Valentin Morasch

Self-optimizing assembly of laser systems

Laser assembly can be a tedious task if performed manually. Especially if miniaturization of the laser is desired, robot-based assembly can greatly improve quality, performance and throughput, while self-optimization is regarded as a strategy to reduce planning efforts and increase the robustness of the assembly. An automated laser assembly system has been developed together with a concept to increase the autonomy through a multi-agent system control structure. The multi-agent system allows assembly steps like sequence planning, measurement of components and deviations, selection of components, soldering elements onto a carrier plate and active resonator alignment to be handled by the system itself and enables the assembly system to uniquely plan every laser system and execute its assembly within a flexible robot-based assembly cell.

Passive alignment and soldering technique for optical components

The passive-alignment-packaging technique presented in this work provides a method for mounting tolerance-insensitive optical components e.g. non-linear crystals by means of mechanical stops. The requested tolerances for the angle deviation are ±100 μrad and for the position tolerance ±100 μm. Only the angle tolerances were investigated, because they are more critical. The measurements were carried out with an autocollimator. Fused silica components were used for test series. A solder investigation was carried out. Different types of solder were tested. Due to good solderability on air and low induced stress in optical components, Sn based solders were indicated as the most suitable solders. In addition several concepts of reflow soldering configuration were realized. In the first iteration a system with only the alignment of the yaw angle was implemented. The deviation for all materials after the thermal and mechanical cycling was within the tolerances. The solderability of BBO and LBO crystals was investigated and concepts for mounting were developed.

Soldering techniques for the assembly of high power solid-state lasers

Soldering techniques are of increasing interest for the manufacturing of laser systems. High thermal conductance required for effective and long-term-stable cooling of laser components and a low sensibility to environmental influences like temperature changes and humidity are the main reasons to join components by soldering. Compared to conventional mounting techniques, soldering demands highly complex process control. Detailed knowledge about the influence of mechanical stress caused by thermal expansion mismatch is necessary to properly choose not only the process strategy but also the dimensions of the components. This paper reports on the development of soldering techniques for the surface-mounted assembly of laser components such as lenses, mirrors, laser-crystals and nonlinear crystals used for the assembly of a miniaturized marking laser system “MicroSlab”[1].

Single-frequency Nd:YGG laser at 935 nm for future water-vapour DIAL systems

For future satellite based water vapour DIAL systems, efficient and rugged laser sources are required preferably around 935 nm. The quasi 4-level transition from R2 to Z5 in Nd:YGG is a promising candidate for its direct generation. Q-switch operation at 100 Hz with pulse energies up to 7.7 mJ is reported as well as single frequency operation with an injection seeded system stabilized by ramp-and-fire-method. The pulse energy of a 4.5 mJ oscillator was scaled to 32 mJ with an InnoSlab-based amplifier at nearly diffraction limited beam quality of M2 < 1.4. Heterodyne measurements show a line width of less than 28 MHz.

Integrative Business and Technology Cases

In order to strengthen the relevance and integrativity of research in the Cluster of Excellence, current best practice “business and technology cases” were selected. Hereby the theories, hypotheses, predictions and technology projects developed in the Cluster of Excellence are evaluated and advanced in close collaboration with leading production companies in Germany and Europe. To make the work more transparent, different application scenarios will be developed.

Self-optimization of robot-based resistance soldering for the assembly of optical elements in solid-state laser systems

During the assembly of customized miniaturized solid-state lasers, robot-based operations can significantly reduce cycle times and improve performance and quality. Automation of the resistance soldering technique for optical components based on planar technology described can be self-optimized to compensate component and process tolerances, cope with different element geometries and therefore reduce planning efforts and facilitate the operators work.

Business and Technology Cases

Um die Relevanz und Integrativitat der Forschungsarbeiten im CoE zu verstarken, wurden aktuelle Best Practice „Business and Technology Cases“ ausgewahlt. Hierdurch werden die erarbeiteten Theorien, Hypothesen, Pradiktionen und Technologieansatze in Zusammenarbeit mit fuhrenden Produktionsunternehmen aus Deutschland und Europa uberpruft und weiterentwickelt. Um die durchzufuhrenden Arbeiten transparent zu machen, werden ferner unterschiedliche Anwendungsszenarien entwickelt.