An optical line of sight sensor for the pinhole facility

A scale model of the optical line-of-sight sensor that measures the pointing angle error to the sun for the Space-Shuttle-based pinhole facility has been designed and tested in the laboratory. This sensor consists of a pinhole camera with two pairs of perpendicularly mounted linear photodiode arrays to detect the intensity distribution of the solar image produced by the pinhole. The video signal of the arrays is digitized and transferred into a microcomputer. The deflection of the image center, which expresses the pointing error, is calculated from these data. The experimental results show that the sensor can estimate the pointing error of 0.0167 arc-s resolution and 0.0032 arc-s r.m.s. accuracy for the full-scale system when the pinhole is 32 m from the detector