Development of a Built-In Micro-Laser Doppler Velocimeter

Our research group previously developed an integrated micro-laser Doppler velocimeter only 2.8 × 2.8 mm in area and 1-mm thick by minimizing a number of components with multifunctional parts, such as a glass cover with lenses for hermetic sealing and laser collimation, a silicon base for casing, a mirror mount, a laser diode bench, and others. In this paper, by applying a fast Fourier transform analysis to the sensor output, we successfully measured the velocities of plastic, paper, and aluminum objects over a wide velocity range, from 10 μm/s to 10 mm/s, within a 3.3% measurement error, without attaching any scale to the measurement target. We also verified feasible measurement distances for each object and examined how tilt installation error affected the measurements.