GB1237547A - Differential spectral absorption analyser - Google Patents

Differential spectral absorption analyser

Info

Publication number
GB1237547A
GB1237547A GB3763868A GB3763868A GB1237547A GB 1237547 A GB1237547 A GB 1237547A GB 3763868 A GB3763868 A GB 3763868A GB 3763868 A GB3763868 A GB 3763868A GB 1237547 A GB1237547 A GB 1237547A
Authority
GB
United Kingdom
Prior art keywords
frequency
component
detector
band
modulation
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
GB3763868A
Inventor
Harry John Smith
Brian James Scott
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
STC PLC
Original Assignee
Standard Telephone and Cables PLC
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Standard Telephone and Cables PLC filed Critical Standard Telephone and Cables PLC
Priority to GB3763868A priority Critical patent/GB1237547A/en
Publication of GB1237547A publication Critical patent/GB1237547A/en
Expired legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
    • G01J3/28—Investigating the spectrum
    • G01J3/42—Absorption spectrometry; Double beam spectrometry; Flicker spectrometry; Reflection spectrometry
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J1/00—Photometry, e.g. photographic exposure meter
    • G01J1/10—Photometry, e.g. photographic exposure meter by comparison with reference light or electric value provisionally void
    • G01J1/20—Photometry, e.g. photographic exposure meter by comparison with reference light or electric value provisionally void intensity of the measured or reference value being varied to equalise their effects at the detectors, e.g. by varying incidence angle
    • G01J1/34—Photometry, e.g. photographic exposure meter by comparison with reference light or electric value provisionally void intensity of the measured or reference value being varied to equalise their effects at the detectors, e.g. by varying incidence angle using separate light paths used alternately or sequentially, e.g. flicker
    • G01J1/36—Photometry, e.g. photographic exposure meter by comparison with reference light or electric value provisionally void intensity of the measured or reference value being varied to equalise their effects at the detectors, e.g. by varying incidence angle using separate light paths used alternately or sequentially, e.g. flicker using electric radiation detectors
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
    • G01J3/28—Investigating the spectrum
    • G01J3/30—Measuring the intensity of spectral lines directly on the spectrum itself
    • G01J3/32—Investigating bands of a spectrum in sequence by a single detector
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
    • G01J3/28—Investigating the spectrum
    • G01J3/42—Absorption spectrometry; Double beam spectrometry; Flicker spectrometry; Reflection spectrometry
    • G01J3/433—Modulation spectrometry; Derivative spectrometry
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
    • G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
    • G01N21/314—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry with comparison of measurements at specific and non-specific wavelengths
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J1/00—Photometry, e.g. photographic exposure meter
    • G01J1/42—Photometry, e.g. photographic exposure meter using electric radiation detectors
    • G01J2001/4242—Modulated light, e.g. for synchronizing source and detector circuit
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J1/00—Photometry, e.g. photographic exposure meter
    • G01J1/42—Photometry, e.g. photographic exposure meter using electric radiation detectors
    • G01J1/44—Electric circuits
    • G01J2001/4406—Plural ranges in circuit, e.g. switchable ranges; Adjusting sensitivity selecting gain values
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
    • G01J3/12—Generating the spectrum; Monochromators
    • G01J2003/1226—Interference filters
    • G01J2003/123—Indexed discrete filters
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
    • G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
    • G01N21/35—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light
    • G01N21/3504—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light for analysing gases, e.g. multi-gas analysis

Abstract

1,237,547. Spectral analysis. STANDARD TELEPHONES & CABLES Ltd. Aug. 7, 1968, No. 37638/ 68. Heading G1A. [Also in Divisions G2 and H4] In a differential spectral absorption analyser a rotatable filter wheel, Fig. 2, is located together with a test sample, in the optical path from a radiation source to a photo-detector, and provides both an overall intensity modulation of the beam at a frequency f 2 and also a modulation of each of two particular wavelengths contained in the beam at a frequency f 1 , the photo-detector output component of frequency f 1 providing the analyser output while the f 2 component (f 2 > 2f1) is fed back to an amplifier associated with the detector to provide automatic gain control to eliminate source or detector fluctuations. The filter wheel comprises a plurality of equiangularly spaced filters, alternate ones of which form a first set having a different pass band from the second set. The filters 9, for example, will have a pass-band chosen to match a strong absorption band of the substance whose concentration is being measured, while the other filter set will have a pass-band located where the substance is transparent. Thus, presence of the substance in the optical path will result in the modulation of frequency f 1 . The overall intensity modulation at a frequency f 2 is provided by ruled lines 10. After amplification (2) and removal of the f 2 component (3, 6) the f 1 component is supplied to a synchronous detector (7) controlled by pulses generated from the filter wheel drive motor. The synchronized output is displayed on a meter which may also include means for indicating failure of the light source. A separate filter circuit (4) is provided in the feedback path to suppress the f 1 component. To measure the concentration of a specific vapour the two wavelengths are usually chosen in the infrared region.
GB3763868A 1968-08-07 1968-08-07 Differential spectral absorption analyser Expired GB1237547A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB3763868A GB1237547A (en) 1968-08-07 1968-08-07 Differential spectral absorption analyser

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB3763868A GB1237547A (en) 1968-08-07 1968-08-07 Differential spectral absorption analyser

Publications (1)

Publication Number Publication Date
GB1237547A true GB1237547A (en) 1971-06-30

Family

ID=10397900

Family Applications (1)

Application Number Title Priority Date Filing Date
GB3763868A Expired GB1237547A (en) 1968-08-07 1968-08-07 Differential spectral absorption analyser

Country Status (1)

Country Link
GB (1) GB1237547A (en)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4516857A (en) * 1981-05-04 1985-05-14 Her Majesty The Queen In Right Of Canada, As Represented By The Minister Of National Defence Correlation spectrometer for nerve agents
EP0876014A2 (en) * 1997-05-01 1998-11-04 AT&T Corp. Automatic gain control for free-space optical telecommunication links
GB2334097A (en) * 1998-02-06 1999-08-11 British Gas Plc System to detect the presence of water on a surface
WO2005064314A1 (en) * 2003-12-22 2005-07-14 Koninklijke Philips Electronics N. V. Optical analysis system, blood analysis system and method of determining an amplitude of a principal component
WO2006026766A2 (en) * 2004-09-01 2006-03-09 Honeywell International Inc. Frequency-multiplexed detection of multiple wavelength light for flow cytometry
WO2013188914A1 (en) * 2012-06-21 2013-12-27 The University Of Sydney Sensitive rapid response optical sensor and method
WO2014054022A1 (en) * 2012-10-05 2014-04-10 Klein Medical Limited Spectroscopic analysis
AU2009299563B2 (en) * 2008-10-01 2015-03-05 Thorn Security Limited A particulate detector

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4516857A (en) * 1981-05-04 1985-05-14 Her Majesty The Queen In Right Of Canada, As Represented By The Minister Of National Defence Correlation spectrometer for nerve agents
EP0876014A2 (en) * 1997-05-01 1998-11-04 AT&T Corp. Automatic gain control for free-space optical telecommunication links
EP0876014A3 (en) * 1997-05-01 1999-12-29 AT&T Corp. Automatic gain control for free-space optical telecommunication links
GB2334097A (en) * 1998-02-06 1999-08-11 British Gas Plc System to detect the presence of water on a surface
GB2334097B (en) * 1998-02-06 2002-08-07 British Gas Plc Method and apparatus to detect the presence of water on a surface
WO2005064314A1 (en) * 2003-12-22 2005-07-14 Koninklijke Philips Electronics N. V. Optical analysis system, blood analysis system and method of determining an amplitude of a principal component
WO2006026766A2 (en) * 2004-09-01 2006-03-09 Honeywell International Inc. Frequency-multiplexed detection of multiple wavelength light for flow cytometry
WO2006026766A3 (en) * 2004-09-01 2006-06-01 Honeywell Int Inc Frequency-multiplexed detection of multiple wavelength light for flow cytometry
US7612871B2 (en) 2004-09-01 2009-11-03 Honeywell International Inc Frequency-multiplexed detection of multiple wavelength light for flow cytometry
AU2009299563B2 (en) * 2008-10-01 2015-03-05 Thorn Security Limited A particulate detector
WO2013188914A1 (en) * 2012-06-21 2013-12-27 The University Of Sydney Sensitive rapid response optical sensor and method
WO2014054022A1 (en) * 2012-10-05 2014-04-10 Klein Medical Limited Spectroscopic analysis

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