Multiplication noise in the human visual system at threshold

Abstract

Several kinds of light used in vision experiments produce photon statistics that are distinctly non-Poisson. Representative examples are light from a cathode-ray tube and an image-intensifier device. For the class of vision experiments in which the photon statistics play an important role, excess fluctuations produced by such light sources can alter the observed results and obscure the visual mechanisms being studied. They must therefore be accounted for in a proper way. We use the results of a Hecht-Shlaer-Pirenne type experiment, carried out with modulated Poisson light, to illustrate the point. Sensitivity and modulation depth, as well as sensitivity and reliability, are shown to be traded against each other. Finally, we demonstrate that number-state light, which is comprised of photons of an ideal kind, provides the ultimate tool for extracting information about the intrinsic noise distribution in the visual system at threshold. The state of the art in producing such light is discussed.

Measurement of Photon Statistics with Live Photoreceptor Cells

“…Note that the capability of the entire visual system of living human subjects to distinguish between the light sources of different statistics was shown in [4]. Our experiments suggest that responses of single rods are at the basis of this phenomena.…”

“…Influence of well controlled light statistics on the response of the entire visual system was studied only in behavioral experiments with human subjects [4,12]. However, noise properties of individual rods are difficult to access in this case, as several hundred of rods are simultaneously illuminated, and their collective response undergoes several intermediate stages of the visual processing.…”

“…Understanding such properties of nature-given photodetectors stimulates considerable interest in interfacing them with sources of non-classical light, such as light with a "fixed" number of photons, and "squeezed" light [3]. Implementation of such "bio-quantum" interfaces would contribute to a better understanding of the performance of the visual system near the threshold [4], allow a reference-free calibration of its quantum efficiency [5], along with a direct detection of entangled multi-photon states [6]. Study of the statistics of rod responses to excitations by classical light sources allows careful characterization of rods, and open possibilities for future studies of non-classical light.…”

Сжатые Состояния Света

“…Помимо естественного удобства его при менения в фундаментальных экспериментах оптической физики существует ряд обширных областей, где использование квадратурно сжатого света или сжатого по флуктуациям числа квантов света может иметь значительные пре имущества. Среди них можно отметить: спектроскопию [40], интерферомет рию [41], прецизионные измерения [17,42], оптическую связь [15,43,44] и визуализацию изображений [45]. Квантовые флуктуации могут ограничи вать чувствительность приборов во всех этих областях.…”

“…Часто предполагается, что пуассоновское распределение фотонов за дает неопределенности, свойственные человеческому зрительному отклику вблизи порога видимости [47], однако безусловно также присутствуют шумы сетчатой оболочки и центральной нервной системы (рис. 42) [45]. Исполь зование сжатого по флуктуациям числа квантов света как возбудителя могло бы прояснить роль очевидных источников шума.…”