CN210720960U - Patterned liquid crystal photo-alignment device based on orthogonal circularly polarized light interference - Google Patents
Patterned liquid crystal photo-alignment device based on orthogonal circularly polarized light interference Download PDFInfo
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Abstract
The utility model discloses a patterning liquid crystal light orientation device based on orthogonal circular polarized light interferes, and the device includes lighting components, the miniature subassembly of pattern, focus servo assembly, motion control part, polarization pattern formation subassembly, light path calibration monitoring subassembly and phase compensation subassembly, and the light path of phase compensation subassembly in to polarization pattern formation subassembly carries out direct compensation. The utility model discloses utilize the phase difference that phase type spatial light modulator LCOS produced, control the polarization information of circular polarized light for the polarization direction of the linear polarized light that the circular polarized light interfered formation is accurate controllable, and combines the sensitive nature of light orientation material to the linear polarization light polarization direction, can realize the directional arrangement of liquid crystal.
Description
Technical Field
The utility model relates to a liquid crystal orientation arranges the control field, especially relates to a patterning liquid crystal photo-alignment device based on orthogonal circular polarized light interferes.
Background
Liquid crystal is a functional material having both liquid and crystal properties, and is widely used in various liquid crystal displays. However, the arrangement of the liquid crystal molecules is not as strong as the crystal structure, and under the external action (such as electric field, magnetic field, stress action), the liquid crystal molecules will be changed from the initial arrangement to other arrangement modes, thereby causing the change of the optical characteristics, which is the basis of the liquid crystal display. The alignment of liquid crystals is achieved by providing sufficient orientation anchoring force through an alignment film, and the liquid crystal alignment technology has been developed for this purpose.
The alignment control method widely used in the industry at present is a rubbing alignment technique which accomplishes alignment of liquid crystals by rubbing an alignment film, but it is liable to generate defects such as static electricity, dust, and damage to the film surface. In order to solve the technical problem of rubbing alignment, techniques such as oblique deposition technique and surface chemical treatment technique have been developed, but some of them have a problem that they are not suitable for use. The photo-alignment technology is a non-contact alignment method for liquid crystal alignment development in recent years, and has the advantages of localization, small pollution and simple and convenient operation. There are two main types of current approaches to achieving photoalignment. One type of the liquid crystal display device is required to be masked, and comprises contact type mask exposure, projection type mask exposure and projection type dynamic mask exposure, wherein the contact type mask exposure and the projection type mask exposure are required to manufacture corresponding masks aiming at different patterns, and have the defects of high production cost, low efficiency and the like, while the current projection type dynamic mask exposure (based on DMD dynamic mask exposure) cannot realize different selected areas under single exposure to form different liquid crystal orientation patterns, needs multiple exposures, and also has the problems of low efficiency, difficult alignment and the like; the other type is mask-free, utilizes holographic interference, but can only generate a liquid crystal alignment pattern with one-dimensional or two-dimensional periodicity and single alignment, and is difficult to prepare a complex pattern.
Specifically, in application numbers: 201210225093.9, the patent names: the utility model discloses a method and device for realizing the control of the random orientation of liquid crystal by the digital controlled micromirror array photoetching, which discloses a light-operated orientation technology based on DMD dynamic mask, the dynamic mask function is realized by controlling the deflection of the micromirror in the DMD, although the method can realize the orientation arrangement of the liquid crystal selection area without changing the mask, but the recording of the random orientation arrangement pattern of the liquid crystal selection area can not be realized in the single light-operated orientation process, the light-operated orientation operation can only realize the recording of the single-direction polarization pattern, if the recording of the polarization patterns in different selection areas and different directions is realized, a plurality of design drawings are required to be drawn and continuously and repeatedly loaded on a DMD control chip to realize the orientation in different selection areas, and the polarization direction of light is required to be controlled once by rotating the polaroid sheet once every loading, thereby causing the low production efficiency and the.
Specifically, in application numbers: 201820881217.1, the patent names: the utility model discloses a based on LCOS dynamic mask light control orientation technique, the phase delay of every pixel of the electric control phase delay device of pixelation is controlled through voltage to the light path of this method simple, but this method adopts transmission-type spatial light modulator, and energy loss is great. Moreover, due to the limitation of the LCOS operating area, large-sized, high-precision patterned liquid crystal alignment cannot be realized.
SUMMERY OF THE UTILITY MODEL
In order to solve the technical problem, the utility model provides a patterning liquid crystal light orientation device based on orthogonal circular polarized light interferes.
In order to achieve the above purpose, the technical scheme of the utility model is as follows:
a patterned liquid crystal photo-alignment device based on orthogonal circularly polarized light interference comprises:
the lighting assembly is used for providing a light source and realizing collimation and uniform surface light spots;
the pattern micro-assembly is used for micro-projecting the modulated light field on the photosensitive material;
the focal length servo assembly comprises a vertical direction correcting 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 loaded with the light polarization photosensitive material so as to realize light field splicing;
the polarization pattern generating assembly is used for forming two orthogonal circularly polarized lights and interfering the two orthogonal circularly polarized lights to form linearly polarized lights meeting the requirement of a polarization orientation angle;
the light path calibration monitoring component is used for calibrating and monitoring the whole interference light path of the polarization pattern generation component;
and the phase compensation component is used for performing phase compensation according to the linearly polarized light polarization direction information fed back by the light path calibration monitoring component, and directly compensating the light path in the polarization pattern generation component.
On the basis of the technical scheme, the following improvements can be made:
preferably, the polarization pattern generation module includes: the spatial light modulator comprises a spatial light modulator, a first beam splitter, a first quarter wave plate, a second quarter wave plate and a reflector;
incident light of the polarization pattern generation assembly forms a first light beam and a second light beam through a first beam splitter;
linearly polarized light of the first light beam is changed into circularly polarized light after passing through the first quarter-wave plate for the first time, the reflecting mirror reflects incident light of the first light beam which passes through the first quarter-wave plate for the first time, emergent light of the reflected first light beam is changed into linearly polarized light after passing through the first quarter-wave plate for the second time, and the polarization direction of the linearly polarized light is vertical to the polarization direction of the initial incident light of the first light beam;
the spatial light modulator modulates the incident light of the second light beam, and performs phase modulation and reflection on a light field incident on the working surface of the spatial light modulator to form emergent light of the second light beam;
emergent light of the first light beam and emergent light of the second light beam are emitted through the first beam splitter again and then are changed into two beams of orthogonal circularly polarized light through the second quarter-wave plate, so that interference of the two beams of circularly polarized light is realized, and linearly polarized light is formed.
Preferably, the polarization pattern generation module includes: the device comprises a spatial light modulator, a polarization beam splitter, a quarter wave plate and a reflector;
incident light of the polarization pattern generation assembly is unpolarized light, the incident light forms a first light beam and a second light beam through the polarization beam splitter, the first light beam is s-polarized light, and the second light beam is p-polarized light;
the incident light of the first light beam is reflected by the reflector, and the polarization direction of the emergent light of the first light beam reflected by the reflector is vertical to the polarization direction of the p-polarized light;
the spatial light modulator modulates the incident light of the second light beam, performs phase modulation and reflection on a light field incident on the working surface of the spatial light modulator to form emergent light of the second light beam, and the crystal axis direction of the spatial light modulator is parallel to the polarization direction of the second light beam;
emergent light of the first light beam and emergent light of the second light beam are emitted through the polarization beam splitter again and then are changed into two beams of orthogonal circularly polarized light through the quarter-wave plate, so that interference of the two beams of circularly polarized light is realized, and linearly polarized light is formed.
Preferably, the phase compensation module includes: the piezoelectric ceramic is arranged on a telescopic rod of the stepping motor and connected with the reflecting mirror;
the telescopic rod of the stepping motor is used for coarse adjustment, and the piezoelectric ceramic is used for fine adjustment;
the phase compensation component changes the optical path by changing the position of the reflector according to the feedback information of the optical path calibration monitoring component, so that the phase difference between the first light beam and the second light beam is 0 under the condition that the spatial light modulator does not perform phase modulation on the incident light field.
As a preferred scheme, emergent light of the polarization pattern generation assembly passes through the second beam splitter and then enters the pattern micro assembly, the light path calibration monitoring assembly and the focal length servo assembly respectively.
Preferably, the optical path calibration monitoring module includes: the device comprises an analyzer, a first focusing lens and a photoelectric detector, wherein the first focusing lens is arranged between the analyzer and the photoelectric detector, and incident light of the light path calibration monitoring assembly is monitored by the photoelectric detector after sequentially passing through the analyzer and the first focusing lens.
Preferably, the focus servo assembly includes: the second focusing lens, the CCD, the monitoring light source and the third beam splitter;
the second focusing lens is arranged between the third beam splitter and the CCD.
Preferably, the optical path from the second beam splitter to the receiving surface of the CCD is equal to the optical path from the second beam splitter to the workpiece.
Compared with the prior art, the utility model discloses following beneficial effect has:
first, compared with the DMD plus wave plate technique, a single exposure can control the arbitrary alignment of the liquid crystals in the exposure region corresponding to the spatial light modulator pixel without changing the mask and refreshing the dynamic mask using the DMD multiple times, and rotating the polarizer to change the polarization direction of the light.
Second, compared with the LCOS plus wave plate solution, the spatial light modulator LCOS does not need to reflect at a certain angle, and can achieve complete normal incidence, and compared with the LCOS reflective optical path, there is no error generated by paraxial light, the LCOS reflective optical path has strict requirement on paraxial light, the requirement is less than five degrees, and the paraxial error is avoided by normal incidence.
And thirdly, orthogonal circularly polarized light interferes to form linearly polarized light, so that the superposition of light intensity is realized, and compared with the technical scheme of LCOS plus wave plate light path, the requirement on the power of light source components is reduced.
Fourthly, the optical path is automatically calibrated by utilizing negative feedback, the calibration precision is higher, the compensation mentioned in other patents is phase compensation by utilizing the spatial light modulator, the compensation used in the patent is directly compensated for the optical path, the error of phase modulation of the spatial light modulator is reduced (the fluctuation of voltage can cause the working error of the spatial light modulator), and the calibration of the spatial light modulator is not required to be carried out again after the device is restarted every time.
Fifthly, the reflector is adjusted by combining a precise stepping motor and piezoelectric ceramics, the precise stepping motor coarsely adjusts the optical path, and the piezoelectric ceramics finely adjusts the optical path, so that the calibration accuracy of the optical path is higher, the higher optical path accuracy can realize higher liquid crystal orientation arrangement accuracy, and the accuracy of the prepared polarizing optical device is improved.
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 an optical path diagram of a patterned liquid crystal photo-alignment device based on orthogonal circularly polarized light interference according to an embodiment of the present invention.
Fig. 2 is a partial optical path diagram of an illumination assembly and a polarization pattern generation assembly according to an embodiment of the present invention.
Fig. 3 is a flowchart of a patterned liquid crystal photo-alignment device based on orthogonal circularly polarized light interference according to an embodiment of the present invention.
Fig. 4 is a calibration flowchart of the optical path calibration monitoring component according to an embodiment of the present invention.
Wherein:
1-an illumination assembly, 11-a light source component, 12-a collimated beam expanding assembly, 13-a polarizer,
2-the pattern micro-assembly is adopted,
3-focus servo assembly, 31-second focusing lens, 32-CCD, 33-monitoring light source, 34-third beam splitter,
a 4-polarization pattern generation assembly, 41-a first beam splitter, 42-a mirror, 43-a second beam splitter, 44-a spatial light modulator, 45-a first quarter wave plate, 46-a second quarter wave plate, 47-a polarization beam splitter, 48-a quarter wave plate,
5-optical path alignment monitoring component, 51-analyzer, 52-first focusing lens, 53-photodetector,
6-phase compensation component, 61-piezoelectric ceramic, 62-precision stepping motor, 621-telescopic rod,
7-platform, 8-imaging lens group, a-first beam, b-second beam.
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.
To achieve the objects of the present invention, in some of the embodiments of patterned liquid crystal photo-alignment devices based on orthogonal circularly polarized light interference,
as shown in fig. 1 and 3, a patterned liquid crystal photo-alignment device based on orthogonal circularly polarized light interference includes:
the lighting assembly 1 is used for providing a light source and realizing collimation and uniform surface light spots;
the pattern miniature assembly 2 is used for projecting the modulated light field on a photosensitive material in a miniature manner;
the focal length servo assembly 3 comprises a vertical direction correcting 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 7 loaded with the light polarization photosensitive material so as to realize light field splicing;
the polarization pattern generation assembly 4 is used for forming two orthogonal circularly polarized lights and interfering the two orthogonal circularly polarized lights to form linearly polarized lights meeting the requirement of a polarization orientation angle;
the light path calibration monitoring component 5 is used for calibrating and monitoring the whole interference light path of the polarization pattern generation component 4;
and the phase compensation component 6 is used for performing phase compensation according to the linearly polarized light polarization direction information fed back by the light path calibration monitoring component 5, and the phase compensation component 6 directly compensates the light path in the polarization pattern generation component.
In some embodiments of the present invention, the lighting assembly 1 comprises:
a light source section 11 for providing a light source having a wavelength within an absorption wavelength range of the photoalignment material;
a collimation and beam expanding assembly 12, which is used for adjusting the linear light source or point light source emitted from the light source component into a parallel surface light source with uniformly distributed energy and transmitting the parallel surface light source to the orthogonal circularly polarized light interference assembly;
the polarizer 13 is used for converting the light source into linearly polarized light with a required polarization direction or improving the polarization degree of the polarized light.
The light source unit 11 is used to provide a light source for projection exposure, the light source wavelength being in the absorption wavelength range of the photoalignment material. The light source part 11 provides a pulse light source, which works in a constant temperature and humidity environment, wherein the drift amplitude of the central wavelength is less than 3nm, the half-wave width of the light source is less than 5nm, and the energy higher than eighty percent is concentrated in the half-wave width of the central wavelength. The pulse width of the pulse light source is picosecond to second, the single pulse energy is in the magnitude of nano-focus to milli-focus, the unit area energy is higher than the threshold energy of the photosensitive material and lower than the damage threshold of the phase modulation device LCOS, the wavelength is 340nm to 600nm, the half width is less than 5nm, the pulse light source is selected according to the photosensitive characteristic of the photosensitive material, and the repetition frequency of the pulse light source is matched with the refreshing rate of the phase modulation device LCOS at 1Hz to 10 kHz.
The polarizer 13 is used for converting the light emitted from the light source part 11 into linearly polarized light and determining the polarization direction of the incident light. The light source component 11 emits pulsed light, and the pulsed light forms collimated uniform light spots with divergence angles smaller than 10mrad and light intensity uniformity better than 80% after passing through the collimating and beam expanding component 12 and the polarizer 13. The phase error of the central wavelength drift, half width, temperature and wave plate error of the pulse light source to the polarization degree of the output pattern of the polarization pattern generation component is less than 1 percent; after a linear light source or a point light source emitted by the light source part 11 passes through the collimation and beam expansion assembly 12 and the polarizer 13 and is adjusted into a collimated linear polarized surface light source, and the phase modulation is performed by the polarization pattern generation assembly 44, the ratio of the polarization direction to the intensity in the direction perpendicular to the polarization direction needs to be greater than 10 to 1.
In order to further optimize the effect of the present invention, in other embodiments, the rest of the feature technologies are the same, except that the polarization pattern generation assembly 4 includes: a spatial light modulator 44, a first beam splitter 41, a first quarter wave plate 45, a second quarter wave plate 46, and a mirror 42;
incident light of the polarization pattern generation assembly 4 passes through the first beam splitter 41 to form a first light beam a and a second light beam b;
linearly polarized light of the first light beam a is changed into circularly polarized light after passing through the first quarter-wave plate 45 for the first time, the reflecting mirror 42 reflects incident light of the first light beam a which passes through the first quarter-wave plate 45 for the first time, emergent light of the reflected first light beam a is changed into linearly polarized light after passing through the first quarter-wave plate 45 for the second time, and the polarization direction of the linearly polarized light is vertical to the polarization direction of the initial incident light of the first light beam a;
the spatial light modulator 44 modulates the incident light of the second light beam b, performs phase modulation on the light field incident on the working surface of the spatial light modulator, and reflects the light to form the emergent light of the second light beam b;
the emergent light of the first light beam a and the emergent light of the second light beam b are emitted through the first beam splitter 41 again, and then are changed into two beams of orthogonal circularly polarized light through the second quarter-wave plate 46, so that the interference of the two beams of circularly polarized light is realized, and linearly polarized light is formed.
The adopted spatial light modulator 44 is an LCOS device, the working frequency is 1Hz to 10kHz, the selected working frequency is 100Hz, the damage threshold of a pulse light source is more than 300mJ/cm2, the pixel number is 1920 x 1080, the size of a single pixel is 8 microns, the size of the whole spatial light modulator 44 is 1.54cm x 0.86cm, and the phase modulation precision is better than 0.03pi when the phase modulation amount is more than 2pi at 442 nm. The first beam splitter 41 is used for separating the first light beam a and the second light beam b to realize two-beam interference, and the spatial light modulator 44 is used for modulating incident light of the second light beam b, phase-modulating and reflecting a light field incident on a working surface of the spatial light modulator.
As a further improvement of the embodiment of the present invention, the phase compensation assembly 6 includes: a stepping motor 62 and a piezoelectric ceramic 61 arranged on the stepping motor telescopic rod 621, wherein the piezoelectric ceramic 61 is connected with the reflector 42;
the telescopic rod 621 of the stepping motor 62 is used for coarse adjustment, and the piezoelectric ceramic 61 is used for fine adjustment;
the phase compensation unit 6 performs phase compensation by changing the optical path by changing the position of the mirror 42 according to the feedback information of the optical path calibration monitoring unit 5 so that the phase difference between the first light beam a and the second light beam b is 0 without phase-modulating the incident light field by the spatial light modulator 44.
As the embodiment of the utility model provides a further improvement, the emergent light of polarization pattern generation subassembly 4 gets into pattern shrink subassembly 2, light path calibration monitoring subassembly 5 and focus servo subassembly 3 respectively behind second beam splitter 43.
As a further improvement of the embodiment of the present invention, the optical path calibration monitoring module 5 includes: the device comprises an analyzer 51, a first focusing lens 52 and a photoelectric detector 53, wherein the first focusing lens 52 is arranged between the analyzer 51 and the photoelectric detector 53, and incident light of the optical path calibration monitoring assembly 5 sequentially passes through the analyzer 51 and the first focusing lens 52 and is monitored by the photoelectric detector 53.
As shown in fig. 4, the optical path calibration monitoring component 5 performs calibration monitoring on the entire interference optical path of the polarization pattern generation component 4, drives the precision stepper motor to drive the analyzer 51 to rotate under the condition that the spatial light modulator 44 does not apply phase modulation on the optical field of the second light beam b, monitors the maximum light intensity passing through the analyzer 51 through the photodetector 53, records the polarization direction angle θ of the analyzer 51 at this time, and finishes initialization by obtaining the phase difference between the first light beam a and the second light beam b as 2 θ according to the polarization direction angle.
As a further improvement of the embodiment of the present invention, the focal length servo assembly 3 includes: a second focusing lens 31, a CCD32, a monitoring light source 33, and a third beam splitter 34;
the second focusing lens 31 is disposed between the third beam splitter 34 and the CCD 32.
As a further improvement of the embodiment of the present invention, the optical path from the second beam splitter 43 to the CCD receiving surface is equal to the optical path from the second beam splitter 43 to the workpiece.
The focal length servo assembly 3 judges whether defocusing exists according to light spots of a monitoring light source projected on a workpiece acquired by the CCD, if defocusing exists, the imaging lens group 8 moves up and down, so that interference light spots are accurately focused on the surface of a photosensitive material, and after accurate focusing, the light source component 11 emits light to perform patterned liquid crystal photo-orientation on the photosensitive material.
As the utility model discloses embodiment's further improvement, the pattern shrinker subassembly 2 comprises imaging lens group 8 for the light field projection after will being modulated by spatial light modulator 44 can change the objective of different multiples according to the demand of difference on the light-operated orientation material, and imaging lens group 8 can remove the focusing.
On the other hand, the utility model also provides a patterned liquid crystal photoalignment method based on orthogonal circular polarized light interference, specifically includes following steps:
s1, providing a collimated polarized surface light source by the lighting assembly 1;
s2, performing initial calibration on the interference light path, making the polarized surface light source enter the polarization pattern generating assembly 4, making the incident light pass through the first beam splitter 41 to form a first light beam a and a second light beam b, and the spatial light modulator 44 does not apply phase modulation on the light field of the second light beam b;
s3, the optical path calibration monitoring component 5 calibrates and monitors the whole interference optical path of the polarization pattern generating component 4, and under the condition that the spatial light modulator 44 does not apply phase modulation to the optical field of the second light beam b, the precise stepping motor is driven to drive the analyzer 51 to rotate, the photodetector 53 monitors the maximum light intensity passing through the analyzer 51, and records the angle θ of the direction of polarization of the analyzer 51 at this time, and the angle of polarization direction can be used to obtain the phase difference between the first light beam a and the second light beam b as 2 θ, as shown in fig. 4, and then sends the phase difference to the phase compensating component 6;
s4, the phase compensation module 6 performs phase compensation according to the polarization direction information of the linearly polarized light fed back by the optical path calibration monitoring module 5, and the phase compensation module 6 changes the optical path by changing the position of the mirror 42 in the polarization pattern generation module 4 according to the feedback information of the optical path calibration monitoring module 5, so as to implement phase compensation, so that the phase difference between the first light beam a and the second light beam b is 0 under the condition that the spatial light modulator 44 does not perform phase modulation on the incident light field;
s5, formally starting patterned liquid crystal light orientation work, wherein the light path calibration monitoring assembly does not need to work, the spatial light modulator 44 applies phase modulation to the light field of the second light beam b, linearly polarized light of the first light beam a is changed into circularly polarized light after passing through the first quarter-wave plate 45 for the first time, the reflector 42 reflects incident light of the first light beam a which passes through the first quarter-wave plate 45 for the first time, emergent light of the reflected first light beam a is changed into linearly polarized light after passing through the first quarter-wave plate 45 for the second time, and the polarization direction of the linearly polarized light is perpendicular to the polarization direction of the initial incident light of the first light beam a; the spatial light modulator 44 modulates the incident light of the second light beam b, performs phase modulation on the light field incident on the working surface of the spatial light modulator, and reflects the light to form the emergent light of the second light beam b;
the emergent light of the first light beam a and the emergent light of the second light beam b are emitted through the first beam splitter 41 again, and then are changed into two beams of orthogonal circularly polarized light through the second quarter-wave plate 46, so that the interference of the two beams of circularly polarized light is realized, and linearly polarized light is formed;
s6, the pattern shrinking component 2 shrinks the polarization pattern output by the polarization pattern generating component 4 and writes the polarization pattern into the light polarization photosensitive material;
s7, the servo focusing assembly adjusts the distance between the imaging objective lens group and the light polarization sensitive material surface, so that the focal plane of the imaging objective lens group is always kept at the light polarization sensitive material surface;
s8, recording the single light control orientation on the light polarization photosensitive material;
s9, moving the platform 7 carrying the light-polarizing photosensitive material to the next designated position for the next pattern light field recording.
Step S9 may be followed by:
and S10, splicing each alignment unit together to form the optical alignment structure with large-area polarization light pattern on the optical polarization photosensitive material.
In a particular embodiment, the incident light has a polarization direction of
The splitting ratio of the first beam splitter 41 is 6: 4, and the linearly polarized light of the first beam a and the second beam b is still in the x direction. The fast axis of the first quarter-wave plate 45 forms +45 degrees with the x direction, the linearly polarized light of the first light beam a is changed into circularly polarized light after passing through the first quarter-wave plate 45 for the first time, and is changed into linearly polarized light after passing through the first quarter-wave plate 45 for the second time
The polarization direction is the y-direction. After the movement of the mirror 42, the optical path difference is adjusted so that the first light beam a has one
When the emergent light is
The crystal axis direction of the spatial light modulator 44 is parallel to the x direction, and the spatial light modulator 44 modulates the incident light of the second light beam b and reflects the reflected light to obtain the emergent light
Where δ is the phase retardation created by the spatial light modulator 44 and the polarization direction is still the x direction. The light intensities of the two linearly polarized light beams exiting from the first beam splitter 41 are equal. The fast axis of the second quarter-wave plate 46 is at-45 degrees to the x-direction, the beam of the first light beam a
And a second light beam b
After exiting the first beam splitter 41, the light is converted into two orthogonal circularly polarized light beams by the second quarter-wave plate 46
Two orthogonal circularly polarized lights form interference and become linearly polarized light
At this time, the emergent light of the polarization pattern generation assembly 4 is deflected clockwise compared with the incident light
And (4) degree.
In another specific embodiment, the incident light is assumed to be natural light. The splitting ratio of the first beam splitter 41 is 1: 1, and the linearly polarized light of the first light beam a and the second light beam b is still in the x direction. The fast axis of the first quarter-wave plate 45 forms +45 degrees with the x direction, the linearly polarized light of the first light beam a is changed into circularly polarized light after passing through the first quarter-wave plate 45 for the first time, and is changed into linearly polarized light after passing through the first quarter-wave plate 45 for the second time
The polarization direction is the y-direction. The crystal axis direction of the spatial light modulator 44 is parallel to the x direction, and the spatial light modulator 44 modulates the incident light of the second light beam b and reflects the reflected light to obtain the emergent light
Where δ is the phase retardation created by the spatial light modulator 44 and the polarization direction is still the x direction. The fast axis of the second quarter-wave plate 46 is at-45 degrees to the x-direction, the beam of the first light beam a
And a second light beam b
After exiting the beam splitter 1, the light is converted into two orthogonal circularly polarized light beams by the second quarter-wave plate 46, wherein
Two orthogonal circularly polarized lights form interference and become linearly polarized light
At this time, the emergent light of the polarization pattern generation assembly 4 is deflected compared with the incident light
And (4) degree.
In order to further optimize the implementation effect of the present invention, in other embodiments of the patterned liquid crystal photo-alignment device based on orthogonal circularly polarized light interference, the rest of the feature technologies are the same, except that, as shown in fig. 2, the polarization pattern generation assembly 4 includes: a spatial light modulator 44, a polarization beam splitter 47, a quarter wave plate, and a mirror 42;
the incident light of the polarization pattern generation assembly 4 is unpolarized light, and the incident light passes through the polarization beam splitter 47 to form a first light beam a and a second light beam b, wherein the first light beam a is s-polarized light, and the second light beam b is p-polarized light;
the incident light of the first light beam a is reflected by the reflector 42, and the polarization direction of the emergent light of the first light beam a reflected by the reflector 42 is vertical to the polarization direction of the p-polarized light;
the spatial light modulator 44 modulates the incident light of the second light beam b, performs phase modulation on the light field incident on the working surface of the spatial light modulator and reflects the light field to form emergent light of the second light beam b, and the crystal axis direction of the spatial light modulator 44 is parallel to the polarization direction of the second light beam b;
the emergent light of the first light beam a and the emergent light of the second light beam b are emitted through the polarization beam splitter 47 again, and then are changed into two beams of orthogonal circularly polarized light through the quarter-wave plate 48, so that the interference of the two beams of circularly polarized light is realized, and linearly polarized light is formed.
Since the polarization pattern generation assembly 4 employs the polarization beam splitter 47, the illumination assembly 1 may include only: a light source component 11 and a collimated beam expanding assembly 12.
On the other hand, the utility model also provides another kind of patterning liquid crystal photoalignment method based on orthogonal circular polarized light interference, specifically includes following steps:
s1, providing a collimated unpolarized area light source by the illumination assembly 1;
s2, performing initial calibration on the interference light path, making the non-polarized surface light source enter the polarization pattern generation assembly 4, making the incident light pass through the polarization beam splitter 47 to form a first light beam a and a second light beam b, where the first light beam a is S-polarized light and the second light beam b is p-polarized light, and the spatial light modulator 44 does not apply phase modulation on the light field of the second light beam b;
s3, the optical path calibration monitoring component 5 calibrates and monitors the whole interference optical path of the polarization pattern generation component 4, under the condition that the spatial light modulator 44 does not apply phase modulation to the light field of the second light beam b, the precision stepper motor is driven to drive the analyzer 51 to rotate, the photodetector 53 monitors the maximum light intensity passing through the analyzer 51, the analyzing direction angle theta of the analyzer 51 at the moment is recorded, the phase difference between the first light beam a and the second light beam b is 2 theta which can be obtained by the analyzing direction angle, and then the phase difference is sent to the phase compensation component 6;
s4, the phase compensation module 6 performs phase compensation according to the polarization direction information of the linearly polarized light fed back by the optical path calibration monitoring module 5, and the phase compensation module 6 changes the optical path by changing the position of the mirror 42 in the polarization pattern generation module 4 according to the feedback information of the optical path calibration monitoring module 5, so as to implement phase compensation, so that the phase difference between the first light beam a and the second light beam b is 0 under the condition that the spatial light modulator 44 does not perform phase modulation on the incident light field;
s5, formally starting patterned liquid crystal light orientation work, wherein the light path calibration monitoring component does not need to work, the spatial light modulator 44 applies phase modulation to the light field of the second light beam b, the incident light of the first light beam a is reflected by the reflector 42, and the polarization direction of the emergent light of the first light beam a reflected by the reflector 42 is vertical to the polarization direction of the p-polarized light; the spatial light modulator 44 modulates the incident light of the second light beam b, performs phase modulation on the light field incident on the working surface of the spatial light modulator and reflects the light field to form emergent light of the second light beam b, and the crystal axis direction of the spatial light modulator 44 is parallel to the polarization direction of the second light beam b; emergent light of the first light beam a and emergent light of the second light beam b are emitted through the polarization beam splitter 47 again and then are changed into two beams of orthogonal circularly polarized light through the quarter-wave plate, so that interference of the two beams of circularly polarized light is realized, and linearly polarized light is formed;
s6, the pattern shrinking component 2 shrinks the polarization pattern output by the polarization pattern generating component 4 and writes the polarization pattern into the light polarization photosensitive material;
s7, the servo focusing assembly adjusts the distance between the imaging objective lens group and the light polarization sensitive material surface, so that the focal plane of the imaging objective lens group is always kept at the light polarization sensitive material surface;
s8, recording the single light control orientation on the light polarization photosensitive material;
s9, moving the platform 7 carrying the light-polarizing photosensitive material to the next designated position for the next pattern light field recording.
Step S9 may be followed by:
and S10, splicing each alignment unit together to form the optical alignment structure with large-area polarization light pattern on the optical polarization photosensitive material.
The utility model provides a projection formula liquid crystal light control orientation device and method based on circular polarized light interference principle utilizes the phase difference that phase type spatial light modulator LCOS produced, controls the polarization information of circular polarized light for the polarization direction of the linear polarized light that the circular polarized light interfered the formation is accurate controllable. And the oriented arrangement of the liquid crystal can be realized by combining the property that the optical orientation material is sensitive to the polarization direction of linearly polarized light. The device can complete the random orientation arrangement of the liquid crystal in any pixel space in the exposure area under the condition of single exposure. And through the movement of the two-dimensional workpiece platform, the splicing of a plurality of exposure breadth can be completed, and the control of large-breadth liquid crystal orientation arrangement is realized.
Compared with the prior art, the utility model discloses following beneficial effect has:
first, in contrast to the DMD plus waveplate technique, a single exposure can control the arbitrary alignment of the liquid crystals in the region of the exposure region corresponding to the pixels of the spatial light modulator 44 without the need to change the mask and refresh the dynamic mask with the DMD multiple times and rotate the polarizer to change the polarization direction of the light.
Second, compared with the LCOS plus wave plate solution, the spatial light modulator 44LCOS does not need to reflect at a certain angle, and can achieve complete normal incidence, and compared with the LCOS reflective optical path, there is no error generated by paraxial light, the LCOS reflective optical path has strict requirement on paraxial light, the requirement is less than five degrees, and the paraxial error is avoided by normal incidence.
And thirdly, orthogonal circularly polarized light interferes to form linearly polarized light, so that the superposition of light intensity is realized, and compared with the technical scheme of LCOS plus wave plate light path, the requirement on the power of the light source part 11 is reduced.
Fourthly, an orthogonal circularly polarized light interference exposure light path is adopted, the principle that orthogonal circularly polarized light interference forms linearly polarized light is utilized, two beams of orthogonal circularly polarized light are subjected to phase modulation, further, the random change of the polarization direction of the linearly polarized light is realized, based on the reflective phase spatial light modulator 44, the phase difference delta in the pixel is controlled, and after orthogonal circularly polarized light interference, the polarization rotation angle of the linearly polarized light in the corresponding pixel is equal to that of the linearly polarized light in the corresponding pixel
Fifthly, the optical path is automatically calibrated by using a negative feedback system, the calibration precision is higher, the compensations mentioned in other patents are phase compensations by using the spatial light modulator 44, and the compensation used in the patent is to directly compensate the optical path, so that the error of phase modulation of the spatial light modulator 44 is reduced (the fluctuation of voltage can cause the working error of the spatial light modulator 44), and the calibration of the spatial light modulator 44 is not required to be carried out again after the device is restarted each time.
Sixthly, the reflector 42 is adjusted by combining the precise stepping motor 62 and the piezoelectric ceramic 61, the precise stepping motor 62 coarsely adjusts the light path, and the piezoelectric ceramic 61 finely adjusts the light path, so that the calibration accuracy of the light path is higher, the higher light path accuracy can realize higher liquid crystal orientation arrangement accuracy, and the accuracy of the prepared polarizing optical device is improved.
Seventh, the writing accuracy and efficiency can be balanced by zooming or magnifying the polarization pattern of the phase spatial light modulator 44 by the imaging lens group 8;
eighth, different orthogonal circularly polarized light interference exposure light paths can be obtained by using a polarization beam splitter without the need for the polarizer 13 and the quarter wave plate for changing the polarization direction of linearly polarized light.
Ninth, high quality large-area patterned liquid crystal photo-alignment can be achieved by the movement of the stage 7.
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 patterned liquid crystal photo-alignment device based on orthogonal circularly polarized light interference provided by the above embodiments, when a patterned liquid crystal photo-alignment method based on orthogonal circularly polarized light interference is performed, only the division of the above functional modules is illustrated, 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 device may be divided into different functional modules to complete all or part of the above described functions. In addition, the embodiment of the patterned liquid crystal photo-alignment device based on orthogonal circularly polarized light interference and the embodiment of the patterned liquid crystal photo-alignment method based on orthogonal circularly polarized light interference provided by the above embodiments belong to the same concept, and specific implementation processes thereof are detailed in the method embodiments 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. With regard to the preferred embodiments of the present invention, it should be noted that, for those skilled in the art, many variations and modifications can be made without departing from the inventive concept, and these are within the scope of the present invention.
Claims (8)
1. A patterned liquid crystal photo-alignment device based on orthogonal circularly polarized light interference comprises:
the lighting assembly is used for providing a light source and realizing collimation and uniform surface light spots;
the pattern micro-assembly is used for micro-projecting the modulated light field on the photosensitive material;
the focal length servo assembly comprises a vertical direction correcting 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 loaded with the light polarization photosensitive material so as to realize light field splicing;
it is characterized by also comprising:
the polarization pattern generating assembly is used for forming two orthogonal circularly polarized lights and interfering the two orthogonal circularly polarized lights to form linearly polarized lights meeting the requirement of a polarization orientation angle;
the light path calibration monitoring component is used for calibrating and monitoring the whole interference light path of the polarization pattern generation component;
and the phase compensation component is used for performing phase compensation according to the linearly polarized light polarization direction information fed back by the light path calibration monitoring component, and directly compensating the light path in the polarization pattern generation component.
2. The patterned liquid crystal photoalignment device based on orthogonal circularly polarized light interference of claim 1, wherein the polarization pattern generation assembly comprises: the spatial light modulator comprises a spatial light modulator, a first beam splitter, a first quarter wave plate, a second quarter wave plate and a reflector;
incident light of the polarization pattern generation assembly forms a first light beam and a second light beam through the first beam splitter;
linearly polarized light of the first light beam is changed into circularly polarized light after passing through the first quarter-wave plate for the first time, the reflecting mirror reflects incident light of the first light beam passing through the first quarter-wave plate for the first time, emergent light of the reflected first light beam is changed into linearly polarized light after passing through the first quarter-wave plate for the second time, and the polarization direction of the linearly polarized light is perpendicular to the polarization direction of the initial incident light of the first light beam;
the spatial light modulator modulates the incident light of the second light beam, and performs phase modulation and reflection on a light field incident on the working surface of the spatial light modulator to form emergent light of the second light beam;
emergent light of the first light beam and emergent light of the second light beam are emitted through the first beam splitter again and then are changed into two beams of orthogonal circularly polarized light through the second quarter-wave plate, so that interference of the two beams of circularly polarized light is realized, and linearly polarized light is formed.
3. The patterned liquid crystal photoalignment device based on orthogonal circularly polarized light interference of claim 1, wherein the polarization pattern generation assembly comprises: the device comprises a spatial light modulator, a polarization beam splitter, a quarter wave plate and a reflector;
incident light of the polarization pattern generation assembly is unpolarized light, the incident light passes through the polarization beam splitter to form a first light beam and a second light beam, the first light beam is s-polarized light, and the second light beam is p-polarized light;
the incident light of the first light beam is reflected by the reflector, and the polarization direction of the emergent light of the first light beam reflected by the reflector is vertical to the polarization direction of p-polarized light;
the spatial light modulator modulates the incident light of the second light beam, performs phase modulation and reflection on a light field incident on the working surface of the spatial light modulator to form emergent light of the second light beam, and the crystal axis direction of the spatial light modulator is parallel to the polarization direction of the second light beam;
emergent light of the first light beam and emergent light of the second light beam are emitted through the polarization beam splitter again and then are changed into two beams of orthogonal circularly polarized light through the quarter-wave plate, so that interference of the two beams of circularly polarized light is realized, and linearly polarized light is formed.
4. The device of claim 2 or 3, wherein the phase compensation component comprises: the piezoelectric ceramic is arranged on a telescopic rod of the stepping motor and is connected with the reflecting mirror;
the telescopic rod of the stepping motor is used for coarse adjustment, and the piezoelectric ceramic is used for fine adjustment;
and the phase compensation component changes the optical path by changing the position of the reflecting mirror according to the feedback information of the optical path calibration monitoring component, so that the phase difference between the first light beam and the second light beam is 0 under the condition that the spatial light modulator does not perform phase modulation on the incident light field.
5. The device according to claim 4, wherein the emergent light from the polarization pattern generator passes through the second beam splitter and then enters the pattern shrinking component, the optical path calibration monitoring component and the focus servo component.
6. The device of claim 5, wherein the optical path alignment monitoring component comprises: analyzer, first focus lens and photoelectric detector, first focus lens set up in between analyzer and the photoelectric detector, the incident light of light path calibration monitoring components passes through in proper order behind analyzer and the first focus lens, quilt photoelectric detector monitors.
7. The device of claim 6, wherein the focus servo assembly comprises: the second focusing lens, the CCD, the monitoring light source and the third beam splitter;
the second focusing lens is arranged between the third beam splitter and the CCD.
8. The device of claim 7, wherein the optical path from the second beam splitter to the CCD receiving surface is the same as the optical path from the second beam splitter to the workpiece.
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| CN113138505A (en) * | 2021-02-23 | 2021-07-20 | 西北工业大学 | Ferroelectric liquid crystal geometric phase device and preparation system and preparation method thereof |
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