We have developed a fiber-based confocal optical microscope that operates inside of a commercial scanning electron microscope (SEM) instrument (JEOL 6400; JEOL Ltd., Tokyo, Japan) enabling the excitation of a sample either by a laser or by electron beam, and hence combining the complimentary techniques of photoluminescence and cathodoluminescence. The instrument uses single-mode fibers that enter the SEM by vacuum feedthroughs. The illumination and collection fibers operate as effective pinholes providing, in combination with a microscope objective (NA = 0.3), high spatial resolution (~2 μm) and excellent collection efficiency. The high spatial resolution ensures that the light collected from the sample is in a region of optimal laser beam and electron beam overlap. The capabilities of this instrument are tested by experiments involving the excitation of europium ions in situ doped in GaN thin films.

Atomic force microscopy (AFM) is a specialised form of scanning probe microscopy, which was invented by Binnig and colleagues in 1986. Since then, AFM has been increasingly used to study biomedical problems. Because of its high resolution, AFM has been used to examine the topography or shape of surfaces, such as during the molecular imaging of proteins. This, combined with the ability to operate under known force regimes, makes AFM technology particularly useful for measuring intermolecular bond forces and assessing the mechanical properties of biological materials. Many of the constraints (e.g. complex instrumentation, slow acquisition speeds and poor vertical range) that previously limited the use of AFM in cell biology are now beginning to be resolved. Technological advances will enable AFM to challenge both confocal laser scanning microscopy and scanning electron microscopy as a method for carrying out three-dimensional imaging. Its use as both a precise micro-manipulator and a measurement tool will probably result in many novel and exciting applications in the future. In this article, we have reviewed some of the current biological applications of AFM, and illustrated these applications using studies of the cell biology of bone and integrin-mediated adhesion.