Chapter 9. Calibration, Maintenance And Troubleshooting; Calibration Of Thermopile Or Rp Sensors - OPHIR vega User Manual

Chapter 9.
Calibration, Maintenance and Troubleshooting

9.1 Calibration of Thermopile or RP Sensors

9.1.1. Absorber types and Method of Calibration of
Ophir Power Meters
9.1.1.1. Types of Ophir Laser Absorbers
Two types of absorber surface are used in Ophir thermal
measuring sensors.
1. Surface Absorbers:
BB (broadband) absorber
On standard, high power density, broadband Ophir power
monitor sensors, a special refractory coating is used to
provide high absorptivity from the UV through the IR. This
coating can withstand very high power densities, up to 28
kW/cm², without changing calibration. The absorption of
this coating is above 85% for most of its range, as shown
in graph 1 below.
EX (excimer) absorber
The EX absorber provides high absorption in the UV, and
it can withstand both the pulse energies and the average
power of excimer lasers. These discs also have excellent
absorption for 10.6 µm and other wavelengths. They can
therefore be used for other types of lasers as well. The
absorption of the various Ophir absorbers as a function of
wavelength is shown in graph 1 below.
LP1 (long pulse) absorber
This absorber has a very high damage threshold for long
pulse (ms) or continuous lasers and is therefore
offered for use with high power and energy lasers. It is
calibrated for the spectral range 250 – 2200nm with some
sensors also being calibrated for 2940nm.
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