Photodetector system with adjustable position-dependent sensitivity.

摘要

A photodetector system (10) for producing electrical signals responsive to the orientation of a light source, such as the sun, with respect thereto utilizes in certain embodiments a diffuser (11) to eliminate position-dependent sensitivities of the photocathode. The extent to which the diffuser (11) or the photocathode itself is exposed to the incident radiation can be controlled by a shroud (12) or by applying an absorptive coating (32) in a predetermined pattern on an absorber cap (40), or on the diffuser (11) directly. In a shrouded embodiment of the invention, the diffuser element (11) is arranged within a mountable body (13) with the shroud (12) extending thereover. The shroud (12), by its configuration and its height above the photodetector, defines the range of angles of elevation and azimuth at which the diffuser (11) can be illuminated. Such angles can also be controlled with printed or sprayed-on markings (30) on the diffuser or absorber cover (11) which form an opaque coating so as to prevent light transmission over predetermined regions. In addition to transmissive and nontransmissive regions, a fine dot pattern (32) may be applied to the diffuser or the absorber cover (11), which may be translucent or transparent, or to the diffuser (11) directly, so that only partial transmission of the light can be achieved therethrough. The absorber cover (11) may be provided with a light absorbing coloration or dye therethrough, and have a predetermined variation in thickness, so that the amount of light transmitted therethrough is responsive to the thickness at the point of incidence of the light. Thus, the light which is transmitted to the photodetector is modulated in response to the orientation of the light source with respect to the photodetector system.