposure pattern;
when the single polarization pattern is recorded on the light polarization sensitive material in the step S6, the motion control unit moves the platform carrying the light polarization sensitive material to the next designated position for the next light orientation, which is implemented by the following steps:
the computer control system transmits the position data to the motion control part, the motion control part converts the received data into a control signal and transmits the control signal to the motor driver, the motor driver controls the motion of the motor according to the received control signal, and the detection device is responsible for monitoring the motion of the motor in real time and transmitting the motion position and the motion speed of the motor to the motion control part; and then the motion control part feeds back the current positions and the current speeds of the focusing platform and the sample carrying platform to the computer control system.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116500872A (en) * | 2023-06-28 | 2023-07-28 | 鹏城实验室 | Continuous rotary exposure system and method |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116500872A (en) * | 2023-06-28 | 2023-07-28 | 鹏城实验室 | Continuous rotary exposure system and method |
| CN116500872B (en) * | 2023-06-28 | 2023-10-27 | 鹏城实验室 | Continuous rotary exposure system and method |
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