Frequency and time domain characteristics of the insect visual system in optic flow

Frequency and time domain properties of the monochromatic, dichromatic, and trichromatic visual system in an insect have been studied. The research method is based on the representation of the optical flow field of the insect visual system in the form of a dynamic link with an input and output. The Gaussian function was used to approximate the spectral curves. The study of the inertial properties of such a link in the time domain was performed by applying signals to its input in the form of a δ-function or a unit function. The steady-state forced oscillations at the output of the investigated dynamic link are determined when a harmonic effect is applied to the input. A technique for constructing spectral sensitivity curves for monochrome, dichromatic, and trichromatic vision of insects in the frequency domain is proposed; it has been established that the spectra exhibit the properties of ultra wideband signals. It has been found that the dynamic link of the insect visual system is capable of amplifying the optical signal over ultraviolet and blue parts of the spectrum in the time and frequency domain. It has been revealed that at a frequency equal to or higher than the frequency of dielectric relaxation, the optical flow field of the insect's visual system does not sense electromagnetic radiation. This phenomenon is most pronounced in ultraviolet and blue parts of the spectrum. It has been established that the optical signal wideband index μ varies from 0.41 to 1.21; thus, the visual system of an insect has ultra wideband properties. It has been shown that the number of periods of light oscillations in the visual system of insects, which has a spectrum in the form of a Gaussian curve, is related to the exponent μ by a simple relationship. New knowledge gained can be used for creation of matrix solid-state photodetectors in ultraviolet and blue parts of the spectrum.

monochrome vision, insects, spectrum, dynamic link, impulse response, transient response