Thermopile Sensors
StarBright User Manual
35
5.3.1
Measuring Pulses of Very Low Energy
When it is necessary to measure pulses of very low energy, i.e., less than 0.5% of the maximum
range of the instrument, the following two alternative methods allow greater accuracy to be
obtained.
A continuous train of pulses may be fired, and the average power measured using
Power
mode. The energy per pulse can be calculated by:
Average Energy per pulse = Average power / Pulse Repetition Rate
A train of a known number of pulses may be fired, and the total energy measured in
Energy
mode. This train should not exceed 5 seconds duration. The energy per pulse can be calculated
by:
Average Energy per pulse = Total Energy / Number of Pulses
In both of the above methods, the pulse repetition rate must exceed 3Hz. Higher rates will
generally give improved accuracy, but care should be taken not to exceed maximum power
ratings.
5.3.2
Measuring Energy of Rapidly Repeating Pulses
With a typical Thermopile sensor, StarBright will only measure individual pulses every 5 seconds or
so. You can also calculate the average energy of rapidly repeating pulses by measuring average
power on the power setting and using the formula:
Average Energy per Pulse = Average Power / Pulse Repetition Rate
For rapidly repeating pulses, you can use one of the Ophir Pyroelectric sensors, as long as the
pulse energies do not exceed the ratings of the Pyroelectric absorbers. The Pyroelectric sensors
are compatible with StarBright and just have to be plugged in to be used.