Another intriguing possibility arising from wafer-scale lens manufacture results from the combination of materials and process. Because the master only comes in contact with liquid polymer, it does not have to be rigid like a mold for an injection-molded lens. Instead, the master can be compliant or slightly rubbery. This makes it possible to design optical surfaces with re-entrant features. None of the other volume manufacturing techniques have that capability.

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In common with lenses manufactured using traditional processes, wafer-scale lenses can be coated to provide additional optical functionality or mechanical durability.

Wafer-scale processing makes it possible to manufacture small, simple lenses very economically in high volume. But with minimal additional manufacturing effort, it is possible to fabricate optically complex components. The challenge of wafer-scale lens technology is determining how to leverage the technical possibilities offered to produce optical designs where a multi-functional component substitutes for a single discrete lens in an optical train. Figure 3 shows an example of the type of integrated optical component that can be realized using wafer-scale lens manufacturing techniques.

Conclusions

Wafer-scale manufacturing ideally suits the manufacture of miniature optical lenses. The smaller the area of the part, the more economically attractive the process becomes. The wafer-scale manufacturing process entails replication of masters on flat substrates from liquid precursors. This provides great flexibility in terms of the materials for each optical surface as well as the lens shape and profile. The substrate can be optically active and provide additional functionality like filtering, stopping and diffraction. Wafer-scale manufacturing therefore makes it possible to produce multi-functional optical components in the same form factor as a single discrete lens.

Yehudit Dagan is vice president of marketing for Tessera Technology’s wafer-level camera (WLC) technology. She holds a bachelor’s degree in physics and a master’s degree in heat transfer engineering, both from Tel Aviv University, Israel, as well as a master’s degree in management from the Polytechnic University in New York. She can be reached at ydagan@tessera.com.

Giles Humpston serves as director of applications for Tessera (UK). He is a metallurgist by profession and has a doctorate in alloy phase equilibria. Also, he is a cited inventor on more than 75 patents and has co-authored several textbooks on metallic joining processes. He can be reached at ghumpston@tessera.com.

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