Abstract: The intensity of the optical radiation varies within a wide range. The proportion of parasitic radiation registered by the photodiodes (D1 to Dn) increases with increasing radiation intensity. To exclude this parasitic radiation from evaluation, the photodiodes (D1 to Dn) are followed by analog comparators (K1 to Kn) with a variable reference voltage (Uref1). The reference voltage (Uref1) is varied by an analog comparator (Kz1) in porportion to the radiation intensity determined by a central photodiode (Dz).

Abstract: In a sensor head (1), hemispherical in form, a plurality of optical fibers (4) is uniformly distributed over the convexly arched surface area (3), and mounted therein. The other ends of the optical fibers (4) are gathered into a bundle (6) whose end face opposes a detector matrix (8) comprising a plurality of detectors. By a subsequently arranged evaluating circuit, and by assigning the detectors to the individual optical fibers (4), there is determined the direction and, by summing up the individual charges of the detectors, there is also recognized the intensity of the incident radiation.Some additional bundles (15) of optical fibers (16) are disposed by being distributed among the optical fibers (4). From each such bundle (15), an equal number of optical fibers (16) is led to each of several detectors (17). These detectors (17) are provided with individual filters (18, 19, 20) or a common filter (23) having certain wavelength responsive regions.