Thermopile Sensors
StarBright User Manual
34
To measure single shot energy when using Thermopile sensors:
1.
Set
Measuring
to
Energy
. The measuring mode is set to
Energy
, and you can specify the
expected laser
Range
,
Wavelength
and
Threshold
.
2.
Set
Range
to the appropriate manual range. (In
Energy
mode, there is no autoranging.) The
correct range is the lowest one that is larger than the expected maximum pulse energy of the
laser.
3.
Set
Wavelength
to the correct laser wavelength.
4.
Set
Threshold
to change the energy threshold to
LOW
,
MED
, or
HIGH
to set the hardware
threshold in the sensor to screen out noise that would otherwise be seen as energy pulses.
(This screens out false triggers.) The factory setting of the energy threshold is
Med
for
medium. If the unit triggers on noise, set the threshold to
High
. If you are measuring small
energies and the unit does not trigger, set the threshold to
Low
.
If the StarBright is used in a noisy environment or where there is a high level of background
thermal radiation, the instrument may trigger spuriously on the noise or background radiation.
It would then fail to measure the intended pulse. Since there is always some degree of noise
or background radiation, the instrument is designed not to respond to pulses below some
preset minimum size. This "Minimum Energy Threshold" is typically set to 0.3% of full scale of
the selected range. If this level is found to be too sensitive for the user's particular
environment, it may be altered by the user. The threshold should not, however, be raised
higher than necessary. This will cause a degradation in the accuracy of energy measurements
of pulses below about 4 times the threshold level.
5.
When the StarBright screen flashes
READY
on and off, fire the laser. The display will go blank
while the energy is being integrated. After about 2-4 seconds (depending on the sensor), the
correct energy will be displayed.
6.
Return to Step 1 for the next measurement.
shows a sample analog Needle display showing laser energy measurement
data with options for
. (Click the above links for more details.)
Figure
5-3 Thermopile Energy Bargraph
Note:
The soft key legend options such as
Zoom
,
Offset
,
Persist
,
Reset
vary per
Graph Type
.
