Dual-technology optical sensor head for 3D surface shape measurements on the micro- and nanoscales

New material applications and novel manufacturing processes are driving a systematic rise in market demands concerning surface inspection methods and the performance of non-contact profilers. However, analysis of the specifications and application notes of commercial optical profilers shows that no single system is able to offer all the features a general purpose user would like simultaneously. Whereas white light interferometers can achieve very fast measurements on the micro and nano-scale without any range limitation, they can not easily deal with steep smooth surfaces or structured samples containing dissimilar materials. PSI techniques allow the user to perform shape and texture measurements even below the 0.1 nm scale, but they have an extremely short measurement range. Imaging confocal profilers overcome most of these difficulties. They provide the best lateral resolution achievable with an optical profiler, but they have a resolution limit, which is dependent on the NA and cannot achieve the 0.1 nm vertical resolution. In this paper we introduce a new dual-technology (confocal & interferometer) illumination hardware setup. With this new sensor head it is possible to choose between standard microscope imaging, confocal imaging, confocal profiling, PSI and white light interferometry, by simply placing the right objective on the revolving nosepiece.