Calendar

Optics and Photonics
Aug. 26-30, 2007
San Diego, CA
http://spie.org

Introduction to CODE V
Oct. 29-Nov. 2, 2007
Pasadena, California
Click here for details and to enroll

Advanced Topics in CODE V November 5-9, 2007
Pasadena, California
Click here for details and to enroll

Quick Tip – Finding the Most Effective Compensators during Tolerancing and Alignment

For any optical system that is destined to be manufactured, a critical step in the design process is defining a tolerance budget to accurately predict the as-built performance, including the effects of compensators.  CODE V's Wavefront Differential Tolerancing feature (TOR) provides optical engineers with a powerful tool to quickly and accurately determine the effect of manufacturing tolerances, including which compensators are most effective in reducing manufacturing costs.  Once the system is built, CODE V's Alignment feature (ALI) can be used to reduce or eliminate aberrations caused by any misalignments.  It predicts the adjustments needed to user specified optomechanical adjustments (i.e., compensators) in order to recover performance loss due to misalignments during assembly.  Measured wavefront data for the as-built system is imported into CODE V from commercial interferometers (e.g., Zygo, Veeco, 4D Technology, etc.) and CODE V then determines the adjustment motions.

During both the tolerancing and alignment processes, determining the most effective set of tolerances can greatly reduce the cost associated with building the final system.  Both CODE V's TOR and ALI options provide the use of a Singular Value Decomposition (SVD) algorithm to determine which compensators are most effective.  Users can initially define a large set of compensators, based on any possible adjustments that can be made to the as-built system.  SVD can then be used to determine the most effective subset of the larger set of compensators.  Often two or more compensators can have similar effects on the alignment solution and lead to exaggerated compensation motion.  Using SVD helps designers identify the minimum set of compensators to achieve the final performance goals, eliminating any unnecessary adjustments, and thereby reducing manufacturing costs.  SVD can also be used to determine how best to redistribute the motions of the compensators to simplify the alignment processes and avoid part interference.

For more information on what SVD is, its benefits, and examples of how it can be used in CODE V's TOR and ALI options, a copy of a presentation from the 2007 CODE V User Group Meetings,  titled "Compensator Selection Using Singular Value Decomposition (SVD) for Tolerancing & Alignment," is available for download ORA's Customer Service Web Site, www.oraservice.com.  You can find this presentation under CODE V Support > User Group Presentations.

Updates to ORA's Customer Service Web Site

The following additions have been recently made to ORA's Customer Service area of the web, www.oraservice.com , under CODE V Support:

• The July issue of CODE V Enews, which highlighted several new presentations developed for the 2007 CODE V User Group meetings, can be found under CODE V Enews & Tips.  The User Group presentations themselves can be found under User Group Presentations.
  
  
• Two new technical papers written by ORA Engineers can be found under Technical Papers:

"Slope Error Tolerances for Optical Surfaces," John R. Rogers, paper TD04-4, SPIE Optifab conference, Rochester, NY, May 2007, (Invited paper).  A corresponding presentation on this paper can also be found under the 2007 User Group Presentations.

"Lens Design for Chip Manufacture: Lens tolerancing on linewidth calculations in hyper-NA, immersion lithography systems", R.L. Gordon, M.P. Rimmer, Proc. SPIE, Vol. 6154