Optimization of UV lenses

10. January 2020

UV lasers become increasingly popular among various domains in the laser industry.

To support this triumphal process, Sill Optics is presenting innovations on a regular basis, satisfying wishes and requirements.

Comprehensive analysis with our customers showed that UV lasers admittedly offer many advantages via their short wavelengths and the associated high photon energy, but it takes a toll on the optical elements. Besides challenges at glass selection and preferably low absorbtion coatings, this statement is also true for the mechanical parts.

A long-term exposure to UV irradiation leads to bleaching of the typically black anodized aluminum housing. The light absorbing effect therefore vanishes. Additionally residues of redundant substances may lower transmission or increase the risk of damage due to deposition on top of lens elements. As an example beam expanders are often one of the first optical elements after the laser and therefore exposed to higher amounts of scattering irradiation.

For that reason Sill Optics established some standard products from anodized aluminum without any color additives. The origin of all our beam expanders, the EXP-series is now available with a complete colorless anodizing. The new EXN-series can be obtained with any of the magnification ratios or coatings known from the EXP-series. The same applies to the EXK-series, our beam expanders with short overall length. The equivalent with natural anodizing is called EKN-series.

In addition to the fixed magnification ratio beam expanders, Sill Optics also offers a few types of zoom beam expanders for many years. The most popular models are S6EXZ5310/xxx with 1-3x magnification ratio and the S6EXZ5075/xxx with 1-8x magnification ratio. The mechanical design of those models is more complex compared to the beam expanders with fixed ratio. Thus, many parts have not been from black anodized aluminum anyway. The remaining parts, which may come into contact with the internal radiation or stray light will be switched to colorless anodizing successively. For that reason, all zoom beam expanders will keep the original part numbers, but colors will change. Although this modifications were driven by impact of UV lasers, the changes will be implemented for all wavelengths.

Besides beam expanders all other optical components, as for example f-theta lenses, can of course also be made naturally anodized. Please ask our staff for this modification. The capabilities of Sill Optics regarding material of lens housings does not end at anodized aluminum. On demand, mountings made of stainless steel, titanium or Invar (64FeNi) are also possible, for example offering advantages in applications with large temperature variations or medical applications.