Laser Damage Testing
REO provides some of the highest laser damage resistant optics in the world and is committed to the highest possible standard for testing and qualification of these optics. With our own fully automated laser damage test capability, REO not only conducts routing production testing of our products, but also continuously advances the state of the art in understanding laser damage mechanisms and test methodologies.
REO’s primary test system is comprised of a ~20ns pulse length 1064nm Laser Induced Damage Threshold (LIDT) test system for verification of high fluence operational specifications of optical substrates and their dielectric coatings according to ISO 21254-2 or other similar test protocols.
The system is fully automated, ensuring high levels of production efficiency, reliable and measurable consistency of performance, and extensive data collection to allow analysis and reference for future studies and improvements of the test system as well as optical component fabrication and performance.
The four functional subsystems of the test station are shown in the schematic below. First, a stable high-energy laser and attenuator is used as the energy source for providing carefully measured and controlled energy doses to the Device Under Test (DUT). Next, an optical system is implemented to focus the laser to achieve a desirable spatial profile at the DUT as well as condition the beam for optimal beam waist and focal length performance, and also to split off a diagnostic beam for metrology of energy and spatial characteristics. Third, an inspection system consisting of a microscope, digital camera system, and dark-field illumination system is used to record damage events. Fourth, a motorized XYZ stage is used as a transport system to move the DUT between the test beam and the inspection station.
The control of the laser and attenuator, the transport system, and inspection system is fully automated. Also, all sensor systems are monitored and logged via a separate software system. This allows for real time automation feedback as well as minimal operator time and intervention while running a test.
The operation of the system involves defining test parameters, the loading and alignment of a DUT, and initiation of the test. Analysis of the metrological and inspection data is performed by software upon completion of the testing sequence. Final reports are generated from the automated data analysis results. Human review of automatic analysis is available for improvements and more careful event analysis.