Application Cases

Experiment Name: Grating Characteristic Response Time Test

Test Equipment: Voltage amplifier, Signal generator, Attenuator, Oscilloscope, Detector, etc.

Experimental Process:

Figure 1: Optical path diagram for response time testing of flexible PDLC grating

To test the response time of a one-dimensional flexible Polymer Dispersed Liquid Crystal (PDLC) grating, an optical path for dynamic response measurement was set up as shown in Figure 1. A green laser with a wavelength of λ = 532 nm was used. The laser passed through an attenuator and an adjustable aperture, then through the one-dimensional flexible PDLC grating, and finally through another adjustable aperture to illuminate a detector connected to a signal generator. When the applied voltage exceeded the threshold voltage of the liquid crystal in the flexible PDLC grating, the detector detected changes in the transmitted light intensity and transmitted the signal to an oscilloscope. During the complete charging and discharging processes of the liquid crystal, the rise and fall times of the one-dimensional flexible PDLC grating response were obtained.

Experimental Results:

Figure 2: Response time test of the one-dimensional flexible PDLC grating

When a voltage waveform composed of a DC signal and a 1 kHz AC square wave signal was applied to the one-dimensional flexible PDLC grating, the dynamic response test results of the grating were obtained, as shown in Figure 2(a). Upon applying the voltage, the measured rise time of the grating was 10.002 ms. After removing the voltage, since the flexible substrate lacks an alignment layer, the effective refractive index of the liquid crystal molecules did not change monotonically during the recovery process. As a result, the measured response curve exhibited a trend where the transmittance dropped below the initial transmittance level before voltage application. The time to switch from the energized to the de-energized state was 176.243 ms. To avoid the influence of the alignment layer, two 1 kHz AC square wave signals with different voltage amplitudes were applied to the flexible PDLC grating, and the measured response time curve is shown in Figure 2(b). The rise time was 3.225 ms, and the fall time was 98.29 ms.

By setting up a dynamic response test optical path, the rise and fall times of the one-dimensional flexible PDLC grating at different curvature radii were measured. To eliminate the influence of the alignment layer, two square wave signals with different voltage amplitudes were applied to the one-dimensional flexible PDLC grating. The measured rise and fall times at different curvature radii were 3.225 ms and 98.29 ms, respectively.

Voltage Amplifier Recommendation: ATA-2048

Figure: ATA-2048 High-Voltage Amplifier Specifications

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