Blaze characteristics of echelle gratings.
ABSTRACT A new model for the blaze function of the two in-plane mountings of echelle gratings is described and extended to account for defects in the edges of the grooves. Expressions for the relative efficiency are given. The model shows that the wavelength for the maximum blaze intensity differs slightly from the wavelength lambda(0) satisfying mlambda(0) = d[sinalpha + sin(2theta - alpha)], the difference being a function of the spectral order. The off-blaze orders of the wavelengths diffracted at the central blaze for the mounting alpha < theta (alpha = angle of incidence, theta = blaze angle) lie at the minima of the blaze function for a perfect echelle. Results are given from measurements of the blaze angle and the groove edge defects of three echelles.
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Article: Echelle gratings acting as one.[Show abstract] [Hide abstract]
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.Applied Optics 09/2003; 42(22):4549-59. · 1.69 Impact Factor
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ABSTRACT: Based on a previous study of echelle grating groove shapes, the groove edge defects of the master and its replicas were measured. It was found that the master and an even number of consecutive replicas have edge defects of several microns, whereas the first replica can be made almost without edge defects (< 0.1 μm). To eliminate the large groove edge defects of the master, the echelle gratings should be ruled in such a way that the included angle of the grooves is less than 90 deg. In this way the rough edges of the master are hidden in the steep corners of the replica's grooves, giving the replica the highest possible efficiency. Only replicas that are the mirror-images of the master should be used for spectroscopy.Physica Scripta 12/2006; 28(1):86. · 1.03 Impact Factor
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ABSTRACT: The SOIR instrument on board the ESA Venus Express mission has been operational since the insertion of the satellite around Venus in April 2006. Since then, it has delivered high quality IR solar occultation spectra of the atmosphere of Venus. The different steps from raw spectra to archived data are described and explained in detail here. These consist of corrections for the dark current and for the non-linearity of the detector; removing bad pixels, as well as deriving noise. The spectral calibration procedure is described, along with all ancillary data necessary for the understanding and interpretation of the SOIR data. These include the full characterization of the AOTF filter, one of the major elements of the instrument. All these data can be found in the ESA PSA archive.Optics Express 09/2013; 21(18):21148-21161. · 3.55 Impact Factor