Method for pre-configuring liquid crystal phase retarder under continuous laser operation

Abstract

A method for pre-configuring a liquid crystal phase retarder under continuous laser operation is disclosed. This method can be divided into two cases: For passive liquid crystal phase retarders, the temperature field of the passive liquid crystal phase retarder under continuous laser loading is simulated first, and the temperature-dependent birefringence change is calculated. Then, a suitable cell thickness is designed to pre-compensate the decrease in phase delay of the passive liquid crystal phase retarder under high-power laser loading. For active liquid crystal phase-tunable retarders, the phase delay versus voltage curve under different laser powers is recalibrated, and the corresponding voltage is selected based on the calibration curve to achieve the desired phase delay. This method allows for the pre-configuration of liquid crystal phase retarders applied under continuous laser operation, enabling the liquid crystal phase retarder to achieve the desired phase modulation even at higher laser powers. This invention is simple, efficient, and highly practical.

Description

Technical Field

[0001] This invention relates to a method for pre-compensating the phase modulation performance of liquid crystal phase delayers under continuous laser operating conditions, and particularly to a method for pre-configuring liquid crystal phase delayers under high-power continuous laser operating conditions. Background Technology

[0002] Liquid crystal phase retarders can be divided into passive liquid crystal phase retarders and active liquid crystal tunable phase retarders. Passive liquid crystal phase retarders do not require an applied voltage and can only achieve fixed phase adjustment of the beam. Active liquid crystal tunable phase retarders can achieve continuous and variable active phase control of the beam by adjusting the applied voltage. However, regardless of whether it is a passive or active liquid crystal phase retarder, laser light passing through the liquid crystal phase retarder will exhibit a significant thermal effect, causing the device to heat up. This is especially true under high-power continuous laser operation, as the refractive index of liquid crystal is sensitive to temperature, making the phase modulation characteristics of the liquid crystal tunable retarder susceptible to change under continuous laser operation. How to pre-configure the liquid crystal phase retarder to achieve the desired phase modulation under continuous laser operation is of great scientific and practical significance for the application of liquid crystal phase retarders in higher-power continuous lasers. Previous research mainly focused on reducing the temperature rise of liquid crystal devices under laser operation, thereby reducing its impact on the phase modulation characteristics of the liquid crystal device. This invention proposes a simple method for pre-compensating for changes in the phase modulation characteristics of liquid crystal phase retarders under continuous laser operation. Summary of the Invention

[0003] This invention proposes a method for pre-configuring a liquid crystal phase retarder under continuous laser operation, based on the influence of temperature on the phase modulation performance of the liquid crystal phase retarder. This method is simple and easy to implement, and can pre-compensate for the influence of different laser parameters on the phase modulation characteristics of the liquid crystal phase retarder when the temperature has not reached the clearing point, thereby enabling the liquid crystal phase retarder to achieve the desired phase modulation at higher laser power to a certain extent.

[0004] The technical solution of the present invention is as follows:

[0005] A method for pre-configuring a liquid crystal phase retarder under continuous laser operation, characterized in that the method comprises two cases:

[0006] The first scenario applies to passive liquid crystal phase delayers:

[0007] i. Simulate the temperature field of a liquid crystal phase retarder under continuous laser loading to obtain the continuous laser power P. i At that time, the temperature T of the liquid crystal layer in the passive liquid crystal phase retarder i ;

[0008] ii. Calculate the birefringence Δn(T) of the liquid crystal after temperature change. i The formula is as follows:

[0009]

[0010] In the formula, (Δn)0 is the birefringence of the liquid crystal in the crystalline state, and T c The clearing point of the liquid crystal material is β, where β is a material constant.

[0011] iii. Assuming no continuous laser is applied, and the cell thickness is d0 when the phase delay is δ, then when the continuous laser P is applied... i At that time, the box thickness d i satisfy At that time, the phase delay is still δ;

[0012] The second scenario applies to active liquid crystal phase-adjustable delay devices:

[0013] i. Measuring different continuous laser powers P i The curve of phase delay of the active liquid crystal phase-adjustable delay device versus voltage is then generated, and this curve is recalibrated. Specifically, the power is P. i A continuous laser beam was applied to an active liquid crystal phase-tunable retarder. After the retarder reached temperature stability, the applied external voltage was varied from 0V to slightly above the saturation voltage. The phase delay was measured at each voltage, and plots were generated for different powers P. i The curve of phase delay as a function of voltage.

[0014] ii. When the continuous laser power is P i At that time, by selecting the voltage according to the corresponding calibration curve to achieve the required phase delay, P can be made i The expected phase delay output of an active liquid crystal phase-adjustable delayer under laser power loading.

[0015] The technical effects of this invention are:

[0016] This invention simulates the effect of temperature field simulation and pre-compensates for the thermal effects caused by continuous laser irradiation on the phase modulation characteristics of a passive liquid crystal phase retarder by increasing cell thickness. It pre-configures an active liquid crystal phase-tunable retarder under continuous laser operation by recalibrating the phase retardation versus voltage curve. This method is simple and easy to implement. For a passive liquid crystal phase retarder, the decrease in phase retardation can be obtained through temperature field simulation and temperature-dependent birefringence calculations, based on the phase retardation calculation formula. Pre-compensation can be achieved by increasing the cell thickness. This allows passive liquid crystal phase retarders to achieve the desired phase modulation even at higher laser powers; for active liquid crystal phase-tunable phase retarders, different continuous laser powers P can be measured. i, such as P i The phase delay versus voltage curves were generated for operating power P = 500mW, 1000mW, 1500mW, and 2000mW. These phase delay versus voltage curves were then recalibrated, and the results were applied to lasers with the above power P. i When the desired phase delay is achieved, a corresponding phase delay curve can be selected so that the desired phase delay can still be generated under higher power lasers. Attached Figure Description

[0017] Figure 1 The phase delay of the active liquid crystal adjustable delay device under continuous laser loading after recalibration is shown as a function of voltage.

[0018] Figure 2 according to Figure 1 The calibration curve shows the effect of phase pre-configuration under different laser loading powers. Detailed Implementation

[0019] The present invention will be further described below with reference to examples and accompanying drawings, but this should not be construed as limiting the scope of protection of the invention.

[0020] Please see Figure 1 The graph shows the phase delay of the liquid crystal adjustable delay unit under continuous laser loading after recalibration, as a function of voltage.

[0021] A method for pre-configuring a liquid crystal phase retarder for continuous laser operation, comprising two cases:

[0022] The first case is for passive liquid crystal phase retarder applications.

[0023] i. Temperature field simulation of a liquid crystal phase retarder under continuous laser loading with a wavelength of 1064 nm was used to obtain the laser power P. i The temperature T of the liquid crystal layer in the liquid crystal phase retarder at power values ​​of 500mW, 1000mW, 1500mW, and 2000mW. i = 32.25℃, 38.51℃, 44.78℃, 51.04℃.

[0024] ii. The temperature obtained from simulation in i is calculated using the formula Calculate the birefringence Δn(T) of the liquid crystal after temperature change. i = 0.1827, 0.1706, 0.1553, 0.1337.

[0025] iii. Assuming no continuous laser is applied, and the phase delay for a 1064nm laser is δ = 360°, the designed cell thickness is d0 ≈ 5.52μm. For a continuous laser P... i Afterwards, the box thickness was designed as follows: That is, di ≈5.82, 6.24, 6.85, 7.96 μm, still capable of operating at laser power of P i A phase delay of δ = 360° is achieved.

[0026] The second type applies to the case of applying voltage to an active liquid crystal phase-adjustable delay circuit.

[0027] i. First, different continuous laser powers P i =500mW, 1000mW, 1500mW, and 2000mW were applied to an active liquid crystal phase-adjustable delay circuit. After the active liquid crystal phase-adjustable delay circuit reached temperature stability, the applied external voltage was changed from 0V to 24V, and the phase delay at each voltage was measured. The phase delay P at different power levels was plotted. i The curve of phase delay versus voltage, as shown in the figure. Figure 1 .

[0028] ii. When the continuous laser power is P i = 500mW, 1000mW, 1500mW, 2000mW, according to Figure 1 The corresponding curve adjustment voltage is selected based on the required phase delay, such as 90°, and the result is as follows. Figure 2 .

[0029] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for pre-configuring a liquid crystal phase retarder under continuous laser operation, characterized in that, This method has two cases: The first scenario applies to passive liquid crystal phase delayers: i. Simulate the temperature field of a liquid crystal phase retarder under continuous laser loading to obtain the continuous laser power P. i At that time, the temperature T of the liquid crystal layer in the passive liquid crystal phase retarder i ; ii. Calculate the birefringence of the liquid crystal after temperature change. The formula is as follows: In the formula, The birefringence of liquid crystal in crystalline state. For the cleaning point of liquid crystal material, These are material constants; iii. Assuming no continuous laser is applied, and the cell thickness is such that the phase delay is δ, then... Then load continuous laser P i At that time, the box thickness satisfy At that time, the phase delay is still δ; The second scenario applies to active liquid crystal phase-adjustable delay devices: i. Measuring different continuous laser powers P i The curve of phase delay of the active liquid crystal phase-adjustable delay device versus voltage is then generated, and this curve is recalibrated. Specifically, the power is P. i A continuous laser beam was applied to an active liquid crystal phase-tunable retarder. After the retarder reached temperature stability, the applied external voltage was varied from 0V to slightly above the saturation voltage. The phase delay was measured at each voltage, and plots were generated for different powers P. i The curve of phase delay versus voltage; ii. When the continuous laser power is P i At that time, by selecting the voltage according to the corresponding calibration curve to achieve the required phase delay, P can be made i The expected phase delay output of an active liquid crystal phase-adjustable delayer under laser power loading.

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