Development of modal testing system for micro devices

In order to make good use of micro devices of small size and lightweight such as MEMS, DVD pickup actuator, etc., the dynamic behavior should be considered. However due to the difficulty of measuring FRI's with conventional exciter because of additional constraint and mass by its armature and load cell, the extended modal analysis such as structural modification, sensitivity analysis, may not be utilized. Therefore a very small electro-magnetic exciter, so called micro exciter of coin size, is developed and used to measure FRFs for micro devices. First compared with conventional exciter, the advantage of micro exciter is revealed to apply small size and lightweight structures. Next how the micro exciter is useful to measure FRFs and conduct structural modification is verified by applying to MEMS like structure numerically and experimentally. Finally a DVD pickup actuator is tested and a structural modification when the optical lens becomes heavier can be properly predicted.