CN211123567U - High-speed exposure patterning liquid crystal photo-alignment device - Google Patents
High-speed exposure patterning liquid crystal photo-alignment device Download PDFInfo
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- CN211123567U CN211123567U CN201921982261.2U CN201921982261U CN211123567U CN 211123567 U CN211123567 U CN 211123567U CN 201921982261 U CN201921982261 U CN 201921982261U CN 211123567 U CN211123567 U CN 211123567U
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Abstract
The utility model discloses a high-speed exposure patterning liquid crystal photo-alignment device, which comprises an illumination component, a polarization pattern generation component, an imaging detection component, a focal length servo system and a motion control component which are connected in sequence; an illumination unit for providing a light source for performing continuous stroboscopic exposure; a polarization pattern generation section for outputting a polarization pattern; an imaging detection component for detecting the generated pattern imaging; the focal length servo system 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. The utility model discloses utilize that pulse laser energy is big, the pulse width is short, repetition frequency is high characteristics, realize single frame polarization pattern record based on single or a plurality of pulses, it is big to have the area, efficient, good reliability's advantage.
Description
Technical Field
The utility model relates to a liquid crystal orientation arranges the control field, especially relates to a high-speed exposure patterning liquid crystal photo-alignment device.
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:
photoalignment is a non-contact liquid crystal aligning method which is newly developed, and the photoalignment technology is divided into four types at present, wherein the photoalignment technology utilizes photosensitive materials to perform oriented photocrosslinking, isomerization or photocracking reaction under the irradiation of ultraviolet or blue light polarized light to obtain the required arrangement: 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 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, and pattern recording of different orientation arrangements of liquid crystals in different selected areas can be realized by single projection orientation.
Patent application No. CN201820881217.1 discloses a photo-alignment apparatus for realizing arbitrary distribution by one exposure, which introduces a photo-alignment method for single exposure using a pixelated electrically controlled phase delay device, wherein the phase delay of each pixel of the pixelated electrically controlled phase delay device is controlled by a corresponding voltage respectively for generating the phase delay of arbitrary pattern distribution, but the problem of generating a phase pattern by one exposure is that the data size is proportional to the format size, which limits the format size of the prepared device, and also considers that a high-precision high-resolution photo-alignment pattern cannot be generated.
Foreign beam corporation has provided an apparatus and method for photoalignment using continuous laser irradiation L COS phase modulation devices (De Sio L, Roberts D E, L iao Z, et al. digital polarization holistic geological phase Optics [ J ]. Optics express,2016,24(16):18297-18306.) which use low energy continuous lasers for exposure, tens of seconds to tens of minutes are required for single field exposure in consideration of the amount of image information and properties such as exposure uniformity and material heat capacity, thermal diffusion, etc., and the exposure format is limited by image information and cannot photoalign large area formats.
Therefore, a new apparatus and method for outputting polarization patterns using pulsed laser illumination in the field of liquid crystal display is desired.
SUMMERY OF THE UTILITY MODEL
In order to solve the problems of the prior art, in one aspect, the present invention provides a high-speed exposure patterning liquid crystal photo-alignment device, which comprises an illumination component, a polarization pattern generation component, an imaging detection component, a focal length servo system and a motion control component, which are connected in sequence;
the illumination component is used for providing a light source for continuous stroboscopic exposure and realizing single-polarization collimation uniform surface light spots;
the polarization pattern generating component comprises a quarter-wave plate and a phase modulator which are sequentially connected and is used for outputting a pixilated programmable polarization pattern to a workpiece; the phase modulator is connected with the imaging detection component; the phase modulation device is a liquid crystal phase modulation device and is used for loading different phases to each pixel;
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 embodiments of the present invention, the illumination component 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 lighting component is in the picosecond to second level, and the wavelength of the pulse laser is 340nm to 600 nm; the energy per unit area of the pulse light source is higher than the threshold energy of the optical polarization sensitive material on the liquid crystal substrate and lower than the damage threshold of the phase modulation device.
As a further improvement of the embodiment of the present invention, the pulse width of the pulse laser is smaller than or equal to the image maintaining time of the phase modulation device, and when an image of the phase modulation device is maintained, at least one pulse laser peak is irradiated onto the phase modulation device.
As a further improvement of the embodiment of the present invention, the illumination component includes a collimating assembly and a polarizer;
the collimation assembly is used for adjusting the linear light source or the point light source into a parallel surface light source and outputting the parallel surface light source to the polarization pattern generation component;
the polarizer is used for generating single polarized light, and the polarizer is connected with the collimation assembly and used for controlling the initial polarization direction of the light and generating a surface light source with any polarization direction within the range of 0-179 degrees.
As a further improvement of the embodiment of the present invention, the phase modulation device is a pixel type phase retarder whose phase difference is adjustable; reflecting the polarized surface light source into light spots containing different polarization information and transmitting the light spots to the light splitting component;
the phase delay modulation of the phase modulation device on the pulse light source is more than 2 pi;
the single gray level controlled by a computer program has the phase modulation precision superior to 0.01 pi so as to realize random phase delay modulation in one period; the phase delay amount drift of the phase modulation device is less than 0.005 pi.
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 light path of the imaging objective lens group is perpendicular 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.
As a further improvement of the embodiment of the present invention, the platform is disposed below the imaging objective lens group and has a two-dimensional motion track for bearing the light polarization sensitive material and driving the light polarization sensitive material to move in a two-dimensional plane under the driving of the motion control component, so that the surface of the light polarization sensitive material is always kept at 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 cylindrical lens, an imaging objective lens group, a polarizing plate, 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 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 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 a reflection image projected to the light polarization sensitive material surface, and the first imaging CCD and the phase modulator form a conjugate image.
As a further improvement of the embodiment of the present invention, the quarter-wave plate is disposed between the phase modulator and the imaging detection assembly;
the phase modulator is a liquid crystal spatial light modulator and is a pixel type phase delayer with adjustable phase difference; the polarization rotation direction is/2; the polarization direction of incident light, the crystal axis direction of the phase modulation device and the crystal axis direction of the quarter-wave plate form included angles of 0 degree, 45 degrees and 90 degrees.
As a further improvement of the embodiment of the present invention, the polarization pattern generation component includes a first quarter wave plate, a phase modulation device, and a second quarter wave plate connected in sequence;
the long axis direction of the first quarter-wave plate, the crystal axis direction of the phase modulation device and the crystal axis direction of the first quarter-wave plate form included angles of 0 degree, 45 degrees and 90 degrees.
As a further improvement of the embodiment of the present invention, the motion control unit further includes a controller and a motor driving device, wherein the controller is configured to convert the collected light path data into a control signal and send the control signal to each executing unit;
the controller comprises a motion control module comprising a platform motion control unit;
the motor driving device is used for driving a motor to drive the focusing platform and the platform to move, and the detection device is used for monitoring the movement of the motor in real time and sending the movement position and the movement speed of the motor to the movement control module;
and the platform motion control unit is used for controlling the light polarization sensitive material to move in a two-dimensional plane so as to realize the splicing of polarized light fields or the interconnection of different polarized light fields through the pattern splicing assembly.
In another aspect, the present invention also provides a high-speed exposure patterning liquid crystal photo-alignment method, comprising the steps of:
s1, adjusting the linear light source or point light source emitted by the light source into a collimated polarized light source through a polarizing collimator;
s2, loading corresponding phases by a phase modulation device of the polarization pattern generation component according to the pattern information, and reflecting the polarization surface light source into light spots containing different polarization information to transmit the light spots to the light splitting component;
s3, the light splitting component transmits the light with polarization information to the imaging detection assembly;
s4, adjusting the distance between the imaging objective lens group and the light polarization sensitive material surface by the servo focusing system to ensure that the focal plane of the imaging objective lens group is always kept at the light polarization sensitive material surface;
s5, recording the single light control orientation on the light polarization sensitive material;
and S6, moving the platform carrying the light polarization sensitive material to the next designated position for the next pattern light field recording.
As a further improvement of the embodiment of the present invention, after the step S3, the method further includes the following steps: the miniature imaging component forms a fixed miniature multiplying power through the ratio of focal lengths of the cylindrical lens and the imaging objective lens group, and miniature is carried out on the polarization pattern output by the phase modulation component, so that a polarization pattern light field is output.
As a further improvement of the embodiment of the present invention, after step S6, the method further includes:
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.
As a further improvement of the embodiment of the present invention, step S2 is to adjust the polarization information of each pixel point in each sub-image through a gray scale image, specifically including that the phase modulation device adjusts and controls the polarization level of each pixel point through voltage, and each pixel point determines the size of voltage through different gray scale information, so as to realize the adjustment and control of the polarization information by the gray scale image;
the gray-scale image is written in real time or pre-loaded;
the phase modulation device is a high-speed liquid crystal phase modulation device and is used as a real-time programmable phase plate to perform wavefront correction on linearly polarized light, so that pixelation control on a polarization pattern is realized.
As a further improvement of the embodiment of the present invention, step S4 specifically includes:
detecting the value of the wavelength of light emitted by the light source outside a polarized photosensitive absorption wavelength region;
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, after the step S6 of recording the single polarization pattern on the light polarization sensitive material, the platform carrying the light polarization sensitive material is moved to the next designated position for the next orientation, which is specifically realized by the following steps:
the controller transmits the position data to the motion control module, the motion control module 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 module; and then the motion control module feeds back the current position and the speed of the platform to the controller.
Compared with the prior art, the utility model discloses following beneficial effect has:
1. the utility model discloses the high-speed exposure patterning liquid crystal photoalignment method of utilizing pulsed laser illumination can the phase change in real time control single exposure area, accomplishes the exposure of high accuracy high resolution, simultaneously, utilizes the characteristics that pulsed laser energy is big, the pulse width is short, repetition frequency is high, realizes single frame polarization pattern record based on single or a plurality of pulses, has the area big, efficient, advantage that the reliability is good;
2. the utility model discloses a light source adopts ultraviolet or blue light after the beam expanding collimation, adjusts the light field with the phase modulator, can produce different polarization phase place, and the recombination becomes imaging system and carries out the shrink, finally realizes the polarization modulation of arbitrary direction in the unit pixel, has effectively overcome "the problem that polarization orientation is single, the flexibility ratio is low, machining efficiency is low";
3. the utility model adopts the assistance of the focusing servo system to control the objective lens to move up and down, focus in real time and improve the resolution;
4. the utility model 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;
5. the utility model adopts the light energy not concentrated, and eliminates the abutted seam between each light-operated orientation view field by controlling the relation between the size of a single view field and the single translation distance, thereby improving the resolution;
6. the utility model has the advantages of single exposure polarization pattern high accuracy is controllable wantonly, the large tracts of land is write, efficient, has important meaning to design and preparation jumbo size, high accuracy, multi-functional liquid crystal optical device.
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 described 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 without creative efforts.
Fig. 1 is a schematic structural diagram of a high-speed exposure patterned liquid crystal photo-alignment device according to an embodiment of the present invention;
FIG. 2 is a schematic diagram showing the selection of the pulse laser frequency and the refresh frequency of the phase modulation device of the high-speed exposure patterned liquid crystal photo-alignment device according to the embodiment of the present invention;
fig. 3 is a schematic diagram of the peak absorption characteristics of a light polarization sensitive material employed in an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention clearer, the following description will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.
The utility model provides a high-speed exposure patterning liquid crystal photo-alignment device, as shown in figure 1, comprising an illumination component, a polarization pattern generation component, an imaging detection component, a focal length servo system and a motion control component which are connected in sequence;
the illumination component is used for providing a light source for continuous stroboscopic exposure and realizing single-polarization collimation uniform surface light spots;
the polarization pattern generating component comprises a quarter-wave plate and a phase modulator which are connected in sequence and is used for outputting a pixilated programmable polarization pattern to a workpiece; the phase modulator is connected with the imaging detection component; the phase modulation device is a liquid crystal phase modulation device and is used for loading different phases to each pixel;
an imaging detection component for detecting the generated pattern imaging; the focal length servo system comprises a normally open light source insensitive to the light polarization sensitive material 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 an embodiment of the present invention, the illumination component is a pulsed light source, specifically, a pulsed laser; in other alternative embodiments the illumination means may also be a continuous light source with a controllable barrier system; the pulse width of the pulse laser generated by the lighting component is in the range of picoseconds to seconds, and the wavelength of the pulse laser is 340nm to 600 nm; the energy per unit area of the pulse light source is higher than the threshold energy of the optical polarization sensitive material on the liquid crystal substrate and lower than the damage threshold of the phase modulation device.
In other alternative embodiments, the pulsed light source may also be a continuous laser plus mechanical or electro-optical barrier, or a pulsed L ED or continuous L ED plus controllable barrier system.
Preferably, the pulse width of the pulse laser is less than or equal to the image holding time of the phase modulation device, and when one image of the phase modulation device is held, at least one pulse laser peak is irradiated onto the phase modulation device.
The embodiment of the utility model provides an optical wavelength that the laser instrument sent is 442nm, the monopulse energy is 0.2mJ, and the pulsewidth is 10ns, is pulse light and S polarization, and the adjustment of collimating is carried out through expanding the beam system, after the polarizer again, forms a facula diameter and is 2cm, and the divergence angle is less than 10mrad, and S polarization, light intensity uniformity is superior to the even facula of 80% collimation.
Specifically, in an embodiment of the present invention, the illumination component includes a collimating assembly and a polarizer; the collimating component and the polarizing plate form a collimating polarizing component.
The collimation assembly is used for adjusting the linear light source or the point light source into a parallel surface light source and outputting the parallel surface light source to the polarization pattern generation component;
the polarizer is used for generating single polarized light, is connected with the collimation component and is used for controlling the initial polarization direction of the light and generating a surface light source with any polarization direction within the range of 0-179 degrees.
In the embodiment of the present invention, the phase modulation device is a phase difference adjustable pixel type phase retarder; reflecting the polarized surface light source into light spots containing different polarization information and transmitting the light spots to the light splitting component; the phase delay modulation of the phase modulation device on the pulse light source is more than 2 pi; the single gray level controlled by a computer program has the phase modulation precision superior to 0.01 pi so as to realize random phase delay modulation in one period; the phase delay amount drift of the phase modulation device is less than 0.005 pi.
Further, the imaging detection assembly further comprises a miniature imaging component;
the miniature imaging component is used for carrying out miniature on 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 the motor drives the imaging objective lens group to vertically move up and down to form a focusing surface on the platform.
In the embodiment of the present invention, the platform is disposed below the imaging objective lens group and has a two-dimensional motion track for bearing the light polarization sensitive material and driving the light polarization sensitive material to move in a two-dimensional plane under the driving of the motion control component, so that the surface of the light polarization sensitive material is always kept on the focal 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.
The imaging detection assembly comprises a first light splitter, a tube lens, an imaging objective lens group, a polarizing film, a first lens and a first imaging CCD which are sequentially connected;
the front focal plane of the imaging objective group is positioned on the back focal plane of the cylindrical 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 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 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 and the phase modulator form conjugate images.
In the embodiment of the present invention, the quarter-wave plate is disposed between the phase modulator and the imaging detection module; the phase modulator is a liquid crystal spatial light modulator and is a pixel type phase delayer with adjustable phase difference; the polarization rotation direction is one half/2; the polarization direction of incident light, the crystal axis direction of the phase modulation device and the crystal axis direction of the quarter-wave plate form included angles of 0 degree, 45 degrees and 90 degrees.
In another practical way, the polarization pattern generation component comprises a first quarter-wave plate, a phase modulation device and a second quarter-wave plate which are connected in sequence; the number of quarter-wave plates may not be unique.
Wherein, the major axis direction of the first quarter-wave plate, the crystal axis direction of the phase modulation device and the crystal axis direction of the first quarter-wave plate form included angles of 0 degree, 45 degrees and 90 degrees.
In the embodiment of the present invention, the motion control unit further includes a controller, a motor driving device, and a motor detecting device, wherein the controller is configured to convert the collected light path data into a control signal and send the control signal to each executing unit;
the controller comprises a motion control module, and the motion control module comprises a platform motion control unit;
the motor detection device is used for monitoring the motion of the motor in real time and sending the motion position and the motion speed of the motor to the motion control module;
and the platform motion control unit is used for controlling the light polarization sensitive material to move in a two-dimensional plane so as to realize the splicing of the polarized light fields or the interconnection of different polarized light fields through the pattern splicing assembly.
In some embodiments, to address the problem of generating arbitrary polarization orientations, a polarization pattern generation component, comprising a quarter-wave plate and a phase modulator connected in series, is used to generate a pattern of arbitrary polarization distribution; the phase modulation device regulates and controls the polarization level of each pixel point through voltage, and each pixel point determines the size of the voltage through different gray scale information, so that the regulation and control of the gray scale image on the polarization information are realized. The gray scale map can be written in real time or pre-loaded; the phase modulation device can be but is not limited to an ultra-high speed liquid crystal spatial light modulator, and can be used as a real-time programmable phase plate to perform wavefront correction on linearly polarized light, so that pixelation control on a polarization pattern is realized. The resolution of the original polarized light field is determined by the pixel size of the liquid crystal spatial light modulator.
Polarization pattern forming tool based on phase modulation deviceThe fast axis direction of the first quarter wave plate is orthogonal to the fast axis direction of the second quarter wave plate, and the fast axis direction of the first quarter wave plate and the fast axis direction of the second quarter wave plate respectively form an angle of 45 degrees with the liquid crystal arrangement main axis direction of the phase modulator, after the collimated light spot passes through the first quarter wave plate, the collimated light spot is incident at an angle of 3 degrees with the normal line of the phase modulator, the phase modulator is uniformly irradiated, the phase modulator adopted in the embodiment is an L COS device, the working frequency is 50Hz to 400Hz, and the damage threshold value of pulse laser is more than 300mJ210ns, 1920 x 1080 pixels, 8 microns of single pixel size, 1.54cm x 0.86cm of the size of the whole phase modulation device, and the phase modulation precision is better than 0.03 pi when the phase modulation amount is larger than 2 pi for 442 nm.
The light splitting component is respectively connected with the miniature imaging component and the imaging detection component and is used for filtering light with specified wave bands to respectively enter the miniature imaging component and the imaging detection component;
the motion control part also comprises a pattern splicing assembly, and the pattern splicing assembly is used for splicing the miniature polarization pattern light field.
It should be noted that the embodiment of the present invention is a fast optical alignment apparatus based on a reflective phase modulation device (L COS), and in other optional embodiments, the embodiment may also be a fast optical alignment apparatus based on a transmissive L COS, that is, the polarization pattern generation component includes a first quarter-wave plate, a phase modulation device, and a second quarter-wave plate, which are connected in sequence, wherein the long axis direction of the first quarter-wave plate, the crystal axis direction of the phase modulation device, and the crystal axis direction of the first quarter-wave plate are in the same direction.
The embodiment of the present invention provides a control logic specifically comprising: the control software in the industrial personal computer transmits the position data to the motion control module, the motion control module converts the received data into a control signal and transmits the control signal to the motor driver, and the motor driver controls the motion of the motor according to the received control signal; the detection device is responsible for monitoring the motion of the motor in real time and sending the motion position and the motion speed of the motor to the motion control module; and the motion control module feeds back the current position and speed of the platform to the software.
The phase modulator L COS in the optical system is connected with the industrial personal computer through a data transmission line, so that control software can transmit phase diagram data to L COS.
In another aspect, the present invention also provides a high-speed exposure patterning liquid crystal photo-alignment method, comprising the steps of:
s1, adjusting the linear light source or point light source emitted by the light source into a collimated polarized light source through a polarizing collimator;
s2, loading corresponding phases by a phase modulation device of the polarization pattern generation component according to the pattern information, and reflecting the polarization surface light source into light spots containing different polarization information to transmit the light spots to the light splitting component;
s3, the light splitting component transmits the light with polarization information to the imaging detection assembly;
s4, adjusting the distance between the imaging objective lens group and the light polarization sensitive material surface by the servo focusing system to ensure that the focal plane of the imaging objective lens group is always kept at the light polarization sensitive material surface;
s5, recording the single light control orientation on the light polarization sensitive material;
and S6, moving the platform carrying the light polarization sensitive material to the next designated position for the next pattern light field recording.
In the embodiment of the present invention, the following steps are further included after step S3: the miniature imaging component forms a fixed miniature multiplying power through the ratio of the focal lengths of the cylindrical lens and the imaging objective lens group, and miniature the polarization pattern output by the phase modulation component so as to output a polarization pattern light field.
Further, the high-speed exposure patterned liquid crystal photoalignment method further includes, after the step S6:
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.
Step S2 is to adjust the polarization information of each pixel in each sub-image by using a gray scale image, specifically including that the phase modulation device adjusts the polarization level of each pixel by using voltage, and each pixel determines the magnitude of the voltage by using different gray scale information, so as to adjust and control the polarization information by using the gray scale image;
the gray-scale image is written in real time or pre-loaded;
the phase modulation device is a high-speed liquid crystal phase modulation device and is used as a real-time programmable phase plate to perform wavefront correction on linearly polarized light, so that pixelation control on a polarization pattern is realized.
Preferably, the wavelength of light emitted by the light source is detected to be a value outside the polarization photosensitive absorption wavelength region; in step S4, detecting that the wavelength of light emitted from the light source is any value between 550nm and 650 nm;
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.
In an embodiment of the present invention, after the step S6 of recording the single polarization pattern on the light polarization sensitive material, the platform carrying the light polarization sensitive material is moved to the next designated position for the next alignment, which is specifically realized by the following steps:
the controller transmits the position data to the motion control module, the motion control module 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 module; and then the motion control module feeds back the current position and the speed of the platform to the controller.
After the single light-operated orientation is recorded on the light polarization sensitive material, the moving distance of the platform carrying the light polarization sensitive material to the next specified position is the size of a single orientation unit through the motion control module, and the moving mode is that the platform is moved and scanned line by line in sequence; specifically, the time of each moving step is integral multiple of the pulse width of the pulse laser, and the same pattern light field can be exposed by using multiple laser pulses.
The relationship between the pulse laser frequency and the phase modulation device refresh frequency is shown in fig. 2, the pulse laser frequency corresponds to the phase modulation device frequency, and the pulse width is less than or equal to the image maintaining time of the phase modulation device, that is, when one image of the phase modulation device is maintained, one pulse laser peak irradiates the phase modulation device.
In the image maintaining time of the phase modulation device, a plurality of pulse laser peaks can be irradiated on the receiving window of the phase modulation device, so that the single exposure energy can be enhanced.
The wavelength absorption characteristics of the photoalignment material used in this example are shown in fig. 3; the adopted material is an azo photo-alignment material, corresponding to the material 3 in fig. 3, a better photo-alignment effect can be obtained when laser with the wavelength of 442nm is used for illumination, pulse laser light sources with different wavelengths can be selected according to the photo-alignment material, or corresponding photo-alignment materials can be selected according to the pulse laser light sources with different wavelengths, a miniature part adopts a miniature objective lens with the power of 20 times, namely, the area of a light spot is reduced by 400 times, the energy density is improved by 400 times, the size of a single pixel after the miniature is only 0.4 micron, and the exposure direct writing of high-precision pattern information can be realized. At this time, the photosensitive amount of the photo-alignment material was 50mJ/cm2Above the photoalignment energy threshold and below the damage threshold.
It should be noted that the "stroboscopic" defined in the present invention is to emit light and/or quench light at a certain preset frequency.
Compared with the prior art, the utility model discloses following beneficial effect has:
1. the utility model discloses the high-speed exposure patterning liquid crystal photoalignment method of utilizing pulsed laser illumination can the phase change in real time control single exposure area, accomplishes the exposure of high accuracy high resolution, simultaneously, utilizes the characteristics that pulsed laser energy is big, the pulse width is short, repetition frequency is high, realizes single frame polarization pattern record based on single or a plurality of pulses, has the area big, efficient, advantage that the reliability is good;
2. the utility model discloses a light source adopts ultraviolet or blue light after the beam expanding collimation, adjusts the light field with the phase modulator, can produce different polarization phase place, and the recombination becomes imaging system and carries out the shrink, finally realizes the polarization modulation of arbitrary direction in the unit pixel, has effectively overcome "the problem that polarization orientation is single, the flexibility ratio is low, machining efficiency is low";
3. the utility model adopts the assistance of the focusing servo system to control the objective lens to move up and down, focus in real time and improve the resolution;
4. the utility model 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;
5. the utility model adopts the light energy not concentrated, and eliminates the abutted seam between each light-operated orientation view field by controlling the relation between the size of a single view field and the single translation distance, thereby improving the resolution;
6. the utility model has the advantages of single exposure polarization pattern high accuracy is controllable wantonly, the large tracts of land is write, efficient, has important meaning to design and preparation jumbo size, high accuracy, multi-functional liquid crystal optical device.
Above-mentioned all optional technical scheme can adopt arbitrary combination to form the optional embodiment of this utility model, and the repeated description is no longer given here.
It should be noted that: in the above embodiment, when the high-speed exposure patterned liquid crystal photo-alignment apparatus and system is used to perform a high-speed exposure patterned liquid crystal photo-alignment method, only the division of the functional modules is taken as an example, and in practical applications, the above function distribution may be completed by different functional modules according to needs, that is, the internal structure of the system may be divided into different functional modules to complete all or part of the above-described functions. In addition, the embodiments of the high-speed exposure patterned liquid crystal photo-alignment device and the high-speed exposure patterned liquid crystal photo-alignment method provided by the embodiments belong to the same concept, and specific implementation processes thereof are described in the embodiments of the methods and are not described herein again.
The above description is only for the preferred embodiment of the present invention, and is not intended to limit the present invention, and any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention should be included within the protection scope of the present invention.
Claims (11)
1. A high-speed exposure patterning liquid crystal photo-alignment device is characterized by comprising an illumination component, a polarization pattern generation component, an imaging detection component, a focal length servo system and a motion control component which are sequentially connected;
the illumination component is used for providing a light source for continuous stroboscopic exposure and realizing single-polarization collimation uniform surface light spots;
the polarization pattern generating component comprises a quarter-wave plate and a phase modulator which are sequentially connected and is used for outputting a pixilated programmable polarization pattern to a workpiece; the phase modulator is connected with the imaging detection component; the phase modulation device is a liquid crystal phase modulation device and is used for loading different phases to each pixel;
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 high-speed exposure patterned liquid crystal photoalignment device of claim 1, wherein the illumination component 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 lighting component is in the picosecond to second level, and the wavelength of the pulse laser is 340nm to 600 nm; after the beam expanding collimation and the beam splitting step are carried out on a single pulse or a plurality of pulses of the pulse light source, the accumulated energy density is lower than the damage threshold of a phase modulator at the position of the phase modulator; after the subsequent imaging step, the accumulated energy density on the surface of the sample is higher than the threshold energy of the light polarization sensitive material.
3. The high-speed exposure patterned liquid crystal photoalignment device of claim 2, wherein the pulse width of the pulsed laser is less than or equal to the image-maintaining time of the phase modulation device, and when an image of the phase modulation device is maintained, at least one pulse laser peak is irradiated onto the phase modulation device.
4. The high-speed exposure patterned liquid crystal photoalignment device of claim 1, wherein the illumination component comprises a collimating component and a polarizer;
the collimation assembly is used for adjusting the linear light source or the point light source into a parallel surface light source and outputting the parallel surface light source to the polarization pattern generation component;
the polarizer is used for generating single polarized light, and the polarizer is connected with the collimation assembly and used for controlling the initial polarization direction of the light and generating a surface light source with any polarization direction within the range of 0-179 degrees.
5. The high-speed exposure patterned liquid crystal photoalignment device according to claim 1, wherein the phase modulation device is a phase difference adjustable pixel-type phase retarder; reflecting the polarized surface light source into light spots containing different polarization information and transmitting the light spots to the light splitting component;
the phase delay modulation of the phase modulation device on the wavelength of the pulse light source is more than 2 pi;
the single gray level controlled by a computer program has the phase modulation precision superior to 0.01 pi so as to realize random phase delay modulation in one period; the phase delay amount drift of the phase modulation device is less than 0.005 pi.
6. The high-speed exposure patterned liquid crystal photoalignment device 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 light path of the imaging objective lens group is perpendicular 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.
7. The high-speed exposure patterning liquid crystal photoalignment device of claim 6, wherein the platform is disposed below the imaging objective lens set and has a two-dimensional motion track for carrying the light polarization sensitive material and driving the light polarization sensitive material to move in a two-dimensional plane under the driving of the motion control unit, so that the surface of the light polarization sensitive material is always kept at the focus plane of the imaging objective lens set;
and the motion control component is connected with the miniature imaging component and is used for splicing the miniature polarization pattern light field.
8. The high-speed exposure patterned liquid crystal photoalignment device of claim 1, wherein the imaging detection assembly comprises 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.
9. The high-speed exposure patterned liquid crystal photoalignment device of claim 8, wherein the focus servo system comprises 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 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 a reflection image projected to the light polarization sensitive material surface, and the first imaging CCD and the phase modulator form a conjugate image.
10. The high-speed exposure patterned liquid crystal photoalignment device of claim 1, wherein the quarter-wave plate is disposed between the phase modulator and an imaging detection assembly;
the phase modulator is a liquid crystal spatial light modulator and is a pixel type phase delayer with adjustable phase difference; the polarization rotation direction is/2; the polarization direction of incident light, the crystal axis direction of the phase modulation device and the crystal axis direction of the quarter-wave plate form included angles of 0 degree, 45 degrees and 90 degrees.
11. The high-speed exposure patterned liquid crystal photoalignment device of claim 1, wherein the polarization pattern generation component comprises a first quarter-wave plate, a phase modulation device, a second quarter-wave plate connected in sequence;
the long axis direction of the first quarter-wave plate, the crystal axis direction of the phase modulation device and the crystal axis direction of the first quarter-wave plate form included angles of 0 degree, 45 degrees and 90 degrees.
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