Editing Optical spectrometer (section)

===Slitless spectrograph===
In conventional spectrographs, a slit is inserted into the beam to limit the image extent in the dispersion direction.  A [[slitless spectrograph]] omits the slit; this results in images that [[convolution|convolve]] the image information with spectral information along the direction of dispersion.  If the field is not sufficiently sparse, then spectra from different sources in the image field will overlap.  The trade is that slitless spectrographs can produce [[spectral imaging|spectral images]] much more quickly than scanning a conventional spectrograph.  That is useful in applications such as [[solar physics]] where time evolution is important.