Realization of the Hadamard Multiplex Advantage Using a Programmable Optical Mask in a Dispersive Flat-Field Near-Infrared Spectrometer

Abstract

Spectrometry and hyperspectral imaging are finding numerous applications for micro-optoelectromechanical systems (MOEMS). A type of MOEMS device in the form of a digital micromirror array (DMA) has been made commercially available by Texas Instruments USA for projector display applications. We use this device as a spatial light modulator (SLM) in a new type of flat-field, near-infrared dispersive spectrometer (NIRDMAS). Attributes of the DMA used in this manner are presented for discussion. Features that make a DMA attractive for spectrometry and imaging are described. A brief introduction to Hadamard transform (HT) techniques is presented to show that the DMA may be the best Hadamard encoding mask yet developed. A comparison of a conventional raster scanning (CRS) scan and a Hadamard transform spectrometry (HTS) scan with respect to the Hadamard multiplex advantage using a nonphoton noise-limited, single-element detector is presented. A signal-to-noise ratio comparison using four spectral lines from a mercury-argon calibration lamp demonstrates that the theoretical noise reduction is approached for the HTS scan compared to the CRS scan. Some future applications of MOEMS in spectrometry and hyperspectral imaging are suggested.