In the design of any optical system, managing cost versus performance is always a challenge. When faced with this challenge, it is important to realize that properly tolerancing the design is every bit as important as the design itself.
Often suppliers face a situation where a customer requires that lenses and related optical components meet quality or performance standards that are out-of-line with the end-user application. Lack of design experience, uncritical use of catalog specifications, and overreliance on computer-aided design systems all contribute to this problem.
However, there are a few tips designers can use to avoid overspecification and achieve a high performing, cost-effective product.
Five Tolerancing Guidelines for Smart Designers:
Test tolerances throughout the design process. This will help to identify and resolve tolerances and avoid tolerances that are too tight.
- Don't rely solely on the "optimization" features of design software. Today's optical design packages are extremely capable and fast, but optimization and good judgment aren't easy to automate.
- Where useful, request recent measurements of test plates used by the parts fabricator, so that current values can be incorporated into the uncertainty of each optical surface.
- Incorporate variability of materials into the tolerance equation, adjusting the design to accommodate the range of refractive indices for optical glass, for example, based on recent measurements of lots from which lenses or other elements will be fabricated.
- Work with your supplier, who should have the in-house expertise and knowledge of parts and materials availability and cost/performance tradeoffs that come from years of project success.
Download our Tolerancing Guide for more advice on balancing optical surface quality and cost.