Pyroelectric Sensors - THORLABS PM200 Operation Manual

3 Operating Instruction
Accelerator settings
Different from S3xxC series, for a custom thermal element the time constant
'Tau' can be entered in the Measurement Settings panel. Accelerator modes are
the same, as for S3xxC sensors.

3.15.3 Pyroelectric Sensors

Pyroelectric sensors allow the energy measurement of short light pulses. The
PM200 works with Thorlabs ES1xxC and ES2xxC series pyroelectric power
sensors. The sensor will be ready to operate few seconds after plugging to the
DB9 connector.
Attention
Refer to the sensor data sheet and pay attention to the optical damage threshold!
Exceeding these values will permanently destroy the sensor!
A pyroelectric sensor converts the incident energy pulse into a voltage pulse,
largely independent of the incident radiation wavelength. The amplitude of this
voltage pulse is proportional to the laser pulse energy and is measured by a
peak detector circuit. The voltage peak decays in time, so the max. repetition rate
is limited.
When a pyroelectric sensor is connected the PM200 cannot be switched to auto-
range mode. The measurement value will be updated with each incoming pulse.
When no pulses appear the measurement display will be held on the last
measured value until the "Reset Min / Max" button will be pressed.
Trigger Level
The trigger level can be set either directly by clicking to the value in the
measurement panel or from the 'Measurement Settings' panel.
When an incoming pulse exceeds the set trigger level, the peak detector circuit
gets armed and is waiting until the pulse peak is reached. After finding the
maximum voltage the level is kept and the microprocessor reads the AD
converted voltage for displaying the pulse energy. Finally the peak detector
circuit gets a reset and is ready for the next pulse.
The trigger level can be adjusted between 0% and 99% of each selected energy
range. Only pulses that are higher than the adjusted trigger level are recognized
by the PM200. The trigger level should be set between the noise level and the
expected pulse height.
Average Power Measurement
With continuously repeating pulses the PM200 calculates the average power
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