Abstract:
A diffraction-grating-type monochromator apparatus having an improved apparatus for rotating the grating is described. The grating is fixedly mounted at the pivot of a follower arm which is pivoted by an arm bearing portion engaging the sloped surface of a wedge-shaped bearing member driven in a direction at an acute angle to the plane of the sloped surface. The wedge-shaped member is a solid wedge or a member in which the acute angle between the sloped surface and the direction of the drive is adjustable.