Silicon photovoltaic cell as low-level-light detector

Abstract

It is the objective of this paper to discuss the photometric capabilities of silicon photovoltaic cells operated in “short circuit mode” at low-level-light. In order to predict the performance of photometric circuits of silicon cells are evaluated by applying the damped least-square method to the voltage-to-current diode characteristic of silicon cells. The linear response of silicon cells combined with a DC amplifier circuit is considered, using the cell parameters. This indicates that a low noise DC amplifier in the nanovolt region is suitable for the measurement of low-level-light. As an example of a low noise DC amplifier, a galvanometer amplifier is manufactured for trial. It is shown that the silicon cell combined with the galvanometer amplifier circuit has sufficient sensitivity in comparison with the type of multi-alkali photocell (detectable minimum flux 4.2×10^-6lm) to detect the luminous flux as small as 1.6×10^-9lm. As an application of this silicon cell combined with a galvanometer circuit, a standard observer is manufactured by using a group of cells plus filters. It is suggested that the spectral sensitivity of the observer approximately matches the CIE spectral luminous efficiency function V(λ).