TCSPC Lifetime Imaging by Scan Stages

8 Other TCSPC Microscopy Techniques 5.8.1 TCSPC Lifetime Imaging by Scan Stages 

Commercial confocal and two-photon laser scanning microscopes scan the laser beam by fast galvano-driven mirrors. Typical pixel dwell times are of the order of a few microseconds. Depending on the number of pixels, a complete frame is scanned within 25 ms to several seconds. 

Images can also be obtained by scanning the sample by a piezo-driven scan stage. The principle is the same as in the laser scanning microscope, but the optical beam scanner is replaced with a scan stage that moves the sample. The sample scanning technique is shown in Fig. 5.96. 

From the vantage point of TCSPC, imaging by a piezo stage is a slow scan procedure. That means a full fluorescence decay curve is recorded in the current pixel before the scanner moves to the next one. Lifetime images can be therefore acquired by almost any TCSPC module and operation mode. Applications of onedimensional TCSPC with slow scanning are described in [76] and [74]. These 

The benefit of scanning the sample using a scan stage is that the microscope remains relatively simple. Because there are no moving parts in the beam path confo-cal detection is much easier than in a microscope with optical beam scanning. 

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