In the field of optical microscopy, it is well known that spatial resolution is limited by diffraction of light. There have been variously efforts to achieve resolution beyond diffraction limit. However, most previous methods rely on nonlinearities of fluorescence, and thus require high-intensity lasers or special labeling strategies. In 2011, a novel superresolution technique based on a dielectric microlens and simple bright field microscope was demonstrated. The scheme is unexpectedly simple, since neither labeling nor intense laser is necessary, while the resolution is significantly higher than diffraction limit. Nevertheless, the contrast of bright field microscope is poor. In this work, we combine a dielectric microlens along with confocal laser scanning microscopy to considerably enhance image contrast. By simply inserting a microsphere onto the sample, the resolution is undoubtedly better than diffraction limit of the objective. Meanwhile, the contrast exhibits almost one order of enhancement. Field of view and magnification of the microlens imaging system are also characterized. Comparing with bright field microscope, laser scanning confocal microscopy provides better contrast under this microslens assisted super-resolution scheme. Our finding will contribute to material science and biomedicine research.
Due to the high attenuation in vitreous silica, acoustic attenuations in the THz regime are typically measured by
incoherent techniques such as Raman, neutron, and X-ray scattering. Here, we utilized multiple-quantum-well structures
to demonstrate acoustic spectroscopy of vitreous silica up to THz regime. The acoustic properties of silica thin films
prepared by chemical deposition methods were characterized in the sub-THz regime. This technique may be useful in
resolving debated issues relating to Boson peak around 1 THz.