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
  • G01N21/25—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
• • 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
  • G01N21/33—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using ultraviolet light
• • 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
  • G01N2021/3155—Measuring in two spectral ranges, e.g. UV and visible
• • 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
  • G01N2021/3513—Open path with an instrumental source
• • 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
  • G01N2021/3595—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light using FTIR

Definitions

• the present invention relates to a method and apparatus for sensing the nature of a gaseous composition, including one containing particulate matter.
• the invention is particularly useful for sensing vehicular emissions over a roadway, and is therefore described below with respect to such an application.
• Vehicular emissions particularly those resulting from inefficient combustion, have been identified as a major contributor to the air pollution in urban and rural areas.
• Vehicular emissions include carbon monoxide (CO), nitrogen oxides (NO x ), hydrocarbons (HCs), and particulate matter (PM). Such emissions contribute to the formation of photochemical smog, acid deposition, and elevated CO levels, while reactions of NO x and HCs also contribute to ozone (O 3 ) formations. These pollutants cause serious respiratory problems and increases toxicity and mortality. The effects are more severe in urban areas where traffic is dense, than in rural areas.
• the testing capacity of RS systems is far greater than the conventional system; that is, an RS device can perform inspection of thousands of vehicles per day. Taking into account the high correlation between pollutants emitted by vehicles, and the mechanical condition of the vehicle, remote sensing could also be an important tool in identifying faulty vehicles.
• a broad object of the present invention is to provide a method and apparatus for sensing the nature of a gaseous composition having advantages in one or more of the above respects.
• a more particular object of the invention is to provide a method and apparatus for sensing vehicular emissions caused by vehicles, having advantages in one or more of the above respects.
• a method for sensing the nature of a gaseous composition adjacent a surface comprising: disposing substantially parallel to the surface an optical transmission channel including an optical radiation source at one end thereof and a retro-reflector at the opposite end thereof, which retro-reflector is movable axially of the optical transmission channel substantially parallel to the surface towards and away from the optical radiation source; at a first location of the optical transmission channel, diverting a part of the optical radiation therein towards the surface, and detecting by a Light Detection and Ranging (LIDAR) detector system the particulate matter in the gaseous composition at the first location, to produce an output corresponding thereto; at a second location of the optical transmission channel, diverting another part of the optical radiation in the optical transmission channel towards a retro-reflector fixed with respect to the surface, and detecting by a Fourier Transform Infrared Spectroscopy (FTIS) detector system the gaseous composition at the second location, while moving the movable retro-
• LIDAR Light Detection and Rang
• apparatus for sensing the nature of a gaseous composition adjacent a surface comprising: a housing to be disposed substantially parallel to the surface and housing an optical transmission channel including an optical radiation source at one end thereof, and a retro-reflector at the opposite end thereof, which retro-reflector is movable axially of the optical transmission channel substantially parallel to the surface towards and away from the optical radiation source; a first beam splitter within the housing at a first location of the optical transmission channel, and effective to divert a part of the optical radiation therein out of the housing towards the surface; a Light Detection and Ranging (LIDAR) detector system for detecting the particulate matter in the gaseous composition at the first location, and producing an output corresponding thereto; a second beam splitter within the housing at a second location of the optical transmission channel effective to divert another part of the optical radiation therein out of the housing towards the surface; a Fourier Transform Infrared Spectroscopy (FTIS) detector system for
• LIDAR Light Detection and Ranging
• detector systems are well-known optical remote sensing systems that measure properties of scattered light to find range and/or other information of a distant target.
• Like radar which uses radio waves, namely light that is not in the visible spectrum, they determine range to an object by measuring the time delay between transmissions of a pulse and detection of the reflected signal.
• the primary difference between LIDAR and RADAR is that with LIDAR, much shorter wavelength of the electromagnetic spectrum are used, typically in the ultraviolet, visible or near infrared range. In general, it is possible to image a feature or object only about the same size as a wavelength, or larger. Thus, LIDAR is highly sensitive to aerosols and cloud particles.
• FTIS detector systems are known system which include two mirrors, or retro— reflector reflectors, located at a right angle to each other and oriented perpendicularly, with a beam splitter placed at the vertex of the right angle and oriented at a 45° angle relative to the two mirrors.
• the beam splitter receives radiation from one port, divides the radiation into two parts, each of which propagates down one of two arms, and is reflected off one of the mirrors in the form of two beams.
• the two beams are then recombined and transmitted out of another port.
• an interference pattern is produced as two phase shifted beams interfere with each other.
• Such a detector system is used in the present invention to detect, and to produce a measurement of, the gaseous composition by measuring the absorption spectrum of the gaseous ingredients.
• the output is processed, together with the output of the LIDAR detector system, to determine the nature of the gaseous composition.
• the foregoing method is particularly useful for detecting vehicle emissions over a roadway and for determining whether such emissions exceed a predetermined baseline value. The preferred embodiment of the invention described below is therefore used for this purpose.
• a method of detective excessive emissions from vehicles travelling over a roadway comprising: disposing an emission detector system over the roadway to overlie a section thereof through which the vehicles travel; detecting a vehicle approaching or travelling in the roadway section; and upon detecting a vehicle in or approaching the roadway section, actuating the emission detector system to measure the emission from the vehicle.
• the optical transmission channel is located to overlie the roadway, and the fixed retro— reflector is fixed to the roadway to underlie the optical transmission channel.
• the optical transmission channel is located to extend transversely across the roadway, and the movable retro-reflector is movable transversely of the roadway towards and away from the optical radiation source.
• the roadway includes a plurality of lanes; one of the above-described optical transmission channels is located to extend transversely across each of the lanes and cooperates with a retro-reflector fixed to the roadway to underlie each of the optical transmission channels.
• Such a method and apparatus for sensing and measuring vehicles emissions thus enable simultaneous inspection of both the gases and the particulate material of vehicle emissions by a combination of LIDAR and FTIS detector systems using a common lighting module serving as the optical radiation source.
• the lighting module is a halogen lamp emitting radiation having a high UV and infrared content.
• Such a system enables the use of known lighting modules and off-the-shelf optical-electrical-mechanical components, thereby enabling significant cost reduction in the initial installation as well as in the maintenance of the installation.
• Such a system may also be made more reliable and accurate, in comparison with the current data processing, by the use of continuous baseline calibration integrated in the measurement scheme.
• the overhead installation layout in the described preferred embodiment enables high capacity measurements on various road configurations (multi-lane roads, cross— junctions, two— way traffic loads, etc.).
• the fixed retro-reflectors are preferably coated retro-reflectors, integrated into the road surface. Multiple gaseous pollutants can be monitored simultaneously, as well as different particulate matter size distributions. It will thus be seen that, in general, the. described method and apparatus provide high reliability both with respect to spark-ignition and diesel vehicles. They permit unmanned operation, which allows performing all measurement operations in an automatic manner. In case a malfunctioning vehicle is detected, such information could be sent to a remote operator automatically for alerting the driver or an inspector. Further features and advantages of the invention will be apparent from the description below.
• FIG. 1 pictorially illustrates one form of two-lane roadway in which each lane is provided with an overhead apparatus constructed in accordance with the present invention for detecting and measuring vehicular emissions by vehicles travelling in the respective lane;
• FIG. 2 more particularly illustrates the construction of one unit utilized in the apparatus of FIG. 1 for detecting and measuring vehicular emissions in the respective lane of the roadway;
• FIG. 3 is a flowchart illustrating one manner of using the systems of FIGs. 1 and 2 for detecting undue vehicular emissions in each of the two lanes of the roadway of FIG. 1.
• the present invention in some embodiments thereof, relates to a method and apparatus for sensing gaseous emissions, and more particularly, but not exclusively, to sensing of vehicular emissions from vehicles travelling over a roadway in order to detect an undue level of emissions caused by such vehicles.
• Fig. 1 pictorially illustrates an embodiment of the invention embodied in such a system, including a roadway 2 divided into two lanes 2a, 2b for detecting emissions, shown as plumes 3, 4, of two vehicles 5, 6 as each travels over one of the lanes 2a, 2b.
• the apparatus includes an overhead horizontal structure 7 extending transversely across both lanes 2a, 2b, and supported at its opposite ends by a pair of vertical structures 8 and 9 straddling the opposite sides of the roadway 2.
• the overhead horizontal structure 7 mounts two detector units, generally designated 10, one over
• each of the emission detector units 10 includes a housing 11 extending transversely across, and substantially parallel to, each lane 2a, 2b.
• Housing 11 includes an optical transmission channel having an optical radiation source 12 at one end and a retro— reflector 13 at the opposite end.
• Optical radiation source 12 includes a Tg-Halogen lamp 12a emitting radiation having a high UV and infrared content, and a parabolic reflector 12b oriented to direct such radiation to the retro-reflector 13 at the opposite end of the optical transmission channel. As shown by arrow 14, retro-reflector 13 is to be moved axially of the optical transmission channel and substantially parallel to the surface of the respective lane 2a monitored by the respective unit 10.
• the end of collimating section 19 of the optical transmission channel proximate to the optical radiation source 12 is provided with a first beam splitter 20, and the opposite end of collimating section 19, proximate to the movable retro- reflector 13, is provided with a second beam splitter 30.
• Beam splitter 20 diverts a part of the radiation within section 19 of the optical transmission channel towards a Light Detection and Ranging (LIDAR) detector system, generally designated by box LIDAR; whereas beam splitter 30 diverts another part of the radiation within section 19 of the optical transmission channel to a Fourier Transform Infrared Spectroscopy (FTIS) detector system, generally designated by box FTIS.
• LIDAR Light Detection and Ranging
• FTIS Fourier Transform Infrared Spectroscopy
• the LIDAR detector system includes a diverging lens 21 for transmitting the part of the radiation diverted by beam splitter 20 towards plume 3 produced by the vehicle travelling along the respective lane 2a 2b (Fig. 1). This light, after reflection by the plume 3, is focused by a converging lens 22 onto a detector 23 which thereby produces an output corresponding to the particulate matter in plume 3 emitted from the vehicle travelling along the respective lane 2a.
• the part of the radiation within section 19 of the optical transmission channel diverted by beam splitter 30 to the FTIS detector system is directed through plume 3 towards a retro-reflector 31 fixed into, or with respect to, the surface of the roadway defined by the respective lane 2a.
• Fixed retro-reflector 31 is located with its axis perpendicular to the axis of movable retro-reflector 13 such that the beam reflected from the movable retro-reflector 13 introduces a time delay with respect to the beam reflected from the fixed retro-reflector 31.
• the two beams thus interfere, allowing the temporal coherence of the light to be measured at each different time delay setting, to effectively convert the time domain into a spatial coordinate.
• the spectrum can be reconstructed using Fourier Transform of the temporal coherence of the light.
• Such spectrographs are capable of very high spectral resolution observations of light sources, particularly those rich in infrared radiation for measuring the gas composition of the exhaust plume 3.
• the emission sensor unit 10 illustrated in Fig. 10 further includes a processor, generally designated 40, which includes a connection 41 to the optical radiation source 12, another connection 42 to the output of the LIDAR detector system, and another connection to the FTIS detector system.
• Processor 40 includes one or more outputs, such as output 44 to a signaling device, output 45 to a display device, and/or output 46 to a recording or other processing device.
• Fig. 3 illustrates a preferred example of the operation of each of the emission sensor units 10 as controlled by its respective processor 40 to detect undue emission from a vehicle travelling in the respective lane.
• the processor 40 may provide a signal of its condition in its signaling device 44, may produce a display of this condition in its display device 45, and/or may record the condition in its recording or other processing device 46.
• processor 40 controls the apparatus to sense the emissions of each vehicle travelling over the respective part of the roadways. This is done is by sensing the air composition over the selected part of the roadway when not being traversed by a vehicle and determining a baseline value, as shown by boxes 51a, 51b; then detecting a vehicle travelling over the respective part of the roadway, as indicated by boxes 52a, 52b; and then actuating the LIDAR detector system to detect the particulate matter in the gaseous emission as shown by block 54a, and the FTIS detector system to detect the level of the gaseous emission, as indicated by block 54b. That is, the operation performed by box 54a involves temporal filtering for data retrieval and Fast Fourier Transform of the retrieved data for the spectra analysis; and the operation by block 54b involves the temporal filtering for data retrieval.
• the baseline data measured by block 51a is subtracted from that measured by block 54a; and similarly, as indicated by block 55b, the baseline data measured in block 51b is subtracted from that produced by block 54b. If either of these measurements indicates an undue level of vehicle emission from the respective vehicle, a video monitoring system is triggered, as indicated by block 57. As mentioned earlier, the video monitoring system could produce an alarm signal, could display the respective measurement, and/or could be recorded for further processing or other use.

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

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Cited By (11)

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• 2009
  • 2009-09-02 EP EP09787556A patent/EP2338044A2/de not_active Withdrawn
  • 2009-09-02 WO PCT/IL2009/000851 patent/WO2010026579A2/en not_active Ceased

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