Producibility of low scatter, HIPed beryllium optics requires the manufacturer to know more than just the surface roughness or BRDF of his parts in work. The limitations of his test apparatus (spatial frequency range, height resolution, steepness of slopes, polarization sensitivity, available wavelengths) require that `overlapping' data be taken. This doesn't just mean that the `same' data needs to be taken on similar instruments. Instead, a collection of both quantitative and qualitative data from different types of analysis equipment must be combined to form a more complete picture of the interactions between the material and the wavelengths of interest. This paper discusses the results from several different tests which (when combined) give the manufacturer enough information to determine whether or not there is any more that can be done in his shop to improve the scatter function. We demonstrate that a variety of objective and subjective testing is necessary to determine the `true' characteristics of uncoated HIPed beryllium mirrors. We show results of testing, give a discussion on the interpretation of the data and demonstrate how it was used to optimize production results.
Many groups today are researching the characteristics of beryllium, in an attempt to find ways of producing high quality (low scatter) stable beryllium optics. This paper discusses a two-part study in which (1) an attempt is being made to determine the best, raw beryllium mixture and preparation, machining and polishing processes, test and analysis methods, and (2) a proposed model for the prediction of scatter from beryllium surfaces (based on a knowledge of surface and subsurface interactions with incident wavelengths) will be refined against empirical data. We discuss design of the experiment, the model, and some of the early results.