| Popis: |
Micro-lenses and micro-lens arrays are widely used for various applications. Monolithic arrays of cylindrical lenslets made of glass, semiconductors or crystals provide great advantages to laser applications, e.g. high efficiency, intensity stability and very low absorption. However, up to now, mainly symmetrical micro-lens surfaces are utilized in most applications due to design and manufacturing restrictions. The manufacture and application benefits of asymmetrical cylindrical-like micro-lens surfaces are enabled by LIMO's unique production technology. The asymmetrical shape is defined by uneven-polynomial terms and/or an asymmetrical cut-off from an even polynomial surface. Advantages of asymmetrical micro-lenses are off-axis light propagation, the correction of aberration effects or intensity profile deformations when the illuminated surfaces are not orthogonal to the optical axis. First application results of such microlens arrays are presented for beam shaping of high power diode lasers. The generation of a homogeneous light field by a 100 W laser with tilted illumination under an angle of 30-50° is shown. A homogeneity of better than 90% was achieved for a field size of 270 mm x 270 mm. In laser direct write processes a top hat profile has several advantages compared to a Gaussian beam profile, especially the throughput of the system and quality of the structures can be improved. Novel patterning results with TopHat-converted single mode lasers and a special Gaussian-to-TopHat galvo scan system are demonstrated for solar cell technology. |
