Design and Analysis of Combinatorially Assembled Optical Systems

Producing high quality optical systems at reasonable cost is a challenge and

solutions enabling cost-efficient production in small to medium quantities need

to be developed in order for Germany to stay competitive on the global market.

Both, performance and cost are largely influenced by manufacturing and

assembly tolerances and frequently compensation such as alignment is required

to achieve the demanded performance.

This dissertation systematically develops combinatorial assembly as a

compensation strategy which does not require iterations and as such is suitable

for automated production of small series. A pool of components and

subassemblies, necessary for the assembly of a series of systems, is

characterized prior to the assembly and measurement results are stored in a

database. Then, optimal component combinations are found during a modelbased

selection process.

The application of combinatorial assembly to optical systems requires a delicate

choice of parameters for characterization, modules and tolerances before

components are manufactured. Predicting the as-built performance of

combinatorially assembled systems with high accuracy is therefore necessary

and a dedicated tolerance analysis concept based on Monte Carlo analyses is

proposed. The concept is universally applicable to problems that can be

modelled with ray-tracing and is implemented using a combination of raytracing

software, logic calculator and database. This makes it possible to

accurately analyze the impact of tolerances, production volume and additional

uncertainties on the performance of combinatorially assembled optical systems.

For optimal compensation, tolerance distributions should match each other in a

specific way and it is illustrated that this can be difficult to realize for some lens

designs due to manufacturing limits. In order to reduce this restriction, design

strategies increasing combinatorial compensation are derived. Adapting the

optical design from the outset to suit combinatorial assembly can shift

tolerance sensitivities from one component to another. Compensation can be

enhanced and the influence of uncharacterized parameters reduced. In using

combinatorial assembly in conjunction with desensitization, systems with higher

nominal performance yet reduced tolerance demands can be build. This is an

entirely new approach and a first step towards a more integrated development

of optical systems.