Design of High-Resolution Monochromator for the Vacuum Ultraviolet An Application of Off-Plane Eagle Mounting*†

Abstract

The possibility of constructing a high-resolution monochromator for the vacuum ultraviolet is discussed; off-plane Eagle mounting is chosen as the most suitable one. Considering all optical restrictions arising from an off-plane setting, the resolving power of the grating in the off-plane Eagle mounting is calculated numerically for the following conditions: 3-m concave grating (5- × 3-in. ruled area) with 30 000 lines/in. or 15 000 lines/in., 0 to 5800 A in the first order, and distance of the entrance slit from the Rowland plane 6 cm. In order to have compactness, a link mechanism introduced by Bair et al. is chosen in the scanning system and a tentative design of a 3-meter vacuum monochromator is shown schematically. As the result, it is recommended to use the off-plane Eagle mounting in constructing a high-resolution monochromator for the vacuum ultraviolet.