Patent US3586441A successfully refreshed from Google Patents.
US3586441A
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US
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Atomic absorption spectroanalysis system
Assignee: THERMO JARRELL ASH Corp WALTHAM MA A CORP OF
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Filing: 1967-07-12
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Granted: 1971-06-22
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Expires: 1987-07-12
Abstract
Abstract An atomic absorption spectroanalysis system includes a burner for generating a flame, two radiation sources, and two pairs of radiation sensors. An optical system passes radiation from each source along a first path through the flame for sensing by a corresponding sensor to produce an I signal, and along a second path outside the flame for sensing by a corresponding second sensor to produce an Io signal. The radiation output of each source is modulated and the output signals from each sensor are demodulated and then logarithmically combined to provide two log I/Io signals. Compensation circuitry connected to the logarithmic circuit arrangement provides compensation for radiation absorption deviations of the radiation passing through the flame as a function of Beer''s Law. The system also includes circuitry for providing a zeroing adjustment of each log I/Io signal while a known standard or blank is being introduced into the flame.
Inventors
- 👤 Stanley Babcock Smith
- 👤 Jerrold Zindler
- 👤 Rauf Argon
- 👤 David E Blackmer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 07:41
CPC Classifications
G; G01; G01N; G01N21/00; G01N21/62; G01N21/71; G01N21/72; G01N21/17; G01N21/25; G01N21/31; G01N21/3103
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
356 words
An atomic absorption spectroanalysis system comprising a burner for generating a flame, two radiation sources, each said source generating a characteristic radiation, two pairs of radiation sensors, each pair being responsive to one of said sources, an optical system for passing radiation from each source along a first path through said flame for sensing by the corresponding first sensors of each said paris of sensors to produce I signals, and passing radiation from each source along a second path outside of said flame for sensing by the corresponding second sensor of each of said pairs of sensors to produce Io signals, a first logarithmic circuit arrangement including a first logarithmic converter responsive to the output of a first sensor of one pair for providing a signal proportional to log I as a function of the output of a first radiation source and a second logarithmic converter responsive to the output of a second sensor of said one pair for providing a signal proportional to log Io as a Function of the output of a first radiation source, and a first summing network responsive to said first and second logarithmic converters to provide, as an output, a log I/Io signal, a second logarithmic circuit arrangement including a third logarithmic converter responsive to the output of a first sensor of the second pair for providing a signal proportional to log I as a function of the output of the second radiation source and a fourth logarithmic converter responsive to the output of the second sensor of said second pair for providing a signal proportional to log Io as a function of the output of the second radiation source, and a second summing network responsive to said third and fourth logarithmic converters to provide as an output, a second log I/Io signal, compensation circuitry connected in each logarithmic circuit arrangement between the two logarithmic converters of each said logarithmic circuit arrangement for providing compensation for radiation absorption deviations of the radiation passing through said flame as a function of Beer''s Law, and circuitry for establishing a signal ratio as a function of said first and second log I/Io signals.
Claim 2
Dependent Claim
356 words
An atomic absorption spectroanalysis system comprising a burner for generating a flame, two radiation sources, each said source generating a characteristic radiation, two pairs of radiation sensors, each pair being responsive to one of said sources, an optical system for passing radiation from each source along a first path through said flame for sensing by the corresponding first sensors of each said paris of sensors to produce I signals, and passing radiation from each source along a second path outside of said flame for sensing by the corresponding second sensor of each of said pairs of sensors to produce Io signals, a first logarithmic circuit arrangement including a first logarithmic converter responsive to the output of a first sensor of one pair for providing a signal proportional to log I as a function of the output of a first radiation source and a second logarithmic converter responsive to the output of a second sensor of said one pair for providing a signal proportional to log Io as a Function of the output of a first radiation source, and a first summing network responsive to said first and second logarithmic converters to provide, as an output, a log I/Io signal, a second logarithmic circuit arrangement including a third logarithmic converter responsive to the output of a first sensor of the second pair for providing a signal proportional to log I as a function of the output of the second radiation source and a fourth logarithmic converter responsive to the output of the second sensor of said second pair for providing a signal proportional to log Io as a function of the output of the second radiation source, and a second summing network responsive to said third and fourth logarithmic converters to provide as an output, a second log I/Io signal, compensation circuitry connected in each logarithmic circuit arrangement between the two logarithmic converters of each said logarithmic circuit arrangement for providing compensation for radiation absorption deviations of the radiation passing through said flame as a function of Beer''s Law, and circuitry for establishing a signal ratio as a function of said first and second log I/Io signals.
Claim 3
Dependent Claim
74 words
The spectroanalysis system as claimed in claim 1 and further including means for modulating the radiation output of each said radiation source and synchronous demodulation circuitry comprising a demodulation circuit for demodulating the output signal of each said sensor, each said compensation circuit being connected between the outputs of the two demodulation circuits associated with each particular source for applying a compensation signal to the inputs of the logarithmic converters associated with that source.
Claim 4
Dependent Claim
72 words
The spectroanalysis system as claimed in claim 2 wherein each said compensation circuitry includes a feedback amplifier, a control for adjusting the gain of said feedback amplifier, and a voltage dividing network for subtracting a portion of the signal produced by radiation in said second path as a function of absorbance so that the absorbance response of said system is a linear function of the concentration of the constituent in said flame.
Claim 5
Dependent Claim
46 words
The spectroanalysis system as claimed in claim 1 and further including a servo feedback loop connected to the output of each said summing network for providing a zeroing adjustment of said log I/Io signal while a known standard or blank is being introduced into said flame.
Claim 6
Dependent Claim
64 words
The spectroanalysis system as claimed in claim 1 wherein said circuitry for establishing a signal ratio includes an output device responsive to each said summing network and further including circuitry for applying the output of one of said summing networks as a reference signal to the output device responsive to the other of said summing networks to provide compensation for variations in flame conditions.
Claim 7
Dependent Claim
40 words
The spectroanalysis system as claimed in claim 5 and further including mode selector mechanism for selectively applying the outputs of said summing networks to their corresponding output devices and applying both of said outputs to one of said output devices.
Claim 8
Dependent Claim
36 words
The spectroanalysis system as claimed in claim 1 and further including an adjustable scale expander circuit responsive to the output of each said summing network for modifying the magnitude of the output of said summing networks.
Claim 9
Dependent Claim
65 words
The spectroanalysis system as claimed in claim 1 and further including synchronous demodulation circuits corresponding to and responsive to the output of each said sensor, each said demodulation circuit converting an AC signal produced by its associated sensor to a DC signal for application to the corresponding logarithmic converter, and a clock source for applying signals simultaneously to said radiation sources and said demodulator circuits.
Claim 10
Dependent Claim
77 words
The spectroanalysis system as claimed in claim 8 wherein each said compensation circuitry includes a feedback amplifier, a control for adjusting the gain of said feedback amplifieR, and a voltage dividing network for subtracting a portion of the signal produced by radiation in said second path as a function of radiation absorbance in said first path so that the absorbance response of said system is a linear function of the concentration of a constituent in said flame.
Claim 11
Dependent Claim
186 words
An atomic absorption spectroanalysis system comprising a radiation source, a radiation sensor, a burner structure for generating a flame inserted into the optical path between said source and said sensor, said burner structure including a fuel line, means for connecting a source of fuel to said fuel line, an oxidant line, means for connecting a source of oxidant to said oxidant line, a chamber connected to said fuel and oxidant lines to mix the fuel and oxidant, means for introducing a sample to be analyzed into said chamber for mixing with the fuel and oxidant, and a burner head mounted on said chamber for defining the configuration of flame relative to said optical path, said system being characterized by the provision of a fixed restriction defining a circular unobstructed flow control orifice in each of said fuel and oxidant lines between and spaced from the respective fuel and oxidant source connection means and said chamber, and pressure adjusting means disposed in each of said fuel and oxidant lines between each said fixed restriction and said connection means for adjusting flow through said fuel and oxidant lines.
Claim 12
Dependent Claim
186 words
An atomic absorption spectroanalysis system comprising a radiation source, a radiation sensor, a burner structure for generating a flame inserted into the optical path between said source and said sensor, said burner structure including a fuel line, means for connecting a source of fuel to said fuel line, an oxidant line, means for connecting a source of oxidant to said oxidant line, a chamber connected to said fuel and oxidant lines to mix the fuel and oxidant, means for introducing a sample to be analyzed into said chamber for mixing with the fuel and oxidant, and a burner head mounted on said chamber for defining the configuration of flame relative to said optical path, said system being characterized by the provision of a fixed restriction defining a circular unobstructed flow control orifice in each of said fuel and oxidant lines between and spaced from the respective fuel and oxidant source connection means and said chamber, and pressure adjusting means disposed in each of said fuel and oxidant lines between each said fixed restriction and said connection means for adjusting flow through said fuel and oxidant lines.
Claim 13
Dependent Claim
23 words
The system as claimed in claim 10 further characterized in that each said orifice has a diameter in the range of 0.024-0.032 inch.
Claim 14
Dependent Claim
226 words
The system as claimed in claim 10, further characterized by the provision of a second radiation source, both of said sources being hollow cathode tubes, three additional radiation sensors, each set of two of said radiation sensors being associated with and responsive to a corresponding hollow cathode tube, an optical system for passing radiation from each tube along a first path through said flame for sensing by the corresponding first sensor of each set to produce I signals and along a second path outside of said flame for sensing by the corresponding second sensor of each set to produce Io signals, and a logarithmic amplifier arrangement responsive to the outputs of each set of sensors for establishing first and second log I/Io signal ratios as a function of the effect of the flame on the radiation from said tubes in said first path, said amplifier arrangement including a logarithmic amplifier corresponding and responsive to each sensor for producing an output as a logarithmic function of the signal from that sensor, a summing network responsive to the outputs of the amplifiers corresponding to each tube for providing, as an output, a log I/Io signal, an output device for displaying said first log I/Io signal ratio, and circuitry for applying said second log I/Io signal ratio to said output device to provide compensation for variations in flame conditions.
Claim 15
Dependent Claim
71 words
The system as claimed in claim 12 wherein said logarithmic amplifier arrangement further includes compensation circuitry associated with each said tube and connected between the outputs of each said set of radiation sensors for subtracting a portion of each said Io signal from that Io signal and the corresponding I signal to provide compensation for radiation absorption deviations of the radiation passing through said flame as a function of Beer''s Law.
Claim 16
Dependent Claim
40 words
The system as claimed in claim 13 wherein said logarithmic amplifier arrangement further includes an adjustable scale expander amplifier circuit responsive to the output of each said summing network for modifying the magnitude of the output of said summing networks.
Claim 17
Dependent Claim
148 words
An atomic absorption spectroanalysis system comprising a burner for generating a flame, a radiation source for generating a characteristic radiation, a pair of radiation sensors, an optical system for passing radIation from said source along a first path through said flame for sensing by a first sensor to produce an I signal, and passing radiation from said source along a second path outside of said flame for sensing by the second sensor to produce an Io signal, compensation circuitry associated with said radiation source and connected between the outputs of said two sensors for subtracting a portion of said Io signal from both said I and Io signals to provide compensation for radiation absorption deviations of the radiation passing through said flame as a function of Beer''s Law, and circuitry for generating an output signal as a function of the ratio between the compensated I and Io signals.
Claim 18
Dependent Claim
148 words
An atomic absorption spectroanalysis system comprising a burner for generating a flame, a radiation source for generating a characteristic radiation, a pair of radiation sensors, an optical system for passing radIation from said source along a first path through said flame for sensing by a first sensor to produce an I signal, and passing radiation from said source along a second path outside of said flame for sensing by the second sensor to produce an Io signal, compensation circuitry associated with said radiation source and connected between the outputs of said two sensors for subtracting a portion of said Io signal from both said I and Io signals to provide compensation for radiation absorption deviations of the radiation passing through said flame as a function of Beer''s Law, and circuitry for generating an output signal as a function of the ratio between the compensated I and Io signals.
Claim 19
Dependent Claim
71 words
The spectroanalysis system as claimed in claim 15 wherein said compensation circuitry includes a feedback amplifier, a control for adjusting the gain of said feedback amplifier, and a voltage dividing network for subtracting a portion of the signal produced by radiation in said second path as a function of absorbance so that the absorbance response of said system is a linear function of the concentration of a constituent in said flame.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-06-21 | 1974-12-21 | 1975-06-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-06-21 | 1978-12-21 | 1979-06-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-06-21 | 1982-12-21 | 1983-06-22 | $7700.00 | Window Closed / Lapsed |