Gentec-EO FLASH - Manual (Page 18)

Revision 1.5 14
FLASH Series Instruction Manual Gentec Electro-Optics Inc. All rights reserved
2.2 Safety operation notes
Diffusive surfaces :
When using the FLASH be aware of the diffused back reflection ~ 5-15%.
Specular surfaces : When using the FLASH with the windows ‘’W’’ option be aware of the diffused back
reflection ~ 8-10%.
As on any diffusive surface, the light on the sensor coating is scattered more or less uniformly as a
Lambertian diffuser. It is recommended to use the head with a black protective sleeve to limit wide-angled
diffused reflections.
Safety laser glasses recommended.
Detector temperature while in operation:
During usage, the detector head can become hot enough to
cause burns.
2.3 Damage to the optical absorber material
Damage to the optical absorber material is usually caused by exceeding the manufacturer's specified
maximum incident average power density. Refer to the specifications from section 1.4 of this manuel.
The FLASH series can measure up to 10kW. The beam diameter should always be as large as possible
to avoid damage to the absorber. We recommend between 70% and 90% of the nominal head
aperture, e.g. 4.6-5.2 cm in diameter for both Flash power meters.
In any case, the beam’s incident area should not be less than 10% of the detector’s aperture. Please
contact Gentec-EO to make measurements with such smaller beams.
The damage threshold is decreasing with the laser beam power. The following table calculates the
diameter correspo
nding 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.
Yag 1,064 µm
Laser FLASH-500-55 FLASH-3K-55
Beam Damage Damage 1/e² Min. 1/e² Damage Damage 1/e² Min. 1/e²
Power Threshold 1
Beam Diam.
2
,
3
Beam Diam.
2 ,3,4 Threshold
1
Beam Diam.
2 ,3 Beam Diam.
2 ,3, 4
1 Peak Intensity.
2 For Gaussian beam profile, the peak intensity is twice the beam power.
3 Diameter of a circle corresponding to 86% of the entire beam power.
4 Including a security factor of 50%