Principles of Operation 123 123
Two common applications are natural extensions of the CW Integrate
measurement mode:
Pulse laser energy measurement using a thermopile detector
Energy from exposure over a period of time (dosage)
Figure 70 Measuring Laser Pulse Energy with a Thermopile.
Thermopiles are often used to measure pulsed laser energy by integrating the response of the
detector to the pulse.
9.9 Analog Output
The Model 1936/2936 Series provides an analog output for signal
monitoring. The analog output is the actual amplified detector signal and is
uncorrected for the effects of the detector’s responsivity, calibration, and
ZERO. The analog output signal is a representation of what the meter “sees”
at its input. However, the analog output signal may be filtered if the user
selects any cutoff frequency from the drop down menu of the analog filter
(see paragraph 4.1.6). Also, the analog output signal is amplified and scaled
to the selected analog output level (see Table 5).
The user can select the analog output level with a command,
PM:ANALOG:OUT (see Section 8.3) The analog output maximum level
corresponds to the maximum full-scale input range the meter is set on. For
example, if one selects the analog output level at 0.5 V into 50 Ω, and the
meter is set on 250 mW maximum full-scale input range, the analog output
signal will have a transfer function of 250 mW/0.5 V. Therefore, if the analog
output BNC is connected to an oscilloscope or voltmeter with 50 Ω input
impedance and the user reads 0.25 V, the detector power is 125 mW.
The selectable analog output levels are given in Table 5.
Full Scale Voltage (Load > 100 kΩ)
Full Scale Voltage (Load = 50 Ω)
Table 5 Analog Output Range Table.
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