When to use
bandwidth-limiting filters
Use bandwidth-limiting filters to improve the signal-to-noise ratio of
the data and also prevent detector saturation by allowing only energy
in your particular area of interest to pass to the detector element.
An optional filter wheel (available for the Nicolet 6700 only) lets
you automatically move a filter into the beam path before collecting
data. See “Using the filter wheel” in the “Spectrometer Options”
chapter for more information.
In Spectrometer Help Topics view “Setting up experiments” for
instructions for installing filters in the sample compartment or
optional filter wheel.
When to use energy screens
Depending on the types of detectors you use, your system may include
a set of four energy screens. These metal screens help prevent detector
saturation and signal distortion by blocking out a portion of the energy
at all frequencies of the infrared beam. If your experiments deal with
information from a broad range of frequencies, these screens may be
the most effective means of reducing the light level.
The energy screens are labeled A, B, C and D. The following table
shows the percentage of the infrared energy that each screen passes.
It also lists the detectors typically used with each screen, as a
starting point for correcting linearity problems.
Screen % Transmitted* Detectors Typically Used With Screen
None 100 DTGS
A 30
MCT-A
B 10
C 3
D 1
* These are nominal values that may vary due to diffraction and detector variations.
66 Thermo Electron Corporation
