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Pulse frequency
1 MHz
100 kHz
10 kHz
1 kHz
100 Hz
10 Hz
1 Hz
Fig. 16.5:
Selection of the appropriate measurement mode based on laser parameters
For the blue field laser beams, the quasi-cw operation is most suitable. However, be aware that as the
pulse frequency decreases, the required integration time increases to ensure the quasi-cw case. As a rule
of thumb, the integration time of a focal plane measurement should be approximately the same as the time
for 35 pulses. If the laser beam to be measured falls below a pulse frequency of approx. 500 Hz, you should
switch to trigger operation.
While it is almost always possible to measure with the integration time control in the cw or quasi-cw ope-
ration, it only makes sense to use it for very long pulse durations (>1 ms) in trigger operation. With the help
of the attenuation filters, the integration time is adjusted in such a way that it is only a fraction of the pulse
duration. The trigger signal will then merely specify to the device the starting time for the measurement. The
integration time may increase or decrease during the course of the caustic measurement without leaving the
pulse path (see Fig. 16.6 and "Example 2: very long pulse duration" on page 115).
min Delay (12 μs)
Fig. 16.6:
Measuring parameters for pulsed laser systems with pulse duration greater than 1 ms
For all other cases, it is advisable to specify a fixed integration time in order to always measure a fixed num-
ber of pulses by cleverly selecting the filters and the delay and integration time ("Example 1: fixed integration
time" on page 115).
114
Quasi-cw operation
Trigger operation
1 μs
10 μs
100 μs
P
Laser
Integrationszeit
Integration time (e. g. 100 μs)
cw operation
1 s
10 s
100 s
tp – 1 ms
MSM+ HB
Pulse duration
t
Revision 00 EN - 02/2022
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