| 摘要 |
PURPOSE:To prevent a lowering of resolving power by eliminating the loss of quantity of light for an intermediate slit, by forming an image at a definite position by the second diffraction grating even when the image forming position due to the first diffraction grating changes by the wavelength of a scanning range. CONSTITUTION:In a double monochrometer having a route wherein light enters from an inlet slit 1 to reach the first diffraction grating 2, an intermediate slit 3, the second diffraction grating 4 and an outlet slit 5, the arrangements and ruling modes of the first and second diffraction gratings 2, 4 are controlled and, further, the width of the intermediate slit 3 is set to such a size that the diffracted light from the first diffraction grating 2 does not impinges against the slit 3 in the total scanning wavelength region to form an image substantially showing no focal dispersion. That is, even when the image forming position due to the first diffraction grating 2 changes by each wavelength of the scanning range, the diffracted light having the wavelength of the total scanning range or at least a partial range is formed into an image at a definite position. The planning of the diffraction ruling of the concave grating optimum to this double monochrometer can be executed by utilizing a holography technique.
|
