Fabrication of an imaging diffraction grating for use in a MEMS-based optical microspectrograph

Abstract

The design, fabrication and performance of a highly miniaturized optical spectrometer are described. The volume of the opto-electronic system is only 50 mm 3 . The main components are a planar imaging diffraction grating and a commercially available CCD camera. System integration is based on MEMS technologies on a glass wafer. The imaging grating circumvents the need for collimating optics, while the planar grating design is essential for limiting fabrication complexity and enabling assembly of the optical and electronic parts. The system consists of two glass plates placed in parallel with well-defined spacing and comprises all spectrometer components including slit and diffraction grating. The glass plates were fabricated using a single glass wafer with standard lithography applied. The spectrometer demonstrated a 6 nm FWHM spectral resolution in an operating range from 600 nm to 700 nm.