Frequency domain cross-correlation fluorometry with phase-locked loop frequency synthesizers
First Claim
Patent Images
1. 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.
0 Assignments
0 Petitions
Accused Products
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.
85 Citations
9 Claims
-
1. 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. - View Dependent Claims (2, 3, 4)
-
-
5. 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; andderiving 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. - View Dependent Claims (6, 7, 8, 9)
-
Specification