Lenses & Protective Glass for Fiber Lasers
Other optics include lenses and protective windows for fiber laser systems. Fiber optics or laser applications that use wavelengths around 1060 - 1080 nm, the wavelength for fiber lasers is standard 1070 nm, of course, cannot use the same optics as for systems based on the CO2 wavelength.
Within the wavelength range of 1060 - 1080 nm, the material in lenses and protective windows is usually BK7 or FS (Fused Silica/Quartz) glass, which is about the same as in regular camera lenses. BK7 is of a slightly lower quality than FS or quartz, so FS is usually used, which has a higher thermal stability than BK7 and is therefore more insensitive to rapid temperature changes.
A material used for better and more durable glass is sapphire glass, which is industrially produced sapphire, which has very good properties that protect against scratches and is thermally very stable. Sapphire is, however, considerably more expensive than FS, but in sensitive applications the advantages can outweigh the price.
There are additional qualities of glass, but these are uncommon and we can mention one that is the best of all, diamond. Diamond is more expensive than the others but also so good that if you protect it from dirt, it will last almost forever. Particularly suitable for lenses that are protected by protective windows, but protective windows can sometimes be made of diamond with advantage, as in addition to the excellent physical properties, it is also easier to clean as dirt etc. does not stick as easily to the diamond surface. Diamond, however, is harder to get hold of and, as mentioned, considerably more expensive.
As a coating, there are as usual a lot of different substrates and a lot of secrets lie behind it, but AR - Anti Reflex is the commonly used one and the parameter that is usually mentioned when talking about protective glass and lenses in FS or other fiber laser-adapted optical elements.
Protective windows is available in a variety of different dimensions for different machines. Contact us if you need protective glass, we can produce all dimensions. What we usually ask for is diameter (for round glasses) or side length (width x length) and thickness.
Please contact us if you would like help in producing protective glass and lenses for your fiber laser!
Cleaning and maintenance
An effective cleaning agent for fiber laser optics is Isopropanol (IPA), which can be used with advantage during daily maintenance.
Used together with cleaning papers specifically intended for cleaning laser optics as these are of high quality and do not lint, the same applies to special tops intended for fiber laser optics. It is unnecessary to save money on the wrong cleaning equipment and thereby risk damaged optics that are significantly more expensive to replace.
If the optics are heavily soiled, it can be saved if you use acetone after an initial cleaning with acetic acid (20%, diluted with water). Acetone can of course be used for daily maintenance just like IPA.
Cleaning should always be done in a clean, dust-free environment, e.g. never remove the focusing lens directly from a dirty industrial environment, as the risk is very high that dust particles will enter the cutting head and thus it can quickly become contaminated and require thorough and expensive cleaning in a clean room.
