Application Cases

Experiment Name: Strain and Surface Displacement Testing of Deformable Mirror Actuators

Testing Equipment: Deformable mirror, high-voltage amplifier, wavefront interferometer, Keyence laser displacement sensor, and real-time simulation system.

Figure 1: Monoelectrode deformable mirror with bonded strain rosette

Experiment Process:

A testing system for the shape and surface displacement of a lateral piezoelectric deformable mirror was set up. In the open-loop condition, the dSPACE system outputs a reference signal $ur(t)$, which is amplified by the high-voltage amplifier and used as the input signal for the deformable mirror to drive its motion. In the closed-loop condition, the strain signal S(t), amplified by the strain amplifier, is compared with ur(t). A PID controller in MATLAB/Simulink performs the corresponding control [133], and the output signal is uc(t). The wavefront interferometer can test the deformation of the deformable mirror's surface. Using MATLAB, the strain data S(t) is input into the predictive model for calculation and compared with the measured surface shape to obtain the model's prediction accuracy. Meanwhile, the maximum surface deformation signal x(t) is collected by the dSPACE system through the displacement sensor and can be used for nonlinear error correction experiments.

Figure 2: Testing system for monoelectrode deformable mirror with integrated strain feedback layer

Experimental Results:

Figure 3: Strain and surface displacement testing of deformable mirror actuators

The figure above shows the strain test results under zero input conditions. Within a short period, the strain of each petal of the strain rosette is within ±1με. This fluctuation is mainly caused by noise interference in the amplifier and falls within the range of systematic error. The figure (b) shows the strain feedback from the strain rosette when the electrode is energized with 100V, with a test duration of 5 minutes. The change states of the three petals of the strain rosette are consistent before and after the step signal is applied, with average strain values of 34.20με, 35.78με, and 34.65με, respectively. The maximum error between them is only 0.58με. This indicates that the strain feedback from each petal of the strain rosette is relatively uniform and that the bonding position of the strain rosette is well symmetrical. The creep process has a small rise, and the fluctuation range after stabilization is within 3με, demonstrating the long-term stability of the strain rosette. The figure (c) shows the displacement signal of the mirror center position measured by the displacement sensor, with a PV value of approximately 2.50μm, consistent with the strain variation process.

Voltage Amplifier Recommendation: ATA-7010

Figure: Specification Parameters of the ATA-7010 High-Voltage Amplifier

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