Acousto-Optical Imaging Spectrometers for Visible and Near Infra-Red Ranges

Possibility of using GLM data for studying plasma phenomena

“…Since AOF, unlike an interference filter, has a limited spatial resolution, theoretical studies have been carried out [Voloshinov, Moskera, 2006;Mantsevich et al, 2020] in order to find conditions providing the highest angular resolution. As a result, tunable AOF were developed [Epikhin et al, 2013, Molchanov, et al, 2014. The AOF [Perchik, 2013] designed for spectral monitoring of the ocean surface is considered to be perfectly adequate for wide-angle detection of lightning from geostationary orbit.…”

Angular resolution in acousto-optic image filtering

“…The values of angular-range asymmetry а = ∆φ || (λ)/∆ (λ) measured in [10,13] and calculated from formulas (6) and (7) are listed in Table 1, as well as the parameters of AOFs used in these studies (it is all the known publications where the data required for comparison are reported). The asymmetry coefficient a is chosen for comparison for the following reasons: first, it does not depend on λ but only on the parameters of the AOF and the adjacent system of light-beam formation; second, the possible coefficient of increasing the angular ranges due to nonideality of elements of the optical scheme in Fig.…”

“…We find that . (13) When inequality (13) is satisfied, the spectral and angular resolutions are independent, which is an additional functional possibility of an AOF filter. For example, this filter can combine low spectral resolution (accordingly, high aperture ratio) and arbitrarily high angular resolution, limited only by the technological capabilities of forming an acoustic beam with large transverse sizes.…”

“…Image transfer through an acousto-optic (AO) cell was investigated experimentally and theoretically in a number of studies [4][5][6][7][8][9][10][11][12][13]. It was suggested in some publications that the main reason for deterioration of the angular resolution is acoustic-beam divergence (for example, when filtering collimated beams of white light [6,7] and strongly divergent laser (monochromatic) beams [9,12]).…”

“…The purpose of this study was to consider a mechanism of decrease in the angular resolution in a single noncollinear AOF (on the assumption that the main physical reasons for this effect are aperture limitations of light and sound beams) and possibilities of reducing this effect and forming an AOF with symmetric angular resolution. Figure 1 shows the optical scheme for forming spectral images with application of a single noncollinear AOF based on paratellurite crystal (ТеО 2 ) used in practice [6,13]. Let planar object O under consideration be in the focal plane of lens L1.…”