Comparing with the writing method of plane pattern, spherical pattern' has some remarkable different on several points. Firstly, it is difficult to spin-coated a uniform photoresist film on a spherical substrate, especially the ratio of spherical radius to caliber is smaller, and the spin-coated way must match the ratio of spherical radius to caliber. Secondly, if the sphere couldn't be regarded as a plane, a so-called concentric optical scan movement way must be applied for the generation of spherical pattern, because the reflex of substrate will affect the quantity of illumination. Commonly, an alignment technique is indispensable with pattern generation of spherical surface by the concentric optical scan in order to ensure the orthogonal intersection of focusing laser beam and writing surface. Thirdly, a uniform velocity control must be considered for the laser direct writing method on a spherical substrate. Otherwise, the exposure time of photoresist will be different, and the line widths of pattern will be also different at different areas. Fourthly, commonly, because the errors of concentric machine and substrate surface shape are bigger, so focusing servo-control technique is also needful for writing a pattern on a spherical substrate. Focusing servo-control may keep the focal spot on the spherical surface by a focus detection and control system in the course of writing pattern. Using these techniques, we fabricated a line width of 7μm and a period of 600μm isometric mesh on the concave of a spherical substrate.

Date Published: 19 November 2007
PDF: 7 pages
Proc. SPIE 6724, 3rd International Symposium on Advanced Optical Manufacturing and Testing Technologies: Design, Manufacturing, and Testing of Micro- and Nano-Optical Devices and Systems, 67240B (19 November 2007); doi: 10.1117/12.782499

Published in SPIE Proceedings Vol. 6724:
3rd International Symposium on Advanced Optical Manufacturing and Testing Technologies: Design, Manufacturing, and Testing of Micro- and Nano-Optical Devices and Systems
Sen Han; Tingwen Xing; Yanqiu Li; Zheng Cui, Editor(s)