The Torus Grating

We are reporting spectroscopy studies of Nitrogen filled capillary discharge. The identification procedure of spectra was carried out with the use of an extreme ultraviolet grazing incidence spectrometer with toroidal grating. The source of radiation and the object under study is a pinching alumina capillary discharge in Nitrogen, where stimulated emission in the 13.4 nm wavelength region is expected. To simplify the alignment of the spectrometer during the experiment the off Rowland circle registration scheme is used. In this scheme, spectra are recorded in a single plane and thus exact focusing of the input slit takes place only for one single wavelength, which corresponds to the intersection of the plane of registration with the Rowland circle. Appropriate image processing must be applied to reconstruct the spectra profile and to calibrate wavelength positions. The cooled extreme ultraviolet sensitive CCD camera was used in the role of planar detector. It has a 512×512 elements matrix with 24 µm square pixels. The 16-bit dynamic range together with very low-noise provide a good data source for image post-processing. The experimental impossibility to record simultaneously zeroth order maximum and the first diffraction order spectrum was a crucial problem in the presented process. The presented methodology can be applied to any experiment using toroidal grating spectrometer.

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“…For the theoretical review see Haber [1]. The cross section of the screen with the Rowland circle defines on preferred wavelength.…”

Section: Distortion Eliminationmentioning

confidence: 99%

The wavelength reconstruction from toroidal spectrometer image data

Blazej¹,

Tamas²,

Pı́na³

et al. 2007

WIT Transactions on Modelling and Simulation, Vol 46

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“…Single-reflection designs also give the highest efficiency, an extremely important consideration in the EUV spectral region, where normal-incidence reflectivity is rather low. Two main approaches have been used in the past for correcting the optical aberrations in single-reflection spectrometers: uniform-line-spaced gratings ruled on an aspherical blank [11] or varied-line-space gratings ruled on a spherical blank (SVLS gratings) [12]. In the former case, the groove spacing is constant and aberrations are corrected by the aspherical surface of the grating, usually a toroidal blank (TULS gratings).…”

Section: The Spectrometer: Varied-line-spaced Gratings For Extended Smentioning

confidence: 99%

“…Eq. (9) and (10) (11) so the spatial resolution parallel to the slit and the spectral resolution are mainly limited respectively by the telescope aberrations and by the slit width projected on the detector focal plane. In particular, the spectral resolution is constant within the whole field-of-view and limited to 8.6 pm.…”

Section: The Grazing-incidence Designmentioning

confidence: 99%

Design of the extreme-ultraviolet spectrometer for imaging spectroscopy on the Solar Orbiter mission

Poletto

Gasparotto

Tondello

et al. 2004

UV and Gamma-Ray Space Telescope Systems

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We present the optical design of the spectrometer for imaging spectroscopy in the extreme-ultraviolet (EUV) spectral region for the Solar Orbiter mission. The instrument consists of a telescope making an image of the Sun on an entrance slit of a grating spectrometer. Two different optical designs are presented: a) a normal-incidence off-axis paraboloid telescope feeding a normal-incidence spectrometer and b) a grazing-incidence Wolter-type telescope feeding a normalincidence spectrometer. The spectral region of operation is the 58-63 nm region, with the possibility of extending the range to the 116-126 nm region. The two designs are discussed in terms of optical performance, effective area and thermal load.

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“…As usual the optical path from the source A to the image B is expanded in a power-series of the coordinates y,z of a point P on the grating surface: AP + PB = î.. a..y'zj (2) 13 1J the y -axis is perpendicular and the z -axis is parallel to the grooves. In general the higher order a 3 coefficients are progressively smaller and correspond to the various aberrations.…”

Section: Properties Of a Toroidal Gratingmentioning

confidence: 99%

Evaluation Of Toroidal Gratings In The EUV

et al. 1988

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Toroidal gratings can be used for imaging spectrometers. These can provide stigmatic images and are very useful for space applications. Two cases are described: an Ultraviolet Coronagraph for the solar SOHO mission and a high resolution spectrometer for the stellar Lyman mission. The toroidal gratings have been produced by replicating an elastically deformed spherical one. By properly applying the distorting forces also coma-corrected surfaces can be achieved.

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The Torus Grating

Cited by 101 publications

References 6 publications

The wavelength reconstruction from toroidal spectrometer image data

The wavelength reconstruction from toroidal spectrometer image data

Design of the extreme-ultraviolet spectrometer for imaging spectroscopy on the Solar Orbiter mission

Evaluation Of Toroidal Gratings In The EUV

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