title: Echelle gratings acting as one.
abstract: A new device for producing order-sortable echelle spectra by use of consecutive diffactions in several echelle grating surfaces is described. This echelle emulating device (EED) comprises a prism placed in the path between a pair of echelle grating surfaces. The refractive angle of the prism is fixed through a simple relation. The device reproduces all the main properties of a single virtual echelle, obtained from a simple grating equation describing the combined action of the gratings and the prism. The spectral order of the EED is the sum of the spectral orders of the individual gratings. A spectrograph that utilizes the device is described, and several applications are discussed.
authors.affiliation: Multichannel Instruments AB, Pilotgatan 2,128 32 Skarpnäck Stockholm, Sweden. peter@systematix.se
authors.forename: Peter
authors.initials: P
authors.lastname: Lindblom