Advancement in Optical Coatings Technology at LASER COMPONENTS

09 Aug 2010

A new measurement system for optical broadband monitoring of layer thickness opens the door to innovative products. The following sections summarise new capabilities and growth areas.

Optical Coatings at LASER COMPONENTS Dielectric coatings have been manufactured in house at LASER COMPONENTS since 1986. The term ‘laser optics’ covers everything from mirrors, lenses, and output couplers, to polarisers used in laser systems. Using new technology and engineered process control, both existing products can be improved and new innovative products manufactured.

Our in-house optics production site has a wide variety of coating technologies. The most common method is known as physical vapour deposition (PVD) or e-beam. In this method, dielectric materials are evaporated using an electron beam in a vacuum. These inexpensive coatings feature very high damage thresholds, particularly with laser pulses in the nanosecond range.

Designed for use with the highest laser power achievable, we have ion-assisted deposition (IAD) coatings available. The coating chamber features a powerful ion source. The condensed layers are exposed to a jet of low-energy ions. The resulting layers are very compact and do not exhibit thermal drift.

Online Measurement of Coating Thickness The demands made on high-quality coatings in the laser industry are constantly increasing. To meet some of these demands, such as extremely high production precision and batch reproducibility, a broadband monitoring system for the optical in-situ measurement of layer thickness was recently installed in the IAD coater.

In contrast to conventional testing methods, with in-situ monitoring, the thickness of the deposited layer is measured directly on a substrate inside the chamber. A major advantage is that the entire visible optical spectrum is used to monitor the layer thickness.

The combination of ion-assisted coatings with the broadband monitoring of layer thickness leads to advantages when implementing complex coatings. Coatings with improved specifications can be implemented just as easily as new products.

The broadband monitoring system makes it possible to manufacture a multitude of other complex coating designs. For example, very steep edges in short and long-pass mirrors can be produced. In dichroic mirrors a transmission of far above 95% can be achieved. The reflection values are over 99%.