Four Decades of Advances from MSDP to S4I and SLED Imaging Spectrometers

The European Solar Telescope

“…So far, four types of IFU devices have been successfully tested in solar physics: a subtractive double pass (e.g. Beck et al 2018;Mein et al 2021); image slicers; microlens arrays; and optical fibres. The latter will be used in the Diffraction Limited Near Infrared Spectropolarimeter (DL-NIRSP) (see the general information in Elmore et al 2014) on DKIST.…”

“…Reviews of the radiative transfer modelling of filaments and prominences can be found in Labrosse et al (2010) and Gunár (2014). The high spatial and temporal resolutions that will be provided by the next generation of 4m class solar telescopes, combined with spectral and imaging capabilities of instruments like the multichannel subtractive double pass (Mein et al 2021), will greatly benefit the radiative transfer modelling of not only filaments and prominences, but also the chromosphere more generally.…”

“…Gelly et al 2016) and the VTT; multi-wavelength simultaneous spectropolarimetry capabilities similar to combinations such as the Visible Imaging Polarimeter (VIP; Beck et al 2010) with the Tenerife Infrared Polarimeter (TIP; Collados et al 2007) or the polarimetric Littrow Spectrograph (POLIS, Schmidt et al 2003) with TIP at the VTT, as well as THÉMIS in multi-line spectropolarimetric mode (e.g. López Ariste et al 2000;Paletou & Molodij 2001) and in the multichannel subtractive double pass (MSDP) mode (Mein et al 2021); efficient NB tunable filters, as, for example, the Interferometric BIdimensional Spectropolarimeter (IBIS; Cavallini 2006), the CRisp Imaging SpectroPolarimeter (CRISP; Scharmer et al 2008), or the CHROMospheric Imaging Spectrometer (CHROMIS; Scharmer 2017) instruments; fastmodulation high-precision spectropolarimetry as with, for instance, the Zurich Imaging Polarimeter (ZIMPOL; Gandorfer et al 2004;Ramelli et al 2010); and simultaneous control of multiple polarimetric imaging and spectrograph instruments as, for instance, at the VTT.…”

The Solar Line Emission Dopplerometer project

“…The SLED is a promising, highly optimized and compact version of the MSDP spectrograph; the principle behind the instrument is illustrated in Figure 1. The MSDP was first described by Mein (1977), and has been upgraded many times over the last four decades on several telescopes in Europe (Meudon Solar Tower, Pic du Midi Turret Dome, Vacuum Tower Telescope and THEMIS at Tenerife, Białków coronagraph; see Mein et al (2021)).…”

“…As a future option, the SLED could operate in polarimetric mode for magnetic field strength and direction determination. Mein et al (2021) describe a full Stokes polarimeter optimized for the MSDP imaging spectroscopy. It uses a calcite beam splitter which reduces the FOV in the x-direction by a factor two, and hence provides two simultaneous measurements (I+S, I-S with S = Stokes Q, U, V in sequence).…”