| 摘要 |
PURPOSE:To output the definite number of photons, by controlling a neutral density (ND) filter by a pulse motor to set the transmissivity of the ND filter corresponding to each wavelength. CONSTITUTION:Incident monochromatic light 13 passes through an ND filter 16 to be split into two by a half mirror 15 and the split reflected monochromatic light 13c is inputted to a control A/D.D/A converter 19 through a reflecting mirror 23 and a light quantity detector 17. A pulse motor 26 is driven by the D/A converting signal from the converter 19 to control the angle theta of rotation of the filter. The transmitted monochromatic light 13b split passes through an emitting slit 21 to irradiate a specimen. Since the transmissivity alpha(theta) of the filter 16 can be set to an arbitrary value from 0 to 1 by the angle theta of rotation, the angle thetai of rotation of the filter 16 corresponding to each wavelength lambdai within a predetermined wavelength range is calculated from the relation between the angle theta of rotation and the transmissivity alpha(theta) and the angle thetaof rotation of the filter 16 to the wavelength lambdai of the monochromatic light 13 is set as thetai and the transmissivity of the filter 16 is set to alpha(thetai) to make it possible to make the number of the photons of emitted light constant.
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