Electrooptical automatic system for technological and ecological monitoring using a laser and fibre optics

Summary form only given. In the report a compact universal multipurpose automatic electrooptical system designed as a hazemeter and a spectrophotometric monitor of liquid objects is described. The system involves a laser source, fibre optics and a spectrometer with interference filters. A semiconductor laser diode with emission wavelength 630-680 nm, output power 1-1.5 mW and 4.5 V supply voltage is used. A coherent triple fibre-optical joint is applied which is evenly submerged into the liquid by means of a special reverse serve motor, type DARL-3628 for satellite systems, that is steered by a reed sensor with linear actuator. Additional experiments with another source-the colimatorpen GaAlAs diode laser with collimating optics type CQL71A (A670RN)-PHILIPS with emission wavelength 780-870 nm and varying output power in the range 2-100 mW-have been performed. When the infrared light source is used, the system exhibits some advantages in comparison to the case utilising a laser diode emitting in the visible optical range. The probe containing the three fibre-optical light guides is submerged in the investigated medium at a proper depth while the light source, the detector, and the measuring system are out of the liquid and they can be remotely operated or exchanged. The considered electrooptical system could be applied in investigations of liquid clarity (nephelometric measurements), absorption spectra and light scattered spectra. There are two modifications of the system: stationary and mobile with self-sufficient supply. The results of the laboratory tests, calibrations in respect to standard samples according international references and scales are presented, and also some preliminary results and a comparison to the service conditions in the brewing and food industries are given.