US4840485A
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US
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Frequency domain cross-correlation fluorometry with phase-locked loop frequency synthesizers
Assignee: I S S USA Inc
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Filing: 1988-07-27
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Granted: 1989-06-20
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Expires: 2008-07-27
Abstract
Abstract Frequency domain cross-correlation fluorometers may be improved over present designs by providing a coherent signal at one frequency to means for detecting luminescence from a sample, which is elicited by light modulated at another frequency, in which the two frequencies, obtained from a pair of phase-locked loop frequency synthesizers, are different from each other by at least 100 hertz, which is a significantly greater difference than used in corresponding prior art fluorometers. This permits the use of the phase-locked loop frequency synthesizers, rather than the currently used direct synthesis synthesizers, providing significant advantages.
Inventors
- 👤 Enrico Gratton
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 22:39
CPC Classifications
G; G01; G01N; G01N21/00; G01N21/62; G01N21/63; G01N21/64; G01N21/6408
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
157 words
Apparatus for cross-correlation frequency domain fluorometry, which comprises: a source of electromagnetic radiation; means for amplitude modulating the electromagnetic radiation at a first frequency; means for directing the amplitude-modulated electromagnetic radiation at a sample; means for detecting the luminescence of the sample; means for providing a signal coherent with amplitude modulated signals produced by said amplitude modulating means, at a second frequency, to said detecting means; means for modulating the gain of said detecting means by said signal; said amplitude modulating means and means for providing a signal at a second frequency each comprising a separate phase-locked loop frequency synthesizer; said second frequency being different from said first frequency by at least 100 hertz; and means for deriving a resultant signal from said electromagnetic radiation and said detecting means at a frequency of the difference between said first and second frequencies, to detect phase shift and modulation changes of said luminescence from that of said electromagnetic radiation.
Claim 2
Dependent Claim
157 words
Apparatus for cross-correlation frequency domain fluorometry, which comprises: a source of electromagnetic radiation; means for amplitude modulating the electromagnetic radiation at a first frequency; means for directing the amplitude-modulated electromagnetic radiation at a sample; means for detecting the luminescence of the sample; means for providing a signal coherent with amplitude modulated signals produced by said amplitude modulating means, at a second frequency, to said detecting means; means for modulating the gain of said detecting means by said signal; said amplitude modulating means and means for providing a signal at a second frequency each comprising a separate phase-locked loop frequency synthesizer; said second frequency being different from said first frequency by at least 100 hertz; and means for deriving a resultant signal from said electromagnetic radiation and said detecting means at a frequency of the difference between said first and second frequencies, to detect phase shift and modulation changes of said luminescence from that of said electromagnetic radiation.
Claim 3
Dependent Claim
21 words
The apparatus of claim 1 in which the difference between said first and second frequencies is no less than 500 hertz.
Claim 4
Dependent Claim
18 words
The apparatus of claim 2 in which said first and second frequencies differ by 500 to 2000 hertz.
Claim 5
Dependent Claim
32 words
The apparatus of claim 1 in which said means for amplitude modulating the electromagnetic radiation at a first frequency includes Pockels cell means, driven by one of said phase-locked loop frequency synthesizers.
Claim 6
Independent Claim
142 words
A method for frequency domain cross-correlation fluorometry, which comprises the steps of: providing a source of electromagnetic radiation; amplitude modulating the electromagnetic radiation at a first frequency with a Pockels cell driven by a phase-locked loop frequency synthesizer; directing the amplitude-modulated electromagnetic radiation at a sample; detecting with a detector the luminescence of the sample while modulating the gain of said detector with a signal at a second frequency to said detector; with said signal at a second frequency being coherent with the modulation of said electromagnetic radiation and said second frequency being different from said first frequency by at least 100 hertz; and deriving a resultant signal from said electromagnetic radiation and said detector at a frequency of the difference between said first and second frequencies, to detect phase shift and modulation of said luminescence from that of said electromagnetic radiation.
Claim 7
Independent Claim
142 words
A method for frequency domain cross-correlation fluorometry, which comprises the steps of: providing a source of electromagnetic radiation; amplitude modulating the electromagnetic radiation at a first frequency with a Pockels cell driven by a phase-locked loop frequency synthesizer; directing the amplitude-modulated electromagnetic radiation at a sample; detecting with a detector the luminescence of the sample while modulating the gain of said detector with a signal at a second frequency to said detector; with said signal at a second frequency being coherent with the modulation of said electromagnetic radiation and said second frequency being different from said first frequency by at least 100 hertz; and deriving a resultant signal from said electromagnetic radiation and said detector at a frequency of the difference between said first and second frequencies, to detect phase shift and modulation of said luminescence from that of said electromagnetic radiation.
Claim 8
Dependent Claim
21 words
The method of claim 5 in which the difference between the first and second frequencies is no less than 500 hertz.
Claim 9
Dependent Claim
18 words
The method of claim 6 in which said first and second frequencies differ by 500 to 2000 hertz.
Claim 10
Dependent Claim
27 words
The method of claim 7 in which said electromagnetic radiation is modulated at said first frequency by Pockels cell means, driven by a phase-locked loop frequency synthesizer.
Claim 11
Dependent Claim
27 words
The method of claim 8 in which the gain of said detector is modulated at the second frequency by the signal from a phase-locked loop frequency synthesizer.
References Cited (Backward Citations)
US3886370A
Cited
US4594511A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-06-19 | 1992-12-19 | 1993-06-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-06-19 | 1996-12-19 | 1997-06-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-06-19 | 2000-12-19 | 2001-06-20 | $7700.00 | Window Closed / Lapsed |