A piezoelectrically operated optical chopper by quartz micromachining

The fabrication and operation of a piezoelectrically operated monolithic optical chopper (6 mm×7 mm) are reported. The chopper is made by anisotropic etching of a Z-cut quartz wafer (100 μm thick) in an aqueous solution of NH₄HF₂. Newly developed piezoelectric operating scheme using meandering electrodes on a flexible quartz suspension (10~50 μm wide, 2 mm long) was found to produce large displacement (deforming ratio 3% by size) at a resonant frequency. Typical operational parameters are the amplitude of oscillation of 55 μm (peak to peak) at a driving voltage of 100 V and the chopping frequency in the 2-5 kHz range depending on the suspension width and length. The resonant frequency is accurately calculated when the cross-sectional profile of the suspension is taken into account. We also successfully demonstrated a chopping operation on a collimated laser beam with the chopper