Choice of photodetector characteristics for acousto-optic devices for bioelectric signals processing

Abstract

It has been established recently that acousto-optic devices based on Bragg cells can be used for the bioelectric signals spectral processing. This processing can be realized only if acousto-optic spectrum analyzers with time or time-andspace integration are used. The frequency range of the processing system is defined by the complex of the acousto-optic Bragg cell and multielement photodetector characteristics. Two possible principles of the photodetector characteristics have been considered – direct and reverse principles. It has been shown that two parameters of photodetector play especially important part for the signal processing by means of acousto-optic device: charge accumulation time which defines the lower boundary of analyzed frequency range, and number of pixels per one resolvable interval which defines the upper boundary. The performed analysis has shown that the requirements for the second parameter are strongly defined by the investigated signal dynamic range, any distortion of which can produce the loss of important diagnostic information. It also has been shown that the correct choice of photodetector characteristics provides the acousto-optic processing system applicability for bot electrocardiographic and electroencephalographic signals obtained in the ultra high resolution mode.