Patent ID: 7072037

Claim:
A double monochromatic spectroscopic device with a pre-spectroscope and a main spectroscope arranged between an inlet slit and an outlet slit, comprising: a light source for projecting a calibration light to the inlet slit; a light intensity measuring section for measuring a light intensity of the calibration light outgoing from the outlet slit, a control unit including a storage section for storing zero-order light positions, which are an angular position of a diffraction grating of the pre-spectroscope and an angular position of a diffraction grating of the main spectroscope at which a main light ray incident on the inlet slit reaches the outlet slit via the pre-spectroscope and the main spectroscope, said control unit being operable, in response to signals from said light intensity measuring section, to selectively actuate and monitor a main spectroscope diffraction grating drive unit and a pre-spectroscope diffracting grating drive unit so as to independently control the angular position of the main spectroscope diffraction grating and the anaular position of the pre-spectroscope diffraction grating; a main spectroscope calibrating section including said main spectroscope diffraction grating drive unit and operable in response to control signals from said control unit, for rotating the main spectroscope diffraction grating while said pre-spectroscope diffraction grating drive unit is positioned in a state corresponding to the zero-order light position of the pre-spectroscope diffraction grating so as to detect an angular position of the main spectroscope for a predetermined wavelength with the light intensity measuring section; and a pre-spectroscope calibrating section including said pre-spectroscope diffraction grating drive unit and operable in response to control signals from said control unit, for rotating the pre-spectroscope diffraction grating while said main spectroscope diffraction grating is positioned in a state corresponding to zero-order light position of the main spectroscope diffraction grating so as to detect an angular position of the pre-spectroscope for the predetermined wavelength with the light intensity measuring section.