Grinding aspheric and freeform micro-optical molds

Yazid E. Tohme

doi:10.1117/12.712706

7 March 2007 Grinding aspheric and freeform micro-optical molds

Yazid E. Tohme

Proceedings Volume 6462, Micromachining Technology for Micro-Optics and Nano-Optics V and Microfabrication Process Technology XII; 64620K (2007) https://doi.org/10.1117/12.712706
Event: MOEMS-MEMS 2007 Micro and Nanofabrication, 2007, San Jose, California, United States

Abstract

Fueled by the need for better performing optics, glass optics are now replacing plastic optics in many industrial and consumer electronic devices. One of these devices is the mobile phone camera. The optical sub-assembly in a mobile phone includes several micro lenses that are spherical and/or aspherical in shape and require form tolerances in the submicron range. These micro glass lenses are mass produced by a replication process known as glass press molding. The process entails the compression of a glass gob between two precise optical quality molds at an elevated temperature, usually near the transition temperature of the glass material. The elevated forces and temperatures required in the glass molding process limits the materials of the molds to very tough materials such as tungsten carbide or silicon carbide. These materials can withstand large pressing forces at high temperatures without any significant deformation. These materials offer great mechanical properties for glass press molding but they are also a challenge to machine to submicron accuracy. The work in this paper discusses a deterministic micro grinding manufacturing process referred to as wheel normal grinding, which is utilized to produce these optical quality molds. Wheel normal grinding is more accurate and more deterministic than most other grinding techniques and can produce molds to the form and finish tolerances required for optical molding. This method relies on the ability to recognize and compensate for grinding wheel wear and machine repeatable errors. Results will be presented to illustrate the accuracy of this micro grinding technique.

Citation Download Citation

Yazid E. Tohme "Grinding aspheric and freeform micro-optical molds", Proc. SPIE 6462, Micromachining Technology for Micro-Optics and Nano-Optics V and Microfabrication Process Technology XII, 64620K (7 March 2007); https://doi.org/10.1117/12.712706

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