Stray light minimised optical coatings and their application in UV inspection optics

In UV inspection systems, the reduction of stray light has a special emphasis. As stray light is induced by many different sources residual reflections and scattering of surface roughness are the most pronounced effects for optical coatings. Optical coatings are used to maximise the transmission of lenses in optical systems and play an important role to minimise residual reflections in refracting optical systems. As a consequence they reduce the stray light level that maintains a high image quality or low signal to noise ratio. This makes the development of appropriate optical coatings one key in the design of successful high quality UV inspection optics. In this presentation the influences of the coating on the stray light level in an UV inspection microscope objective is shown. Solutions to minimise the stray light level will be presented and their effects in an instance of a high numerical aperture UV inspection lens are given. The scattering of coatings, that is very important in laser applications, will be considered here in conjunction with the application in UV inspection objectives.