Due to the tendencies in biological research towards multiple stainings and increased use of newly developed dyes like fluorescent proteins, the application areas of multispectral confocal imaging increase rapidly. We present here the most recent advances in this technology particularily concerning but not limited to the excitation module, the detection module, and the beamsplitter optics of multispectral confocal microscopes.
In confocal microscopy manifold combinations of dyes are used. The entire wavelength range from near-ultraviolet to near-infrared is used to excite these dyes. Their emission is then detected primarily in the visible range. In addition to the number of dyes, the number of possible excitation laser lines is already large and constantly increasing. Due to the almost unlimited number of possible combinations, programmable devices are required. This is true for excitation-modules, beam-splitters and detection modules. Systems using filters with fixed spectral properties can practically fulfill the requirements for only a very small subset of applications. Programmable devices have been realized for excitation using Acousto Optical Tunable Filters (AOTF's). Freely definable spectral detectors are available for a perfect adaptation to the desired emission bands. The missing link for a completely filter-free design is now introduced using an Acousto Optical Beam Splitter (AOBS).