Patent US4047819A successfully refreshed from Google Patents.
US4047819A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus for measuring optical density with stray light compensation
Assignee: SmithKline Instrument Inc
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Filing: 1975-04-10
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Granted: 1977-09-13
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Expires: 1995-04-10
Abstract
Abstract Apparatus for measuring the optical density of a sample includes a dual beam spectrophotometer producing sample and reference signals which are compared with the discharge curve of a resistive-capacitive circuit to provide start-stop signals, the time interval between the two signals being indicative of optical density. Embodied within this linearization means is a novel method of correcting for nonlinearities due to stray light. The start and stop signals are used to drive a linear ramp generator, the stop signal terminating the ramp at an analog signal level indicative of optical density.
Inventors
- 👤 Paul R. Goldberg
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 18:18
CPC Classifications
G; G01; G01J; G01J1/00; G01J1/10; G01J1/16
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
128 words
Apparatus for measuring the optical density of a sample comprising: electro-optical means for measuring the light attenuating properties of said sample and producing a signal indicative of said attenuation, including a radiation source and detector to detect radiation transmitted through said sample and produce a sample signal; reference means for producing a reference signal including means for detecting radiation from said source; a resistive-capacitive circuit providing an exponential discharge voltage; means for adjusting the dc level of said sample signal relative to said exponential discharge voltage; means for comparing said reference and sample signal with the exponential discharge voltage of said resistive-capacitive circuit for producing start and stop signals respectively, the time interval between said start and stop signal being indicative of the optical density of said sample.
Claim 2
Dependent Claim
128 words
Apparatus for measuring the optical density of a sample comprising: electro-optical means for measuring the light attenuating properties of said sample and producing a signal indicative of said attenuation, including a radiation source and detector to detect radiation transmitted through said sample and produce a sample signal; reference means for producing a reference signal including means for detecting radiation from said source; a resistive-capacitive circuit providing an exponential discharge voltage; means for adjusting the dc level of said sample signal relative to said exponential discharge voltage; means for comparing said reference and sample signal with the exponential discharge voltage of said resistive-capacitive circuit for producing start and stop signals respectively, the time interval between said start and stop signal being indicative of the optical density of said sample.
Claim 3
Dependent Claim
31 words
Apparatus as in claim 1 including adjustable gain amplifier means connected in front of said comparing means for adjusting the magnitude of said sample signal to adjust for zero optical density.
Claim 4
Dependent Claim
41 words
Apparatus as in claim 1 in which said means for adjusting the dc level of said sample signal relative to said exponential discharge voltage includes means for adjusting the dc offset level of said sample signal derived from said electro-optical means.
Claim 5
Dependent Claim
37 words
Apparatus as in claim 1 in which said means for adjusting the dc level of said sample signal relative to said exponential discharge voltage includes means for adjusting the dc offset level of said exponential discharge voltage.
Claim 6
Dependent Claim
46 words
Apparatus as in claim 1 including a linear ramp generator means for generating a linear analog voltage ramp an responsive to said start signal for initiating said ramp and to said stop signal for terminating said ramp, said termination level being indicative of said optical density.
Claim 7
Dependent Claim
130 words
Apparatus for measuring the optical density of a sample comprising: electro-optical means for measuring the light attenuating properties of said sample and producing a sample indicative of said attenuation, including a radiation source; a detector to detect radiation transmitted through said sample and generate a sample signal; reference means for producing a reference signal a resistive-capacitive circuit including charging means; adjustable gain amplifier means connected between said electro-optical means and said comparing means for adjusting the magnitude of said sample signal to adjust for zero optical density; means for comparing said reference and adjusted sample signal with the exponential discharge voltage of said resistive-capacitive circuit for producing start and stop signals respectively, the time interval between said start and stop signal being indicative of the optical density of said sample.
Claim 8
Dependent Claim
130 words
Apparatus for measuring the optical density of a sample comprising: electro-optical means for measuring the light attenuating properties of said sample and producing a sample indicative of said attenuation, including a radiation source; a detector to detect radiation transmitted through said sample and generate a sample signal; reference means for producing a reference signal a resistive-capacitive circuit including charging means; adjustable gain amplifier means connected between said electro-optical means and said comparing means for adjusting the magnitude of said sample signal to adjust for zero optical density; means for comparing said reference and adjusted sample signal with the exponential discharge voltage of said resistive-capacitive circuit for producing start and stop signals respectively, the time interval between said start and stop signal being indicative of the optical density of said sample.
Claim 9
Dependent Claim
36 words
Apparatus as in claim 6 which includes means for adjusting the dc offset level of said sample signal derived from said electro-optical means relative to that of said exponential discharge voltage for correcting for stray light.
Claim 10
Dependent Claim
31 words
Apparatus as in claim 6 which includes means for adjusting the dc offset level of said exponential discharge voltage relative to that of said sample signal for correcting for stray light.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-09-12 | 1981-03-14 | 1981-09-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-09-12 | 1985-03-14 | 1985-09-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-09-12 | 1989-03-14 | 1989-09-13 | $7700.00 | Window Closed / Lapsed |