On inherent spatio-spectral image distortion in AOTF-based imagers

Grigoriy N. Martynov; Alexey V. Gorevoy; Alexander S. Machikhin; Vitold E. Pozhar

doi:10.1117/12.2592557

20 June 2021 On inherent spatio-spectral image distortion in AOTF-based imagers

Grigoriy N. Martynov, Alexey V. Gorevoy, Alexander S. Machikhin, Vitold E. Pozhar

Proceedings Volume 11782, Optical Measurement Systems for Industrial Inspection XII; 1178219 (2021) https://doi.org/10.1117/12.2592557
Event: SPIE Optical Metrology, 2021, Online Only

Abstract

Acousto-optical tunable filters (AOTFs) based on interaction of light and ultrasound in uniaxial birefringent crystals are widely used in imaging spectroscopy applications due to random spectral access, narrow controllable bandwidth, compactness, overal ease-of-use and image trasmittance capability. The spectral transmission of AOTF-based spectral imagers is usually characterized for paraxial light beam, but AOTFs inherently have non- uniform spatio-spectral transmission, so the central wavelength of the transmission window varies with the angle of incident light. We demonstrate that the spatio-spectral characteristics of acousto-optic (AO) interaction may be described either by the dependency of ultrasound frequency on the incident light angle for a given wavelength or by the dependency of wavelength on the incident angle for a given sound frequency. These dependencies are derived from the phase matching condition and are determined by the refractive indices, sound phase velocities and the AO diffraction geometry. We experimentally estimate the appearance of this specific spatio-spectral structure on the images acquired by AOTF-based imagers based on both collimating and confocal (telecentric) schemes and show that the variations of central wavelength and spectral bandwidth are noticeable for collimating setup even in the commonly used small field of view. The results of the study may be applied in design of AOTF- based spectral imagers and image processing algorithms.

Conference Presentation

Citation Download Citation

Grigoriy N. Martynov, Alexey V. Gorevoy, Alexander S. Machikhin, and Vitold E. Pozhar "On inherent spatio-spectral image distortion in AOTF-based imagers", Proc. SPIE 11782, Optical Measurement Systems for Industrial Inspection XII, 1178219 (20 June 2021); https://doi.org/10.1117/12.2592557

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