Volker Wilke

Laser Scanning In Microscopy

Scanning techniques in optical microscopy up to now were employed in the rather limited field of microscope photometry. The use of lasers as a light source offers new possibilities because of the high intensity and good collimation of the laser beam. Modern electronic and scanning techniques make - in addition to the photometric possibilities - the build-up of high quality microscopic images possible.

Applications Of The Microscope System LSM

The new universal confocal LSM is a second-generation laser scanning microscope. This means, that laser scanning microscopy now made the transition from experimental set-up lab types to integrated workstations, where the manual handling of mechanical and optical components is left to the computer. The built-in microcomputer - now not only drives scanners and transforms signals into images but also controls directly the microscope functions. It turned out that this is a crucial step for making the LSM an universal instrument for widespread use in research and development. The switching from conventiona] microscopy to laser scanning modes and vice versa is performed by simply pressing keys. Not only images can be stored on the built-in hard disk but at the same time automati cally the corresponding set of parameters: Even weeks or months after creating an image the settings of the instrument belonging to this image can be called from the operators panel by loading a parameter file which defines the laser line used and its intensity setting, nosepiece position, zoom factor, averaging conditions, microscopy mode (transmitted, reflected or fluorescence) and parameters for signal conditioning. Since the microscope stand is motorized at a high degree, the computer recreates automatically the exact conditions desired after dialing the number of the parameter file. In this way working with the LSM becomes not only reproducible, but also the user is freed from the handling of mechanical parts and typing commands on a keyboard. Finally the automatized LSM allows true remote control by a host computer necessary for the most demanding 3D-reconstruction. The characteristics pointed out so far are prerequisites for the daily use by microscopists in life science, semiconductor research, development and testing and materials research.

Broadly Tunable UV Source Based on Stimulated Raman Scattering

Stimulated Raman scattering (SRS) in hydrogen is a convenient means for frequency-shifting of tunable dye laser radiation into spectral regions where tunable lasers are not available [1–4]. We have obtained full coverage of the spectrum from 185 nm to 880 nm without gaps using a state-of-the-art dye laser repetitively pumped (10 pps) by a Nd: YAG laser as an excitation source.