| 摘要 |
PROBLEM TO BE SOLVED: To improve wavelength precision taken out of a spectrograph by correcting the periodical error of a reduction mechanism using a harmonic drive in a spectrophotometer. SOLUTION: In a correction expression storage section 62,θ' =θ+ A x sin(C1 xθ+θa) + B x sin(C2 xθ+θb) +θc is stored as a correction expression of a rotational angle. In this case, C1 and C2 are coefficients determined by the structure of the reduction mechanism 22 and can be determined theoretically in the beginning. Conversely, since A, B,θa,θb,θc need to be obtained for each apparatus, they are calculated by fitting, such as the least square, by a coefficient determination section 65, based on the measurement result of a plurality of emission line spectra. When a target wavelength is set when measuring an actual sample, a rational angle correction section 64 applies the above correction expression for correcting the rotational angleθcorresponding to the target wavelength to calculate an angleθ'. Then, a motor 23 is controlled so that a diffraction grating 21 is rotated by that angleθ'. COPYRIGHT: (C)2004,JPO
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