Wideband Visible Wavelength Range MEMS Fabry–Perot Tunable Filter With Highly Accurate Calibration System

A novel microelectromechanical systems (MEMS) Fabry-Perot tunable filter (FPTF) and calibration system for accurately controlling the wavelength of the transmission peak in the wide wavelength range of visible light are reported. The MEMS FPTF consists of a Fabry-Perot filter having Ag alloy mirrors, an electrostatic actuator, and a capacitive gap sensor. The calibration system consists of the capacitive gap sensor, a capacitance measurement circuit, and a voltage controller. Through introducing the calibration system to MEMS FPTF, wavelength accuracy of more than ±1 nm is achieved. This is the accuracy level required for high-accuracy spectrum measurement in the range from 400 to 700 nm.