Application Cases

Experimental Name: Displacement Measurement Experiment with Dual Homodyne Interferometer Using Sine-Triangular Composite Phase Modulation

Experimental Purpose: To test the phase difference drift between the two interference signals caused by environmental parameter variations during prolonged measurement when the measuring mirror M2 remains stationary in the dual homodyne interferometer stability experiment.

Test Equipment: Voltage amplifier, He-Ne laser, measuring mirror, interferometer, signal generator, etc.

Figure 1: Experimental Setup of the Dual Homodyne Interferometer Displacement Measurement System

Experimental Process:
The experimental setup of the dual homodyne interferometer displacement measurement system is shown in Figure 1. After aligning the optical path, the measuring mirror M2 remains stationary. The EOM employs linear phase modulation with a modulation signal generated by the signal generator. The sawtooth wave frequency is set to 500 Hz, and the amplitude is initially set to approximately 7.5V, then finely adjusted to ensure the interference signal forms a complete cosine waveform. The phase difference between the interference signals detected by PD1 and PD2 is continuously measured and recorded over an extended period. To maintain experimental environment stability and minimize interference from other factors, the experiment was conducted during nighttime. The experimental results are shown in Figure 2.

Experimental Results:

Figure 2: Experimental Results of the Hourly Phase Difference Stability Test

Figure 2 shows that the phase difference variation is approximately 80 degrees over 6 hours, averaging about 0.2 degrees per minute. For displacement measurement experiments typically conducted at millimeter-per-second speeds, the entire measurement process can be completed within minutes. Therefore, under favorable environmental conditions, the phase difference drift during a single displacement measurement remains minimal.

Voltage Amplifier Recommendation: ATA-2048 High-Voltage Amplifier

Figure: ATA-2048 High-Voltage Amplifier Specifications and Parameters

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