Geometrical features of micro-systems can be determined by either tactile or optical profiling techniques, which show different non-linear transfer characteristics. This has to be considered especially, if the instrum...Geometrical features of micro-systems can be determined by either tactile or optical profiling techniques, which show different non-linear transfer characteristics. This has to be considered especially, if the instruments operate close to their physical limitations. Depending on the specific measuring task either point-wise or areal optical measurement may be advantageous. Hence, examples for both approaches are discussed. Furthermore, systematic effects, which are related to the measuring principle have to be taken into account, e.g. if sharp edges or slopes are present on the measuring object. As it is shown, for white-light interferometry these difficulties can be solved by a two-wavelength technique.展开更多
To improve the lateral resolution in microscopic imaging,microspheres are placed close to the object’s surface in order to support the imaging process by optical near-field information.Although microsphere-assisted m...To improve the lateral resolution in microscopic imaging,microspheres are placed close to the object’s surface in order to support the imaging process by optical near-field information.Although microsphere-assisted measurements are part of various recent studies,no generally accepted explanation for the effect of microspheres exists.Photonic nanojets,enhancement of the numerical aperture,whispering-gallery modes and evanescent waves are usually named reasons in context with microspheres,though none of these effects is proven to be decisive for the resolution enhancement.We present a simulation model of the complete microscopic imaging process of microsphere-enhanced interference microscopy including a rigorous treatment of the light scattering process at the surface of the specimen.The model consideres objective lenses of high numerical aperture providing 3D conical illumination and imaging.The enhanced resolution and magnification by the microsphere is analyzed with respect to the numerical aperture of the objective lenses.Further,we give a criterion for the achievable resolution and demonstrate that a local enhancement of the numerical aperture is the most likely reason for the resolution enhancement.展开更多
文摘Geometrical features of micro-systems can be determined by either tactile or optical profiling techniques, which show different non-linear transfer characteristics. This has to be considered especially, if the instruments operate close to their physical limitations. Depending on the specific measuring task either point-wise or areal optical measurement may be advantageous. Hence, examples for both approaches are discussed. Furthermore, systematic effects, which are related to the measuring principle have to be taken into account, e.g. if sharp edges or slopes are present on the measuring object. As it is shown, for white-light interferometry these difficulties can be solved by a two-wavelength technique.
基金support of this research work by the DFG(German Research Foundation)[Grant no.LE 992/14-1,LE 992/15-1].
文摘To improve the lateral resolution in microscopic imaging,microspheres are placed close to the object’s surface in order to support the imaging process by optical near-field information.Although microsphere-assisted measurements are part of various recent studies,no generally accepted explanation for the effect of microspheres exists.Photonic nanojets,enhancement of the numerical aperture,whispering-gallery modes and evanescent waves are usually named reasons in context with microspheres,though none of these effects is proven to be decisive for the resolution enhancement.We present a simulation model of the complete microscopic imaging process of microsphere-enhanced interference microscopy including a rigorous treatment of the light scattering process at the surface of the specimen.The model consideres objective lenses of high numerical aperture providing 3D conical illumination and imaging.The enhanced resolution and magnification by the microsphere is analyzed with respect to the numerical aperture of the objective lenses.Further,we give a criterion for the achievable resolution and demonstrate that a local enhancement of the numerical aperture is the most likely reason for the resolution enhancement.
