Gentec-EO UM-B - Manual (Page 13)

13
Revision 2.1
UM-B Series Instruction Manual Gentec Electro-Optics Inc. All rights reserved
3.3.2 Working at other wavelengths than 1.064µm
For measurements with a UM-B Series wattmeter at wavelengths other than 1.064µm, a
correction factor must be set to compensate for the change in sensitivity of the wattmeter
caused by the change in absorption of the optical absorber at different wavelengths.
To correct for the change in absorption refer to the spectral curve of the “ Personal
Wavelength Correction
TM “ certificate supplied for the wattmeter and calculate K by taking
the percentage difference between the absorption @1.064µm and that at the desired
wavelength.
 
 
μm 064 . 1 @
1
A
A
K


Power = (V
peak
-V
offset
) / Calibration sensitivity / K
Here
 
1

A = Absorption of the UM-B @ the desired wavelength.
 
μm
064 . 1 @ A = Absorption of the UM-B @ 1.064µm
A sample calculation follows:
 
1

A = 92 %.
 
μm 064 . 1 @ A = 94 %
K =
 
 
μm 064 . 1 @
1
A
A

x 100
K =
% 94
% 92
x 100 = 0.9787 x 100 = 97.87 %
Ex:
-
(V
peak
-V
offset
) = 1 volt
-
Detector calibration sensitivity @1.064µm (100 Volts / Watt)
Power = 1 Volt / 100 V/W / 97.87% = 10.218 mW