Gentec-EO UM-B - Manual (Page 12)

12
Revision 2.1
UM-B Series Instruction Manual Gentec Electro-Optics Inc. All rights reserved
Gaussian beam stopped at 1/ e 2 ) applied to a diameter equal to 80% of the
detector aperture. The use of a divergent lens, a Lambertian diffuser such as opal
glass, or any other method of beam spreading, is recommended for this purpose.
Please take note that all of the laser light must be directed within the detector
aperture and that the transmission loss through the optical component must be
known.
6- Adjust the oscilloscope so it triggers on the wattmeter pulse or on the chopper sync. signal.
7- Measure the baseline to peak voltage generated by the wattmeter.
8- Determine the wattmeter Volt/watt sensitivity from the detector identification label or calibration
certificate. Choose the value stated for the wavelength being used.
9- Calculate the optical energy using the following equation:
Power = (V
peak
-V
offset
) / Calibration sensitivity
Ex:
- V
peak
-V
offset
= 1 volt
- Detector calibration sensitivity (100 Volts / watt)
Energy = 1 Volt / 100 V/W = 10 mW
NOTE: Exclude any DC offset from the pulse peak value measurement.