article posted 21 March 2016
Andrea Barz studied chemistry at the Friedrich-Schiller-University in Jena. She wrote her doctoral thesis on the chemistry of phosphate glasses and its structural analysis working in this field until
2006. Since then she has been doing research in laser material processing and optical technology at the Ernst-Abbe-University of Applied Sciences in Jena.
Development of a new joining technology for coated optical components
Andrea Barz*1, Jens Bliedtner1, Carolin Lampert1, Stefan Schippel2
1 Ernst-Abbe-University of Applied Sciences, Jena, Germany
2 Layertec GmbH, Mellingen, Germany
Currently the achievable imaging quality in the field of optical assembling is limited due to insufficient or very costly joining technologies. The frequently used joining technologies bonding and cementing can lead to wedge errors of the components. Their low long-term stability under the influence of UV and high energy radiation such as laser radiation is another limiting factor of such optical systems. Changes of the cementing or bonding materials (discolouration, decomposition) lead to a reduc- tion or complete loss of the component's functionality.
Therefore, a new joining technology for coated optical components is developed with- in a research project, which allows high accuracy of fit and shape with small angle
and centering errors of the assembly, e.g. for beam splitter cubes. Here, optical ele- ments with functional dielectric and metallic coatings are firmly bonded resulting in a total system without the need for a separate mounting of the individual components (fig. 1).
Fig. 1: Coated diffusion-joined component
Thus, all optical function elements have defined shape and position to each other. They are joined through a thermally supported diffusion process, preserving the func- tional layers and without using any adhesives (fig. 2).
Fig. 2: SEM-image, cross section of a joined component
Wedge errors as well as the input of extraneous chemical material can be avoided by joining without interlayers.
Resulting from this are monolithic optical components with
• higher mechanical strength and dynamic stability
• high thermal stress resistance as well as radiation resistance,
• higher resistance to thermal shock and UV-radiation as well as lower material fatigue and ageing.
The new joining technology does not only enable the manufacture of known optical assemblies with improved characteristics but also allows the fabrication of new opti- cal components.
Thus, it is interesting for a wide range of applications in the fields of laser and medical technology, metrology, sensor and communication technology as well as image processing.