Near-field assisted low-coherence interference microscopy for 3D measurement of sub-micrometer structures

Figure 1- High precision Linnik interferometer



Figure 2 - Measurement of a Blu-ray Disc with the help of near-field support by a microsphere (d = 15 µm)

Optical metrology is often the method of choice for measuring topographies and laterally extended structures, as it can capture surfaces quickly and without markers. While axially a resolution in the single-digit nanometer range can be achieved, in the lateral direction it is physically limited. Overcoming this limit is a topic of interest of many areas of current research.

In this project, a resolution enhancement is achieved with the help of microspheres that function as an additional optical element applied in the near field. The project is focusing particularly on interference microscopes with high numerical apertures, which even without microspheres offer a high resolution that cannot be improved by selecting other optical components.

Furthermore, during the project it should be clarified which physical mechanisms the resolution improvement is based on and a theoretical explanatory model should be developed.

Funded by :


M.Sc. Lucie Hüser

L. Hüser, P. Lehmann
Microsphere-assisted interferometry with high numerical apertures for 3D topography measurements
Applied Optics 59.6 (2020): 1695-1702

Kassamakov, Ivan, et al.
3D super-resolution optical profiling using microsphere enhanced Mirau interferometry
Scientific reports 7.1 (2017): 1-7

Wang, Zengbo, et al.
Optical virtual imaging at 50 nm lateral resolution with a white-light nanoscope
Nature communications 2.1 (2011): 1-6