Dr. Yazid E. Tohme Profile

Dr. Yazid E. Tohme

Director of Engineering at FARO Technologies Inc

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Publications (3)

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Proceedings Article | 14 May 2007 Paper

Advances in the production of freeform optical surfaces

Yazid Tohme, Suneet Luniya

Proceedings Volume 10316, 1031612 (2007) https://doi.org/10.1117/12.719648

KEYWORDS: Optics manufacturing, Freeform optics, Content addressable memory, Manufacturing, Computer aided design, Diamond machining, Optical design, Surface finishing, Phase measurement, Software development

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Recent market demands for free-form optics have challenged the industry to find new methods and techniques to manufacture free-form optical surfaces with a high level of accuracy and reliability. Production techniques are becoming a mix of multi-axis single point diamond machining centers or deterministic ultra precision grinding centers coupled with capable measurement systems to accomplish the task. It has been determined that a complex software tool is required to seamlessly integrate all aspects of the manufacturing process chain. Advances in computational power and improved performance of computer controlled precision machinery have driven the use of such software programs to measure, visualize, analyze, produce and re-validate the 3D free-form design thus making the process of manufacturing such complex surfaces a viable task. Consolidation of the entire production cycle in a comprehensive software tool that can interact with all systems in design, production and measurement phase will enable manufacturers to solve these complex challenges providing improved product quality, simplified processes, and enhanced performance. The work being presented describes the latest advancements in developing such software package for the entire fabrication process chain for aspheric and free-form shapes. It applies a rational B-spline based kernel to transform an optical design in the form of parametrical definition (optical equation), standard CAD format, or a cloud of points to a central format that drives the simulation. This software tool creates a closed loop for the fabrication process chain. It integrates surface analysis and compensation, tool path generation, and measurement analysis in one package.

Proceedings Article | 14 May 2007 Paper

Solutions for the fabrication of freeform optical surfaces

Robert Cassin, Yazid Tohme

Proceedings Volume 10316, 103161U (2007) https://doi.org/10.1117/12.719678

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The fabrication of different spherical and aspherical optical surfaces often presents various challenges. Additionally, the fabrication of freeform optics presents special and often unique challenges beyond standard rotationally symmetric components. Consequently, not all freeform optics can be manufactured utilizing standard methods. Diverse manufacturing techniques are necessary depending on part size, surface frequency content, surface slopes, and required materials. These techniques could include single point diamond machining using our slow slide servo technique, fast tool servo machining, raster fly-cutting, micro-milling, and freeform deterministic grinding. There is a recognized need in the industry to simplify and improve the production of aspheric and freeform optical surfaces. Recognizing this demand Moore Nanotechnology Systems has developed an innovative new software tool called NanoCAM™. This presentation will describe the latest advancements made at Moore Nanotechnology Systems to integrate the entire production cycle in one comprehensive software tool that can interact with all systems from optical design tools, to production machines as well as measurement equipment. NanoCAM™ solves the complex challenges involved with freeform machining, and the result is improved product quality, simplified processes, and enhanced performance. NanoCAM™ is designed to be used with the Nanotech 250UPL, Nanotech 450UPL, and Nanotech 350FG as well as the Nanotech Fast Tool Servo (NFTS-6000).

Proceedings Article | 7 March 2007 Paper

Grinding aspheric and freeform micro-optical molds

Yazid Tohme

Proceedings Volume 6462, 64620K (2007) https://doi.org/10.1117/12.712706

KEYWORDS: Aspheric lenses, Glasses, Diamond, Spindles, Spherical lenses, Optics manufacturing, Surface finishing, Tolerancing, Glass molding, Freeform optics

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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.

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Conference Committee Involvement (3)

Optifab 2009

11 May 2009 | Rochester, New York, United States

SPIE Optifab

11 May 2009 | Rochester, United States

Optifab 2007

14 May 2007 | Rochester, New York, United States

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