Abstract: Various characteristics in laser absorption spectroscopy using multiple reflections are improved. A gas measurement apparatus 1 according to the present disclosure measures a gas concentration by laser absorption spectroscopy. The gas measurement apparatus 1 includes a first corner cube 10, a second corner cube 20 disposed opposite the first corner cube 10, a laser source 30 that emits a laser beam to the first corner cube 10, and a light receiving element 40 that receives the laser beam that has been reflected multiple times through a target gas between the first and second corner cubes 10 and 20. The second corner cube 20 is disposed so that a centerline parallel to incident and exit light centering at incident and exit positions of the first corner cube 10 is displaced from a centerline parallel to incident and exit light centering at incident and exit positions of the second corner cube 20.

Abstract: A light modulating apparatus which is to be used in a transmission system using wavelength division multiplexing has: a signal generating section for producing a transmission signal and the like; a first light modulating section for modulating light emitted from a light source, on the basis of the transmission signal; a variable phase shifter which changes a phase of a light quantity control signal; a second light modulating section for modulating a light signal emitted from the first light modulating section, on the basis of an output of the variable phase shifter; a branching section for branching a light signal emitted from the second light modulating section, into an output light signal and an electric signal; and an analysis controlling section for sampling the electric signal, controlling the variable phase shifter on the basis of sampled data, and adjusting a timing of the modulation in the second light modulating section.

Abstract: A phase control circuit includes: a variable delay circuit for delaying a clock signal; a first flip-flop circuit having a clock input terminal to which the delayed clock signal is input and a data input terminal to which a data signal is input; a second flip-flop circuit having a clock input terminal to which the data signal is input and a data input terminal to which the delayed clock signal is input; and an integration circuit for controlling a delay amount of the variable delay circuit based on an output signal of the second flip-flop circuit.

Abstract: An optical sampling apparatus has an electron beam generating apparatus which generates an electron beam by irradiating a cathode with an optical signal, a deflection electrode which deflects the generated electron beam, a sampling slit which transmits a part of the deflected electron beam, and a charge detection section which detects the quantity of charges or accumulated current of the transmitted electron beam. It is possible to perform accurate sampling in a high band.

Abstract: An optical sampling apparatus has an electron beam generating apparatus which generates an electron beam by irradiating a cathode with an optical signal, a deflection electrode which deflects the generated electron beam, a sampling slit which transmits a part of the deflected electron beam, and a charge detection section which detects the quantity of charges or accumulated current of the transmitted electron beam. It is possible to perform accurate sampling in a high band.