The path to volume production for CPV optics

A crucial prerequisite for a commercial success of large-scale CPV is the capability for mass production of the manufacturing processes. For the optical components (primary and secondary lenses) there do exist various production concepts with different potential for cost efficient mass production. The most promising concept is (compression) injection molding, a process technology for optical components already proven in mature industries like Automotive or Semiconductor. While the capability of the injection molding process for a real mass production is already well established, it needs to be proven that also the high quality requirements in CPV can be met. Injection molded PMMA Fresnel lenses can be manufactured with peak-to-valley deviations less than 10 μm, showing nearly no inner stress and very low and homogeneous edge radii in the order of 5 μm. A second approach for primary Fresnel lenses, namely injection molding of Silicone on Glass allows to take advantage of the mass production capability of injection molding also for this 2 component lens. The inherent advantage of this production method is clearly the achievable lower cycle time (= lower cost) and the high quality, e.g. no bubbles or intrusions. For volume production, this process can be extended to a fully automated production line with standard production equipment. For secondary CPV lenses, the requirements for the material are significantly higher, especially for larger concentration ratios. Since the conditions are comparable to lenses for high-brightness LEDs, the materials and technologies used there can be transferred to CPV secondary lens applications. Transparent silicone lenses have been proven to withstand the radiation density as well as the high temperatures. Thus, the use of injection-moldable silicone lenses for CPV is obvious.