Primes PMT 01 - 12.4.2 Perform Measurement of the Laser Power

35,0(6
PocketMonitorPMT
28
Revision 01/2020 EN
12.4.2 Perform measurement of the laser power
1. Observe the safety instructions in chapter 12.1 on page23.
2. Set the laser to an on-time that corresponds to the desired irradiation time (10s or 20s).
If you switch the laser on manually, the temporal inaccuracy is included in the measured
value.
• The device does not check the actual irradiation time.
3. To set the desired irradiation time (10s
or 20s), set a 24 V pulse.
• at pin 4: setting of 20 s
• at pin 5: setting of 10 s
1
2
5
4
3
24 V pulse: 10s
24 V pulse: 20s
Pin diagram socket (top view, plug-in side)
4. Switch on the laser.
• To do so, use the shutter if possible. The power control of lasers often causes overshoo-
ting, which distorts the measurement.
• The radiation heats up the absorber. As soon as the temperature of the absorber rises
above a pre-set threshold value, the measurement begins.
5. Switch off the laser.
• After the irradiation time has run out the thermalization time begins (depending on the
absorber type 10s – 60s).
• During thermalization time the output current is reset to 4 mA.
6. To determine an offset, measure the
output current at pin3 with an ammeter
during the thermalization time.
• If the actual measured current deviates
from the 4mA value, you can use this
measurement deviation to correct an
offset.
7. To determine the laser power, measure
the output current at pin3 with an am-
meter after the thermalization time.
8. Calculate the laser power from the
output current according to Tab. 12.3 on
page29.
• The current output after the thermaliza-
tion time remains constant until a new
pulse is applied to pin4 or pin5.
1
2
5
4
3
Current output
4–20mA
Pin diagram socket (top view, plug-in side)