Abstract: A high-accuracy multi-wavelength optical microscope for providing a satisfactory contrast of image and much information about a sample. The microscope includes a plurality of light sources, a wavelength varietor independently varying the wavelength of the individual light sources, and polarization plane rotators on the optical path for each light source.

Abstract: A control system for a transistor inverter comprising a circuit for detecting the load current or the output voltage from the inverter to produce a detection output; a circuit for outputting a control instruction for adjusting the load current; a leading angle forming circuit for combining the detection output with the control instruction to form a control signal corresponding to a leading angle at which the inverter output voltage is controlled with a leading phase relative to the load current; and a circuit receiving the control signal from the leading angle forming circuit and for forming a switching control signal, which is supplied to the switching devices in the inverter. The load current is not controlled directly by controlling the frequency of the inverter, but by changing the phase difference .gamma. between the load current and the inverter output voltage.

Abstract: This invention relates to an apparatus for measuring the radioactive concentration of a radioactive material-containing liquid. In order to improve the measuring sensitivity of and miniaturize the apparatus, it includes a vertically-disposed outer cylinder, an inner cylinder disposed in and concentrically with the outer cylinder, a radiation detector disposed in the inner cylinder, a radioactive liquid feed means for supplying a radioactive material-containing liquid in the form of an annular current into an annular space between the inner and outer cylinders, a first cleaning water feed means for supplying a cleaning liquid along the inner surface of the outer cylinder, and a second cleaning water feed means for supplying a cleaning liquid along the outer surface of the inner cylinder. The cleaning water prevents the radioactive material from being deposited on the inner surface of the outer cylinder and the outer surface of the inner cylinder, and the measuring sensitivity of the apparatus from decreasing.

Abstract: A photoacoustic analyzer comprises an analyzing cell having a beam entrance window and including a cylindrical piezoelectric transducer element forming at least a part of the wall thereof, and a laser beam emitter emitting a laser beam directed toward and into the analyzing cell through the beam entrance window. In the photoacoustic analyzer, the ratio r/r.sub.o between the radius r of the inner side of the analyzing cell and the radius r.sub.o of the incident laser beam is selected to lie within the range of 1.ltoreq.r/r.sub.o .ltoreq.8.

Abstract: An apparatus for measuring the concentration of radioactivity in a radioactive fluid discharged from a nuclear power plant. The apparatus comprises a radioactivity concentration measurement pipe arranged to extend vertically, fluid supplying means for supplying the fluid into the measurement pipe in such a manner that the fluid flows down through the measurement pipe along the axis of the measurement pipe without contacting the inner surface of the latter, radioactivity concentration measuring means disposed at the outside of the measurement pipe for measuring the radioactivity concentration in the fluid flowing in the measurement pipe, and means for discharging the radioactive fluid to the outside of the measurement pipe. The apparatus further comprises a gas supply pipe opening at its one end to the atmosphere and communicated at its other end with the inside of the measurement pipe, and a check valve disposed in the gas supply pipe and operated at a pressure higher than the atmospheric pressure.