Performance characteristics of several new types of photomultiplier tubes (PMT) with microchannel plates (MCP) are presented in this paper. They are the MCP-PMT with 6-microm diam channels, MCP-PMT with an S-l photocathode, and MCP-PMT with multi (discrete) anode and gatable MCP-PMT. Important requirements of an optical detector for picosecond lasers, fluorescence measurements, and material analysis are low light detectability, ultrafast time response, and versatile operation including modulation. The basic configuration, characteristics, and practical results of these detectors are described.
A microchannel-plate photomultiplier (MCP-PMT) has been applied to the time-correlated single-photon counting technique. Electrical and timing characteristics were investigated for the two types of MCP-PMT’s, nonproximity type (Hamamatsu R1264) and proximity type (R1564), which are different in distance between the photocathode and MCP. In the proximity type, the transit-time spread was found to be 60 ps, i.e., a factor of 4 shorter than that in conventional photomultipliers with a dynode string. It was concluded that both types of MCP-PMT’s are fully applicable to the single-photon counting method and that the proximity type MCP-PMT in particular leads to further improvements in the cathode transit-time difference and the wavelength effect of the timing properties. Some examples of experimental results are shown for fluorescence decay curves and picosecond time-resolved spectra.
A novel system has been developed to evaluate biochemically induced blood platelet aggregation by means of a particle counting technique that uses light scattering. Variations in the particle size and concentration were measured by detecting the scattered light intensity and the number of particles, respectively, passing through a laser beam. The system is capable of performing sensitive, in situ continuous measurements of platelet aggregation by counting and sizing of aggregates.-
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