Patent ID: 6069697
Filing Date: 2000-05-30
Classification: G01M

Abstract:
An optical transmission characteristic measuring apparatus for measuring optical transmission characteristics of an optical device, comprising:an external resonance type tunable-wavelength light source unit comprising a semiconductor laser element, an optical element and a diffraction grating, for variably setting a wavelength of an output light in a first wavelength range in accordance with a first wavelength range setting signal and inputting the output light to the optical device;a spectroscope unit for variably setting a selected wavelength in a second wavelength range in accordance with a second wavelength range setting signal, and for performing spectroscopy of light passing through the optical device;a light receiving unit for receiving the light having undergone spectroscopy in the spectroscopy unit and for photoelectrically converting the received light into a signal;an A/D conversion unit for converting the signal produced by the light receiving unit into a digital signal;an input unit for inputting wavelength information indicating a desired measurement wavelength range with respect to the optical device;a memory unit for storing first wavelength setting data based on rotational angle data of the diffraction grating of the tunable-wavelength light source unit with respect to the wavelength of the output light, and second wavelength setting data on the selected wavelength employed by the spectroscope unit in advance;a first tunable-wavelength control unit for controlling the diffraction grating of the tunable-wavelength light source unit using a predetermined range of the first wavelength setting data as the first wavelength setting signal, thereby variably controlling the wavelength of the output light from the tunable wavelength light source unit in the first wavelength range, said predetermined range of the wavelength setting data indicating the rotational angle data of the diffraction grating in the desired measurement wavelength range and being read out from the memory unit based on the wavelength information which indicates the desired measurement wavelength range;a second tunable-wavelength control unit for controlling the spectroscope unit using a predetermined range of the second wavelength setting data of the spectroscope unit as the second wavelength setting signal, thereby variably controlling the selected wavelength of the spectroscope unit in the second wavelength range, said predetermined range of the wavelength setting data corresponding to the desired measurement wavelength range employed by the spectroscope unit and being read out from the memory unit based on the wavelength information which indicates the desired measurement wavelength range; anda processing unit for synchronously and variably controlling: (i) the predetermined range of the first wavelength setting data indicating data on the rotational angle of the diffraction grating of the tunable-wavelength light source unit in the desired measurement wavelength range and read out from the memory unit, and (ii) the predetermined range of the second wavelength setting data of the spectroscope unit in the desired measurement wavelength range, so that the wavelength of the output light of the tunable-wavelength light source unit and the selected wavelength of the spectroscope unit are variably set in an equal wavelength relationship in the first and second wavelength ranges, thereby performing wide dynamic range measurement of the optical transmission characteristics of the optical device in accordance with the digital signal from the A/D conversion unit.