Abstract

Scanning devices are used in many laser applications. With the recent progress in miniaturizing laser sources through the application of diode pumped microchip-lasers, the miniaturization of the scanning device could lead to a great reduction in cost and size of the overall system. We developed an integrated micro-opto-electro-mechanical system (MOEMS) using electrostatic force to control the displacement of optical microlens. A monolithic structure including the microlenses and the mechanical system was etched in a silica layer on silicon substrate. Silica offers high transmission for wavelength down to the ultraviolet region and appropriate mechanical properties. The electrostatic force is applied between the electrodes of variable capacitors formed by two comb like structures one of which is fixed on the support, the other is movable and displaces the microlenses. Both are made conductive by a thin film aluminium coating. The laser beam is deflected by the lateral displacement of two converging lenses with respect to a fixed diverging lens. These lenses are cylindrical with curvature in the substrate-plan and corrected for 3rd order aberrations to decrease the distortion of the wavefront. The scanner shows a mechanical resonance frequency of about 800 Hz depending on the exact geometric of the mechanical system and a maximal scan angle of 10°. According to the application the scanner can be used at small frequencies with exact relation between voltage and scan angle, or near the resonance frequency for continous scanning driven by a much smaller voltage. Our scanner was designed for use in a microchip-laser based scanning micro range finder.

© 1998 Optical Society of America