  The Multichannel Subtractive Double Pass (MSDP) is an imaging spectroscopy
technique, which allows observations of spectral line profiles over a 2D field
of view with high spatial and temporal resolution. It has been intensively used
since 1977 on various spectrographs (Meudon, Pic du Midi, the German Vacuum
Tower Telescope, THEMIS, Wroc{\l}aw). We summarize previous developments and
describe the capabilities of a new design that has been developed at Meudon and
that has higher spectral resolution and increased channel number: Spectral
Sampling with Slicer for Solar Instrumentation (S4I), which can be combined
with a new and fast polarimetry analysis. This new generation MSDP technique is
well adapted to large telescopes. Also presented are the goals of a derived
compact version of the instrument, the Solar Line Emission Dopplerometer
(SLED), dedicated to dynamic studies of coronal loops observed in the forbidden
iron lines, and prominences. It is designed for observing total solar eclipses,
and for deployment on the Wroc{\l}aw and Lomnicky peak coronagraphs
respectively for prominence and coronal observations.
