Freeform surface optical components have gained increasing attention in recent years, and higher requirements have been put forward for economical and efficient fabrication techniques.Single point diamond turning with fast tool servo is the method to process nonrotational symmetric surface with high quality. However, the surface quality of different areas is not always the same in this way. In this paper, a microlens array is fabricated by fast tool servo cutting. The reason of surface difference is analyzed theoretically, and the Position-Velocity-Time interpolation method is used to improve the surface quality and reduce the difference between different regions. A microlens array consisting of 900 spherical lenslets was machined, the size of each spherical lenslet is 1.08 mm×0.5 mm. The form error of lenslet is about 1.5 um at the edge and 1 um at the center respectively, and the roughness value of Sa are 11 nm and 8.6 nm, the results show that the theory and simulation are correct, and the ability of fast tool servo technology to realize freeform processed with high precision is demonstrated.

In this paper, PbI2 thin films with a uniform surface morphology and compact structure were prepared by adjusting the spin coating process parameters. On such a basis, the PbS/PbI2 heterojunction was fabricated on the PbI2 surface by the method of in situ chemical replacement growth. The results show that the PbS/PbI2 heterojunction grown by this method has a clear interface and is closely combined. The introduction of a PbS layer enables its spectral response range to cover the visible and near-infrared regions. Compared with the PbI2 thin film device, its responsivity is increased by three orders of magnitude, its response time reduced by 42%, and its recovery time decreased by nearly 1/2 under 450 nm illumination. In the case that there is no response for the PbI2 thin film device under 980 nm illumination, the specific detectivity of the PbS/PbI2 heterojunction device still amounts to 1.8 × 108 Jones. This indicates that the in situ chemical replacement is a technique that can construct a high-quality heterojunction in a simple process. PbS/PbI2 heterojunction fabricated by this method has a visible–near-infrared light detection response range, which provides a new idea for creating visible–near-infrared common-path detection systems.

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