CN111208085A - Multi-laser gas detection device - Google Patents
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Abstract
The invention provides a multi-laser gas detection device comprising at least two laser light sources, which may comprise a laser for detecting absorption of gas in an area, a laser for exciting luminescence of gas in the area, and a laser for detecting optical path length. Gas leaks are detected by determining the absorption or emission spectrum of the gas in this region. The detection system uses the determined absorption and path lengths to calculate the concentration of the gas in the region. The detection system may also generate an image indicative of a gas leak in the area.
Description
Technical Field
The invention belongs to the technical field of optical gas detection, and particularly relates to a multi-laser gas detection device.
Background
In the existing gas optical detection technology: the infrared video detection is a passive optical system, is distinguished by the absorbed intensity of background sunlight, depends on sunlight, has poor image contrast, and is difficult to exclusively identify target gas. Since the non-dispersive infrared spectrum has no wavelength selectivity, the gas species identification capability is low, any multiple gases can not be covered necessarily, and the absolute concentration cannot be obtained.
The single laser semiconductor laser cannot meet the simultaneous detection of multiple gases in many application scenes, especially the cross detection of some related gases, or the multiple lasers simply combine multiple detection devices together, and two sets of independent light paths and detectors are used for detecting different gas concentrations. The concentration thickness measured in the scene with non-fixed reflecting surfaces can not be converted into absolute concentration.
Disclosure of Invention
In view of the above, the present invention is directed to a multi-laser gas detection apparatus for remotely detecting a gas leak in a target using a plurality of laser beams.
The core idea of the scheme is as follows: using a laser light source to illuminate a target area and measuring the light energy scattered and/or reflected and/or emitted by an object in the target area, the composition and concentration of a substance of interest in a gas can be detected by analyzing the received light because light having a particular wavelength is absorbed by gas molecules as it passes through the target gas, while at the same time the gas molecules emit light having another particular wavelength as they decay down after being excited. Multiple laser beams are used to remotely detect gas leaks in a target.
In order to achieve the purpose, the technical scheme of the invention is realized as follows:
in a first aspect, the present invention provides a multi-laser gas detection apparatus comprising:
at least two main laser sources respectively emitting light beams having a certain wavelength;
the optical detector comprises a detector and a set of optical path device, and is used for collecting a reflected beam reflected by the beam emitted by the main laser source and converting the reflected beam into an electric signal;
the controller is used for controlling the parameter characteristics of the laser emitted by the main laser source;
and the analyzer is used for detecting and analyzing the electric signals output by the optical detector by adopting a time division multiplexing method or a modulation phase locking method to obtain the absorption rate of the light beam emitted by each main laser.
Further, the controller modulates the different light beams at different frequencies, the modulation frequencies being selected such that harmonics of each modulated signal do not overlap; the analyzer obtains the electrical signal obtained at the modulation frequency by a phase-locked method using the different modulation frequency as a reference frequency.
Further, the controller controls the plurality of main laser sources to emit light with different beam widths and delays, the optical detector collects the reflected light beams and converts the reflected light beams into electric signals, the analyzer demultiplexes the electric signals, and each demultiplexed electric signal can be associated with a single light beam to obtain the corresponding absorptivity of the light beam through the triggering synchronization of the controller.
The controller controls the ranging laser source to emit a second light beam with a second wavelength, and the wavelength of the second wavelength is selected to avoid the absorption of the gas possibly existing;
the distance measuring light detector collects a second reflected light beam of the second light beam, and the analyzer calculates the optical path of the light beam through the emitted second light beam and the second reflected light beam; the analyzer calculates the concentration of the gas to be detected from the obtained absorbance and optical path according to the following equation:
A＝ε·L·C
where A is the absorbance, ε is the molar absorbance of the species, L is the optical path of the light beam as it passes through region 400, and C is the concentration of the species.
In a second aspect, the present invention provides another multi-laser gas detection apparatus comprising:
at least one primary laser source emitting a beam of light having a wavelength;
the optical detector comprises a detector and a set of optical path device, and is used for collecting a reflected beam reflected by the beam emitted by the main laser source and converting the reflected beam into an electric signal;
the irradiation laser source emits irradiation beams which are excited and attenuated to emit beams with another wavelength when the gas to be detected absorbs the irradiation beams;
the infrared camera is used for collecting a luminous image of the gas to be detected after the gas to be detected is excited by the irradiation laser source;
a controller for controlling the main laser source and the parameter characteristics of the emitted laser of the irradiation laser source;
the analyzer is used for detecting and analyzing the electric signals output by the light detectors to obtain the absorption rate of the light beams emitted by each main laser; and analyzing the signals collected by the infrared camera to obtain a display image.
The controller controls the ranging laser source to emit a second light beam with a second wavelength, and the wavelength of the second wavelength is selected to avoid the absorption of the gas possibly existing;
the distance measuring light detector collects a second reflected light beam of the second light beam, and the analyzer calculates the optical path of the light beam through the emitted second light beam and the second reflected light beam; the analyzer calculates the concentration of the gas to be detected from the obtained absorbance and optical path according to the following equation:
A＝ε·L·C
where A is the absorbance, ε is the molar absorbance of the species, L is the optical path of the light beam as it passes through region 400, and C is the concentration of the species.
Compared with the prior art, the multi-laser gas detection device has the following advantages:
(1) the invention does not need to equip a set of detection device and light path for each gas, and can realize the sharing of the detection device and the light path only by adopting the time division multiplexing or modulation phase locking technology on the signal extraction.
(2) The invention is suitable for open type optical path detection, realizes scanning, namely remote measurement, of a possible leakage position at a distance, does not need to walk into or even approach to dangerous gas, is used for vehicle-mounted or handheld type, finds leakage positioning leakage and measures concentration and distance far beyond a leakage point by dozens of hundred meters, and greatly protects the safety of personnel and equipment.
(3) The absorption- > excitation- > luminescence technology adopted by the invention can be regarded as photoluminescence, the wavelength of absorbed light is different from that of luminescence light, the energy transfer between different chemical bond vibration modes after the gas molecules absorb infrared excitation light is utilized, the gas molecules emit light which does not irradiate the gas molecules, so the scattering and the transmission are completely different, only the light emitted in the way carries the characteristic information of the gas molecules, the light can be used for identification and measurement, a bright area with obvious contrast on a dark background is seen on an infrared camera, the interference of a sunlight spectrum is avoided, and the design of filtering and irradiating light is simplified.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate an embodiment of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:
FIG. 1 is a schematic structural diagram of a multi-laser gas detection device according to an embodiment of the present invention;
FIG. 2 is a schematic structural diagram of a multi-laser gas detection apparatus according to embodiment 1 of the present invention;
FIG. 3 is a schematic structural diagram of a multi-laser gas detection device according to embodiment 2 of the present invention;
fig. 4 is a schematic structural diagram of a multi-laser gas detection apparatus according to embodiment 4 of the present invention.
Detailed Description
It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.
The multi-laser gas detection apparatus 100 of the present invention detects gas 300 leaking from a target site 200. as shown in FIG. 1, the gas leak 300 may include any number or combination of gases. In general, laser 110 … 11N emits a beam in a direction toward location 200 to be inspected, and the laser may sequentially emit multiple beams in different directions toward the area that are incident on different target locations in area 400 so that different localized areas within area 400 may be inspected. If the target location 200 has a gas leak 300, the gas leaks into the region 400 through which the emitted and reflected beams pass. The gas absorbs a portion of the light beam according to the chemical bonding characteristics of its own molecules, or emits a portion of another light beam after absorption. The absorbance of the light emitted by the light source, or the emissivity of the light, may be measured and calculated to determine the gas leak 300 and further calculate its gas concentration.
It is particularly emphasized that the gas leak 300 may additionally or alternatively be detected by determining the emission spectrum of the gas in the region 400, in addition to the conventional absorption spectrum. For example, depending on the nature of the gas, the gas in the gas leak 300 may also emit additional light. More specifically, the gas in the gas leak 300 is generally in an unexcited state. When a light beam passing through the region 400 between the detection device 100 and the location 200 is absorbed by the gas, the absorbed light excites the gas in the gas leak 300 into an excited state. After the relaxation time, the energy of the gas in the excited state decays from the excited state to the ground state and emits photons of a different wavelength than the absorbed light. The leak detection module determines whether there is a gas leak 300 by detecting light emitted by the gas in the area 400.
A first light source 111 emitting a light beam … of a first wavelength, an nth light source 11N emitting a light beam of an nth wavelength; the light detector 120 is responsible for detecting light; the controller 130 is coupled to the first light source 111 … through the nth light source 11N. The emitted light beams may be of any wavelength from ultraviolet to infrared, all parallel to each other.
Analyzer 140 is coupled to light detector 120, and light detector 120 may include a single or multiple sensors for detecting light having different wavelengths. Light detector 120 may be a single pixel or a multi-pixel light detector, such as a photodiode array. Photodetector 120 may be any type of photodetector, such as a photodiode, photomultiplier tube, avalanche diode, photovoltaic photodetector, or any other photodetector that can measure the intensity of collected light. Photodetector 120 captures incident light and outputs an electrical signal representative of the intensity of the captured light.
Photodetector 120 may additionally include an optical collection device and an optical filter. An optical collection device collects incident light from the area being inspected, the optical collection device having a focal length such that the collected light is focused onto photodetector 120. Optical filters generally refer to bandpass filters that allow light having a wavelength in an absorption band or an emission band to pass through. The optical filter allows reflected light from the light beam emitted by the light source 111 … 11N or emitted light from the gas to pass through and remove light collected by the optical collection device having other wavelengths outside a certain range, i.e., ambient light (light that is undesirable for detecting gas leak 300), and the filtered light is directed to the light detector 120. In the case where photodetector 120 includes an optical filter, only light of a particular wavelength produces an electrical signal.
The multi-laser gas detection apparatus may be configured such that the light beam emitted by light source 111 … 11N and collected by light detector 120 is more easily analyzed to determine gas leak 300. For example, a multi-laser gas detection apparatus may use the principles of Tunable Diode Laser Absorption Spectroscopy (TDLAS). In these cases, the controller 130 may tune the wavelength by adjusting the temperature and/or injection current density of the light source 111.. 11N. By modulating the wavelength of the emitted light beam with a high frequency modulation signal, the wavelength of the light beam can be locked at a certain absorption spectrum peak of a particular gas in the gas leak 300. The harmonics (e.g., second harmonics) of the electrical signal generated by the photodetector 120 are used to determine the absorbance, i.e., the absorption intensity at a particular wavelength can be determined from the detected harmonics to determine the absorbance. The following examples are intended to illustrate further:
in the case of the example 1, the following examples are given,
the multi-laser gas detection apparatus includes at least two primary laser sources emitting beams having different wavelengths, the emitted beams passing through the region 400, the outer surface of the target site 200 reflecting the beams, the reflected beams passing through the region 400 toward the detection apparatus 100. The primary laser source may select the wavelength of each beam so that it is absorbed by a particular gas in the gas leak 300; each beam will be absorbed to a different degree depending on the gas in the gas leak 300 in the area 400. A plurality of reflected beams corresponding to the emitted beams of the laser sources are collected by the photo-detector 124, and absorptances of the light emitted by at least two of the laser sources are measured by the analyzer 142. By emitting light beams of different wavelengths, the various gases included in the gas leak 300 can be determined. The concentration of the leaking gas can be further measured, and the method of obtaining the concentration is described in detail in example 2.
This embodiment is shown in FIG. 2 and includes two primary laser sources, a first laser source 114 and a second laser source 115, respectively, and a photodetector 124 that collects the first and second reflected beams. The first and second reflected beams are first and second beams, respectively, emitted by the first and second laser sources 114 and 115 and reflected back from an outer surface of the target location 200 being inspected.
Wherein the plurality of laser sources may select a wavelength of the emitted light beam of each laser source such that absorption of light or emission of light by the plurality of gases may be detected. For example, the first laser source 114 may be configured to emit a beam of light at a wavelength that is absorbed by methane, and the second laser source 115 may be configured to emit a beam of light at a wavelength that is absorbed by ethylene.
If light beams of different absorption wavelengths of the same gas are selected, interference of other gases can be completely eliminated by mutual authentication, and the accuracy of measurement can be improved.
Each laser source may be tuned to emit light simultaneously or in a time-shared manner. In order to operate multiple lasers simultaneously and share a set of photodetectors 124, the multi-laser gas detection apparatus may be implemented in two ways.
The mechanism of the first multi-laser gas detection device that uses a set of photodetectors 124 for detection is similar to the phase-lock technique:
the different light beams are modulated at different frequencies. For example, the controller 132 may use a modulation signal at a first frequency to adjust the first laser source 114 to emit an optical beam at a first wavelength and a second frequency to modulate the second laser source 115 to emit an optical beam at a second wavelength. At the same time, the modulation frequencies are chosen such that the harmonics of each modulated signal do not overlap. Each beam having a different wavelength and a different modulation frequency.
Because the two beams are modulated at different frequencies, the analyzer 142 analyzes the electrical signal obtained at the first modulation frequency with a phase lock method based on the first frequency as a reference frequency to determine the presence of the first gas absorbing the first wavelength. The electrical signal obtained at the second modulated greenish frequency is also analyzed to determine the absorption of the second gas.
In particular, the first beam is modulated at a known and constant first frequency, which causes a response at the detector that is also a function of the oscillation in the time domain at the first frequency. The time domain waveform is Fourier transformed to obtain a frequency domain spectrum, a narrow-band filter is used for filtering near a first frequency, and finally a result of inverse Fourier transform filtering is used for obtaining a 'clean' waveform on the time domain, so that the influence of other light beams modulated by other frequencies can be eliminated, and the independent contribution of the light beams to signals is separated, namely phase-locked amplification. Similarly, the same operation is performed on the light beam with the second wavelength at the second frequency, and phase locking is respectively realized, so that respective signals are respectively extracted.
Another mechanism for detecting multiple laser gas detectors by sharing a set of photodetectors 124 is similar to time division multiplexing:
taking the dual laser beam example, the controller 132 causes the first laser source 114 to emit the first beam at a pulse width w1 at time t1, after a delay of d1, the controller 132 causes the second laser source 115 to emit the second beam at a pulse width w2 at time t2, after a delay of d2, the controller 132 again causes the first laser source to emit the first beam, and so on.
The reflected beam is collected by the photodetector 124 and converted to an electrical signal, which is demultiplexed by the analyzer 142. Because both beams are emitted at a particular time in a particular temporal pattern (i.e., width and delay of the beams), synchronization of the triggering of each demultiplexed electrical signal by the controller 132 can be associated with a single beam. Any other form of time domain modulation, such as pulse width modulation or pulse position modulation, may be employed to determine the gas leak 300 in the region 400.
Pulse width modulation or pulse position modulation refers to two or more beams of light being emitted alternately, the respective duty cycles may be regular periodic functions or irregular patterns, and the time-domain modulated synchronization signal is used to trigger a detector to distinguish the contributions of the different beams to the collected signal, thereby achieving time-division multiplexing.
The analyzer 142 demodulates the electrical signals into electrical signals of the first reflected light beam and electrical signals of the second reflected light beam in the phase-lock technique or the time-division multiplexing method described above. The analyzer 142 then uses the electrical signal representative of the first emitted light beam and the electrical signal of the first reflected light beam to calculate the absorbance of the first gas in the region. For example, the analyzer 142 compares the intensity of the first emitted light beam with the intensity of the first reflected light beam to calculate the absorbance of the first gas in the area 400. The analyzer 142 uses the electrical signals of the second transmitted and reflected beams in a similar manner to calculate the absorbance of the second gas in the region 400.
The analyzer 142 compares the calculated absorbance with a preset threshold absorbance and determines that the inspected area has a leak 300 if the calculated absorbance is above the threshold.
In a specific implementation of this embodiment, two lasers are designated as two diode lasers with different infrared wavelengths (for absorption of different gases or different absorption bands of the same gas) using the same TDLAS method. This is not a simple combination of two single laser TDLAS systems. The system consists of two independent laser diodes, a shared optical signal acquisition system and a photoelectric sensor. There are two methods for driving the laser diode. The first (time domain) is to drive one at a time, that is to say alternately the detection circuits are triggered by the drive circuit and synchronized to acquire the optical signals from the respective lasers, enabling it to switch between measuring the absorption of different gases at very high speed. The second (frequency domain) is to modulate the laser waveform at different frequencies and filter the input optical signal carrying the absorption information for the two gases at these different reference frequencies by a phase lock circuit, in such a way that the absorption of the two gases can be separately identified and measured.
In the embodiment, the detection part is completely that a set of common light paths are not distinguished, laser signals corresponding to all gases are collected by the same set of hardware, and signals corresponding to respective gas components are extracted in a time division multiplexing or frequency domain modulation phase locking mode on the electronic and software layers only by matching with a plurality of laser emission ends. The method has the advantages of simple optical system, low cost (without multi-pixel detector elements such as CCD and the like), highest utilization efficiency (all lasers share all the optical systems without sharing), system sensitivity equivalent to all gases and the like.
In the case of the example 2, the following examples are given,
the multi-laser gas detection apparatus, which includes the ranging laser source 113 and the ranging photodetector 123 in addition to the main laser source 112, as shown in fig. 3, the controller 131 controls the ranging laser source 113 to emit a second beam toward the target position 200, the second beam having a second wavelength that needs to avoid absorption by gases that may be present. In some cases, the light beam is in the visible range (i.e., light having a wavelength in the range of 400-780 nm) or in the near infrared range (i.e., light having a wavelength in the range of 780nm-1 μm).
The ranging light detector 123 collects a second reflected light beam that is emitted by the ranging laser source 113 and reflected back from the outer surface of the location 200 being inspected. The analyzer 141 uses a comparison of the emitted and collected beam characteristics to calculate the path length of the beam. For example, the analyzer 141 determines the time of flight or relative phase difference of the light beam to calculate the path length, i.e. the optical path length, and the calculation of the optical path length belongs to the prior art, and is not described herein again. Since the beam emitted by the ranging laser 113 and the beam emitted by the main laser 112 travel substantially the same path, their path lengths are substantially equal.
The analyzer 141 uses the determined absorbance and path length to calculate the concentration of the particular gas in the region 400 between the detection device 100 and the location 200 according to the following equation:
A＝ε·L·C
where A is the absorbance of the light beam for a particular substance,. epsilon.is the molar absorbance of the substance, L is the optical path of the light beam as it passes through region 400, and C is the concentration of the substance.
The thickness of the target gas cannot be directly measured, and can only be replaced by the beam path length, namely, no matter how thick the gas is, the gas is considered as an equivalent gas mass as the beam path length, the average concentration is calculated according to the lambert beer law, when the gas diffusion reaches the equilibrium, the gas is equal to the actual concentration, and the gas diffusion is lower than the actual concentration in other cases, so that the concentration and the concentration-thickness product are provided simultaneously (namely C L in the formula, from A/epsilon, and distance measurement is not needed), and the later avoids any average effect, and provides more information on the gas diffusion degree (the gas mass thickness) than the concentration information (namely, the concentration-thickness product reflects the severity of the leakage together, and the scheme provides the product and the concentration per se at the same time so as to furthest warn the dangerous condition).
The analyzer 141 may calculate a plurality of concentration values corresponding to different positions, each position corresponding to a direction of the light beam emitted by the primary laser source 112. The analyzer 141 may use the concentrations measured in various directions to generate a concentration image, which is a visual representation of the concentration of the gas 300 in the area 400.
In a specific implementation of this embodiment, one of the lasers is designated as a modulated mid-infrared laser, which is a tunable diode laser for the purpose of measuring the bulk density (product of concentration and thickness) of the gas using the TDLAS method, and the other laser is a pulsed near-infrared laser for the purpose of measuring the thickness of the gas using the TOF method, so that the gas concentration can be calculated by dividing the bulk density by the thickness.
In the case of the example 3, the following examples are given,
the multi-laser gas detection apparatus, including at least one primary laser source, may select the wavelength of each beam of light so that it is absorbed by a particular gas in the gas leak 300. As shown in FIG. 4, the present embodiment includes a primary laser source, and the controller 133 controls the primary laser source 116 to emit a beam toward the target location 200 in the region 400, the wavelength of which may be determined based on the gas that may be included in the gas leak 300. The primary laser source emits a beam at a first wavelength, the photodetector 126 collects a first reflected beam, which is the beam emitted by the primary laser 116 and reflected back from the outer surface of the location 200 being inspected, and the analyzer 143 determines the gas leak based on the calculated absorbance.
Subsequently, the irradiation laser light source 117 emits a second light beam to the target position 200 to be inspected. The second light beam has a second wavelength in the infrared range, which corresponds to a certain strongly absorbing wavelength of the gas to be detected, which may be the same as or different from the first wavelength, and the spectrum does not have to have a narrow linewidth like that used for TDLAS lasers. The second wavelength selection is such that when the gas absorbs the laser light of the second wavelength, the energy is excited and attenuated, and the gas emits light of a third wavelength different from the second wavelength, i.e. the second beam excites emission of photons of the third wavelength from the gas.
Both the first wavelength and the second wavelength must be a certain spectral peak of vibration of the target gas molecule, the higher the respective absorption intensity, the better they are, the coupling between their corresponding vibration modes exists, and the efficiency of generating vibration energy transfer is sufficiently high. Generally, the first wavelength selects a near infrared band with the maximum power of the available light source, corresponding to the broad frequency region of the gas molecule vibration absorption band, and the second wavelength selects a middle infrared band with weak background light intensity, corresponding to the fundamental frequency region of the gas molecule vibration absorption band.
The gas luminescence image is generated by the infrared camera 127. The infrared camera 127 is provided with a band-pass filter having the third wavelength as a center wavelength, and therefore, the gas emission image is a visual representation of the region under inspection, highlighting the location at which the third wavelength (i.e., gas) is detected.
Because infrared camera 127 may be configured to select various wavelengths of light to generate a gas luminescence image, analyzer 143 may extract a gas luminescence image of a corresponding wavelength for any possible gas in gas leak 300 to determine the leak. The analyzer 143 analyzes information included in the gas luminescence image to detect the gas leak 300. For example, the gas luminescence image includes the brightness of pixels corresponding to the gas leak 300, bright pixels in the image indicating the presence of leaking gas, approximating the shape of the plume of gas mass, and dark pixels in the image indicating the absence of leaking gas, and therefore, the analyzer 143 analyzes the pixel brightness values to determine the gas leak 300. Infrared camera 127 may be configured to generate images using a variety of different interchangeable filters so that a single gas luminescence image representing multiple gases may be generated.
This embodiment is specifically implemented by maintaining the first laser as a TDLAS infrared diode laser, while designating the second laser in this configuration as the illuminating infrared laser source, which may or may not be the same wavelength as the first laser, and need not be the narrow linewidth laser used for TDLAS. The absorption peak is chosen to match specifically the target gas so that the infrared energy absorbed by the gas molecules will dissipate to other vibrational modes and emit infrared radiation of different wavelengths, and careful selection of the imaging camera's band pass filter according to the most likely emission wavelength region gives the infrared image higher contrast and sharpness.
Fig. 2 through 4 illustrate various configurations of a multi-laser gas detection device, in which the multi-laser gas detection device can emit any number of beams, collect the beams, detect gas leaks, determine absorbance, determine concentration, and generate gas images using any combination of emitted beams and detection methods.
The lasers in the above embodiments are selected from: gas absorption spectra were measured using mid-infrared (mid-IR) and/or near-infrared (near-IR) lasers, which illuminate the gas and monitor the gas infrared emission video, and laser optical path length (gas thickness) was measured using visible (vis) and/or near-infrared (near-IR) lasers.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
Claims (7)
1. A multi-laser gas detection apparatus, comprising:
at least two main laser sources respectively emitting light beams having a certain wavelength;
the optical detector comprises a detector and a set of optical path device, and is used for collecting a reflected beam reflected by the beam emitted by the main laser source and converting the reflected beam into an electric signal;
the controller is used for controlling the parameter characteristics of the laser emitted by the main laser source;
and the analyzer is used for detecting and analyzing the electric signals output by the optical detector by adopting a time division multiplexing method or a modulation phase locking method to obtain the absorption rate of the light beam emitted by each main laser.
2. A multi-laser gas detection apparatus as claimed in claim 1, wherein: the controller modulating the different light beams at different frequencies, the modulation frequencies being selected such that harmonics of each modulated signal do not overlap; the analyzer obtains the electrical signal obtained at the modulation frequency by a phase-locked method using the different modulation frequency as a reference frequency.
3. A multi-laser gas detection apparatus as claimed in claim 1, wherein: the controller controls the plurality of main laser sources to emit with different beam widths and delays, the optical detector collects the reflected beams and converts the reflected beams into electrical signals, the analyzer demultiplexes the electrical signals, and each demultiplexed electrical signal can be associated with a single beam to obtain the corresponding absorptivity of the beam through the triggering synchronization of the controller.
4. A multi-laser gas detection apparatus as claimed in claim 1, wherein: the controller controls the ranging laser source to emit a second light beam with a second wavelength, and the wavelength of the second wavelength is selected to avoid the absorption of the gas possibly existing;
the distance measuring light detector collects a second reflected light beam of the second light beam, and the analyzer calculates the optical path of the light beam through the emitted second light beam and the second reflected light beam; the analyzer calculates the concentration of the gas to be detected from the obtained absorbance and optical path according to the following equation:
A＝ε·L·C
where A is the absorbance, ε is the molar absorbance of the species, L is the optical path of the light beam as it passes through region 400, and C is the concentration of the species.
5. A multi-laser gas detection apparatus, comprising:
at least one primary laser source emitting a beam of light having a wavelength;
the optical detector comprises a detector and a set of optical path device, and is used for collecting a reflected beam reflected by the beam emitted by the main laser source and converting the reflected beam into an electric signal;
the irradiation laser source emits irradiation beams which are excited and attenuated to emit beams with another wavelength when the gas to be detected absorbs the irradiation beams;
the infrared camera is used for collecting a luminous image of the gas to be detected after the gas to be detected is excited by the irradiation laser source;
a controller for controlling the main laser source and the parameter characteristics of the emitted laser of the irradiation laser source;
the analyzer is used for detecting and analyzing the electric signals output by the light detectors to obtain the absorption rate of the light beams emitted by each main laser; and analyzing the signals collected by the infrared camera to obtain a display image.
6. The multi-laser gas detection device of claim 5, wherein: the controller controls the ranging laser source to emit a second light beam with a second wavelength, and the wavelength of the second wavelength is selected to avoid the absorption of the gas possibly existing;
the distance measuring light detector collects a second reflected light beam of the second light beam, and the analyzer calculates the optical path of the light beam through the emitted second light beam and the second reflected light beam; the analyzer calculates the concentration of the gas to be detected from the obtained absorbance and optical path according to the following equation:
A＝ε·L·C
where A is the absorbance, ε is the molar absorbance of the species, L is the optical path of the light beam as it passes through region 400, and C is the concentration of the species.
7. The multi-laser gas detection device of claim 5, wherein: the infrared camera is also provided with a band-pass filter and an optical filter.
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