Multi-shot pulsed laser fluorescence microscope system

摘要

We describe a novel fluorescence microscope system which allows us to capture rapid cellular phenomena as sequential images. This system is based on the "pulsed-laser fluorescence microscope" which we reported two years ago in the first symposium on the same topic. In the previous microscope, only one image could be taken at a certain instance in a fast event. In order to obtain sequential images, the event had to be repeated. The new version allows us to capture several images as a time series in a single measurement without repetition; thus, irreversible fast phenomena can be time resolved. The heart of this system is a highly sensitive framing camera with a gated-microchannel plate serving as an ultra-fast shutter. This camera is basically an image converter in which several images can be projected at different positions on the output phosphor screen. The exposure time of each image can be as short as 100 nanoseconds, whereas the interval between sequential images can be variable between 300 nanoseconds to a few seconds. The camera enables rapid multi-shot imaging under highly intense continuous light. Faster events can be analyzed by combining the camera with a Q-switched Nd:YAG laser producing a burst of quadruple pulses. Four 10-nanosecond images can be captured at intervals of the order of 10 microseconds. With this system, we have been able to examine the behavior of giant-liposomes under an intense electric field. Several deformation patterns and the formation of a large hole(s) in the lipid membrane have been visualized as microsecond sequential images.