Application Cases

Experiment Name: Displacement Measurement Experiment Using Integrated PGC Demodulation Algorithm

Test Equipment: ATA-2082 High-Voltage Amplifier, Electro-Optic Phase Modulator, Reflector, He-Ne Laser, etc.

Experimental Process:

Figure 1: Schematic diagram and experimental setup of hybrid triangular phase modulation SPMI

The experimental setup structure is shown in Figure 1. The signal processing unit generates a hybrid phase modulation signal consisting of a 200 Hz triangular wave and a 200 kHz sine wave. This signal is amplified by a gain-adjustable high-voltage amplifier (HVA, ATA-2082 High-Voltage Amplifier) and applied to the EOM. After amplification, the amplitudes of the sine and triangular wave signals are ±152 V and ±220 V respectively, with the hybrid signal amplitude reaching ±372 V. Given that the half-wave voltage of the EOM is Vπ = 135 V and the angle between the polarization direction of the modulated beam and the z-axis is 45°, the modulation depths zc and zt are approximately 2.35 rad and 3.41 rad, respectively. The linearly polarized beam passing through the EOM is modulated, converting the interference signal into a PGC interference signal. The designed signal processing system collects the PGC interference signal and uses the integrated PGC demodulation algorithm to obtain the linearized demodulated phase.

Experimental Results:

Figure 2: Nanoscale displacement measurement results and FFT analysis

Figure 3: Comparative experimental results of dynamic displacement measurement

Feasibility of the proposed integrated PGC demodulation algorithm was demonstrated through linearized demodulation tests and simulated phase demodulation experiments within a 720° range. The algorithm effectively minimizes periodic nonlinear effects and accurately measures phase. In displacement experiments, nanoscale stepping tests verified that the integrated PGC demodulation algorithm can reduce periodic nonlinear effects caused by modulation depth drift and phase delay. After linearization with the integrated PGC algorithm, the periodic nonlinear error induced by modulation depth drift and carrier phase delay decreased from 1.95 nm to 0.16 nm. Millimeter-scale stepping experiments confirmed the practicality of this demodulation method for dynamic measurements at millimeter scales. In 200 mm distance measurement experiments, the displacement measurement curve of the interferometric setup using the integrated PGC algorithm showed consistent trends with measurements from the Renishaw reference interferometer, with a standard deviation of 0.080 μm between the two measurements. Simulation of the integrated PGC algorithm and displacement experiments demonstrated the feasibility and effectiveness of the designed signal processing system for simultaneous straightness and displacement measurement.

High-Voltage Amplifier Recommendation: ATA-2082

Figure: ATA-2082 High-Voltage Amplifier Specifications

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