The near-field accessed with solid immersion lens technologyThe main reason for using solid immersion lenses is their capability to enhance the spatial resolution. Solids have higher refractive indices than air. When used as the immersion medium, light travels more slowly and the wavelength is shorter in the optically denser medium which results in an improvement in resolution. Mansfield and Kino were the first to recommend the SIL for increasing the spatial resolution of the optical microscope [1]. A SIL is a spherical lens (diameter 2r, refractive index n SIL ) which is polished to a thickness of r (hemisphere type) or (1+1/n SIL )r (supersphere or Weierstrass type) [2,3]. The sphere diameter is usually in the range of single millimeters down to micrometers. The numerical aperture (NA) of the complete system is improved by factor of n SIL (hemisphere type) or (n SIL ) 2 (Weierstrass type) -subject to the condition that the refractive index of the substrate is at least as high as the refractive index of the SIL. If this condition is not met, the refractive index of the substrate limits the effective numerical aperture NA eff of the SIL/ objective optical system (with NA eff = n SIL sinα m , where α m is the marginal ray angle inside the SIL) [4]. The angular range of collected information is determined by the SIL probe, the objective lens, and the detector [5].The SIL technique is also known as "numerical aperture increasing lens (NAIL) microscopy" [6]. For the NAIL technique the inclusion of evanescent waves is crucial for resolution gain [7]. Tom Milster et al. have described the role of propagating and evanescent waves in solid immersion lens systems [8].It must be emphasized here that the lateral resolution of a SIL microscope can exceed the "NAIL Limit", i.e. by the factor of the refractive index n SIL . In order to achieve this, the evanescent component of the light from the substrate has to be identified amongst the predominant propagated component. One approach is to tailor the angular spectrum by annular illumination and collection which can significantly improve the resolution and emphasize Abstract: Scanning Near-Field Optical Microscopy (SNOM) has developed during recent decades into a valuable tool to optically image the surface topology of materials with super-resolution. With aperture-based SNOM systems, the resolution scales with the size of the aperture, but also limits the sensitivity of the detection and thus the application for spectroscopic techniques like Raman SNOM. In this paper we report the extension of solid immersion lens (SIL) technology to Raman SNOM. The hemispherical SIL with a tip on the bottom acts as an apertureless dielectric nanoprobe for simultaneously acquiring topographic and spectroscopic information. The SIL is placed between the sample and the microscope objective of a confocal Raman microscope. The lateral resolution in the Raman mode is validated with a cross section of a semiconductor layer system and, at approximately 180 nm, is beyond the classical diffraction lim...