Sensitivity enhancement of bimaterial MOEMS thermal imaging sensor array using 2-lambda readout

Abstract

Diffraction gratings integrated with MEMS sensors offer sensitive displacement measurements. However, the sensitivity of the interferometric readout may drop significantly based on the sensor position. A two wavelength readout method was developed and tested previously in order to maintain the sensitivity of the readout > %50 maximum sensitivity over a broad range (i.e. several um's for visible wavelengths). This work demonstrates the sensitivity enhancement of a MEMS thermal imaging sensor array. Measurement of the target scene was performed using two lasers at different wavelengths (633, 650 nm). The diffracted 1(st) order light from the array was imaged onto a single CCD camera for both sources. The target scene was reconstructed by observing the change in the 1(st) diffracted order diffraction intensity for both wavelengths. Merging of the data, acquired with two different sources, is performed by assigning each pixel in the final image with the higher sensitivity pixel among two measurements. > 30% increase in the average sensitivity was demonstrated for the sensor array.