Features & Description
EPM2000/EPM2000e Reference Guide
4
COMPATIBLE PROBES
The EPM2000 functions with any of Molectron's pyroelectric/Joulemeter probes with names of the
form Jx (for example: J25, J3, J4).
All PowerMax thermopile probes will function with the EPM2000. Connect thermopile probes that
terminate with a BNC connector to the EPM2000 with the PM-BNC adapter (available separately).
UNDERSTANDING THE EPM2000 INTERNAL TRIGGER
For greatest accuracy and repeatability, each channel of the EPM2000 must trigger reliably for each
laser pulse.
The EPM2000 should be triggered externally, via one of the Trigger In connectors, for best results.
This is particularly true in a noisy environment. The EPM2000 can be set to synchronize with either
the positive or negative transition of this external signal.
Without a reliable external trigger, set the EPM2000 to extract an artificial trigger from the incoming
signal. This is Internal Triggering.
To successfully extract an internally generated trigger, set the EPM2000 to a range such that the
incoming signal is at least 5% of the full scale. Set the trigger level for at least 2% above the noise
level and at least 2% below the peak height.
For example, with a peak height of 300 mJ, set the EPM2000 to a range of 3 J. A peak will occur at
10% of full scale, well above the 5% level. The trigger level should not be set higher than 8%. If the
noise level is 5% of full scale (approximately 150 mJ) then the trigger level should be set no lower
than 7%.
In Figure 1, the EPM2000's internal trigger threshold has been set to 8% (dashed line). Pulse D will
definitely not generate a reliable trigger. Pulse C may generate a trigger, but not reliably. Pulses A
and B will definitely generate reliable triggers.
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