MEMS Tunable Diffraction Grating for Spaceborne Imaging Spectroscopic Applications
School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore
Singapore-MIT Alliance for Research and Technology (SMART), 1 CREATE Way, Singapore 138602, Singapore
Author to whom correspondence should be addressed.
Sensors 2017, 17(10), 2372; https://doi.org/10.3390/s17102372
Received: 17 September 2017 / Revised: 13 October 2017 / Accepted: 14 October 2017 / Published: 17 October 2017
(This article belongs to the Special Issue MEMS Resonators)
Diffraction gratings are among the most commonly used optical elements in applications ranging from spectroscopy and metrology to lasers. Numerous methods have been adopted for the fabrication of gratings, including microelectromechanical system (MEMS) fabrication which is by now mature and presents opportunities for tunable gratings through inclusion of an actuation mechanism. We have designed, modeled, fabricated and tested a silicon based pitch tunable diffraction grating (PTG) with relatively large resolving power that could be deployed in a spaceborne imaging spectrometer, for example in a picosatellite. We have carried out a detailed analytical modeling of PTG, based on a mass spring system. The device has an effective fill factor of 52% and resolving power of 84. Tuning provided by electrostatic actuation results in a displacement of 2.7
at 40 . Further, we have carried out vibration testing of the fabricated structure to evaluate its feasibility for spaceborne instruments.