Accuracy Enhancement in the In-Plane Dynamic Measurement of MEMS Actuators using a Laser Doppler Vibrometer with a 45°-Angled Optical Fiber

On-axis LDV (laser Doppler vibrometer), where the direction of incident beam is the same as that of the movement, intrinsically offers an accurate dynamic measurement, but it is not presently applicable to the MEMS actuator with in-plane motion due to no accessibility of the sidewall. The only available measurement method is off-axis LDV, which still shows a serious measurement error depending on the device pattern of the target surface. The on-axis FLDV (Fiber-optic LDV) with a 45deg-angled optical fiber is proposed to accurately measure the in-plane motion of MEMS actuator. The performance of the proposed FLDV is evaluated in terms of signal stability and the measurable range.