| 摘要 |
1476006 Substance discrimination by fluorescence BLOCK ENG Inc 18 Aug 1975 [21 Aug 1974] 34253/75 Heading G1A A method of distinguishing two substances with different fluorescent decay lifetimes comprises irradiating them with radiation to stimulate fluorescence, reducing the radiation and measuring the intensity of fluorescence after a delay allowing decay. Apparatus for this comprises a source 22, of radiation to stimulate fluorescence, means 24 for modulating its intensity and means 30, 34, 38 for measuring the intensity of fluorescence in delayed synchronism with the modulation. Sample 20 is a liquid medium with particles with fluorochrome dye bound to them and with unbound fluorochrome dye. Source 22, which illuminates it may be a laser emitting short pulses due to an oscillator and mode locker or a carbon arc with interference filter and a Pockels device. Its energy is unsufficient to cause 'bleaching'. Interference filter 26 removes source light and stray radiation. Optics 28 concentrate the fluorescence on to photo-multiplier 30 F.E.T. or diode gate 34 is timed to open each time the fluorescence of the unbound fluorochrome has decayed by 1/e. Alternatively detector 30 or display 40 may be gated on or off. If the bound substance is an energy transfer fluorescing material, the gate is opened when the fluorescence of this material reaches its maximum. Display 40 may be digital or an oscilloscope. |
