Gentec-EO HP - Manual (Page 23)

Version 2.2
19
HP Series Instruction Manual Gentec Electro-Optics Inc. All rights reserved
3 SAFETY OPERATION NOTES
3.1.1 Diffusive surfaces
When using the HP be aware of the diffused back reflection ~ 10-15%.
As on any diffusive surface, the light on the sensor coating is scattered more or less uniformly
as a Lambertian diffuser.
3.1.2 Detector temperature
Detectors can become hot enough during usage to cause burns.
4 DAMAGE TO THE OPTICAL ABSORBER MATERIAL
The HP series are high power meters that can measure up to 12KW. The beam diameter should
always be as large as possible to avoid damage to the absorber. We are recommending between
50% and 80% of the head aperture area, e.g. 7 cm in diameter for the HP100A, 2.5 cm in diameter
for the HP60A-10KW-GD.
The damage threshold is decreasing with the laser beam power. The following table calculates the
diameter corresponding to the damage threshold for a Gaussian beam profile. The “minimum 1/e²
beam diameter” is calculated to obtain a peak intensity 50% lower than the damage threshold and
should be considered as the “safe” minimum diameter. If there are “hot spots” in the beam profile,
they must be considered in the calculation of the peak intensity.
Laser HP100A-3KW-HE HP100A-4KW-HE
Beam Damage Damage 1/e² Min. 1/e² Damage Damage 1/e² Min. 1/e²
Power Threshold 2
Beam Diam.
3
,
4
Beam Diam.
7 , 8 ,5 Threshold
6
Beam Diam.
7 , 8
Beam Diam.
7 , 8 , 9
[kW] [kW/cm²] [cm] [cm] [kW/cm²] [cm] [cm]
0.5 10 0.4 0.5 10 0.4 0.5
1 6 0.7 0.9 8 0.6 0.8
2 4 1.1 1.6 6 0.9 1.3
3 3 1.6 2.3 5 1.3 1.8
4 4 1.6 2.3
2 Peak Intensity.
3 For Gaussian beam profile, the peak intensity is twice the beam power.
4 Diameter of a circle corresponding to 86% of the entire beam power.
5 Including a security factor of 50%