The DeSa Monochromator
The patented double-grating
monochromator by Richard J. DeSa has
stationary optics during scanning.
In its unique rapid-scanning mode,
only the intermediate slit moves.
Conventional scanning by moving the
gratings is possible, too.
All early models have an aperture
of 4.5 and a focal length of 250 mm.
As a subtractive double monochromator,
the DeSa model features exceedingly
low stray light, high light throughput,
a homogeneous output beam, and bandwidth
determined by the moving intermediate
slit. The DeSa monochromator has all
reflective optics, making it usable
throughout the UV/Vis/NIR range. One
RSM can have almost arbitrary wavelength
range(s), wavelength span(s), and
spectral resolution(s), as determined
by the gratings and ScanDisk.
The diagram and the photo
in the right-hand column show the
optical path of the DeSa monochromator.
The mirror- image optics make it possible
to reverse the optical path as the
experimental situation requires, making
the monochromator equally useful for
excitation/ low-light use.