Spectral image filtration by means of acousto-optical tunable filters (AOTFs) has multiple applications. For its implementation, a few different optical schemes are in use. They differ in image quality, number of coupling components, dimensions and alignment complexity. To choose the optical system of AOTF-based spectral imager properly, many factors have to be considered. Though various schemes of acousto-optic (AO) filtration have been tested and discussed, their comparative analysis has not been reported up to now. In this study, we assembled the four most popular schemes (confocal, collimating, tandem and double-path) using the same AO cells and experimentally compared their main features. Depending on the application, each scheme may be the basis of compact cost-effective spectral imaging devices.

Optical biomedical imaging in short wave infrared (SWIR) range within 0.9–1.7 μm is a rapidly developing technique. For this reason, there is an increasing interest in cost-effective and robust hardware for hyperspectral imaging data acquisition in this range. Tunable-filter-based solutions are of particular interest as they provide image processing flexibility and effectiveness in terms of collected data volume. Acousto-optical tunable filters (AOTFs) provide a unique set of features necessary for high-quality SWIR hyperspectral imaging. In this paper, we discuss a polarizer-free configuration of an imaging AOTF that provides a compact and easy-to-integrate design of the whole imager. We have carried out image quality analysis of this system, assembled it and validated its efficiency through multiple experiments. The developed system can be helpful in many hyperspectral applications including biomedical analyses.

The problem of creating an acousto-optic (AO) tunable filter, which allows us to obtain high-quality spectral images both in the visible and near-infrared ranges, is studied. Based on the analysis of the wide-aperture noncollinear geometry of AO diffraction in paratellurite, the AO cell configuration is determined that is optimal in terms of minimizing chromatic shift and is suitable for both ranges. Two identical cells are manufactured and matched for the ranges 450–900 and 900–1700 nm. Experimental verification of the results of optical modeling showed that, over the entire range of 450 to 1700 nm, the calculated AO filter provides high-quality spectral images.

Stereoscopic imagers are widely used in machine vision for three-dimensional (3D) visualization as well as in non-destructive testing for quantitative characterization of cracks, delamination and other defects. Measurement capability in these systems is provided by a proper combination of the optical parameters and data processing techniques. Conventional approach to their design consists of two sequential stages: optical system design and optimization of calibration and image processing algorithms. Such two-stage procedure often complicates both the hardware and the software, and results in a time-ineffective design procedure and cost-ineffective solution. We demonstrate a more effective approach and propose to estimate errors of 3D measurements at the early optical design stage. We show that computer simulation using optical design software allows not only optimizing optical parameters of the imager but also choosing the most effective mathematical model of the system and the equipment necessary for calibration. We tested the proposed approach on the design of miniature prism-based stereoscopic system and analyzed the impact of various factors (aberrations, tolerances, etc.) as on the image quality, so on the quality of calibration and 3D measurements accuracy. The proposed joint design approach may be highly effective for various measurement systems and applications when both optical parameters and image processing algorithms are not defined in advance and are necessary to be optimized.

Sources with the possibility to select a narrow spectral band can be applied in many fields of science and technology. One method for selecting single or multiple spectral bands with the possibility to tune their width is acousto-optical filtering in conjunction with a source of broadband unpolarized radiation. In this case a narrow spectral interval is selected owing to the diffraction in an acousto-optical tunable filter. The main problem in the development of such a source is the obtainment of a sufficient luminous flux. Possible configurations of an optical illumination system allowing an increase in the efficiency and luminous flux in a system with acousto-optical filtering are presented in this study.

An acousto-optic (AO) tunable filter based on a paratellurite (TeO₂) crystal with two piezoelectric transducers that provides arbitrary spectral addressing in a wavelength interval of 450–1700 nm is developed. The geometric parameters of the crystal are calculated from the condition for minimization of the chromatic shift of image in the confocal optical system of the spectrometer within the entire working spectral interval. The resolution and transmittance are experimentally studied versus the aperture of the AO filter and the working wavelength. Examples of spectral images of test objects obtained with the aid of a prototype of a video spectrometer based on the AO filter are presented.