| 摘要 |
The present monochromator comprises a plurality of monochromator portions including one prism and at least one diffraction grating, the prism being arranged in the first or final portion. In order to cover a deviation of light having a required wavelength at an exit slit, resulting from the variation of refractive index of the prism due to the variation of temperature and from the rotational error of the prism and in order to increase the amount of exit light, the width of an entrance or exit slit adjacent to the prism is held always greater by a constant value a than an intermediate slit adjacent to the prism. The value a is selected to be equal to either aT or ar shown by the following expression or greater than it, AT = Dp. DELTA lambda T ar = Dp. DELTA lambda r WHERE Dp is a line dispersion of the monochromator portion due to the prism, DELTA lambda T is a deviation of wavelength resulting from the variation of refractive index of the prism due to the variation of temperature, and DELTA lambda r is a deviation of wavelength resulting from the rotational error of the prism.
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