| 摘要 |
PURPOSE:To improve measurement precision by controlling the wavelength of a semiconductor laser light source so that light diffracted with a signal of known frequency to be superposed upon an electric signal to be measured is made incident to a predetermined position on a photodetector array. CONSTITUTION:The electric signal to be measured which is received by an antenna 5 is mixed with the output of a local oscillator 7 by a mixer 6 and converted to an intermediate frequency. Then, a multiplexer 8 superposed the output signal of an oscillator 9 upon the signal, and the resulting signal is amplified by an amplifier 10 and then applied to a reed screen type converter 3. On the other hand, light 12 from a variable wavelength semiconductor laser 11 which is coupled with an end surface of substrate 1 is made into parallel light by a lens 13 and the light is diffracted with a surface acoustic wave signal 4. The diffracted light 14 is converged by a lens 15 and focused on the photodetector array 16 provided on the end surface of the substrate 1.
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