Thermopile Sensors
StarBright User Manual
33
factors of 1, 10, 100, and so on. When the reading falls below 9% of full scale, the range
changes to one range lower. This change only occurs after a few seconds delay. This
provides overlap (hysteresis) to keep the StarBright from flipping back and forth when
reading close to the end of the scale.
Manual range
: The correct manual range is the lowest one that is larger than the expected
maximum power of the laser. There are certain disadvantages to autorange, since it
changes scale even if you do not want it to do so. If you want to measure in the same
range all the time, it is better to use a manual range.
3.
Set
Wavelength
to the correct laser wavelength.
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 Statistics graph showing laser power measurement statistics
Figure
5-2 Thermopile Power Statistics 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.