Optomechanical Tolerancing and Error Budgets
Optical designers and optomechanical engineers must work together to develop optical systems. Performance, manufacturability, and cost are most often the key requirements to be competitive. Unfortunately, a perfect optical system cannot be built due to limitations of fabrication and alignment methods. Even with the modern available level of manufacturing sophistication, optical and optomechanical components always have dimensional and geometric errors. These errors tend to degrade the expected optical performances as predicted by the optical design code through simulations performed on the nominal optical layout. Considering this, an important task for the optical designers is to perform a comprehensive tolerance analysis in order to determine the level of precision required for the manufacturing of the optical elements and for the positioning of those elements in the layout. Collaboration between optical and optomechanical engineers is required at this stage since a complete tolerance analysis involves both optical and optomechanical tolerances analyses. This process requires iterations between the two disciplines, and the goal is to create a realistic tolerance budget, that is, the allocation of the manufacturing uncertainties on each of the optical components and mechanical parts. This step of the design process is very important because the results of the tolerance analysis directly impact the optical system cost and complexity in terms of manufacturing tolerance and alignment.