Indium Antimonide (InSb) Focal Plane Array (FPA) Detection for Near-Infrared Imaging Microscopy

Abstract

Near-infrared spectroscopy is a sensitive, noninvasive method for chemical analyses, and its integration with imaging technologies represents a potent tool for the study of a wide range of materials. In this communication the use of an indium antimonide (InSb) multichannel imaging detector for near-infrared absorption spectroscopic microscopy is described. In particular, a 128 × 128 pixel InSb staring array camera has been combined with a refractive optical microscope and an acousto-optic tunable filter (AOTF) to display chemically discriminative, spatially resolved, vibrational spectroscopic images of biological and polymeric systems. AOTFs are computer-controlled bandpass filters that provide high speed, random wavelength access, wide spectral coverage, and high spectral resolution. Although AOTFs inherently have a wide range of spectroscopic applications, we apply this technology to NIR absorption microscopy between 1 and 2.5 μm. The spectral interval is well matched to the optical characteristics of both the NIR refractive microscope and the AOTF, thereby providing near-diffraction-limited performance with a practical spatial resolution of 1 to 2 μm. Design principles of this novel instrumentation and representative applications of the technique are presented for various model systems.