The spectrometer accepts light from the solar corona along a long, narrow entrance slit
and during the eclipse, this slit scans to observe the whole corona.
The spectral integrated energy received by a spectrometer's exit slit can be regarded as the slit's response to the superposition of all the shifted monochromatic images of entrance slit
A custom, multireflective entrance slit
plate provides a unique arrangement of nine different slit gaps, ranging from 20 to 100 microns, and three pinholes that you can quickly select using a built-in thumbwheel.
The standard NIRQiest512-1.9 comes with a 150 lines/mm grating, 25micron entrance slit
and a non-fluorescing longpass filter that transmits >1000nm.
A fiber-optic bundle carries light from the image plane to the entrance slit
of the spectrometer.
lb show the geometric relationship between the entrance slit
, the grating, and the exit slit in a scanning spectrometer and a spectrometer with a CCD array detector respectively.
It was built in a mahogany housing for stability and had an adjustable width entrance slit
, a 20-cm focal length quartz collimating lens, a Comu quartz prism, a 20-cm quartz camera lens and a plate holder for a 3.25 x 4in.
Depending on the user-selected configuration of grating options and optical bench entrance slit
size, optical resolution as good as 4.1 nm to 6.3 nm (FWHM) is possible.
A second eyepiece "sees" the field of view around the spectrograph's entrance slit
and works with autoguiders for long-exposure imaging.
For a collimated or narrow-angle source, this is not a problem, because the light can be focused onto the entrance slit
, but for tissue, not only is the light source spatially large, it also has a large angular spread.
Briefly, a Ni-coated toroidal mirror collects 20 mrad horizontally and the full vertical extent of the emission from SURF III and focuses the radiation onto an entrance slit
. The radiation is deflected and refocused by a second toroid and is incident on one of two gratings: a 600 [mm.sup.-1] grating blazed for 20 nm, which we operate between 8 nm and 40 nm, or a 1500 [mm.sup.-1] grating blazed for 8 nm, which we use from 3 nm to 14 nm.