An improved Hadamard encoding mask for multiplexed Raman imaging using single channel detection

Improvement in the signal-to-noise ratio (SNR) of measurements is a common goal for investigators interested in instrument development. Hadamard transform measurement techniques can be employed to improve the SNR in spectrometry and imaging instrumentation using non-photon-noise limited, single channel detectors. Many improvements in the practical implementation and performance of Hadamard transform spectrometry (HTS) and Hadamard transform imaging (HTI) instrumentation have been a direct result of technological advances in mask construction. A recent technological advance, the digital micro-mirror array (DMA), promises to advance HTS and HTI instrumentation development. This paper presents the results of HTI experiments employing the DMA as a Hadamard encoding mask for Raman hyper-spectral imaging in the visible spectral region. Two heterogeneous solid samples were used to investigate the utility of the DMA as an improved two-dimensional (2D) Hadamard encoding mask; naphthalene on double sided tape and solid 1,2-dinitro-benzol with naphthalene on a field of 3,4-dichlorobenzldehyde. The utility of the DMA as an effective 2D Hadamard encoding mask is demonstrated as a prelude to future imaging experiments using single channel detectors in the near-infrared and mid-infrared spectral regions, (C) 2000 Elsevier Science B.V. All rights reserved.