US 5,994,707 A · Modular fiber optic fluorometer and method of use thereof

Abstract

A low cost portable fiber optic fluorometer is packaged as a personal computer peripheral and is based on interchangeable modules. One embodiment of the fluorometer comprises an excitation source, a detector, a signal processor, frequency source, wavelength selector, and an optical interface. The optical interface is exclusively fiber optic-based, thereby simplifying optical alignment and reducing the cost of the fluorometer. In another embodiment, the excitation source is an inexpensive monochromatic excitation source. In this case, the monochromatic excitation source and the first wavelength selector are preferably removable and replaceable, so that the fluorometer is advantageously able to generate different excitation wavelengths and detect different emission wavelengths. A fluorescence measurement method comprises the steps of generating an excitation signal; transmitting the excitation signal to a system under study which, in response, generates an emission signal; and detecting both the excitation signal and the emission signal with the fluorometer, and then using the detected excitation signal as a reference signal to calibrate the fluorometer and to nullify distortion errors in the emission signal. The use of the excitation signal as a reference signal provides an advantageously simple way to calibrate the fluorometer and to nullify distortion errors in the emission signal. An alternative method allows the precise shapes of the emission signal and the excitation signal to be profiled. The fluorometry method and apparatus can both advantageously be used for performing both direct fluorescence lifetime measurements and for performing phase fluorometry.

Claims21

Dependent claims

A fluorescence spectroscopy method comprising the steps of:

(A) venerating an excitation signal at a fluorometer;
(B) transmitting said excitation signal to a system under study which, in response, generates an emission signal, and then transmitting said excitation signal and said emission signal from said system under study to said fluorometer;
and
(C) detecting said excitation signal and said emission signal with said fluorometer, said detected excitation signal and said detected emission signal both being received from said system under study;
(D) using said detected excitation signal as a reference signal to calibrate said fluorometer and to nullify distortion errors in said detected emission signal;
and
(E) processing said emission signal to produce timing information, said processing step including the steps of
(1) detecting when said emission signal crosses a predetermined level;
(2) initiating a first delay when said emission signal crosses said predetermined level;
(3) detecting when a coarse counter changes state;
(4) initiating a second delay when said coarse counter changes state;
(5) causing said first delay and said second delay to terminate approximately simultaneously by adjusting the duration of at least one of said first and second delays;
(6) obtaining said timing information, including
(a) reading the value of said coarse counter to obtain relatively low precision timing information,
(b) determining the duration of said first and second delays to obtain relatively high precision timing information, and
(c) combining said high precision timing information with said low precision timing information.

13 more elements

A fluorescence spectroscopy method comprising the steps of:

(A) generating an excitation signal at a fluorometer;
(B) transmitting said excitation signal to a system under study which, in response, generates an emission signal, and then transmitting said excitation signal and said emission signal from said system under study to said fluorometer;
and
(C) detecting said emission signal with said fluorometer, said detected emission signal being received from said system under study;
and
(D) processing said emission signal to produce timing information, said processing step including the steps of
(1) detecting when said emission signal crosses a predetermined level;
(2) obtaining said timing information based on when said emission signal crosses said predetermined level;
and
(3) adjusting said predetermined level and repeating said detecting and obtaining steps, said adjusting and repeating steps being performed a plurality of times so as to obtain a plurality of data points which profile the exponential decay of said emission signal.

7 more elements

A fluorescence spectroscopy method comprising the steps of:

(A) generating an excitation signal at a fluorometer, said fluorometer either (i) being packaged on an expansion card which is removably insertable into an expansion slot of a personal computer, or (ii) being packaged as a stand-alone peripheral for a personal computer and has a size which is not substantially larger than that of said personal computer;
(B) transmitting said excitation signal to a system under study which, in response, generates an emission signal, and then transmitting said emission signal from said system under study to said fluorometer;
(C) detecting said emission signal with said fluorometer;
(D) processing said emission signal to produce timing information, said processing step including the steps of
(1) detecting when said emission signal crosses a predetermined level;
(2) obtaining said timing information based on when said emission signal crosses said predetermined level;
and
(3) adjusting said predetermined level and repeating said detecting and obtaining steps, said adjusting and repeating step being performed a plurality of times so as to obtain a plurality of data points which profile the exponential decay of said emission signal.

5 more elements

A fluorometer comprising:

(A) a solid-state, modular, removable and replaceable excitation source, said excitation source being substantially monochromatic, and said excitation source generating an excitation signal which is provided to a system under study;
(B) a solid-state, modular, removable and replaceable wavelength selector, said wavelength selector receiving an emission signal generated by said system under study in response to said excitation signal and filtering out components of light received from said system under study which are not components of said emission signal;
(C) a detector, said detector being coupled to said wavelength selector, and said detector detecting said emission signal;
(D) a solid-state signal processor, said signal processor being coupled to said detector, and said signal processor processing said emission signal;
and
(E) an optical interface, including
(1) a fiber optic output, said fiber optic output being coupled to said excitation source,
(2) a first optical fiber, said first optical fiber being coupled to said fiber optic output and delivering said excitation signal to said system under study,
(3) a fiber optic input, said fiber optic input being coupled to said detector, and
(4) a second optical fiber, said second optical fiber being coupled to said fiber optic input and delivering said emission signal from said system under study to said fiber optic input,
(F) a programmable crossing detector which enables said fluorometer to profile the exponential decay of said emission signal;
and
wherein said optical interface is the only optical interface between said fluorometer and said system under study through which fluorometric signals are communicated, and wherein said optical interface is exclusively fiber optic-based.

10 more elements

A fluorescence spectroscopy method comprising the steps of:

(A) generating an excitation signal at a fluorometer;
(B) transmitting said excitation signal to a system under study which, in response, generates an emission signal, and then transmitting said excitation signal and said emission signal from said system under study to said fluorometer;
and
(C) detecting said emission signal and said excitation signal with said fluorometer, said detected emission and said excitation signal being received from said system under study;
and
(D) using a crossing detector to determine a phase difference between said excitation signal and said emission signal.

3 more elements

Dependencies are inferred from the claim text.

Modular fiber optic fluorometer and method of use thereof

Life of this patent

Modular fiber optic fluorometer and method of use thereof

Life of this patent

Abstract

Claims21