Chapter 6. Operation With Pyroelectric Sensors; Pyroelectric & Photodiode Energy Sensors - OPHIR vega User Manual

Operation with Pyroelectric Sensors
Warning:
Before using the sensor for power or energy
measurement, check that your laser power, energy
and energy density do not exceed the sensor ratings
as listed in the table with the sensor specifications.
Otherwise, there is a risk of damaging the absorber.
With the pyroelectric sensor, you have been supplied a
test slide with the same coating as on your pyroelectric
detector. You can also obtain this slide from your dealer.
You should use this slide to test the damage threshold
with your
then either enlarge your beam or lower the laser energy
until damage is no longer seen.
6.1 Pyroelectric & Photodiode Energy Sensors
6.1.1. Pyroelectric sensors – method of operation
When a pulsed heat source, such as a laser, is directed
at the detector sensor, a temperature gradient is created
across the pyroelectric crystal mounted in the sensor.
An electric charge is produced which is proportional to
the energy absorbed. The detector sensor has
sophisticated circuitry unique to Ophir (patented) that
determines the baseline before the pulse is received,
measures the voltage after a pre-determined interval,
amplifies it and holds it for a pre-determined time.
Due to this innovative circuitry, Ophir pyroelectric
sensors can measure very long pulses as well as short
ones. They can measure low energies as well as high.
They can also measure at higher repetition rates than
was possible before.
The Vega meter amplifies this signal and indicates the
energy received by the sensor as well as the frequency at
which the laser is pulsing. Using the energy and
Chapter 6.
laser pulses. If the slide shows damage,
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