High Laser Power – High Damage Thresholds
Both the output power and the pulse energy of lasers are increasing; thus, the demands placed on hard and robust coatings are likewise increasing. Laser optics must withstand extreme stress; for this reason, many customers ask for laser optics with damage thresholds that are as high as possible.
Factors That Influence Damage Threshold
Beyond Borders
The damage threshold of a laser optic depends on many factors: The substrate material and the quality of the polish are just one issue. Usually, the coating is the limiting factor. Different coating materials can be used for the coating, and the different coating techniques result in differences in the hardness of the dielectric coatings. In addition, there is a certain degree of freedom in the coating design used.
These factors can be optimized to ultimately produce laser optics with the highest possible damage thresholds.
Measuring Damage Threshold
After the production of laser optics, the verification of the values at the measuring station ensures that the theoretical approaches fit reality.
Optimizing Layer Designs
Measurement of the damage threshold of different designs on the same substrates and comparison with layer design theory guarantees permanent improvements in coatings. The fact that these efforts are worthwhile has been proven in international studies performed by independent institutes.
THE LASER MARKET
Beyond Borders
The variety of laser systems is immense. The wavelength range extends from 193 nm in the UV to 2940 nm in the infrared and beyond. Suitable wavelengths and pulse lengths are selected depending on the application: for example, a distinction is made between lasers that are required to cut metal and lasers required for a surgical operation on a patient.
Nd:YAG lasers are thus commonly used in industry with wavelengths at 1064 nm and their harmonic or excimer lasers with 193 nm, 248 nm, and 308 nm; however, long-wave lasers with 2100 nm or 2940 nm are primarily used in the medical field.
In addition to the different wavelengths, a distinction in commercial lasers is made between continuous wave (cw)-mode lasers and pulsed systems. The pulse lengths range from the µs region to the ns and ps regions to the fs region.
