The laser damage threshold is an important parameter that characterizes the resistance of a medium to laser-induced damage. Laser damage refers to the permanent changes in the performance or structure of optical materials or optical thin films under the action of a laser. The high concentration of laser energy can cause local deformation or even complete damage to the medium’s interior or surface. The maximum laser power that a medium can withstand per unit area is called the laser damage threshold of that medium.
Main challenges in increasing the laser damage threshold of optical components come from:
Methods for preparing high damage threshold components:
◆Material aspect: For optical component products requiring high resistance to laser damage, the substrate material selection prioritizes parameters such as high resistance to damage, low absorption, and low hydroxyl (OH) content, such as Corning 7980 ArF, Corning 7980 KrF, Corning 7979, Suprasil 300, etc. The specific glass type is then chosen based on the customer’s wavelength of use.
◆Polishing aspect: Special ultra-smooth polishing processes are employed, with white light interferometry detecting surface roughness below 1 Å, and no scratches or pits visible under a 100x microscope, achieving a surface quality of 0/0. Polishing is the most critical process in determining the quality of optical components, and extremely low surface roughness and surface impurities and defects can effectively enhance the resistance of optical components to high laser damage.
◆Coating aspect: Ion beam sputtering (IBS) technology is used, and by optimizing the coating design and improving the coating process parameters, the weak absorption of the coating layer can be controlled to below 5ppm. Extremely low coating layer absorption can greatly reduce the thermal effects produced by the laser on the coating layer, making the product more resistant to laser damage in high laser applications.
The company’s two key technological advantages:
◆Ultra-smooth polishing technology: The roughness reaches the 0.1nm level, meeting the roughness requirements for EUV mask substrates.
◆Ultra-precision coating technology: Breaking through the Mo/Si multilayer film technology, with film thickness control precision better than 0.1nm.
Application fields
