G. Degraaf et al., A MEASUREMENT SYSTEM FOR THE VISUAL ANALYSIS OF INTEGRATED MICROMECHANICAL DEVICES, Sensors and actuators. A, Physical, 37-8, 1993, pp. 772-778
Research on micromechanical devices in silicon often requires visual i
nspection of the dynamic behaviour. Applications include the analysis
of harmonic and parasitic modes in resonant sensors and accelerometers
, the lateral eccentric travel in a micromotor and the lateral motion
of the comb drive. A highly flexible stroboscopic measurement system i
s required for this purpose. Such a research tool has, therefore, been
developed. It is especially suited for the visual inspection of a mic
romechanical structure under a microscope using light-emitting diodes
for generating the sampling light pulses. Digital frequency synthesis
has been used to allow easy, stable and independent control of the mot
ion frequency, the apparent motion frequency and the aperture time. Th
e maximum motion frequency can be set to 400 kHz. The frequency differ
ence between the motion frequency, f(m), and the sampling frequency, f
(s), results in the apparent motion frequency, f(a), which can be cont
rolled in between 0.03 and 3 Hz. The aperture time can also be program
med to allow the selection of the optimum illumination as a compromise
between image sharpness and luminous intensity. A zoom option is also
included to enable the investigation of a part of the periodic motion
and a freezing option is available to obtain a fixed image at any wan
ted position. The hardware of the stroboscope enables remote computer
control of all settings.