Improve/develop metrology for VLA (very low absorption) Coatings: Interferometer-less Coherent Optical Topographic Mapping Technique With Sub-Nanomet

"We present in this proposal an interferometer-less optical topographic mapping technique capable of monitoring, for example, the surface quality of coatings on the optics to be deployed in the ABL program. Unlike crystal monitors that are displaced awayfrom the optic under coating, our proposed remote-sensing technique can directly measure the coating characteristics on the substrate and during the coating/manufacturing processes without pausing and removing the optic out of the coating chamber.Two-dimensional photo-EMF sensor arrays can be developed to monitor the optics surface quality over a wide area, making them especially ideal for diagnosis purposes on large aperture optics used by ABL. Sub-nanosecond response times of the proposedphoto-EMF sensors allow near-instantaneous determination of coating quality which can be used to provide real-time feedback to the coating processes. Successful execution of this proposed program will lead to novel technologies capable of high precision determination of coating thickness and surface flatness. Potential commercial applications range from semiconductor chip fabrication, magnetic diskquality control, mask-less photolithography, as well as optical fiber dispersion characterization for the telecomm industries."