The group's popular Compact Confocal Microscope, for example, was developed for biologists using cells on cover slips and samples labelled with antibodies. Some developments also arise from the group's theoretical pursuit of the limits of the technology. Because new ideas often take several years to fully develop, Stelzer and his colleagues try to anticipate new research directions and follow through with preliminary investigations so that when real working problems arise in such an area, the group will have head start on the solution. The latest version, confocal theta microscopy, was designed by Stelzer and PhD student Steffen Lindek. The new microscope began as an effort to push the limits of confocal resolution, but it has been significantly shaped through a dialogue with developmental biologists, whose molecular studies of embryos at EMBL and elsewhere are increasingly important.
All confocal microscopes use laser light to scan biological specimens across three dimensions.
As it scans, the laser illuminates and excites fluorescently labelled molecules in the sample. The fluorescent molecules emit light back to a detector through an observation objective, while the unlabelled portions effectively remain black. This creates strong contrast and increased resolution. Signals for each coordinate are digitally recorded and reconstructed with a microcomputer to create a three-dimensional map of the specimen. The laser illuminates a precise volume in space.