High-speed light beam scanner based on ferroelectric nematic liquid crystal

Abstract

The utility model discloses a high-speed light beam scanner based on ferroelectric nematic phase liquid crystal, which comprises an FLC half-wave plate, a 1 / 4 wave plate and an LCPG liquid crystal polymer film, the FLC half-wave plate, the 1 / 4 wave plate and the LCPG liquid crystal polymer film are used as a single level to be repeatedly arranged, and transparent ultraviolet curing glue is adopted to sequentially paste all elements. The FLC half-wave plate of each level is powered up and adjusted, and the left-hand and right-hand circular polarization switching effect of each level is achieved, so that the selection requirement of the final emergent level is met, and the scanning function in a large-angle range is achieved. According to the utility model, the LCPG liquid crystal polymer films with different periods and the 1 / 4 wave plate are integrated into a module, so that a scanning function in a wide-angle range is realized; a ferroelectric nematic phase liquid crystal material is poured into the FLC half-wave plate, so that the response speed of the device is greatly improved to be within 1ms; compared with a traditional optical element, the device is high in overall integration level and has remarkable advantages in quality and size.

Description

Technical Field

[0001] The utility model relates to a high-speed beam scanner, in particular to a high-speed beam scanner based on ferroelectric nematic liquid crystal. Background Technique

[0002] The existing beam scanning technologies are mainly mechanical. The traditional beam deflection system relies on mechanical devices to change the optical axis direction to achieve beam deflection. Its structure is complex, the accuracy is low, the volume is large, the energy consumption is high, and it also needs to overcome the influence of inertia during the movement, and the performance will be greatly restricted. The new beam deflection technologies mainly include liquid crystal optical phased arrays, micro-mirror arrays based on micro-electro-mechanical systems, etc. Due to the spacing between pixel electrodes and the relatively large thickness of the liquid crystal layer, the beam deflection angle range is small, there is obvious insertion loss, and the price is also relatively expensive.

[0003] The micro-mirror array of the micro-electro-mechanical system refers to using the action of magnetic force or electrostatic force to make the micro-lens array translate or rotate, so as to achieve the effect of beam deflection. However, problems such as high driving voltage, complex preparation, and small deflection angle limit its application scenarios. Moreover, the above-mentioned solutions all have the problem of slow response speed, which greatly limits the application of the device in fields such as aerospace and vehicle-mounted radars. Therefore, achieving low-cost, large-angle, and high-efficiency beam deflection is still a difficult challenge. Content of the Utility Model

[0004] Purpose of the Utility Model: The purpose of the utility model is to provide a high-speed beam scanner based on ferroelectric nematic liquid crystal.

[0005] Technical Solution: The device of the utility model includes an FLC half-wave plate, a quarter-wave plate, and an LCPG liquid crystal polymer film. Taking FLC half-wave plate - quarter-wave plate - LCPG liquid crystal polymer film - quarter-wave plate as a single order and repeating the arrangement, each component is pasted in sequence by using a transparent ultraviolet curable adhesive. By applying an electric current to the FLC half-wave plate of each order for adjustment, the left-handed and right-handed circular polarization switching effect of each order is realized, so as to meet the selection requirements of the final output order and realize the scanning function within a large angle range.

[0006] Further, the initial slow axis direction of the FLC half-wave plate is on the angular bisector of the slow axis direction of the quarter-wave plate and the horizontal direction.

[0007] Further, the FLC half-wave plate is realized by using a liquid crystal cell with antiparallel orientation and injecting ferroelectric nematic liquid crystal material FD4004N into it.

[0008] Further, a pair of wires of the FLC half-wave plate are respectively connected to the ITO conductive surfaces of two glass substrates, and the magnitude of the electric field between the two glasses is controlled by outputting an alternating square wave signal with a specific frequency by a voltage controller.

[0009] Furthermore, the quarter-wave plate is a QWP liquid crystal polymer film with a homogeneous orientation, a slow axis direction of 45°, and the retardation corresponding to the thickness needs to satisfy 1 / 4 of the designed wavelength.

[0010] Furthermore, the LCPG liquid crystal polymer film has a periodically varying orientation along the horizontal direction, the period size is determined by the designed diffraction angle, and the thickness satisfies 1 / 2 of the designed wavelength.

[0011] Furthermore, a single order of the LCPG liquid crystal polymer film realizes a scanning switch between a pair of ±1 orders.

[0012] Beneficial effects: Compared with the prior art, the present utility model has the following advantages: The present utility model integrates LCPG liquid crystal polymer films with different periods and quarter-wave plates into a module to realize the scanning function within a large angle range; ferroelectric nematic liquid crystal material is filled in the FLC half-wave plate, greatly improving the response speed of the device to within 1 ms; compared with traditional optical elements, the overall integration of the device is high, and the quality and size have significant advantages. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic structural diagram of the present utility model. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0014] The technical solutions of the present utility model will be further described below with reference to the drawings.

[0015] As Figure 1 shown, taking a high-speed beam scanner with a second-order ferroelectric nematic liquid crystal as an example, its basic structure is "FLC half-wave plate - quarter-wave plate - LCPG liquid crystal polymer film - quarter-wave plate - FLC half-wave plate - quarter-wave plate - LCPG liquid crystal polymer film". For each additional stage of cascading, a structure of "quarter-wave plate - FLC half-wave plate - quarter-wave plate - LCPG liquid crystal polymer film" is added.

[0016] The FLC half-wave plate is realized by using a liquid crystal cell with an antiparallel orientation and filling it with ferroelectric nematic liquid crystal material FD4004N (DIC). Each stage of the FLC half-wave plate has a pair of wires respectively connected to the ITO conductive surfaces of two glass substrates, and a specific frequency alternating square wave signal can be output through a voltage controller to control the electric field magnitude between the two glasses. The QWP liquid crystal polymer film and the LCPG liquid crystal polymer film can both be peeled off and reserved after being prepared on a glass substrate. The QWP liquid crystal polymer film has a homogeneous orientation, a slow axis direction of 45°, and the retardation corresponding to the thickness needs to satisfy 1 / 4 of the designed wavelength. The LCPG liquid crystal polymer film has a periodically varying orientation along one direction, the period size is determined by the designed diffraction angle, and the thickness satisfies the half-wave condition of the designed wavelength.

[0017] When the period of the liquid crystal polymer polarization grating becomes smaller, the preparation difficulty of the liquid crystal polymer polarization grating increases sharply, resulting in a significant decrease in the diffraction efficiency. Therefore, large-angle scanning cannot be achieved by directly reducing the grating period. We achieve large-angle scanning by cascading multiple LCPG liquid crystal polymer films and phase retarders. After the LCPG liquid crystal polymer film, the quarter-wave plate, and the FLC half-wave plate are separately prepared, each component is pasted together in sequence using a transparent ultraviolet curing adhesive. It should be noted that the relative angles between the components are consistent with the design, that is, the period change direction of the LCPG liquid crystal polymer film is in the horizontal direction, the slow axis direction of the quarter-wave plate forms a 45° angle with the horizontal direction, and the initial slow axis direction of the FLC is on the angular bisector between the slow axis direction of the quarter-wave plate and the horizontal direction.

[0018] When the device is in use, the left- and right-handed circular polarization switching effect of each level can be achieved by applying or not applying electricity to the FLC half-wave plates at each level, so as to meet the selection requirements of the final output level. The large-angle scanning function can be achieved, and the response time can be controlled within 1 ms. Each layer of the LCPG liquid crystal polymer film structure can achieve a pair of ±1-level scanning switches. Therefore, an n-layer structure can achieve 2n point scanning switches, which can be defined as ±2n-1 levels. For example, if the incident light beam needs to be deflected to the +2n-1 level, the incident polarization state of each FLC half-wave plate is adjusted to left-handed circular polarization. If the incident light beam needs to be deflected to the -2n-1 level, the incident polarization state of each FLC half-wave plate is adjusted to right-handed circular polarization. By adjusting the electricity applied to each layer of the FLC half-wave plate, the function of sequential scanning of all levels is achieved. Taking a 2-layer device as an example, there are a total of 4 levels of ±2, and the total switching speed of a single scan can be less than 1 ms.

Claims

1. A high-speed beam scanner based on ferroelectric nematic liquid crystals, characterized in that: It includes an FLC half-wave plate, a quarter-wave plate, and an LCPG liquid crystal polymer film. The arrangement of FLC half-wave plate - quarter-wave plate - LCPG liquid crystal polymer film - quarter-wave plate is repeated for each single stage. Transparent ultraviolet curable glue is used to paste each component in sequence. By applying an electric current to the FLC half-wave plate of each stage for adjustment, the switching effect of left-handed and right-handed circular polarization of each stage is achieved, so as to meet the selection requirements of the final output stage and realize the scanning function within a large angle range.

2. The high-speed light beam scanner based on ferroelectric nematic liquid crystal according to claim 1, characterized in that: The initial slow axis direction of the FLC half-wave plate is on the angular bisector of the slow axis direction of the quarter-wave plate and the horizontal direction.

3. The high-speed light beam scanner based on ferroelectric nematic liquid crystal according to claim 1, characterized in that: The FLC half-wave plate is realized by using a liquid crystal cell with antiparallel orientation and injecting a ferroelectric nematic liquid crystal material FD4004N into it.

4. The high-speed light beam scanner based on ferroelectric nematic liquid crystal according to claim 1, wherein: The FLC half-wave plate has a pair of wires respectively connected to the ITO conductive surfaces of two glass substrates, and the magnitude of the electric field between the two glasses is controlled by outputting an alternating square wave signal with a specific frequency through a voltage controller.

5. The high-speed light beam scanner based on ferroelectric nematic liquid crystal according to claim 1, characterized in that: The quarter-wave plate is a QWP liquid crystal polymer film with a homogeneous orientation, the slow axis direction is 45°, and the retardation corresponding to the thickness needs to meet 1 / 4 of the designed wavelength.

6. The high-speed light beam scanner based on ferroelectric nematic liquid crystal according to claim 1, wherein: The LCPG liquid crystal polymer film has a periodic gradient along the horizontal direction, the period size is determined by the designed diffraction angle, and the thickness meets 1 / 2 of the designed wavelength.

7. The high-speed light beam scanner based on ferroelectric nematic liquid crystal according to claim 1, characterized in that: Each single stage of the LCPG liquid crystal polymer film realizes a pair of scanning switches of ±1 order.

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