WO2019233178A1 - 一次曝光实现任意分布的光取向装置及一种光学元件的制备方法 - Google Patents

一次曝光实现任意分布的光取向装置及一种光学元件的制备方法 Download PDF

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WO2019233178A1
WO2019233178A1 PCT/CN2019/082347 CN2019082347W WO2019233178A1 WO 2019233178 A1 WO2019233178 A1 WO 2019233178A1 CN 2019082347 W CN2019082347 W CN 2019082347W WO 2019233178 A1 WO2019233178 A1 WO 2019233178A1
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phase delay
degrees
polarization
photo
light
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French (fr)
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李燕
苏翼凯
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Shanghai Jiao Tong University
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Shanghai Jiao Tong University
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    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/0136—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  for the control of polarisation, e.g. state of polarisation [SOP] control, polarisation scrambling, TE-TM mode conversion or separation
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1337—Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers
    • G02F1/13378—Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers by treatment of the surface, e.g. embossing, rubbing or light irradiation
    • G02F1/133788—Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers by treatment of the surface, e.g. embossing, rubbing or light irradiation by light irradiation, e.g. linearly polarised light photo-polymerisation
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/11—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on acousto-optical elements, e.g. using variable diffraction by sound or like mechanical waves
    • G02F1/116—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on acousto-optical elements, e.g. using variable diffraction by sound or like mechanical waves using an optically anisotropic medium, wherein the incident and the diffracted light waves have different polarizations, e.g. acousto-optic tunable filter [AOTF]
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/1303—Apparatus specially adapted to the manufacture of LCDs
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/13363—Birefringent elements, e.g. for optical compensation
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/137—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/13363—Birefringent elements, e.g. for optical compensation
    • G02F1/133638—Waveplates, i.e. plates with a retardation value of lambda/n
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F2202/00—Materials and properties
    • G02F2202/40—Materials having a particular birefringence, retardation

Definitions

  • the invention relates to the field of optical technology, in particular to a photo-alignment device capable of realizing an arbitrary distribution in one exposure and a method for preparing an optical element.
  • Liquid crystal is widely used in liquid crystal display technology, adjustable liquid crystal photonic devices and other fields due to its advantages such as large optical anisotropy, low power consumption, light weight, and easy control of electrical, optical, and magnetic modes.
  • an alignment layer is often required to help the liquid crystal directors (probability statistical directions of the local liquid crystal optical axis) be arranged in a certain direction.
  • the traditional alignment layer is generally obtained by rubbing on a thin layer of a polymer material, which will cause environmental pollution and has poor uniformity in the rubbing orientation.
  • Another advantage of light orientation compared to traditional rubbing orientation is that liquid crystals in different regions can be oriented in different directions, so it can be applied to three-dimensional display based on graphical phase retarders, security and confidential file display, geometric phase liquid crystal holograms, etc. .
  • the geometric phase hologram can be regarded as a mosaic of phase retarders with many optical axes changing in space. It relies on the distribution of the optical axis in space to form the phase distribution in space. It has the advantages of high diffraction efficiency, insensitivity to wavelength and angle, etc. It can be widely used in beam deflection, holographic imaging, augmented reality glasses and other fields.
  • Geometric phase holograms can be prepared in the following ways:
  • the first method is to use two circularly polarized lights with opposite spins to perform holographic interference to generate linearly polarized light with a change in polarization direction in space.
  • the polarization-sensitive medium is exposed to the interference pattern, it is aligned accordingly according to the polarization direction of the light. In this way, it is difficult to generate an optical axis spatial arrangement of an arbitrary pattern distribution.
  • the second method is to realize multiple exposures of the polarization-sensitive medium by ultraviolet light passing through one or more mask plates.
  • the orientation distribution formed by this method is completely determined by the mask pattern. Designing a new orientation distribution requires replacing or moving the mask; the polarization of UV light is generally achieved by mechanically rotating a linear polarizing film; since only one polarization direction can be arranged per exposure, the more orientation directions are required, The more exposures you need.
  • DMD digital micromirror array device
  • the present invention provides a photo-orientation device capable of achieving arbitrary distribution in one exposure and a method for preparing an optical element.
  • a linear polarizing film By designing a linear polarizing film, a pixelated electronically controlled phase delay device, and a phase delay wave plate, With respect to the direction of the optical axis and the phase delay value of each phase delay device, a polarization pattern of any shape can be generated, and a corresponding arrangement contour can be formed on a polarization-sensitive medium.
  • the polarization-sensitive medium affects the optically anisotropic medium, and generates a geometric phase hologram device of any shape.
  • the invention discloses a photo-orientation device capable of realizing an arbitrary distribution by one exposure, including a light source, a linear polarizing film, a pixelated electronically-controlled phase delay device, and a phase delay wave plate, which are sequentially arranged in space, wherein:
  • the light source is used to provide light required for photo-oriented exposure
  • the linearly polarizing film is configured to change the light emitted by the light source into linearly polarized light whose polarization direction is parallel to the direction of the transmission axis of the linearly polarizing film;
  • phase delay of each pixel of the pixelated electronically controlled phase delay device is controlled by a corresponding voltage, and is used to generate a phase delay of an arbitrary pattern distribution;
  • the phase retarder is used to generate a non-pixelized phase delay.
  • one or more optical elements may be added before, after, or between the linearly polarizing film, the pixelated electrically controlled phase delay device, and the phase delay wave plate component.
  • the optical element is a lens, a lens group, a mirror, an attenuator, an aperture, a phase delay device, a polarizer, a beam expander, a filter, a prism, an optical window, an optical substrate, a beam displacement optical element, Diffractive optical element and / or polarization rotation device.
  • phase delay of the phase delay wave plate is between ⁇ / 4 + m ⁇ and 3 / 4 ⁇ + m ⁇ , where m is an integer.
  • the phase delay of the phase delay wave plate is an odd multiple of ⁇ / 2.
  • the direction of the light transmission axis of the linear polarization film and the polarization direction of the extraordinary light incident perpendicularly to the pixelated electronically controlled phase delay device are at an included angle ranging from 30 degrees to 60 degrees, or negative The included angle in the range of 60 degrees to negative 30 degrees, or the included angle in the range of 120 degrees to 150 degrees, or the included angle in the range of negative 150 degrees to negative 120 degrees.
  • the direction of the light transmission axis of the linear polarization film is 45 degrees, or negative 45 degrees, or 135 degrees, or the polarization direction of the extraordinary light incident perpendicularly to the pixelated electronically controlled phase delay device, or Minus 135 degrees.
  • the direction of the transmission axis of the linear polarizing film and the direction of the slow axis of the phase retardation wave plate form an included angle ranging from 30 degrees to 60 degrees, or an included angle ranging from negative 60 degrees to negative 30 degrees, Either an angle ranging from 120 degrees to 180 degrees, or an angle ranging from negative 180 degrees to negative 120 degrees.
  • the direction of the light transmission axis of the linear polarization film is 45 degrees, or minus 45 degrees, or 135 degrees, or minus 135 degrees with the slow axis direction of the phase retardation wave plate.
  • the pixelated electronically controlled phase delay device is a liquid crystal device, and the initial matching of the liquid crystal device is horizontal matching on both sides, or vertical matching on both sides, or horizontal matching on one side and vertical matching on the other side. phase.
  • the pixelated electronically controlled phase delay device includes a transmission type and a reflection type.
  • the light source is ultraviolet light or visible light.
  • the light source is a laser or an LED.
  • the invention further discloses a method for preparing an optical element, which is prepared by using any one of the above-mentioned one-time exposure to achieve an arbitrary distribution of a light alignment device, wherein the optical element includes a polarization sensitive medium and optical anisotropy. Medium, the optically anisotropic medium has a local optical axis orientation profile and can be distributed in any shape.
  • the specific preparation process of the optical element includes the following steps:
  • the optical axis orientation profile in the polarization-sensitive medium is generated by a photo-orientation device
  • the optical axis orientation profile in a polarization sensitive medium determines the local optical axis orientation profile of an optically anisotropic medium.
  • the optical element can control its electro-optical characteristics with a voltage.
  • the polarization-sensitive medium and the optically anisotropic medium are two layers of separated media, or the two media are mixed into one layer, or the same medium has both polarization-sensitive properties and optical anisotropy.
  • the polarization-sensitive medium and the optically anisotropic medium are both exposed by light output from the photo-orientation device; or, the optically anisotropic medium is not exposed by light from the photo-alignment device, but is added to Optics.
  • the polarization-sensitive medium is a photo-alignment material or an azobenzene polymer
  • the optically anisotropic medium is a liquid crystal, a liquid crystal polymer, or an azobenzene polymer.
  • a polarization pattern of any shape can be generated and applied to polarization sensitive media.
  • the corresponding arrangement outline is formed on it.
  • the polarization-sensitive medium affects the optically anisotropic medium, and generates a geometric phase hologram device of any shape.
  • the invention only needs one exposure to realize any shape of polarization pattern and geometric phase hologram device, which greatly simplifies the device preparation process; the invention uses only voltage to accurately control the voltage distribution on the pixelated electronically controlled phase delay device, and only needs one time Exposure can control the optical polarization and the continuous change of the local optical axis of the anisotropic medium in any direction.
  • the polarized pattern of any shape of the invention can be updated in real time by computer-controlled pixelated electronically controlled phase delay devices, without the need to re-do the photomask each time, which greatly reduces the production cost.
  • Example 1 is a schematic diagram of a device according to Example 1 of the present invention.
  • FIG. 2 is a schematic diagram of a device according to some examples of the present invention.
  • Example 4 is a photo-alignment process of Example 2 of the present invention.
  • Example 5 is a geometric phase hologram of the optical axis distribution of an arbitrary liquid crystal generated by a pixelized electronically controlled liquid crystal adjustable phase delay device using a 6 ⁇ 5 pixel in Example 2 of the present invention
  • Example 6 is a photograph of a geometric phase hologram printed with a school abbreviation prepared in Example 2 of the present invention.
  • FIG. 7 is an optical axis distribution diagram of a geometric phase grating with continuously changing polarization directions that can be prepared according to the present invention.
  • FIG. 8 is an optical axis distribution diagram of a geometric phase grating with only two polarization directions that can be prepared according to the present invention.
  • the present invention discloses a photo-orientation device capable of realizing an arbitrary distribution by one exposure, including a light source, a linear polarizing film 1, a pixelated electronically-controlled phase delay device 2, and a phase delay wave arranged sequentially in space.
  • the light source is used to provide light required for photo-oriented exposure
  • the linearly polarizing film 1 is configured to change the light emitted by the light source into linearly polarized light whose polarization direction is parallel to the transmission axis direction of the linearly polarizing film 1;
  • phase delay of each pixel of the pixelated electronically controlled phase delay device 2 is controlled by a corresponding voltage, and is used to generate a phase delay of an arbitrary pattern distribution;
  • the phase retarder is used to generate a non-pixelized phase delay.
  • the light emitted by the light source passes through a linear polarizing film (polarizing plate) 1, a pixelated electronically controlled phase delay device 2, a phase delay wave plate 3, and then enters a polarization sensitive medium 4.
  • polarizing plate linear polarizing film
  • the direction of the transmission axis of the linear polarizing film 1 is drawn with arrows in the figure
  • the direction of polarization of unusual light in the pixelated electronically controlled phase delay device 2 is drawn with arrows.
  • Slow axis direction of the phase retardation wave plate 3 A coordinate system is established with the light propagation direction as the z-axis, the slow axis direction of the 1/4 wave plate as the y-axis, and its fast axis direction as the x-axis.
  • the direction of the light-transmitting axis of the linear polarizer is also the y-axis.
  • the polarization direction of the extraordinary light in the pixelated electronically controlled phase delay device 2 is in the xy plane and forms an angle of 45 degrees with the y-axis.
  • the phase delay of each pixel of the pixelated electronically-controlled phase delay device 2 is controlled by the corresponding voltage and incident.
  • the polarization-sensitive medium 4 is linear polarization or elliptical polarization, and the polarization direction or the major axis direction of the elliptical polarization can be controlled at the pixel level by the pixelated electronically controlled phase delay device 2.
  • one or more optical elements may be added before, after, or between the linearly polarized film 1, the pixelated electrically controlled phase delay device 2, and the phase delay wave plate 3 components, and its essence does not affect The device realizes an arbitrary shape polarization pattern.
  • the optical element is a lens, a lens group, a mirror, an attenuator, an aperture, a phase delay device, a polarizer, a beam expander, a filter, a prism, an optical window, an optical substrate, a beam displacement optical element, Diffractive optical element and / or polarization rotation device.
  • the light spot emitted by the pixelated electronically controlled phase delay device 2 can be enlarged and reduced.
  • the light spot can be reduced, and the pixel image of the pixelated electronically controlled phase delay device 2 can also be reduced, so that the spatial resolution of the prepared geometric phase hologram is improved.
  • phase delay of the phase delay wave plate 3 is between ⁇ / 4 + m ⁇ and 3 / 4 ⁇ + m ⁇ , where m is an integer.
  • the phase delay of the phase delay wave plate 3 is an odd multiple of ⁇ / 2, that is, it is a 1 / 4 ⁇ wave plate.
  • the direction of the transmission axis of the linear polarization film 1 and the polarization direction of the extraordinary light incident perpendicularly to the pixelated electronically controlled phase delay device 2 are at an angle ranging from 30 degrees to 60 degrees, or An angle in the range of negative 60 degrees to negative 30 degrees, or an angle in the range of 120 degrees to 150 degrees, or an angle in the range of negative 150 degrees to negative 120 degrees.
  • the direction of the light transmission axis of the linear polarization film 1 is 45 degrees, or negative 45 degrees, or 135 degrees, with the polarization direction of the extraordinary light incident perpendicularly into the pixelated electronically controlled phase delay device 2. , Or minus 135 degrees.
  • the transmission axis direction of the linear polarizing film 1 and the slow axis direction of the phase retardation wave plate 3 form an included angle ranging from 30 degrees to 60 degrees, or an included angle ranging from negative 60 degrees to negative 30 degrees.
  • the angle is either an angle in the range of 120 degrees to 180 degrees, or an angle in the range of negative 180 degrees to negative 120 degrees.
  • the direction of the light transmission axis of the linear polarization film 1 and the direction of the slow axis of the phase retardation wave plate 3 are 45 degrees, or negative 45 degrees, or 135 degrees, or negative 135 degrees.
  • the pixelated electronically controlled phase delay device 2 is a liquid crystal device, and the initial phase matching of the liquid crystal device is horizontal matching on both sides, or vertical matching on both sides, or horizontal matching on one side and vertical on the other side. Matching.
  • the light source is ultraviolet light or visible light, which can realize exposure of the polarization-sensitive medium 4.
  • the light source is a laser or an LED.
  • the light source is a laser, the light source has good collimation and high energy.
  • the light source is an LED, the light source is non-collimated light, which has the characteristics of small size and low price.
  • the pixelated electronically controlled phase delay device 2 includes a transmission type and a reflection type.
  • the pixelated electronically controlled phase delay device 2 can be connected to a computer for phase delay distribution design, and can perform real-time refresh.
  • the pixelated electronically controlled phase delay device 2 is a horizontally-matched transmissive liquid crystal device, and the liquid crystal is a positive liquid crystal with ⁇ > 0, then:
  • the liquid crystal directors are gradually shifted from a horizontal arrangement to a vertical arrangement, so that the phase delay ⁇ of the pixel gradually decreases with the voltage;
  • the outgoing light is linearly polarized light, and its polarization direction is turned by an angle of - ⁇ / 2 with respect to the transmission axis direction (y-axis) of the linear polarizer, and its intensity is determined by the incident light.
  • the y component is determined.
  • the output light can be formed into an arbitrary polarization distribution of pixelation. That is, the local area of the emitted light (the area corresponding to one pixel) is linearly polarized light with the same polarization direction, and different local areas (areas corresponding to different pixels) can achieve linearly polarized light polarized in different directions.
  • each point of the emitted light may be an elliptically polarized light, but the long axis direction of the elliptically polarized light is similarly controlled by a pixelated electronically controlled phase adjustable device to achieve an arbitrary patterned distribution.
  • methyl red molecules are randomly distributed in all directions, but the long axis of absorption will be perpendicular to the direction of polarization (or the long axis of elliptical polarization) to obtain the most
  • the stable state and the molecular arrangement profile on the polarization-sensitive recording medium are also determined by the aforementioned pixelated electronically controlled phase delay device 2.
  • the pixelated electronically controlled phase delay device 2 is a vertically-aligned transmissive liquid crystal device, and the liquid crystal is a negative liquid crystal with ⁇ ⁇ 0. Also different voltages can produce different phase delays ⁇ .
  • the pixelated electronically controlled phase delay device 2 may be reflective, as shown in FIG. 2.
  • the light passes through the device shown in Figure 2.
  • the light emitted by the light source passes through the linear polarizing film 1, the beam splitting prism 5, the reflective pixelated electronically controlled phase delay device (silicon-based liquid crystal modulator) 6, the beam splitting prism 5, 1 / After 4 wave plates 3, an arbitrary patterned arrangement contour is generated at the polarization-sensitive recording medium 4.
  • the reflective pixelated electrically controlled adjustable phase delay device here has a polarization rotation of 2 times under the same material and the thickness of the liquid crystal cell.
  • the invention further discloses a method for preparing an optical element, which is prepared by using any one of the above-mentioned one-time exposure to achieve an arbitrary distribution of a light alignment device, wherein the optical element includes a polarization-sensitive medium 4 and an optical isotropic
  • An anisotropic medium the optically anisotropic medium has a local optical axis orientation profile, that is, the local optical axis orientation changes along at least one direction along its surface and can be distributed in any shape.
  • the specific preparation process of the optical element includes the following steps :
  • the local optical axis orientation profile of the optically anisotropic medium is determined by the optical axis orientation profile in the polarization-sensitive medium 4.
  • the optical element can control its electro-optical characteristics with a voltage.
  • the polarization-sensitive medium 4 and the optically anisotropic medium are two layers of separated media, or the two media are mixed into one layer, or the same medium has both polarization-sensitive properties and optical anisotropy.
  • the polarization-sensitive medium 4 is the light matching layer SD1
  • the optically anisotropic medium is liquid crystal, which is the first case
  • the polarization-sensitive medium 4 is methyl red
  • the optically anisotropic medium is liquid crystal, which is the second case
  • some Azobenzene polymers which have both polarization sensitivity and optical anisotropy, belong to the third case.
  • the polarization-sensitive medium 4 and the optically anisotropic medium are both exposed by light output from the photo-alignment device; or, the optically anisotropic medium is not exposed by light from the photo-alignment device, but is added after exposure. Into the optics.
  • the polarization-sensitive medium 4 is a photo-alignment material or an azobenzene polymer, and the alignment direction of the molecules can be changed correspondingly according to the polarization direction of the incident light.
  • the optically anisotropic medium is a liquid crystal, a liquid crystal polymer, or an azobenzene polymer.
  • Example 1 we use the device of Example 1 to prepare an optical element with an optical axis-oriented profile.
  • the optical element is prepared by mixing a mixture of the liquid crystal 53 and the polarization-sensitive medium 54, such as a mixture of E7 and methyl red, and then pouring the mixture into the finished liquid crystal cell to receive the exposure of the device in Example 1.
  • methyl red is used as the polarization-sensitive medium 54
  • E7 liquid crystal is used as the optically anisotropic medium.
  • the finished liquid crystal cell is controlled by two layers of Indium Tin Oxide (ITO) glass with spacers and sealed with glue. In the effective area, two small holes are reserved for the liquid crystal 53 to be injected.
  • ITO Indium Tin Oxide
  • Example 1 Because the light formed from Example 1 has a polarization distribution profile, methyl red in different regions of the liquid crystal cell also has different alignment directions, and further drives the LCD E7 director to have different alignment directions. In this way, a device with an arbitrary shape change of the liquid crystal optical axis in the plane of the glass substrate can be manufactured.
  • This exposure process is shown in Figure 4, where 52 is ITO glass, 53 is liquid crystal, and 54 is polarization sensitive medium.
  • Figure 5 shows a geometric phase hologram of any local optical axis distribution generated by a 6X5 pixel pixelated electronically-controlled liquid crystal adjustable phase delay device.
  • Figure 6 shows a geometric phase hologram printed with a school abbreviation. Its generation method is as follows. We use a computer to generate "S”, “J”, “T”, “U” and background. Each letter or background has a different grayscale. When this grayscale image is projected onto a pixelated adjustable phase delay device, different letters or backgrounds correspond to linearly polarized light with different polarization directions.
  • the liquid crystal cell that we poured after mixing E7 and methyl red after receiving exposure formed a pattern with different liquid crystal optical axis arrangements in different regions.
  • the liquid crystal cell of FIG. 6 is obtained by rotating the polarizing plates perpendicular to each other.
  • Figure 7 shows the optical axis distribution of a geometric phase grating with continuously changing polarization directions that can be prepared by this method.
  • Figure 8 shows the optical axis distribution of a geometric phase grating with only two polarization directions.
  • the optically anisotropic layer in the prepared geometric phase hologram is a positive liquid crystal, and a voltage perpendicular to the substrate can be applied to gradually rotate the optical axis of the liquid crystal originally parallel to the substrate to the direction parallel to the electric field. In this way, the local phase difference of the geometric phase hologram can be adjusted by the voltage, thereby adjusting its electro-optical characteristics.
  • the voltage is high, the optical axis of the liquid crystal is almost perpendicular to the substrate without any phase delay, so the geometric phase hologram disappears.
  • this manufacturing method is not limited to manufacturing liquid crystal devices.
  • the recording material polarization-sensitive medium is the photo-alignment layer 51
  • the optically anisotropic medium is liquid crystal.
  • the photo-alignment layer 51 is spin-coated on the ITO glass 52. Two pieces of ITO glass 52 coated with the photo-alignment layer 51 are controlled with a spacer and then sealed with UV glue to form an empty liquid crystal cell.
  • the photo-alignment layers 51 are all inside the empty liquid crystal cell, and are used to arrange liquid crystals. One such empty liquid crystal cell is placed at the polarization-sensitive recording medium 4 in FIG. 1 or FIG. 2.
  • the voltage of each pixel of the pixelated electronically controlled phase delay device 2 can be controlled by a computer, and the local alignment direction of the molecules of the photo-alignment layer 51 can be controlled.
  • the exposure process is shown in Figure 3, where 51 is a photo-alignment layer and 52 is ITO glass. Then the liquid crystal is poured into the cell, and the liquid crystal will be arranged according to the local alignment direction of the photo-alignment layer.
  • the liquid crystal directors are arranged substantially parallel to the glass substrate, and the arrangement direction in the plane is determined by the arrangement of the photo-alignment layers 51 in the corresponding regions. In this way, we can make devices with any shape of the liquid crystal optical axis changing in the plane of the glass substrate.
  • a geometric phase hologram can be similarly generated.

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Abstract

一次曝光实现任意分布的光取向装置及一种光学元件的制备方法，包括在空间上顺序摆放的光源、线性极化膜（1）、像素化电控相位延迟器件（2）和相位延迟波片（3），光源用于提供光取向曝光所需的光；线性极化膜（1）用于将光源发出的光变成极化方向与线性极化膜（1）透光轴方向平行的线性极化光；像素化电控相位延迟器件（2）的每个像素的相位延迟由对应的电压分别控制，用于产生任意图形分布的相位延迟；相位延迟波片（3）用于产生非像素化的相位延迟。通过设计线性极化膜（1）、像素化电控相位延迟器件（2）、相位延迟波片（3）的相对光轴方向，和各个相位延迟器件（2）的相位延迟值，可以生成任意形状的极化图，并在极化敏感介质（4）上形成相应的排列轮廓。

Description

一次曝光实现任意分布的光取向装置及一种光学元件的制备方法 技术领域
本发明涉及光学技术领域，特别涉及一次曝光实现任意分布的光取向装置及一种光学元件的制备方法。
背景技术
液晶由于其大光学各向异性、低功耗、轻巧、容易进行电、光、磁等方式调控等优点被广泛应用于液晶显示技术、可调液晶光子学器件等领域。但是要实现对液晶的调控往往需要取向层帮助才能使液晶指向矢(局部液晶光轴的概率统计方向)按一定方向进行排列。传统的取向层一般靠在聚合物材料薄层材料上摩擦获得，该材料会造成污染环境，且摩擦取向均匀性较差。最近，光取向技术，利用光的极化方向控制极化敏感介质排列方向，并进一步控制液晶指向矢方向的方法，日益成熟，并开始在一些商业产品上得到应用(如面内驱动的小尺寸液晶面板)。用非接触式的光控制液晶的取向，具有环保、易于实现，均匀性更好等优点，是液晶取向未来发展趋势。
光取向，相比于传统摩擦取向的另一个优点是可以实现不同区域液晶沿不同方向取向，因此可以应用于基于图形化相位延迟片的三维显示、安全保密文件显示、几何相位液晶全息图等方面。
几何相位全息图(GPH)可以看作由很多光轴在空间变化的相位延迟片拼接而成。它依靠光轴在空间中分布来形成相位在空间中分布，具有衍射效率高，对波长、角度不敏感等优点，可广泛应用于光束偏转、全息成像、增强现实眼镜等领域。几何相位全息图主要有以下几种制备方式：
第一种方法是利用两个旋性相反的圆极化光进行全息干涉，生成空间上极化方向变化的线极化光。当极化敏感介质暴露于干涉图案时，就根据光的极化方向进行相应排列。该种方式难以生成任意图形分布的光轴空间排列。
第二种方法是由紫外光经过一个或多个掩膜板对极化敏感介质进行多次曝光实现。这种方法所形成的取向分布完全由掩膜板图案决定。设计新的取向分布需要更换或者移动掩膜板；紫外光的极化选择一般由机械转动线性极化膜实现；由于每次曝光只能实现一个极化方向的排列，需要的取向方向越多，需要曝光的次数越多。
另有一种数字微反射镜阵列器件(DMD)的方法，通过刷新DMD上的强度分布图，可以快速生成需要的掩膜板图形，而不需要物理地生产新的掩膜板，更容易实现各种形状的取向分布。但是他们仍然用机械旋转线性极化膜的方法来控制光的极化方向，因此仍然需要多次曝光才能完成复杂图案的光取向。
另有一种激光直写的光取向和几何相位全息图的制备方法。利用二维机械扫描和极性选择器，将全息图或者取向逐点曝光完成。全息图的分辨率越高，需要直写的次数越多。如分辨率为100x100，需要曝光10000次。
发明内容
为了克服现有技术中的不足，本发明提供一次曝光实现任意分布的光取向装置及一种光学元件的制备方法，通过设计线性极化膜、像素化电控相位延迟器件、相位延迟波片的相对光轴方向，和各个相位延迟器件的相位延迟值，可以生成任意形状的极化图，并在极化敏感介质上形成相应的排列轮廓。极化敏感介质又影响光学各向异性介质，生成任意形状的几何相位全息器件。
为了达到上述发明目的，解决其技术问题所采用的技术方案如下：
本发明公开了一种一次曝光实现任意分布的光取向装置，包括在空间上顺序摆放的光源、线性极化膜、像素化电控相位延迟器件和相位延迟波片，其中：
所述光源用于提供光取向曝光所需的光；
所述线性极化膜用于将所述光源发出的光变成极化方向与线性极化膜透光轴方向平行的线性极化光；
所述像素化电控相位延迟器件的每个像素的相位延迟由对应的电压分别 控制，用于产生任意图形分布的相位延迟；
所述相位延迟片用于产生非像素化的相位延迟。
进一步的，所述线性极化膜、像素化电控相位延迟器件和相位延迟波片部件之前、之后、任意两者之间均可加入一个或多个光学元件。
优选的，所述光学元件为透镜、透镜组、反射镜、衰减片、孔阑、相位延迟器件、偏振片、扩束器、滤光片、棱镜、光学窗口、光学基底、光束位移光学元件、衍射光学元件和/或偏振旋转器件。
进一步的，所述相位延迟波片的相位延迟在π/4+mπ到3/4π+mπ之间，其中，m是整数。
优选的，所述相位延迟波片的相位延迟是π/2的奇数倍。
进一步的，所述线性极化膜的透光轴方向与垂直入射到所述像素化电控相位延迟器件中的非寻常光的极化方向成30度到60度范围的夹角，或者成负60度到负30度范围的夹角，或者成120度到150度范围的夹角，或者成负150度到负120度范围的夹角。
优选的，所述线性极化膜的透光轴方向与垂直入射到所述像素化电控相位延迟器件中的非寻常光的极化方向成45度、或者负45度、或者135度、或者负135度。
进一步的，所述线性极化膜的透光轴方向与所述相位延迟波片的慢轴方向成30度到60度范围的夹角，或者成负60度到负30度范围的夹角，或者成120度到180度范围的夹角，或者成负180度到负120度范围的夹角。
优选的，所述线性极化膜的透光轴方向与所述相位延迟波片的慢轴方向成45度、或者负45度、或者135度、或者负135度。
进一步的，所述像素化电控相位延迟器件为液晶器件，所述液晶器件的初始配相为两面水平配相、或者为两面竖直配相，或者一面是水平配相另一面是竖直配相。
进一步的，所述像素化电控相位延迟器件包括透射式和反射式。
进一步的，所述光源为紫外光或可见光。
进一步的，所述光源为激光或者LED。
本发明另外公开了一种光学元件的制备方法，通过采用上述任意一项所 述的一次曝光实现任意分布的光取向装置进行制备，其中，所述光学元件包含极化敏感介质和光学各向异性介质，所述光学各向异性介质有局部光轴定向轮廓，可以呈任意形状分布，所述光学元件的具体制备过程包括以下步骤：
由光取向装置生成极化敏感介质中的光轴定向轮廓；
由极化敏感介质中的光轴定向轮廓决定光学各向异性介质的局部光轴定向轮廓。
进一步的，所述光学元件可用电压控制其电光特性。
进一步的，所述极化敏感介质、光学各向异性介质为两层分离的介质，或者为两种介质混合成一层，或者为既具有极化敏感特性又具有光学各向异性的同一种介质。
进一步的，所述极化敏感介质和光学各向异性介质均被光取向装置输出的光曝光；或，所述光学各向异性介质不被光取向装置输出的光曝光，而是曝光后加入到光学元件中。
进一步的，所述极化敏感介质为光取向材料或偶氮苯聚合物，所述光学各向异性介质为液晶、液晶聚合物或偶氮苯聚合物。
本发明由于采用以上技术方案，使之与现有技术相比，具有以下的优点和积极效果：
通过设计线性极化膜、像素化电控相位延迟器件、相位延迟波片的相对光轴方向，和各个相位延迟器件的相位延迟值，可以生成任意形状的极化图，并在极化敏感介质上形成相应的排列轮廓。极化敏感介质又影响光学各向异性介质，生成任意形状的几何相位全息器件。本发明只需要一次曝光就可以实现任意形状的极化图和几何相位全息器件，大大简化了器件制备工艺；本发明通过精确地用电压控制像素化电控相位延迟器件上电压分布，只需要一次曝光，就可以控制光极化和各向异性介质局部光轴在任意方向的连续变化。本发明的任意形状极化图可以通过计算机控制像素化电控相位延迟器件，进行实时更新，不需要每次重新做光掩膜板，大大降低了制作成本。
附图说明
为了更清楚地说明本发明实施例的技术方案，下面将对实施例描述中所 需要使用的附图作简单的介绍。显而易见，下面描述中的附图仅仅是本发明的一些实施例，对于本领域技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。附图中：
图1为本发明实例1的装置示意图；
图2为本发明一些实例的装置示意图；
图3为本发明一些实例的光取向过程；
图4为本发明实例2的光取向过程；
图5为本发明实例2中采用一6X 5个像素的像素化电控液晶可调相位延迟器件生成的任意液晶光轴分布的几何相位全息图；
图6为本发明实例2中制备的一印有学校缩写的几何相位全息图照片；
图7为本发明可制备的具有连续变化的极化方向的几何相位光栅光轴分布图；
图8为本发明可制备的只有两个极化方向的几何相位光栅的光轴分布图。
【主要符号标记】
1-线性极化膜；
2-像素化电控相位延迟器件；
3-相位延迟波片；
4-极化敏感介质；
5-分光棱镜；
6-反射式像素化电控相位延迟器件；
51-光取向层；
52-ITO玻璃；
53-液晶；
54-极化敏感介质。
具体实施方式
以下将结合本发明的附图，对本发明实施例中的技术方案进行清楚、完整的描述和讨论，显然，这里所描述的仅仅是本发明的一部分实例，并不是 全部的实例，基于本发明中的实施例，本领域普通技术人员在没有做出创造性劳动的前提下所获得的所有其他实施例，都属于本发明的保护范围。
实施例一
如图1所示，本发明公开了一种一次曝光实现任意分布的光取向装置，包括在空间上顺序摆放的光源、线性极化膜1、像素化电控相位延迟器件2和相位延迟波片3，其中：
所述光源用于提供光取向曝光所需的光；
所述线性极化膜1用于将所述光源发出的光变成极化方向与线性极化膜1透光轴方向平行的线性极化光；
所述像素化电控相位延迟器件2的每个像素的相位延迟由对应的电压分别控制，用于产生任意图形分布的相位延迟；
所述相位延迟片用于产生非像素化的相位延迟。
本实施例中，所述光源出射的光依次经过线性极化膜(偏振片)1、像素化电控相位延迟器件2、相位延迟波片3，然后入射到极化敏感介质4。这里，图中用箭头画出了线性极化膜1的透光轴的方向，用箭头画出了在像素化电控相位延迟器件2中的非寻常光的极化方向，用箭头画出了相位延迟波片3的慢轴方向。以光的传播方向为z轴，以1/4波片的慢轴方向为y轴，以它的快轴方向为x轴，建立坐标系。线性极化片透光轴的方向也在y轴，像素化电控相位延迟器件2中的非寻常光的极化方向在xy平面内，且与y轴成45度角。
采用上述光取向装置后，只需要一次曝光就可实现极化敏感介质4中创建局部光轴定向轮廓，像素化电控相位延迟器件2的每个像素的相位延迟由对应的电压分别控制，入射到极化敏感介质4的为线偏振或椭圆偏振，其偏振方向或者椭圆极化长轴方向可以由像素化电控相位延迟器件2实现像素级控制。
进一步的，所述线性极化膜1、像素化电控相位延迟器件2和相位延迟波片3部件之前、之后、任意两者之间均可加入一个或多个光学元件，其本质并不影响本装置实现任意形状的极化图。优选的，所述光学元件为透镜、透 镜组、反射镜、衰减片、孔阑、相位延迟器件、偏振片、扩束器、滤光片、棱镜、光学窗口、光学基底、光束位移光学元件、衍射光学元件和/或偏振旋转器件。特别地，当在像素化电控相位延迟器件2之后任意位置加入透镜组，可以将像素化电控相位延迟器件2出射的光斑进行放大和缩小。尤其缩小其光斑，也可以缩小像素化电控相位延迟器件2的像素的像，使得制备的几何相位全息图的空间分辨率得到提高。
进一步的，所述相位延迟波片3的相位延迟在π/4+mπ到3/4π+mπ之间，其中，m是整数。优选的，所述相位延迟波片3的相位延迟是π/2的奇数倍，即其为1/4λ波片。
进一步的，所述线性极化膜1的透光轴方向与垂直入射到所述像素化电控相位延迟器件2中的非寻常光的极化方向成30度到60度范围的夹角，或者成负60度到负30度范围的夹角，或者成120度到150度范围的夹角，或者成负150度到负120度范围的夹角。优选的，所述线性极化膜1的透光轴方向与垂直入射到所述像素化电控相位延迟器件2中的非寻常光的极化方向成45度、或者负45度、或者135度、或者负135度。
进一步的，所述线性极化膜1的透光轴方向与所述相位延迟波片3的慢轴方向成30度到60度范围的夹角，或者成负60度到负30度范围的夹角，或者成120度到180度范围的夹角，或者成负180度到负120度范围的夹角。优选的，所述线性极化膜1的透光轴方向与所述相位延迟波片3的慢轴方向成45度、或者负45度、或者135度、或者负135度。
进一步的，所述像素化电控相位延迟器件2为液晶器件，所述液晶器件的初始配相为两面水平配相、或者为两面竖直配相，或者一面是水平配相另一面是竖直配相。
进一步的，所述光源为紫外光或可见光，可实现极化敏感介质4的曝光。
进一步的，所述光源为激光或者LED。当所述光源选用激光时，其光源准直性好，能量高。当所述光源选用LED时，其光源为非准直光，具有体积小、价格低的特点。
进一步的，所述像素化电控相位延迟器件2包括透射式和反射式。本实施例中，所述像素化电控相位延迟器件2可连接计算机进行相位延迟分布设 计，并可进行实时刷新。
在一些实施例中，像素化电控相位延迟器件2为水平配相的透射式液晶器件，且液晶为Δε>0的正性液晶，则：
当电压为零时，相位延迟，即非常光和寻常光的相位差是最大值。其值约为δ＝2πΔn d/λ，其中，Δn是液晶的双折射率，d是液晶盒厚，λ是入射光的波长；
随着某个像素对应的电压的逐渐增大时，液晶指向矢越来越从水平排列逐渐转向竖直排列，使得该像素相位延迟δ随着电压逐渐减小；
当电压足够大时，液晶指向矢完全竖直排列，相位延迟δ为0。
对于入射光来说，经过了极化片、像素化电控相位延迟器件2的相位延迟为δ的一像素、1/4波片后，其偏振的琼斯矩阵表达为：
Figure PCTCN2019082347-appb-000001
根据计算结果可以发现，出射光为线性极化光，它的极化方向相对于线性极化片的透光轴方向(y轴)转过了-δ/2的角度，它的强度由入射光的y分量决定。
当像素化电控相位延迟器件2的最大相位延迟为2π，最小相位延迟为0的时候，就可以实现0-180度的任意角度的极化旋转。
因此根据上面计算结果，就可以使出射光形成像素化的任意极化分布。即出射光局部区域(一个像素对应的区域)是具有相同极化方向的线性极化光，不同局部区域(不同像素对应的区域)，可以实现不同方向极化的线性极化光。
实际中，由于误差的原因，出射光的每一点可能是一个椭圆极化光，但是其椭圆极化光的长轴方向类似地由像素化电控相位可调器件，实现任意图形化的分布。
现在的液晶显示技术、硅基液晶技术可以用薄膜晶体管阵列驱动几百万个像素电控液晶可调相位延迟器件，并且与计算机高度兼容，可以直接在计 算机上指定任意像素的灰度，使得像素化电控相位延迟器件2中生成相应的电压分配，并进一步生成任意相撞的相位延迟δ分布，最终生成任意极化方向分布的出射光。
极化敏感介质4，在足够光强曝光后，如甲基红分子在各个方向随机分布，但最终吸收长轴会与往极化方向(或者椭圆极化的长轴方向)垂直，以获得最稳定的状态，进而在极化敏感记录介质上分子排列轮廓也由前述的像素化电控相位延迟器件2决定。
在一些实施例中，像素化电控相位延迟器件2为垂直配相的透射式液晶器件，且液晶为Δε<0的负性液晶。同样不同电压可以产生不同的相位延迟δ。
在本发明的一些实施例中像素化电控相位延迟器件2可以是反射式的，如图2所示。光经过图2中所示的装置，光源发出的光依次经过线性极化膜1、分光棱镜5、反射式像素化电控相位延迟器件(硅基液晶调制器)6、分光棱镜5、1/4波片3后，在极化敏感记录介质4处生成任意图形化的排列轮廓。这里反射式像素化电控可调相位延迟器件相比于图1中的透射式像素化电控可调相位延迟器件，在相同材料、液晶盒厚条件下，产生2倍的极化旋转。
实施例二
本发明另外公开了一种光学元件的制备方法，通过采用上述任意一项所述的一次曝光实现任意分布的光取向装置进行制备，其中，所述光学元件包含极化敏感介质4和光学各向异性介质，所述光学各向异性介质有局部光轴定向轮廓，即局部光轴定向沿着其表面在至少一个方向上改变，可以呈任意形状分布，所述光学元件的具体制备过程包括以下步骤：
由光取向装置生成极化敏感介质4中的光轴定向轮廓；
由极化敏感介质4中的光轴定向轮廓决定光学各向异性介质的局部光轴定向轮廓。
进一步的，所述光学元件可用电压控制其电光特性。
进一步的，所述极化敏感介质4、光学各向异性介质为两层分离的介质，或者为两种介质混合成一层，或者为既具有极化敏感特性又具有光学各向异性的同一种介质。如极化敏感介质4为光配相层SD1，光学各向异性介质为液晶属于第一种情况；极化敏感介质4为甲基红，光学各向异性介质为液晶属 于第二种情况；有些偶氮苯聚合物，同时具有极化敏感和光学各向异性的特点，属于第三种情况。
进一步的，所述极化敏感介质4和光学各向异性介质均被光取向装置输出的光曝光；或，所述光学各向异性介质不被光取向装置输出的光曝光，而是曝光后加入到光学元件中。
进一步的，所述极化敏感介质4为光取向材料或偶氮苯聚合物，可以根据入射光的极化方向，相应地改变分子的排列方向。所述光学各向异性介质为液晶、液晶聚合物或偶氮苯聚合物。
具体实施例中，我们用实施例1的装置来制备具有光轴定向轮廓的光学元件。该光学元件制备过程为，将液晶53和极化敏感介质54的混合物，如E7和甲基红的混合物，混合均匀后灌入成品液晶盒接受实施例1中的装置的曝光。这里，甲基红作为极化敏感介质54，而E7液晶作为光学各向异性介质，成品液晶盒由两层氧化铟锡(Indium Tin Oxide，ITO)玻璃用间隔子控制盒厚，并用胶封住有效区域，留出前后两个小孔，用来注入液晶53。由于从实施例1中形成的光具有偏振分布轮廓，导致液晶盒中不同区域的甲基红，也有不同的排列方向，并进而带动液晶E7指向矢有不同的排列方向。这样就可以制成液晶光轴在玻璃基板平面内任意形状变化的器件。这个曝光过程如图4所示，其中，52是ITO玻璃，53是液晶，54是极化敏感介质。
特别地，当液晶盒的盒厚控制得当，当任意位置液晶的相位差均为固定值时，且液晶光轴方向在玻璃基板的二维平面中随着空间变化，就形成了一种几何相位全息图。
如图5所示为由一6X 5个像素的像素化电控液晶可调相位延迟器件生成的任意局部光轴分布的几何相位全息图。
图6所示为一印有学校缩写的几何相位全息图。它的生成方法如下我们用计算机生成“S”“J”“T”“U”和背景。每个字母或背景都有不同的灰度。当这个灰度图投影到像素化可调相位延迟器件，不同字母或背景就对应有了不同极化方向的线性极化光。我们用E7和甲基红混合后灌入的液晶盒在接受曝光后，形成了不同区域有不同液晶光轴排列的图案。图6液晶盒 是在互相垂直的偏振片下进行转动得到的。我们可以看到，转到不同区域，“S”“J”“T”“U”和背景的亮度会随着液晶盒旋转的角度发生变化，这是因为甲基红和液晶均按照我们给定的灰度图进行光轴方向排列的结果。因为所用光源是白光，而不是单色光，所以对比度不太高。
图7所示该方法可制备的具有连续变化的极化方向的几何相位光栅光轴分布图。如图8所示是只有两个极化方向的几何相位光栅的光轴分布图。我们用图2的装置，将E7和甲基红混合后的液晶盒曝光，得到如图8的光轴分布。为了证明液晶光轴确实有如此周期性排列，我们用不被甲基红吸收的红光(633nm)进行照射，观察到了明显的光栅衍射现象。
在一些实例中，所制备的几何相位全息图中的光学各向异性层是正性的液晶，可以施加垂直于基板的电压，让原本平行于基板的液晶光轴逐渐往平行于电场方向转动。这样就可以用电压调节几何相位全息图的局部相位差，从而调节其的电光特性。当电压加的很大时候，液晶光轴几乎垂直于基板，不产生任何相位延迟，因此几何相位全息图消失。但这种制作方法不局限于制备液晶器件。
在本发明的另一些制备方法实例中，记录物质极化敏感介质为光取向层51，而光学各向异性介质为液晶。光取向层51被旋涂在ITO玻璃52上。两块涂了光取向层51的ITO玻璃52，用间隔子控制间隔，再用UV胶封住，构成一个空液晶盒。光取向层51均在该空液晶盒内侧，用来排列液晶。将一个这样的空液晶盒子放在图1或者图2中极化敏感记录介质4处。就可以用计算机控制像素化电控相位延迟器件2每个像素的电压，进而控制光取向层51分子局部排列方向。曝光过程如图3所示，其中51为光取向层，52为ITO玻璃。再将液晶灌入盒中，液晶就会根据光取向层的局部排列方向，而进行相应的液晶指向矢排列轮廓。液晶指向矢基本上平行于玻璃基板排列，而在面内的排列方向，由其对应区域的光取向层51排列决定。这样，我们可以制成液晶光轴在玻璃基板平面内任意形状变化的器件。
在本发明的一些实例中，在像素化电控相位调制器件与极化敏感介质之间，有光学系统，以将光束大小进行调整，以得到所需的曝光精度和面积。
一些实例中，用极化敏感聚合物即作为极化敏感介质，又具有光学各向 异性特性，也可以类似地生成几何相位全息图。
以上所述，仅为本发明较佳的具体实施方式，但本发明的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本发明揭露的技术范围内，可轻易想到的变化或替换，都应涵盖在本发明的保护范围之内。因此，本发明的保护范围应该以权利要求的保护范围为准。

Claims (18)

  1. 一次曝光实现任意分布的光取向装置，其特征在于，包括在空间上顺序摆放的光源、线性极化膜、像素化电控相位延迟器件和相位延迟波片，其中：
    所述光源用于提供光取向曝光所需的光；
    所述线性极化膜用于将所述光源发出的光变成极化方向与线性极化膜透光轴方向平行的线性极化光；
    所述像素化电控相位延迟器件的每个像素的相位延迟由对应的电压分别控制，用于产生任意图形分布的相位延迟；
    所述相位延迟片用于产生非像素化的相位延迟。
  2. 根据权利要求1所述一次曝光实现任意分布的光取向装置，其特征在于，所述线性极化膜、像素化电控相位延迟器件和相位延迟波片部件之前、之后、任意两者之间均可加入一个或多个光学元件。
  3. 根据权利要求2所述一次曝光实现任意分布的光取向装置，其特征在于，所述光学元件为透镜、透镜组、反射镜、衰减片、孔阑、相位延迟器件、偏振片、扩束器、滤光片、棱镜、光学窗口、光学基底、光束位移光学元件、衍射光学元件和/或偏振旋转器件。
  4. 根据权利要求1所述一次曝光实现任意分布的光取向装置，其特征在于，所述相位延迟波片的相位延迟在π/4+mπ到3/4π+mπ之间，其中，m是整数。
  5. 根据权利要求4所述一次曝光实现任意分布的光取向装置，其特征在于，所述相位延迟波片的相位延迟是π/2的奇数倍。
  6. 根据权利要求1所述一次曝光实现任意分布的光取向装置，其特征在于，所述线性极化膜的透光轴方向与垂直入射到所述像素化电控相位延迟器件中的非寻常光的极化方向成30度到60度范围的夹角，或者成负60度到负30度范围的夹角，或者成120度到150度范围的夹角，或者成负150度到负120度范围的夹角。
  7. 根据权利要求6所述一次曝光实现任意分布的光取向装置，其特征在 于，所述线性极化膜的透光轴方向与垂直入射到所述像素化电控相位延迟器件中的非寻常光的极化方向成45度、或者负45度、或者135度、或者负135度。
  8. 根据权利要求1所述一次曝光实现任意分布的光取向装置，其特征在于，所述线性极化膜的透光轴方向与所述相位延迟波片的慢轴方向成30度到60度范围的夹角，或者成负60度到负30度范围的夹角，或者成120度到180度范围的夹角，或者成负180度到负120度范围的夹角。
  9. 根据权利要求8所述一次曝光实现任意分布的光取向装置，其特征在于，所述线性极化膜的透光轴方向与所述相位延迟波片的慢轴方向成45度、或者负45度、或者135度、或者负135度。
  10. 根据权利要求1所述一次曝光实现任意分布的光取向装置，其特征在于，所述像素化电控相位延迟器件为液晶器件，所述液晶器件的初始配相为两面水平配相、或者为两面竖直配相，或者一面是水平配相另一面是竖直配相。
  11. 根据权利要求1所述一次曝光实现任意分布的光取向装置，其特征在于，所述像素化电控相位延迟器件包括透射式和反射式。
  12. 根据权利要求1所述一次曝光实现任意分布的光取向装置，其特征在于，所述光源为紫外光或可见光。
  13. 根据权利要求1所述一次曝光实现任意分布的光取向装置，其特征在于，所述光源为激光或者LED。
  14. 一种光学元件的制备方法，其特征在于，通过采用权利要求1-13中任意一项所述的一次曝光实现任意分布的光取向装置进行制备，其中，所述光学元件包含极化敏感介质和光学各向异性介质，所述光学各向异性介质有局部光轴定向轮廓，可以呈任意形状分布，所述光学元件的具体制备过程包括以下步骤：
    由光取向装置生成极化敏感介质中的光轴定向轮廓；
    由极化敏感介质中的光轴定向轮廓决定光学各向异性介质的局部光轴定向轮廓。
  15. 根据权利要求14所述一种光学元件的制备方法，其特征在于，所述 光学元件可用电压控制其电光特性。
  16. 根据权利要求14所述一种光学元件的制备方法，其特征在于，所述极化敏感介质、光学各向异性介质为两层分离的介质，或者为两种介质混合成一层，或者为既具有极化敏感特性又具有光学各向异性的同一种介质。
  17. 根据权利要求14所述一种光学元件的制备方法，其特征在于，所述极化敏感介质和光学各向异性介质均被光取向装置输出的光曝光；或，所述光学各向异性介质不被光取向装置输出的光曝光，而是曝光后加入到光学元件中。
  18. 根据权利要求14所述一种光学元件的制备方法，其特征在于，所述极化敏感介质为光取向材料或偶氮苯聚合物，所述光学各向异性介质为液晶、液晶聚合物或偶氮苯聚合物。
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