GB362305A - Improvements in monochromators and like spectroscopic apparatus adapted for double dispersion - Google Patents

Abstract

362,305. Spectroscopic monochromators. MILLER, C., 86, Soorstrasse, Charlottenburg, Berlin. April 15, 1931, No. 11181. [Class 97 (i).] A double monochromator comprises two sets of spectrum-producing parts with auto-collimation and with chromatically uncorrected imaging systems, so combined about an intermediate slit that light passes through the slit out of one set of parts into the other, a common means of wave-length adjustment being provided for the two sets of parts. The spectrum-producing parts shown comprise half prisms 12, 13 each having one refracting and one reflecting surface, and collimating lenses 14, 15, disposed on opposite sides of a slit carrier 2 having slits 3, 4, 5 in vertical alignment. The lenses and prisms are mounted on sliders 6, 7 which can be displaced simultaneously by a right-and-left handed screw 9, 10 operated by a drum 11 carrying a scale of wave-lengths. The prisms 12, 13 are mounted on pillars 27, 28 rotatably mounted on the sliders, these pillars being provided with arms 16, 17 which are spring-urged into contact with fixed pins 18, 19, so that rotation of the prisms is automatically produced when the sliders are displaced, to set the prisms for minimum deviation of the wave-length being used. The incident light is reflected by a prism 22 so as to pass through the slit 3 to be collimated by the lens 14, and is then dispersed by the prism 12 to be focused by the lens 14 as a horizontal spectrum across the slit 4. A narrow band, the wave-length of which is determined by setting the drum 11, passes through the slit and is received by the parts 15, 13 which effect purification of the light, monochromatic light being focused on the slit 5 and directed out of the apparatus by a reflecting-prism 23. The slits may be arranged side by side on the holder 2, or they may be arranged in different transverse planes on three separate holders. By turning the prism 13 so that its refracting edge is towards the rear instead of towards the front as shown, the system 15, 13 can be made to double the dispersion instead of purifying. The same effect can be produced without moving the prism 13, by providing a reversing prism adjacent the slit 4.