4-30
IM AQ6376-01EN
Explanation
CHOP MODE
This mode activates the internal chopper of the monochromator.
Stray light specific to the monochromator is reduced by turning the chopper.
When CHOP MODE is set to CHOP or SWITCH, measurements of better S/N can be
made. You can set the CHOP MODE to CHOP if the sensitivity setting is HIGH1–HIGH3.
You can set the CHOP MODE to SWITCH if the sensitivity setting is HIGH1–HIGH3 or
MID.
CHOP MODE Function List
CHOP
MODE
Function
Merit
Defect
Invalid
Measurement according to the
stray light.
Measurement time is rapid
even for high sensitivity
measurements.
Since the stray light is also
measured, the low level
component is not accurate
if the light source is of high
power.
Stray light suppression ratio: 40
dB or more
Valid
High dynamic measurement
using internal modulation.
Measurement can be taken
with stray light removed.
Long-duration, high
sensitivity measurements
possible since offset does
not change.
Measurement time is long.
Stray light suppression ratio: 60
dB or more
Stray Light from the Monochromator
The instrument has a newly designed, high-performance monochromator. Depending
on the measurement conditions, stray light at a level 30 to 50 dB below the original
spectrum, as well as other stray light specific to the monochromator may occur in
wavelength areas about 400 nm from the peak wavelength. If this stray light is likely to
have a severe impact on measurements, the sensitivity can be set to HIGH 1/CHOP–
HIGH 3/CHOP in order to reduce the effects of the stray light.
Waveform with CHOP MODE invalid
Waveform with CHOP MODE Valid
4.9 Sensitivity Settings