Methods are presented which have been evolved in the authors institute for the development of optical instruments for use in spacecraft, with the aim of demonstrably assuring the quality of a corrplex product in away that can be sensibly implemented in a small scale organisation. Rather than specifying generally applicable organisational checks and controls on the development process, it is attempted to establish for any particular case with administrative type of precision what materially has to be done to establish acceptable confidence in the quality of the product. To this end already the conceptual design is broken dawn into a hierarchy of constituents. Apart from its bookkeeping functions, this breakdown in the structure of its hierarchy is to be regarded as a design for the process of realisation, supplementing the design in its conventional sense which defines the end point of the process. Product- and process design are related and elaboration of the latter can produce corrective feedbacks to the former. It also brings to light the uncertainities that have to be resolved in the development programme before starting to realise the final product. Generally these uncertainities are of the following kinds: a. will components, materials and processes be suitable b. will the concepts be suitable c. will the concepts be compromised or disturbed by system complexities d. will the means and methods to reach and verify quality be suitable. The development programme can be structured to answer such questions. It will consist of several "design stages". Within each stage one or more models will be realised. The models generally can be distinguished into types:
-Evaluation samples. Models without strict configuration and traceabilitycontrol to answer a.
-Development models. Partial models, however to best standards for .the constituent or aspect in question to answer mainly b.
-Engineering models. Models of full complexity but of relaxed quality to answer mainly c and d.
-Qualification models. Models of full complexity and full quality for a dress rehearsel of the complete process.
The breakdown designing the process of realisation then can be repeated for each model. For further clarity the work at each constituent level for each model can be distinguished into: theory, evaluation, design, deliveries, parts manufacture, assembly and test, tools and support equipment. A development programme structured in this way can be evaluated for its own merits and the documented results of the work can be compared to it by an informed person without recourse to a complex organisation.