High-Fidelity Fourier Transform Infrared Spectroscopic Imaging of Primate Brain Tissue

Abstract

We demonstrate a new mid-infrared and near-infrared imaging approach which is ideally suited to microscopic applications. The method employs an indium antimonide (InSb) focal-plane array detector and a commercially available step-scan Fourier transform infrared spectrometer (FT-IR). With either a KBr or a CaF₂ beamsplitter, images from 1 to 5.5 μm (10,000-1818 cm⁻¹) can be rapidly acquired with the use of all the available pixels on the detector. The spectral resolution for each image is easily varied by changing the number of acquired images during the interferometer scan. We apply this technique to noninvasively generate image contrast in sections of monkey brain tissue and to relate these data to specific lipid and protein fractions. In addition, we describe several computational methods to highlight the spatial distributions of components within a sample.