PROCEEDINGS ARTICLE | September 15, 2005
Proc. SPIE. 5901, Solar Physics and Space Weather Instrumentation
KEYWORDS: Diffraction, Optical design, Visible radiation, Diamond machining, Spectroscopy, Manufacturing, Wavefronts, Infrared spectroscopy, Infrared radiation, Diffraction gratings
In this paper we highlight the advances we have made in applying modern diamond-turning technology and techniques to the problem of manufacturing coarse-spaced echelon and echelle gratings for infrared spectroscopy-gratings with groove profiles and coarse line spacings that could not be produced using traditional ruling techniques. Diffraction gratings have been classified into three categories: echelons, echelettes, and echelles. What distinguishes these categories from one another are the gratings': line spacing, order of use, and the methods of manufacture. For example, echelles used in the visible and UV regions are ruled gratings, their grooves being formed to a specific "sawtooth" or blazed profile by a ruling process. In comparison echelons were not ruled gratings but an assembly of plane-parallel optical flats, stacked on one another to form a series of rectangular steps. By applying diamond-turning technology, Bach Research has been able to produce diamond-machined echelons and coarse echelles for use in far and near infrared spectroscopy. These gratings have line spacings from 7.5 to 0.25 mm and groove depths of 0.75 to 0.125 mm. These grooves are intentionally large with respect to the infrared wavelength of interest and were produced by machining directly into bulk-metal substrates. This was accomplished while maintaining the precision in spacing and "blazed" groove profile, so that the resulting grating had a diffracted wavefront quality of 0.7 waves RMS, in the 702nd order of 632.8 nm.
