16
Allow at least 2 laser pulses for the auto scale to select the optimal scale for
your measurement.
This command is a toggle so a checkmark indicates when it is on. Select it
again to turn it off. The default is off.
Keep in mind that the 818P-Series High Power detectors are optimized to
sustain high average power, not high peak energy. Always keep the energy
density below the maximum energy density quoted in the manual for that
specific detector.
The single pulse energy measured in
Energy Mode
is precise to ±5% of the
power measurement calibration. This is larger than the uncertainty in the
power measurement (typically ±2.5%) because the energy calibration is
computed from the power measurement calibration.
2.3.2.6 Trig Level
The
Trigger Level
is only used if a power detector head is used in
Single
Pulse Energy (Energy mode)
mode (see Section 2.3.3.4). This option
allows the user to change the
Trigger Level
in absolute values. This proves
to be especially useful in noisy environments.
To change the Trigger Level value, access the dialog box by selecting
Trig
Level
from the
Settings
menu and enter the desired number in absolute
value. The 841-P-USB will not detect pulses with a value under the Trig
level.
The value of the Trigger level is shown in the status menu confirming that the
Trigger level is activated to a specific user level.
Selecting a high value for the trigger level may cause problems with the
detection of widely varying energy values when in the Autoscale mode. The
Autoscale function uses the energy level of the last pulse to set the scale
level. Therefore it will not detect the next pulses if they are lower than the
trigger level. As a result, the Autoscale may become caught on a high scale
value. To solve this problem, select a lower value for the trig level, then send
the serial command *SHI. If you want to select the higher Scale, send the
serial command *SLO. To select the autoscale, send the serial command
*FAS.
ERRATIC TRIGGERING?
For a few detector heads, in electrically noisy environments, it is
possible that the 841-P-USB will inadvertently trigger on the noise.
In that case, increase the trigger level.