Patent US4198567A successfully refreshed from Google Patents.
US4198567A
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US
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Method and apparatus for discrimination between scattered excitation radiation and low level fast decaying fluorescent radiation
Assignee: Individual
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Filing: 1977-10-25
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Granted: 1980-04-15
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Expires: 1997-10-25
Abstract
Abstract A gated, pulsed laser spectrofluorometer is provided analyzing subpicogram amounts of fluorescent substance in sample volumes of less than 10 μl. This is accomplished by repetitively exciting the fluorescent sample with a subnanosecond, intensive excitation radiation pulse and by gating a fluorescence radiation detector output signal so that detection starts after the excitation radiation pulse has decayed to a negligible intensity and ends when the fluorescence radiation detector output signal caused by the fluorescence emission from the sample has decayed to a level comparable to the electrical noise level of the electronic measuring apparatus connected to said fluorescence radiation detector.
Inventors
- 👤 Peter Eneroth
- 👤 Wladimir Wladimiroff
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 15:00
CPC Classifications
G; G01; G01N; G01N21/00; G01N21/62; G01N21/63; G01N21/64; G01N21/6408
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
252 words
An apparatus for exciting a fluorescent substance in a gaseous, light or solid state and analyzing predetermined parts of the fluorescence emission decay of the substance, comprising: radiation means for generating excitation radiation pulses; drive means for generating a pretrigger signal prior to the generation of each excitation radiation pulse; fractional deflection means for deflecting a portion of the radiation of each of said excitation radiation pulses and passing the remaining portion of the radiation of said excitation pulses to irradiate said fluorescent substance; reference radiation detection means for receiving said deflected portion of radiation and generating a corresponding electrical trigger signal proportional to the intensity of said deflected portion of radiation; filter means for receiving the fluorescence emission radiation of said fluorescent substance and passing filtered fluorescence radiation having particular emission wavelengths; fluorescence radiation detector means for receiving said filtered fluorescence radiation and generating a corresponding fluorescence electrical signal proportional to the intensity of the filtered fluorescence radiation; reference storage means responsive to a reference gating signal to store said trigger signal; fluorescence storage means responsive to a sample gating signal to store said fluorescence signal; and gating means responsive to said pretrigger signal to generate said reference gating signal and responsive to said trigger signal to generate said sample gating signal at a time after said excitation pulse has reached said fluorescent substance and the corresponding scattered radiation from said excitation pulse has diminished to a level of intensity that is less than the intensity of said fluorescence emission radiation.
Claim 2
Independent Claim
252 words
An apparatus for exciting a fluorescent substance in a gaseous, light or solid state and analyzing predetermined parts of the fluorescence emission decay of the substance, comprising: radiation means for generating excitation radiation pulses; drive means for generating a pretrigger signal prior to the generation of each excitation radiation pulse; fractional deflection means for deflecting a portion of the radiation of each of said excitation radiation pulses and passing the remaining portion of the radiation of said excitation pulses to irradiate said fluorescent substance; reference radiation detection means for receiving said deflected portion of radiation and generating a corresponding electrical trigger signal proportional to the intensity of said deflected portion of radiation; filter means for receiving the fluorescence emission radiation of said fluorescent substance and passing filtered fluorescence radiation having particular emission wavelengths; fluorescence radiation detector means for receiving said filtered fluorescence radiation and generating a corresponding fluorescence electrical signal proportional to the intensity of the filtered fluorescence radiation; reference storage means responsive to a reference gating signal to store said trigger signal; fluorescence storage means responsive to a sample gating signal to store said fluorescence signal; and gating means responsive to said pretrigger signal to generate said reference gating signal and responsive to said trigger signal to generate said sample gating signal at a time after said excitation pulse has reached said fluorescent substance and the corresponding scattered radiation from said excitation pulse has diminished to a level of intensity that is less than the intensity of said fluorescence emission radiation.
Claim 3
Dependent Claim
37 words
The apparatus of claim 1 including means for receiving a stored trigger signal and a corresponding stored fluorescence signal and generating a signal corresponding to the ratio of the stored fluorescence signal and the stored trigger signal.
Claim 4
Dependent Claim
42 words
The apparatus of claim 1 including means for maintaining said sample gating signal to store said fluorescence signal for as long as the level of intensity of said fluorescence emission radiation is greater than the level of intensity of associated electrical noise.
Claim 5
Dependent Claim
50 words
The apparatus of claim 1 wherein said fractional deflection means includes a beam splitter adjustably positioned with respect to said fluorescent substance to define an optical delay substantially equal to the activation time of said gating means minus a time corresponding to the pulse width of an excitation radiation pulse.
Claim 6
Dependent Claim
31 words
Apparatus as claimed in claim 1 wherein said radiation means is a nitrogen laser - dye laser combination generating laser radiation pulses with a decay time of less than 1 ns.
Claim 7
Dependent Claim
23 words
Apparatus as claimed in claim 5 in which the laser radiation pulses have a continuously variable spectral wavelength in the region 350-700 nm.
Claim 8
Dependent Claim
22 words
Apparatus as claimed in claim 6 wherein said laser includes a spectral wavelength variation mechanism that is driven by a stepper motor.
Claim 9
Dependent Claim
21 words
Apparatus as claimed in claim 5 in which the laser radiation pulses have a continuously variable spectral width between 1-20 nm.
Claim 10
Dependent Claim
23 words
Apparatus as claimed in claim 1 wherein said filter means is a monochromator having an arrangement of fixed central wavelength interference transmission filters.
Claim 11
Dependent Claim
22 words
Apparatus as claimed in claim 9 in which the monochromator transmission wavelength is continuously variable over the spectral region between 350-1000 nm.
Claim 12
Dependent Claim
21 words
Apparatus as claimed in claim 10 wherein the monochromator includes a wavelength variable mechanism that is driven by a stepper motor.
Claim 13
Dependent Claim
33 words
Apparatus as claimed in claim 1 in which the fluorescence radiation detector means includes a fast photomultiplier having a rise time of the order of the fall time of the excitation radiation pulses.
Claim 14
Dependent Claim
34 words
Apparatus as claimed in claim 2 in which the reference radiation detection means includes a fast vacuum photodiode having a rise time of the order of the fall time of the excitation radiation pulses.
Claim 15
Dependent Claim
27 words
Apparatus as claimed in claim 1 including means for generating an analog signal proportional to the ratio of the stored fluorescence signal and the stored trigger signal.
Claim 16
Dependent Claim
17 words
Apparatus as claimed in claim 14 including means for converting said analog signal into a digital signal.
Claim 17
Dependent Claim
60 words
Apparatus as claimed in claim 1 including a light-tight casing for holding the radiation means, the filter means, the fluorescence radiation detector means, the fractional deflection means and the reference radiation detection means and excluding ambient light from disturbing the measurements as well as preventing the excitation radiation from irradiating surfaces having no relation to the purpose of the measurements.
Claim 18
Dependent Claim
192 words
Method for quantitative analysis of a fluorescent substance with a fast fluorescence decay in a gaseous, liquid or solid state sample, wherein a sample is excited by excitation radiation pulses and certain predetermined parts of the fluorescence emission decay are selected for analysis by means of a fluorescence radiation detector and an associated electronic gating unit, said method comprising the steps of: generating excitation radiation pulses; irradiating a reference radiation detector by a fraction of each of said excitation radiation pulses, said reference radiation detector generating a trigger pulse directly to said electronic gating unit without introducing any other electronic delay but the inherent transit time of the reference radiation detector; delaying the arrival of each of said excitation radiation pulses at said sample by a delay time that is substantially equal to the activation time of said electronic gating unit minus the time-width of an excitation pulse; exciting the sample fluorescence by means of said delayed excitation radiation pulses; detecting the fluorescence emission from the sample by means of said fluorescence radiation detector; and applying said trigger pulse to gate the signal from said fluorescence detector to a signal storage means.
Claim 19
Dependent Claim
192 words
Method for quantitative analysis of a fluorescent substance with a fast fluorescence decay in a gaseous, liquid or solid state sample, wherein a sample is excited by excitation radiation pulses and certain predetermined parts of the fluorescence emission decay are selected for analysis by means of a fluorescence radiation detector and an associated electronic gating unit, said method comprising the steps of: generating excitation radiation pulses; irradiating a reference radiation detector by a fraction of each of said excitation radiation pulses, said reference radiation detector generating a trigger pulse directly to said electronic gating unit without introducing any other electronic delay but the inherent transit time of the reference radiation detector; delaying the arrival of each of said excitation radiation pulses at said sample by a delay time that is substantially equal to the activation time of said electronic gating unit minus the time-width of an excitation pulse; exciting the sample fluorescence by means of said delayed excitation radiation pulses; detecting the fluorescence emission from the sample by means of said fluorescence radiation detector; and applying said trigger pulse to gate the signal from said fluorescence detector to a signal storage means.
Claim 20
Dependent Claim
35 words
The method of claim 17 including generating said excitation radiation pulses by a coaxial nitrogen laser in combination with a dye laser, the excitation pulses each having a fall time of less than 1 nanosecond.
Claim 21
Dependent Claim
32 words
The method of claim 17 wherein said irradiation step includes splitting each radiation pulse with a beam splitter positioned a variable distance from the sample to generate said fraction of excitation radiation.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-04-15 | 1983-10-15 | 1984-04-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-04-15 | 1987-10-15 | 1988-04-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-04-15 | 1991-10-15 | 1992-04-15 | $7700.00 | Window Closed / Lapsed |