Tunable .theta.-2.theta. device

Abstract

A tunable monochromator selects a narrow range of wavelengths from a broadband source of radiation, such as a synchrotron X-ray source, visible light, etc. Wavelength selectivity is obtained by Bragg reflection from crystal surfaces or by diffraction gradings, prisms, etc. The inventive apparatus maintains proper orientation of two rotary members, at least one of which is typically a wavelength selective member. The apparatus allows the angles of incidence and reflection to be changed, thus changing the wavelength selected without changing the output angle or height. Two wavelength selective members can be used, or a detector probe may be positioned relative to a single wavelength selective member, or a desired polarization can be obtained with the use of a single wavelength selective member and a quarter wavelength plate. Other devices employing the .theta.-2.theta. principle, including variable delay lines, can be realized with the device.

Dependencies are inferred from the claim text.