Method and device for measuring the fluorescence decay time (afterglow time) of a fluorescing substance

摘要

The subject-matter of the invention are a method and a device for measuring the fluorescence decay time of the radiation of a fluorescing substance whose fluorescence decay time depends on at least one physical magnitude. The fluorescence radiation is fed back onto the output radiation in a resonant circuit whose frequency is a measure of the physical magnitude. The fluorescence radiation is thereby fed to a photoelectric receiver whose output signals are fed after phase-sensitive rectification and integration to a voltage-controlled oscillator. The fluorescence radiation is rectified only in the decay phase in an alternating fashion sensitive to phase. The total times of the rectification sections of different length are the same in the two directions. The alternatingly rectified signals are integrated. <IMAGE>