Laboratory of Molecular Biophotonics

Hamamatsu Photonics Kabushiki Kaisha

Shinji Ohsuka

Hisayoshi Takamoto

Teruo Hiruma

The present invention relates to a method and apparatus for efficiently measuring the lifetime of the fluorescence emitted from a fluorescent material in response to pulsed light. The measuring apparatus according to the present invention includes, at least, an excitation light source whose excitation power is regulated such that at least one fluorescence photon can be detected per light pulse on average. While repeatedly irradiating a sample containing the fluorescent material with excitation pulses of light from the excitation light source, a fluorescence detection time from irradiation to fluorescence detection and the number of detected fluorescence photons are measured for each excitation pulse of light. Then, on the basis of a data group composed of pairs of the measurement data of fluorescence photon detection time and fluorescence photon number, both of which are measured for each occurrence of excitation pulse of light, the lifetime and fluorescence decay curve of the fluorescence emitted from the fluorescent material are determined.

Method and apparatus for measuring fluorescence

When incident light is incident to a photodetector, photoelectrons are emitted therefrom and then multiplied to output an electric current signal. This current signal is integrated over a predetermined period of time in an integrator to be converted to a voltage signal. This voltage signal is converted to a digital signal by an AD converter. This digital signal is supplied to a histogramming memory, which generates a pulse height distribution of voltage signal. Based on a pulse height distribution N(h) generated with incidence of measurement-object light to the photodetector, a pulse height distribution of single photoelectron events p.sub.1 (h) generated by a generator of pulse height distribution of single photoelectron events, and pulse height distributions of k-photoelectron events p.sub.k (h) (k=2, 3, . . . ) calculated and generated in a generator of pulse height distributions of k-photoelectron events, an estimating unit estimates a distribution of numbers of photoelectrons emitted with incidence of the measurement-object light to the photodetector, and thereby obtains the intensity of the measurement-object light.

Light measuring apparatus for quantifying photons

When incident light is incident to a photodetector, photoelectrons are emitted and multiplied in each of incident zones whereby a plurality of current signals are output. These current signals each are processed to estimate a distribution or a mean value of numbers of photoelectrons generated in each incident zone. Then estimated based on the estimate values of respective incident zones is the number of photoelectrons emitted from the entire photoelectric conversion surface. In this way the intensity of incident light is measured with accuracy.

Light measuring apparatus for quantizing photon

A radiation imaging apparatus comprising scintillators for converting radiation from a sample into scintillation light, image intensifiers for amplifying the scintillation light and forming an amplified image of the radiation, the image guides for directing the scintillation light to the respective image intensifiers. The observing field of a sample is conceptually partitioned into plural sections with each section corresponding to a respective one of the image intensifiers. One end of each image guide faces a respective section of the sample and the other end of each image guide is connected to a respective image intensifier.

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Shizuoka, Japan

Shinji Ohsuka