| 摘要 |
PURPOSE:To take a measurement with high sensitivity by an optical heterodyne detection system without separating light to be measured and reference light spatially by performing signal processing and arithmetic operation according to an AC component obtained by amplifying an electric signal generated by converting the composite signal light of the light to be measured and reference light. CONSTITUTION:The composite signal light 13 is composed of the light 10 to be measured from an input terminal 17 and the reference light 12 generated by a frequency-stabilized power source 28 by nearly matching their polarized wave with each other by a polarized-wave holding optical fiber coupler 16. This is inputted to a photodetector 14 to obtain a beat signal. Further, this signal has its DC component removed and its AC component amplified by an AC amplifier 22 and is inputted to an arithmetic circuit 26 through a band-pass filter 23 and a digital voltmeter 24. Here, the effective value of the AC component is found and the ratio of its squared value and a value corresponding to the light power of the reference light is calculated to obtain an output showing the light power of the light to be measured. |
