Diffraction grating scanner using a micromachined resonator

Abstract

We present a micromachined resonant diffraction grating laser scanner that utilizes in-plane angular vibration of a planar diffraction grating causing the diffracted laser beam to scan. The scanner consists of an electrostatic comb-drive microresonator and a diffraction grating plate having a grating period of 4 μm. The proposed micromachined diffraction grating laser scanner has the potential to scan at high frequencies without the optical performance degradation due to dynamic non-rigid-body deformation compared to out-of-plane micromirror scanners. A prototype grating scanner has been fabricated using the Poly-MUMPS process. It is capable of scanning optical angles of 1.31° (1 st-order), 2.13° (2 nd-order) and 3.42° (3 rd-order) at a resonant frequency of 7.67 kHz for a 635-nm-wavelength incident laser beam, when driven by the electrostatic combdrive push-pull mechanism with 20 V DC bias and 20 V p-p AC voltages. The scanning angle of the device can be significantly increased by reducing the grating period to sub-wavelength level.