GB1248961A - Improvements in and relating to a system and apparatus for measuring the optical transmittance of the atmosphere - Google Patents

Improvements in and relating to a system and apparatus for measuring the optical transmittance of the atmosphere

Info

Publication number
GB1248961A
GB1248961A GB1196769A GB1196769A GB1248961A GB 1248961 A GB1248961 A GB 1248961A GB 1196769 A GB1196769 A GB 1196769A GB 1196769 A GB1196769 A GB 1196769A GB 1248961 A GB1248961 A GB 1248961A
Authority
GB
United Kingdom
Prior art keywords
light
phase
visibility
photo
remote unit
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
GB1196769A
Inventor
Charles Geoffrey Longford
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.)
Allen Lonford & Associates Ltd
Original Assignee
Allen Lonford & Associates Ltd
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 Allen Lonford & Associates Ltd filed Critical Allen Lonford & Associates Ltd
Publication of GB1248961A publication Critical patent/GB1248961A/en
Expired legal-status Critical Current

Links

Classifications

    • 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
    • G01N21/47—Scattering, i.e. diffuse reflection
    • G01N21/49—Scattering, i.e. diffuse reflection within a body or fluid
    • G01N21/53—Scattering, i.e. diffuse reflection within a body or fluid within a flowing fluid, e.g. smoke
    • G01N21/538—Scattering, i.e. diffuse reflection within a body or fluid within a flowing fluid, e.g. smoke for determining atmospheric attenuation and visibility

Landscapes

  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Investigating Or Analysing Materials By Optical Means (AREA)

Abstract

1,248,961. Measuring visibility photoelectrically. ALLEN, LONGFORD & ASSOCIATES Ltd. Feb. 18, 1970 [Nov. 19, 1968, March 6, 1969], Nos. 54866/68 and 11967/69. Heading G1A. Visibility is determined by providing a pair of light detection devices D1, D2 each responsive to light from two light sources S1, S2 whose intensity varies at the same frequency but in a different phase, A sin wt, B sin (wt + a), so that the output signals of the detection devices can be analyzed to provide a signal representing the intensity of the light sources and the transmittivity of the path between the detectors and sources. Each unit 10, 12 of the system consists of a prefocused filament lamp 22 which transmits light through lens 20 to the remote unit and through aperture 25 in wall 19 to silicon photo-cell 24 which also receives light from the remote unit through lens 21. In order to equalize the effective amount of light received under clear conditions from the remote unit source and lamp 22 the photo-cell 24 is rotatable. Also enclosed within the housing is a local amplifier mounted on printed circuit board 28 and a heater 30B. The units are trunnion mounted on rigid stands and are aligned by means of telescopes 11. In operation the output of an oscillator is clipped to provide clock pulses which are supplied to a frequency divider circuit which produces two trains of low frequency pulses phase shifted by 120 degrees to supply the lamp driver circuits. The photo-cells will produce square wave outputs which after amplification are fed to a phase sensing and gating circuit 16 which supplies meter 52. The circuit parameters are selected so that 1 mA is supplied to the meter when the squarewaves are in phase and zero current when 120 degrees out of phase corresponding to a visibility of 100% and zero respectively.
GB1196769A 1968-11-19 1968-11-19 Improvements in and relating to a system and apparatus for measuring the optical transmittance of the atmosphere Expired GB1248961A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB5486668 1968-11-19

Publications (1)

Publication Number Publication Date
GB1248961A true GB1248961A (en) 1971-10-06

Family

ID=10472295

Family Applications (1)

Application Number Title Priority Date Filing Date
GB1196769A Expired GB1248961A (en) 1968-11-19 1968-11-19 Improvements in and relating to a system and apparatus for measuring the optical transmittance of the atmosphere

Country Status (1)

Country Link
GB (1) GB1248961A (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0298584A2 (en) * 1987-05-13 1989-01-11 Combustion Developments Limited Monitoring equipment using transmitted light
CN114414534A (en) * 2022-01-18 2022-04-29 象谱信息产业有限公司 Intelligent induction and agglomerate fog detection device, system and method

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0298584A2 (en) * 1987-05-13 1989-01-11 Combustion Developments Limited Monitoring equipment using transmitted light
EP0298584A3 (en) * 1987-05-13 1990-06-27 Combustion Developments Limited Monitoring equipment using transmitted light
CN114414534A (en) * 2022-01-18 2022-04-29 象谱信息产业有限公司 Intelligent induction and agglomerate fog detection device, system and method
CN114414534B (en) * 2022-01-18 2023-10-31 象谱信息产业有限公司 Intelligent induction and mist detection device, system and method

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