| 摘要 |
PROBLEM TO BE SOLVED: To obtain an optical spectrum monitor which reduces a change in the error of the power of light to be measured and which enhances a separation degree from an adjacent wavelength by a method wherein the deviation between the center of the beam of monochromatic light and the center of a photoldiode(PD) array is found and an output addition value is computed and corrected. SOLUTION: Light to be measured (monochromatic light) which is incident via an optical fiber 1 is changed into parallel light by a lens 2, it is incident on a diffraction grating 3, it is radiated at a diffraction angle which is decided by a wavelength, and it is detected by a PD array 6 via a mirror 4 and a lens 5. The output of the PD array 6 is converted by a signal processing circuit 7, and the wavelength and the power of the incident light are computed by an arithmetic circuit 8. At this time, the computing circuit 8 finds in which position of the PD array 6 the center of the beam of the monochromatic light shone at the PD array 6 is situated. In addition, it computes and corrects a value to which the output of the PD array 6 irradiated with the beam is added. In this case, the number of light receiving elements constituting the PD array 6 whose output is added can be set at three pieces, and the power of the monochromatic light can be found precisely.
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