Apparatus and method for phase fluorometry
First Claim
1. A method of measuring the phase of a sample signal relative to a reference signal comprising:
- (a) generating a sample baseband signal having a first predetermined frequency fo which is greater than 10 Hz;
(b) generating a reference signal correlated to said sample baseband signal;
(c) generating a carrier signal having a second predetermined frequency f which is greater than 1 MHz;
(d) combining said carrier signal f and said sample baseband signal fo to form an up-converted sample signal having a frequency f±
fo equal to the sum or difference of said first and second frequencies;
(e) modulating a light source with said up-converted sample signal to form modulated excitation light;
(f) illuminating a sample with said modulated excitation light;
(g) detecting an emission from said sample;
(h) generating an electrical signal indicative of said emission;
(i) combining said electrical signal and said carrier signal to form a down-converted signal at the baseband frequency which contains the phase and modulation information introduced by the sample; and
(j) processing said down-converted signal and said reference signal.
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Accused Products
Abstract
A phase fluorometer employs a baseband frequency generator to generate a sample baseband signal at a first frequency fo and a reference signal correlated to the sample baseband signal. A second signal generator generates a carrier signal having a second frequency f. The sample baseband signal and the carrier signal are combined to form an up-converted sample signal having a frequency f±fo. A light source is modulated at the up-converted sample signal frequency f±fo to illuminate a sample. A photo detector detects fluorescence emissions from a sample excited by the excitation light and converts the emission into a fluorescence signal. A down-converter combines the carrier signal and fluorescence signal to form a phase-shifted and down-converted sample signal. A processor digitally processes the phase-shifted and demodulated sample signal and the reference signal to determine the fluorescence lifetime.
170 Citations
36 Claims
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1. A method of measuring the phase of a sample signal relative to a reference signal comprising:
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(a) generating a sample baseband signal having a first predetermined frequency fo which is greater than 10 Hz; (b) generating a reference signal correlated to said sample baseband signal; (c) generating a carrier signal having a second predetermined frequency f which is greater than 1 MHz; (d) combining said carrier signal f and said sample baseband signal fo to form an up-converted sample signal having a frequency f±
fo equal to the sum or difference of said first and second frequencies;(e) modulating a light source with said up-converted sample signal to form modulated excitation light; (f) illuminating a sample with said modulated excitation light; (g) detecting an emission from said sample; (h) generating an electrical signal indicative of said emission; (i) combining said electrical signal and said carrier signal to form a down-converted signal at the baseband frequency which contains the phase and modulation information introduced by the sample; and (j) processing said down-converted signal and said reference signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A phase fluorometer comprising:
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first signal generating means for generating a sample baseband signal having a first frequency fo greater than 10 Hz and a reference signal correlated to said sample baseband signal; second signal generating means for generating a carrier signal having a second frequency f greater than 1 MHz; up-converting means for combining said sample baseband signal and said carrier signal to form an up-converted sample signal having an up-converted frequency f±
fo equal to the sum or difference of said first and second frequencies;light source means modulatable at said up-converted frequency f±
fo for generating modulated excitation light to illuminate a sample;photo detector means for detecting an emission from a sample excited by said modulated excitation light and converting said emission into an electrical signal; down-converting means for combining said carrier signal and said electrical signal to form a down-converted signal which contains phase and modulation information introduced by the sample; and processing means for processing down-converted signal and said reference signal. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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27. An instrument for detecting a phase shift comprising:
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first signal generating means for generating a sample baseband signal comprising a pair of waves and having a first frequency fo, and a reference clock signal synchronized to said sample baseband signal; second signal generating means for generating a carrier signal having a second frequency f; up-converting means for combining said sample baseband signal and said carrier signal to form an up-converted sample signal having an up-converted frequency f±
fo equal to the sum or difference of said first and second frequencies;light source means modulatable at said up-converted frequency f±
fo for generating modulated excitation light to illuminate a sample;photo detector means for detecting an emission from a sample excited by said modulated excitation light, and converting said emission into an electrical signal; down-converting means for combining said carrier signal and said electrical signal to form a down-converted signal which contains phase and modulation information introduced by the sample; and processing means for digitally processing said reference clock signal and said down-converted signal to calculate the phase shift of said sample. - View Dependent Claims (28)
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29. A method of measuring the phase of a sample signal relative to a reference signal comprising:
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(a) generating a sample baseband signal having a first predetermined frequency fo which is greater than 10 Hz; (b) generating a reference signal correlated to said baseband sample signal; (c) generating a carrier signal having a second predetermined frequency f which is greater than 1 MHz; (d) combining said carrier signal f and said sample baseband signal fo to form an up-converted signal having a frequency f±
fo equal to the sum or difference of said first and second frequencies;(e) modulating a light source with said carrier signal to form modulated excitation light; (f) illuminating a sample with said modulated excitation light; (g) detecting an emission from said sample; (h) generating an electrical signal indicative of said emission; (i) combining said electrical signal and said up-converted signal to form a down-converted signal at the baseband frequency which contains the phase and modulation information introduced by the sample; and (j) processing said down-converted signal and said reference signal. - View Dependent Claims (30, 31)
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32. A phase fluorometer comprising:
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first signal generating means for generating a sample baseband signal having a first frequency fo greater than 10 Hz and a reference signal correlated to said sample baseband signal; second signal generating means for generating a carrier signal having a second frequency f greater than 1 MHz; up-converting means for combining said sample baseband signal and said carrier signal to form an up-converted signal having an up-converted frequency f±
fo equal to the sum or difference of said first and second frequencies;light source means modulatable at said carrier frequency for generating modulated excitation light to illuminate a sample; photo detector means for detecting an emission from a sample excited by said modulated excitation light and converting said emission into an electrical signal; down-converting means for combining said up-converted signal and said electrical signal to form a down-converted signal which contains phase and modulation information introduced by the sample; and processing means for processing down-converted signal and said reference signal. - View Dependent Claims (33, 34, 35, 36)
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Specification