===== THEMIS MulTi-Ray spectrograph (MTR2) ===== MTR2 is the advanced version of the original MulTi-Ray spectrograph of THEMIS. MTR2 enables the production of high-spectral resolution spectrograms simultaneously in different wavelengths. This enables the study of different physical properties of the distinct layers of the solar atmosphere. ==== Schematics of MTR2 ==== MTR2 is made of a predispersor ("SP1" first one on the left part), forming a low resolution spectrum on the wavelength selector (so called the "mask plate"). From there, only the selected bandwiths travel to the high-resolution echelle spectrograph (right part), ending over the MTR cameras at the SP2 output (one bandwith per camera).\\ The optical layout along Y is fixed (no changes, never). The ruling of the gratings are **along Y** only and the dispersion of both spectra is **along Z** only. The entrance slit is fixed (but for its width), and such are the collimators and camera mirrors. The moving parts are: * The predisperser gratings selection table (EM35). There are 3 selectable predispersers, although only one (the central slot) is mainly used for MTR2 operation. * PThe predisperser rotates about the Y axis to change its grating incidence angle (EM37). This allows shifting the lowres spectrum along Z over the masks stop plate. * The mask plate translates in the Z direction (EM39) * The echelle grating rotates about the Y axis to change its grating incidence angle a (EM32). This allows shifting the highres spectrum along Z at the SP2 output. * The legacy “DPSM engage” mirror (EM71, "out" in normal operation. * Each of the 4 spectrograph mirrors has a mechanical shutter (EM50 to EM53) In short: - The main optical layout (F2 to SP2) is static and does not require changes for daily operation. - Spectral configuration of the multi-line is obtained using: * both gratings rotation * masks plate tuning in translation * manual setup of the spectral cameras at the SP2 output Data and formulae for the MTR2 can be found in the following document: \\ [[this>wdata/WSpectroTools/Spectro_Formulae.pdf | THEMIS spectrograph (auth: CLM)]] ==== Spectrograph simulation tools ==== These tools allow the observer to quick check the feasibility of a setup * [[this>wdata/Instrument/tools/Rep1/MtrSim.html | MTR spectrograph simulator]] (java web version / auth: CLM) * [[this>wdata/WSpectroTools/MTR_Calculator.xls | MTR spectrograph simulator]] (Downloadable excel version / auth: CLM)\\ Please enable macros to get a correct result. Observers can also check the [[technical:mtr2:maskplates| list of existing available mask plates]] to have an idea of readily available combination. ==== Solar spectra resources ==== * [[this>wdata/WSpectralRes/solar_spect.pdf | Solar spectrum ]] (3800 to 8700 Å with identified lines) * [[this>wdata/WSpectralRes/nbsmonograph61.pdf | Solar lines]] (2935 to 8770 Å, **Moore & Minaert (M&M)**, NIST) * [[http://bass2000.obspm.fr/solar_spect.php|Solar spectrum]] (**BASS2000** interactive plot) * [[http://www.astrosurf.com/spectrohelio/atlas-en.php|Solar spectrum]] (**Astrosurf**: interactive 2d with M&M identification)