text: Optical design is not just designing the optical components to satisfy an optical specification in terms of imaging. The uses to which some instruments are put is extreme in some cases where the wavelengths being inspected by the instrument can vary enormously. From 240nm at the Ultra Violet end of the spectrum up to 12 microns in the far Infra Red. Many applications use several band widths for different purposes within the same instrument, one often for ‘aiming’ the telescope and the other for the examination of the incoming light. Specialised coatings for both AR (anti reflection) where lenses or corrector systems are concerned and, high reflectivity surfaces when mirrors are involved. Where IR is involved, there are a select few coatings which are available in conjunction with the material from which the lens is made. Careful analysis of both the use of the instrument and, the wavelengths used within the design to enable the correct choice of coating materials. We use an industry standard design suite of software to carry out this analysis and design, Macleod’s Thin Film Centre is our choice of a highly accurate and flexible program. Which is capable of the most involved and specialised optimisation for every possible application. www.thinfilmcenter.com