Thermopile Sensors
1919-R User Manual
33
3.
Set
Laser
to the appropriate laser setting.
4.
Set
Average
to the period you wish to average power over or set to
NONE
to disable. This
feature is especially useful for lasers with unsteady output. (The
Average
can also be
configured in the
shows a sample bargraph showing laser power measurements.
Figure
5-2 Thermopile Power in Bargraph Display
Note:
The soft key legend options such as
Zoom
,
Offset
,
Persist
,
Reset
vary per
Graph Type
.
5.3
Measuring Laser Energy with Thermopile Sensors
In addition to power, Thermopile sensors can be used to measure single shot energy as well,
where they integrate the power flowing through the disc over time and thus measure energy.
Since the typical time it takes for the disc to heat up and cool down is several seconds, these
Thermopile sensors can only measure one pulse every several seconds at most. Thus they are
suitable for what is called “single shot” measurement. Although the response time of the sensor
discs is slow, there is no limit to how short the pulses measured are since the measurement is of
the heat flowing through the disc as a result of the pulse.
Energy measurements can be displayed in
, or
formats (by pressing
Menu > Display
and choosing the
Graph Type
). Updating measurement
parameters is performed in the main measurement screen. A sample is shown in
at the end of this procedure.
To measure single shot energy when using Thermopile sensors:
1.
Set
Mode
to
Energy
. The measuring mode is set to
Energy
, and you can specify the expected
laser
Range
,
Laser
setting, 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
Laser
to the appropriate laser setting.
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 1919-R 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.
