Hadamard transform Raman imagery with a digital micro-mirror array

Our previous efforts in Hadamard transform Raman imaging in the visible spectral region began with stationary two-dimensional (2D) Hadamard encoding mash and evolved to moving 2D Hadamard encoding masks. We have now advanced to using a spatial light modulator developed by Texas Instruments, herein called a digital micro-mirror array (DMA), as a computer controlled 2D Hadamard encoding mask. The aluminized mirrors in the DMA are 16 um square and rotatable by +/- 10 degrees front an intermediate position. The + 10 degrees position of a micro-mirror directs its spatial resolution element onto the detector and die - 10 degrees position of a micro-mirror directs its spatial resolution element away from the detector. The heterogeneous samples investigated were three layers of immiscible liquids (benzene-water-nitrobenzene) and a layer of solid benzoic acid stuck to a piece of double sided tape with a 1.0 mm(2) chip of naphthalene pressed onto the layer of benzoic acid near one corner of the benzoic acid layer. Macroscopic images of the various components in these samples have been generated with a spatial resolution of 340 um. Spectra of individual pixels at the sample plane have been obtained for the sample of immiscible Liquids. Images of Liquid and solid heterogeneous samples and spectra of individual pixels at the sample plane can be obtained by Hadamard transform Raman imaging using a DMA as a 2D Hadamard encoding mask that operates rapidly and reliably. (C) 1999 Elsevier Science B.V. All rights reserved.