Abstract: Picosecond switching of electric current in response to optical signals is obtained by conversion of the optical signal, such as an optical pulse, into a photoelectron burst (a photoelectronic signal) which is a faithful temporal replica of the optical signal. Electron optics increase the energy of the electrons of the photoelectronic signal which is imaged so as to illuminate essentially the entire gap formed between electrodes on a body of semiconductor material. The photoelectrons are absorbed in the semiconductor material to create throughout the gap a degenerate layer. The gap geometry and the image formed by the optical signal on a photocathode, which provides the photoelectronic signal, are such that space charge effects do not distort the photoelectronic signal and a temporal replica of the optical signal illuminates the entire gap. The gap geometry affords broad bandwidth operation.

Abstract: The invention relates to a fiber optical measuring device for measuring physical and/or chemical parameters. The device comprises a transducer unit and an evaluating unit, connected via at least one light conductor. One or more light sources in the evaluating unit, via said at least one light conductor, illuminate one or more optical filters located in the transducer unit which filter(s) is (are) sensitive to the parameter being measured. An optical detector arrangement in the evaluating unit analyzes the light emanating from the transducer unit. The detector arrangement consists of one or more photo-detectors, arranged to sense the light emitted from the transducer unit after this light has been affected by at least one filter belonging to the detector arrangement. The spectral properties of the detector filter(s) are controlled so that the detector arrangement is able to measure the correlation between the spectra of the transducer and detector filters.