Patent ID: 6323495
Filing Date: 2001-11-27
Classification: G01N

Abstract:
An apparatus for measuring fluorescent lifetime, comprising:a light source adapted to shine a beam of light;a low-pass source filter positioned to absorb low energy light waves from the beam of light emitted by the light source;a sample positioned to receive the beam of light shined from the light source through the low-pass source filter;a photodetector positioned to receive remitted and fluoresced light components from the sample;a filter wheel adapted to selectively dispose one of a plurality of emission filters between the sample and the photodetector; anda microprocessor operationally connected to the light source; the photodetector and the filter wheel;wherein the beam of light interacts with the sample to produce emitted sample light having a remitted component and a fluoresced component;wherein the filter wheel includes a low-pass emission filter, a high-pass emission filter, and an opaque emission filter;wherein the opaque emission filter is adapted to block all light remitted and fluoresced by the sample;wherein the low-pass emission filter is adapted to selectively substantially pass the remitted component of the light from the sample and to substantially absorb the fluoresced component of the light from the sample;wherein the high-pass emission filter is adapted to selectively substantially pass the fluoresced component of the light from the sample and to substantially absorb the remitted component of the light from the sample;wherein the microprocessor is adapted to calculate a baseline phase from the photodetector signal received while the opaque emission filter is in place between the sample and the photodetector for subtraction from later calculations;wherein the microprocessor is adapted to calculate a reference phase from the photodetector signal received while the low-pass emission filter is in place between the sample and the photodetector; andwherein the microprocessor is adapted to calculate the lifetime of the fluoresced signal by comparing the phase of the photodetector signal received while the high-pass filter is in place between the sample and the photodetector relative to the calculated reference phase and calculating the phase shift between the two.