Multi-object spectrometer with micromirror array

Abstract

681.785.554We have designed and built a multi-object spectrometer with micromirror array as a reconfigurable entrance aperture. In interactive mode, the instrument makes it possible to record both the hyperspectrum of the studied region as a whole and also sets of spectra of arbitrarily specified fragments. In this case, a spectral resolution of 0.8 nm or better is provided in the subranges 400-670 nm and 650-900 nm, aperture ratio of the spectroscopic channel at least 1:5. The analytical characteristics of the instrument make it possible to use it to solve a broad range of problems in modern multi-object spectroscopy and hyperspectroscopy.Introduction. In recent decades, in applied spectroscopy the objects of investigation increasingly often are extended regions of space: fragments of the Earth's surface, a stellar cloud, human tissue, etc. Methods allowing us to obtain the optical spectrum for a large number of small fragments of the studied region with a certain spatial and spectral resolution have acquired the name "multi-object" methods (if the full spatial and spectral image I(x, y, λ) is recorded, "hyperspectral" methods). Multi-object spectroscopy and hyperspectroscopy are used in medical diagnostics, for remote (aerospace-based) monitoring of the Earth's surface, in forensics, spectroscopy of single quantum objects, and in astronomy studies [1][2][3][4][5].Today, hyperspectral images (HSI) are most often obtained by scanning the entrance slit of a dispersive spectrometer over the analyte image (or scanning the image over the slit) or by recording the image through sequentially switched narrow-band spectral filters. The major disadvantages of the first approach are the connection between the spatial resolution and the spectral resolution (both are determined by the slit width), use of mechanical scanning systems, and the relatively long time period required for acquisition of hyperspectral images with sufficient spectral and spatial resolution [6][7][8][9][10][11][12]. In the second approach, when using a set of mechanically switched filters, the spectral resolution is usually low, and the use of tunable filters (optoacoustic, electro-optic, interference polarization) does not provide fast response and lets us work only with small aperture angles [13].Development is underway for alternative approaches potentially promising gains in aperture and HSI acquisition time as a result of a multiplex approach and based on the principles of Fourier transform spectroscopy [14,15]. However, at this time the instrumentation cannot compete with traditional types of hyperspectrometers.The use of modern spatial light modulators (SLMs), permitting real-time control of the configuration of the entrance aperture of the imaging spectrometer, is promising for development of new types of hyperspectrometers [16]. The indicated approach has advantages such as the possibility of fast readjustment for operation in different modes, simple realization of the mode with electronically controllable scanning of the entrance slit formed ...

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