CN108181269B - Laser modulation driving device and method for removing background noise - Google Patents
Laser modulation driving device and method for removing background noise Download PDFInfo
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- CN108181269B CN108181269B CN201711465520.XA CN201711465520A CN108181269B CN 108181269 B CN108181269 B CN 108181269B CN 201711465520 A CN201711465520 A CN 201711465520A CN 108181269 B CN108181269 B CN 108181269B
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- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
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Abstract
The embodiment of the invention discloses a laser modulation driving device and a method for removing background noise. The device comprises a main controller, a direct current signal generator, a modulation signal generator, a signal superposition module with an independent enabling end, a voltage-current converter and a laser. The main controller controls the frequency and the scanning range of a direct current driving signal output by the direct current signal generator and the frequency of a modulation signal output by the modulation signal generator, and the signal superposition module superposes the direct current driving signal and the modulation signal to generate a reference light voltage driving signal and a detection light voltage driving signal; detecting the wavelength output by the laser driven by the photovoltage driving signal to be in the absorption region of the gas to be detected, and detecting the concentration of the gas to be detected; the reference photovoltage driving signal drives the wavelength output by the laser to be in the non-absorption region of the gas to be detected, and is used for removing background noise in a contrast mode. According to the method and the device, on the premise that the complexity of the gas detection system is not increased, the interference of background noise is effectively inhibited, and the accuracy of gas concentration measurement is improved.
Description
Technical Field
The embodiment of the invention relates to the technical field of laser manufacturing, in particular to a laser modulation driving device and a method for removing background noise.
Background
The semiconductor laser is a laser which utilizes semiconductor materials as working substances and has the advantages of small size, high efficiency, long service life, easy integration and the like. With the rapid development of semiconductor laser technology, the TDLAS (Tunable Diode laser absorption Spectroscopy) technology is widely used as a new means for gas detection.
The laser gas analyzer prepared based on the TDLAS technology utilizes the characteristics that the narrow line width and the wavelength of a tunable semiconductor laser are changed along with the injection current to realize the measurement of single or a plurality of absorption lines of molecules which are very close to each other and difficult to distinguish, detects the concentration of gas by analyzing the selective absorption of the laser by the gas, and has the advantages of high resolution, high selectivity, high sensitivity, quick response time and the like.
In the process of detecting the gas concentration by adopting the TDLAS technology, the detection system is affected by temperature change, pressure fluctuation, interference of other gases except the gas to be detected and the like, so that the accuracy of the detection result is reduced. In order to improve the accuracy of the concentration of the gas to be measured, the influence of background noise on the laser intensity can be effectively suppressed.
At present, in the prior art, generally, another path of laser is added as reference light, and a measurement result is obtained by performing differential operation on signals received after the reference laser and the detection laser pass through a gas to be measured.
Although the background noise can be suppressed, an additional laser light path needs to be added to the system, which increases the cost of gas concentration detection, increases the complexity of the gas concentration detection equipment to a certain extent, and reduces the reliability of the equipment.
In view of this, a problem to be solved by those skilled in the art is to effectively suppress the influence of background noise on the laser intensity without increasing the complexity of the gas detection system, so as to improve the measurement accuracy of the gas concentration and improve the reliability of the gas detection system.
Disclosure of Invention
The embodiment of the invention aims to provide a laser modulation driving device and a method for removing background noise, a gas detection system is simple in structure and low in complexity, and the influence of the background noise on the laser intensity can be effectively inhibited, so that the measurement precision of the gas concentration is improved, and the reliability of the gas detection system is improved.
In order to solve the above technical problems, embodiments of the present invention provide the following technical solutions:
an embodiment of the present invention provides a laser modulation driving apparatus applied to a laser gas analyzer, including:
the device comprises a main controller, a direct current signal generator, a modulation signal generator, a signal superposition module with an independent enabling end, a voltage-current converter and a laser;
the signal superposition module is respectively connected with the direct current signal generator and the modulation signal generator and is used for superposing a direct current driving signal output by the direct current signal generator and a modulation signal output by the modulation signal generator to generate a laser voltage driving signal, and the type of the laser voltage driving signal comprises a reference light voltage driving signal and a detection light voltage driving signal;
the main controller is respectively connected with the direct current signal generator and the modulation signal generator and is used for determining the frequency and the scanning range of the direct current driving signal and the frequency of the modulation signal so as to generate the reference photovoltage driving signal and the detection photovoltage driving signal; the detection photovoltage driving signal drives the laser to output laser wavelength in the absorption region of the gas to be detected, and the laser wavelength is used for detecting the concentration of the gas to be detected; the reference photovoltage driving signal drives the laser wavelength output by the laser to be in a non-absorption region of the gas to be detected, and is used for contrasting and removing background noise;
the voltage-current converter is respectively connected with the signal superposition module and the laser and is used for converting the laser voltage driving signal into a corresponding laser current driving signal so that the laser emits laser under the driving of the laser current driving signal.
Optionally, the direct current driving signal is a trapezoidal wave driving signal.
Optionally, the frequency of the trapezoidal wave driving signal is 1-100 Hz.
Optionally, the modulation signal is a sine wave modulation signal.
Optionally, the frequency of the sine wave modulation signal is 1KHz to 1 MHZ.
Optionally, the dc driving signal is composed of a first current segment, a second current segment, and a third current segment;
the first current segment is a direct current voltage signal; the second current segment is superposed with the modulation signal to generate an alternating voltage signal; the third current segment is superposed with the modulation signal to generate a detection voltage signal;
the direct-current voltage signal and the alternating-current voltage signal drive the wavelength output by the laser to be in a non-absorption region of the gas to be detected; the detection voltage signal drives the laser to output a wavelength in the absorption region of the gas to be detected.
Optionally, the dc driving signal is composed of a low current segment, a medium current segment, a high current segment, and a ramp current segment;
the ramp current section is a current value corresponding to the high current section which is uniformly reduced to a current value corresponding to the low current section along with time.
Optionally, the laser voltage driving signal includes a first reference light driving section, a second reference light driving section, a third reference light driving section, and a detection light driving section;
the first reference light driving section is a direct current voltage signal corresponding to the low current section, and the third reference light driving section is a direct current voltage signal corresponding to the high current section; the second reference light driving section is an alternating voltage signal generated by superposing the medium current section and the modulation signal; the detection light section is a voltage signal generated by superposing the ramp current section and the modulation signal;
the first reference light driving section, the second reference light driving section and the third reference light driving section drive the wavelength output by the laser to be in a non-absorption area of the gas to be detected; the detection light driving section drives the laser to output a wavelength in the absorption region of the gas to be detected.
Another aspect of the embodiments of the present invention provides a method for removing background noise, which is applied to a gas detection system based on a TDLAS technology, and includes:
driving a direct current signal generator to output a direct current driving signal according to a preset scanning range;
driving a modulation signal generator to output a modulation signal according to a preset frequency, so that the direct current driving signal generates a voltage driving signal for driving a laser under the modulation of the modulation signal, wherein the voltage driving signal comprises a reference photovoltage driving signal and a detection photovoltage driving signal;
receiving a reference signal of the laser after the laser emits laser light to pass through the gas to be detected under the drive of a reference photocurrent drive signal, wherein the reference photocurrent drive signal is converted into the reference photocurrent drive signal;
receiving a detection signal after the laser emits laser light to pass through the gas to be detected under the drive of a detection photocurrent drive signal, wherein the detection photocurrent drive signal is converted into a detection photocurrent drive signal;
carrying out differential operation on the reference signal and the detection signal to remove background noise in the detection process of the gas to be detected;
the reference photocurrent driving signal drives the wavelength output by the laser to be in a non-absorption region of the gas to be detected; the detection photocurrent driving signal drives the laser to output a wavelength in the absorption region of the gas to be detected, and is used for detecting the concentration of the gas to be detected.
Optionally, the performing a differential operation on the reference signal and the detection signal to remove the background noise in the detection process of the gas to be detected includes:
averaging the alternating current reference signal, and adding the alternating current reference signal and the direct current reference signal to obtain an average value as a reference signal;
carrying out differential operation on the reference signal and the detection signal to remove background noise in the detection process of the gas to be detected;
the direct current reference signal is a direct current reference signal after the laser is emitted to pass through the gas to be detected under the drive of the direct current reference photocurrent driving signal; the alternating current reference signal is the alternating current reference signal after the laser is received and emitted to pass through the gas to be detected under the driving of the alternating current reference photocurrent driving signal.
The embodiment of the invention provides a laser modulation driving device, which is applied to a laser gas analyzer and comprises a main controller, a direct current signal generator, a modulation signal generator, a signal superposition module with an independent enabling end, a voltage-current converter and a laser. The main controller controls the frequency and the scanning range of a direct current driving signal output by the direct current signal generator and the frequency of a modulation signal output by the modulation signal generator, and the signal superposition module superposes the direct current driving signal and the modulation signal to generate a reference light voltage driving signal and a detection light voltage driving signal; detecting the wavelength output by the laser driven by the photovoltage driving signal to be in the absorption region of the gas to be detected, and detecting the concentration of the gas to be detected; the reference photovoltage driving signal drives the wavelength output by the laser to be in a non-absorption area of the gas to be detected, and is used for contrasting and removing background noise; the voltage-current converter is respectively connected with the signal superposition module and the laser and is used for converting the laser voltage driving signal into a corresponding laser current driving signal so that the laser emits laser under the driving of the laser current driving signal.
The technical scheme that this application provided's advantage lies in, makes the laser instrument output wavelength be in the detection laser that awaits measuring the gas absorption district and be in the reference laser of non-absorption district through the drive signal of control laser instrument, will detect laser and reference laser and carry out the difference operation through the signal of the gas that awaits measuring to get rid of the background noise among the gas detection process, improved the precision that gas concentration detected. Because the same laser is used for the detection laser and the reference laser, the complexity of the whole gas detection system is greatly reduced, the gas detection system has a simple structure and low complexity, the gas detection cost is saved, and the reliability of the gas detection system is improved.
In addition, the embodiment of the invention also provides a corresponding method for removing background noise for the laser modulation driving device, so that the laser modulation driving device is more feasible, and the method has corresponding advantages.
Drawings
In order to more clearly illustrate the embodiments or technical solutions of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained based on these drawings without creative efforts.
Fig. 1 is a block diagram of a specific implementation of a laser modulation driving apparatus according to an embodiment of the present invention;
fig. 2 is a schematic waveform diagram of a laser voltage driving signal according to an embodiment of the present invention;
fig. 3 is a block diagram of another specific implementation of a laser modulation driving apparatus according to an embodiment of the present invention;
FIG. 4 is a block diagram of one embodiment of an illustrative example provided by an embodiment of the present invention;
fig. 5 is a flowchart illustrating a method for removing background noise according to an embodiment of the present invention.
Detailed Description
In order that those skilled in the art will better understand the disclosure, the invention will be described in further detail with reference to the accompanying drawings and specific embodiments. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The terms "first," "second," "third," "fourth," and the like in the description and claims of this application and in the above-described drawings are used for distinguishing between different objects and not for describing a particular order. Furthermore, the terms "comprising" and "having," as well as any variations thereof, are intended to cover non-exclusive inclusions. For example, a process, method, system, article, or apparatus that comprises a list of steps or elements is not limited to only those steps or elements but may include other steps or elements not expressly listed.
Having described the technical solutions of the embodiments of the present invention, various non-limiting embodiments of the present application are described in detail below.
Referring to fig. 1, fig. 1 is a block diagram of a laser modulation driving apparatus according to an embodiment of the present invention, which is applied to a laser gas analyzer, and the embodiment of the present invention includes the following components:
the laser modulation driving device can comprise a main controller 1, a direct current signal generator 2, a modulation signal generator 3, a signal superposition module 4 with an independent enabling end, a voltage-current converter 5 and a laser 6.
The dc signal generator 2 is connected to the main controller 1, and is configured to output a dc driving signal with a preset scanning range and a preset frequency, where the scanning range and the frequency are determined according to actual requirements, and this is not limited in this application, and optionally, the frequency of the dc driving signal may be 1-100 Hz.
In a specific embodiment, the dc signal generator 2 may be composed of a digital-to-analog converter DA, but the dc signal generator 2 may also be another signal generator outputting a dc driving signal, which is not limited in this application.
The waveform of the dc driving signal may be any waveform, but is not limited thereto, and in a preferred embodiment, the dc driving signal may be a trapezoidal waveform driving signal.
The modulation signal generator 3 is connected to the main controller 1, and is configured to output a modulation signal with a preset frequency, modulate the dc driving signal, and modulate the frequency of the output laser, where the frequency is determined according to actual requirements.
In a specific embodiment, the modulation signal generator 3 may be composed of a DDS chip, and of course, the modulation signal generator 3 may also be another signal generator outputting a modulation signal, which is not limited in this application.
The waveform of the modulation signal may be any shape of wave, which is not limited in this application, and in a preferred embodiment, the modulation signal may be a sine wave modulation signal.
The signal superposition module 4 is respectively connected with the direct current signal generator 2 and the modulation signal generator 3, and the signal superposition module 4 receives signals input by the direct current signal generator 2 and the modulation signal generator 3 and needs to be provided with an independent enabling end. The signal superposition module 4 is used for superposing the direct current driving signal output by the direct current signal generator 2 and the modulation signal output by the modulation signal generator 3 to generate a laser voltage driving signal.
The types of the laser voltage driving signal may include a reference photo voltage driving signal and a detection photo voltage driving signal. Detecting that laser wavelength output by a laser driven by a photovoltage driving signal is in an absorption region of gas to be detected, and detecting the concentration of the gas to be detected; the reference photovoltage driving signal drives the laser to output laser wavelength in a non-absorption region of the gas to be measured, and is used for removing background noise in a contrast mode, so that the interference of the environment on the gas concentration measurement accuracy is eliminated.
In order to avoid removing useful information during the differential operation, the reference photovoltaic driving signal and the detection photovoltaic driving signal do not overlap, that is, the value of the current in the reference photovoltaic driving signal or any one of other types of parameters is different from the value of the parameter in the detection photovoltaic driving signal.
Converting a reference photovoltage driving signal into a reference photocurrent driving signal, emitting laser under the driving of the reference photocurrent driving signal by using a laser to scan the gas to be detected, wherein the energy of the laser cannot be absorbed by the gas to be detected, and receiving the reference signal reflected back after passing through the gas to be detected; converting a detection photovoltage driving signal into a detection photocurrent driving signal, emitting laser to scan the gas to be detected by using a laser under the drive of the detection photocurrent driving signal, absorbing part of energy of the laser by the gas to be detected, and receiving a detection signal reflected back after passing through the gas to be detected; and carrying out differential operation on the reference signal and the detection signal so as to achieve the purpose of eliminating background noise.
The main controller 1 can be an ARM main controller which is composed of a microcontroller main control chip. Of course, the master 1 may be any other processor, which does not affect the implementation of the present application.
The main controller 1 is connected to the dc signal generator 2 and the modulation signal generator 3, respectively, and is configured to determine a frequency and a scanning range of the dc driving signal and a frequency of the modulation signal, so as to generate a reference photo voltage driving signal and a detection photo voltage driving signal.
Since the laser can only be driven by current, and the driving signal output by the signal superposition module 4 is a voltage signal, the voltage signal needs to be converted into a corresponding current signal.
The voltage-current converter 5 is respectively connected with the signal superposition module 3 and the laser 6, and is used for converting the laser voltage driving signal into a corresponding laser current driving signal, so that the laser 6 emits laser light under the driving of the laser current driving signal.
Alternatively, the voltage-current converter 5 may be composed of a MOSFET, and of course, the voltage-current converter 5 may also be another device capable of performing voltage-current conversion, which is not limited in this application.
The laser 6 may be any laser, such as a DFB laser, and the specific type is not limited in this application.
In the technical scheme provided by the embodiment of the invention, the laser outputs the detection laser with the wavelength in the absorption area of the gas to be detected and the reference laser in the non-absorption area by controlling the driving signal of the laser, and the detection laser and the reference laser carry out differential operation through the signal of the gas to be detected, so that the background noise in the gas detection process is removed, and the gas concentration detection precision is improved. Because the same laser is used for the detection laser and the reference laser, the complexity of the whole gas detection system is greatly reduced, the gas detection system has a simple structure and low complexity, the gas detection cost is saved, and the reliability of the gas detection system is improved.
In consideration of the influence of the direct current signal and the alternating current signal on the detection of the concentration of the gas to be detected respectively, the application also provides another embodiment, wherein the direct current driving signal consists of a first current section, a second current section and a third current section; the first current segment is a direct current voltage signal; the second current segment is superposed with the modulation signal to generate an alternating voltage signal; the third current segment is superposed with the modulation signal to generate a detection voltage signal; the direct current voltage signal and the alternating current voltage signal drive the wavelength output by the laser to be in a non-absorption area of the gas to be detected; the wavelength output by the laser driven by the detection voltage signal is in the absorption region of the gas to be detected.
It should be noted that, in a specific embodiment, the value ranges of the first current segment and the second current segment should not include the same value as the value range of the third current segment. Only a part of the wavelengths output by the laser driven by the detection light driving section are in the gas absorption section, for example, when the detection light driving section is in the gas absorption section after a 50mA +/-5 mA direct current signal and a modulation signal are superposed, the selection of the reference section direct current signal should avoid 50mA +/-5 mA, and a useful signal is removed in the process of preventing difference.
And carrying out different processing on the driving signals of the laser at different time to obtain direct-current voltage driving signals and alternating-current voltage driving signals, wherein the direct-current voltage driving signals and the alternating-current voltage driving signals are both used as reference light driving voltage signals.
Converting a reference photovoltage driving signal into a reference photocurrent driving signal, emitting laser to scan the gas to be detected by using the laser under the driving of the reference photovoltage driving signal, and receiving a direct current reference signal reflected back after passing through the gas to be detected; emitting laser to scan the gas to be detected by using a laser under the drive of a reference light alternating current drive signal, and receiving an alternating current reference signal reflected back after passing through the gas to be detected; converting the detection photovoltage driving signal into a detection photocurrent driving signal, emitting laser to scan the gas to be detected under the drive of the detection photocurrent driving signal by using a laser, and receiving the detection signal reflected back after passing through the gas to be detected;
averaging the alternating current reference signal, and adding the alternating current reference signal and the direct current reference signal to obtain an average value as a reference signal; and carrying out differential operation on the reference signal and the detection signal to remove background noise in the detection process of the gas to be detected.
The signal obtained after the laser generated by driving the laser by the direct current driving voltage signal scans the gas to be detected and the signal obtained after the laser generated by driving the laser by the alternating current driving voltage signal scans the gas to be detected are summed to obtain an average value, and then the average value is calculated with the signal obtained after the laser generated by detecting the laser driving voltage signal drives the laser to scan the gas to be detected, so that the interference caused by background noise is removed from the two aspects of alternating current and direct current, and the accuracy of gas concentration detection is further improved.
In another embodiment, the dc driving signal is composed of a low current segment, a medium current segment, a high current segment, and a ramp current segment; the current value corresponding to the high current section of the ramp current section is uniformly reduced to the current value corresponding to the low current section along with the time. For example, the dc driving signal is composed of a low current segment of 10mA, a medium current segment of 20mA, a high current segment of 90mA, and a ramp current segment in which the current is uniformly reduced from 90mA to 10mA over time.
The first reference light driving section is a direct current voltage signal corresponding to a low current section, and the third reference light driving section is a direct current voltage signal corresponding to a high current section; the second reference light driving section is an alternating voltage signal generated by superposing a medium current section and a modulation signal; the detection light segment is a voltage signal generated by superposing the ramp current segment and the modulation signal.
The first reference light driving section, the second reference light driving section and the third reference light driving section drive the wavelength output by the laser to be in a non-absorption area of the gas to be detected; the wavelength output by the laser driven by the detection light driving section is in the absorption region of the gas to be detected.
In this embodiment, the laser voltage driving signal includes a first reference light driving section, a second reference light driving section, a third light reference driving section, and a detection light driving section. For example, as shown in fig. 2, the driving signal dc current 10mA (first reference light driving section), the dc current 20mA superimposed with the modulation signal (second reference light driving section), the dc current 90mA (third reference light driving section), and the ramp current superimposed with the modulation signal (detection light driving section) are formed. The first reference light driving section and the third light reference driving section are direct current signals, and the second reference light driving section is an alternating current signal.
Firstly, averaging signals received after laser generated by the second reference light driving section driving laser passes through gas to be detected, adding and averaging signals received after the laser generated by the first reference light driving section and the third reference light driving section driving laser respectively passes through the gas to be detected, and finally, differentiating the signals received by the laser generated by the detection driving section driving laser through the gas to be detected and the average value to remove the influence of laser energy loss caused by other gases except the gas to be detected.
The average reference signal value obtained by adopting a multi-step averaging method can effectively improve the accuracy of the detection of the concentration of the gas to be detected and remove the background noise to a greater extent.
Optionally, in a specific implementation manner, based on the above embodiment, please refer to fig. 3, the laser modulation driving apparatus may further include a temperature control module 7. The temperature control module 7 is connected with the main controller 1 and the laser 6. When the laser works normally, the temperature control module 7 maintains the normal working temperature of the laser.
In addition, the laser modulation driving device can also comprise an external control interface connected with external equipment, and the control interface can be connected with a keyboard, a liquid crystal display and an upper computer to realize the control of the frequency and the scanning range of the laser driving current, the frequency amplitude of the modulation signal and the temperature of the laser.
For the sake of making the principle and idea of the technical solution provided by the present application more clearly understood by those skilled in the art, the present application also provides a specific embodiment for detecting the concentration of the alcohol gas, please refer to fig. 4, which specifically includes:
the laser modulation driving device comprises an ARM main controller, a direct current signal generator for outputting low-frequency trapezoidal waves, a modulation signal generator for outputting high-frequency sine waves, a signal superposition module with an independent enabling end, a voltage-current converter and a DFB laser. The trapezoidal wave output by the direct current signal generator consists of a low current section of 10mA, a middle current section of 20mA, a high current section of 90mA and a slope current section of which the current is uniformly reduced to 10mA along with the time; the signal superposition module controls the direct current driving signal output by the direct current signal generator and the modulation signal output by the modulation signal generator to be superposed into a laser voltage driving signal. The laser voltage driving signal consists of four sections of direct current 10mA (a first reference light driving section), direct current 20mA superposed with a modulation signal (a second reference light driving section), direct current 90mA (a third reference light driving section) and a ramp current superposed with the modulation signal (a detection light driving section), and the laser voltage driving signal is converted into a driving current through a voltage-current converter and then injected into the DFB laser.
The wavelength output by the laser driven by the detection light driving section sweeps across the absorption peak of the gas to be detected, a part of energy of the laser is absorbed by the alcohol gas, the laser at the moment is absorbed light, and the energy change of the laser is related to the concentration of the gas to be detected. The first reference light driving section, the second reference light driving section and the third reference light driving section drive the laser to start wavelength in a non-absorption area of gas to be detected, and laser emitted by the laser cannot be absorbed when passing through the gas to be detected. The method comprises the steps of averaging signals received after laser generated by the second reference light driving section driving laser passes through gas to be detected, adding and averaging signals received after the laser generated by the first reference light driving section driving laser and the laser generated by the third reference light driving section driving laser respectively pass through the gas to be detected, and finally differentiating the signals received by the laser generated by the detection light driving section driving laser through the gas to be detected and the average value, so that the influence of laser energy loss caused by other factors except absorption of the gas to be detected can be eliminated.
Therefore, the detection light and the reference light which are adopted in the embodiment of the invention use the same laser, so that the complexity of the instrument and the equipment can be greatly reduced, and the cost is saved. And the reference signal is obtained by multiple averaging, the influence of direct signals and alternating current signals on the system is considered, the influence of laser energy loss caused by other factors except the absorption of the gas to be detected can be removed to a greater extent, and the detection precision is further improved.
The embodiment of the invention also provides a corresponding method for removing background noise for the laser modulation driving device, so that the system is more feasible. The method for removing background noise provided by the embodiment of the present invention is described below, and the method for removing background noise described below and the laser modulation driving apparatus described above may be referred to correspondingly.
Referring to fig. 5, fig. 5 is a schematic flow chart of a method for removing background noise according to an embodiment of the present invention, which is applied to a gas detection system based on the TDLAS technology, and specifically includes the following steps:
s501: and driving the direct current signal generator to output a direct current driving signal according to a preset scanning range.
S502: and driving the modulation signal generator to output a modulation signal according to a preset frequency so that the direct current driving signal generates a voltage driving signal for driving the laser under the modulation of the modulation signal, wherein the voltage driving signal comprises a reference photovoltage driving signal and a detection photovoltage driving signal.
S503: and receiving a reference signal after the laser emits laser light to pass through the gas to be detected under the drive of the reference photocurrent drive signal, wherein the reference photocurrent drive signal is converted into a reference photovoltage drive signal.
S504: and receiving a detection signal after the laser emits laser light to pass through the gas to be detected under the drive of the detection photocurrent driving signal, and converting the detection photocurrent driving signal into a detection photovoltaic driving signal.
The wavelength output by the laser is driven to be in a non-absorption area of the gas to be detected by the reference photocurrent driving signal; the wavelength output by the laser driven by the detection photocurrent driving signal is in the absorption region of the gas to be detected, and is used for detecting the concentration of the gas to be detected.
S505: and carrying out differential operation on the reference signal and the detection signal to remove background noise in the detection process of the gas to be detected.
Optionally, the specific process of performing differential operation on the reference signal and the detection signal to remove the background noise in the detection process of the gas to be detected may further include:
averaging the alternating current reference signal, and adding the alternating current reference signal and the direct current reference signal to obtain an average value as a reference signal;
carrying out differential operation on the reference signal and the detection signal to remove background noise in the detection process of the gas to be detected;
the direct current reference signal is a direct current reference signal after the laser emitted by the receiving laser under the drive of the direct current reference photocurrent driving signal passes through the gas to be detected; the alternating current reference signal is the alternating current reference signal after the laser emitted by the receiving laser under the drive of the alternating current reference photocurrent driving signal passes through the gas to be detected.
It should be noted that, the sequence of the steps is not limited, and in the specific detection process, the skilled person can select the preparation sequence according to the specific actual situation.
The implementation process of the method for removing background noise according to the embodiment of the present invention may refer to the description related to the specific implementation of the functions of each functional module of the laser modulation driving apparatus, and is not described herein again.
Therefore, in the embodiment of the invention, the laser outputs the detection laser with the wavelength in the absorption region of the gas to be detected and the reference laser in the non-absorption region by controlling the driving signal of the laser, and the detection laser and the reference laser perform differential operation through the signal of the gas to be detected, so that the background noise in the gas detection process is removed, and the precision of gas concentration detection is improved. Because the same laser is used for the detection laser and the reference laser, the complexity of the whole gas detection system is greatly reduced, the gas detection system has a simple structure and low complexity, the gas detection cost is saved, and the reliability of the gas detection system is improved.
The embodiments are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same or similar parts among the embodiments are referred to each other. The device disclosed by the embodiment corresponds to the method disclosed by the embodiment, so that the description is simple, and the relevant points can be referred to the method part for description.
Those of skill would further appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both, and that the various illustrative components and steps have been described above generally in terms of their functionality in order to clearly illustrate this interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.
The steps of a method or algorithm described in connection with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in Random Access Memory (RAM), memory, Read Only Memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art.
The laser modulation driving apparatus and the method for removing background noise provided by the present invention are described in detail above. The principles and embodiments of the present invention are explained herein using specific examples, which are presented only to assist in understanding the method and its core concepts. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention.
Claims (7)
1. A laser modulation driving device is applied to a laser gas analyzer and comprises:
the device comprises a main controller, a direct current signal generator, a modulation signal generator, a signal superposition module with an independent enabling end, a voltage-current converter and a laser;
the signal superposition module is respectively connected with the direct current signal generator and the modulation signal generator and is used for superposing a direct current driving signal output by the direct current signal generator and a modulation signal output by the modulation signal generator to generate a laser voltage driving signal, and the type of the laser voltage driving signal comprises a reference light voltage driving signal and a detection light voltage driving signal;
the main controller is respectively connected with the direct current signal generator and the modulation signal generator and is used for determining the frequency and the scanning range of the direct current driving signal and the frequency of the modulation signal so as to generate the reference photovoltage driving signal and the detection photovoltage driving signal; the detection photovoltage driving signal drives the laser to output laser wavelength in an absorption region of gas to be detected, and the laser wavelength is used for detecting the concentration of the gas to be detected; the reference photovoltage driving signal drives the laser wavelength output by the laser to be in a non-absorption region of the gas to be detected, and is used for contrasting and removing background noise;
the voltage-current converter is respectively connected with the signal superposition module and the laser and is used for converting the laser voltage driving signal into a corresponding laser current driving signal so as to enable the laser to emit laser under the driving of the laser current driving signal;
the direct current driving signal consists of a first current segment, a second current segment and a third current segment, and the value ranges of the first current segment and the second current segment do not comprise the same value as that of the third current segment; the first current segment is a direct current voltage signal; the second current segment is superposed with the modulation signal to generate an alternating voltage signal; the third current segment is superposed with the modulation signal to generate a detection voltage signal; the direct-current voltage signal and the alternating-current voltage signal drive the laser to output a wavelength in a non-absorption region of the gas to be detected; the detection voltage signal drives the laser to output a wavelength in the absorption region of the gas to be detected; or
The direct current driving signal consists of a low current section, a medium current section, a high current section and a slope current section; the slope current section is a current value corresponding to the high current section which is uniformly reduced to a current value corresponding to the low current section along with time, and correspondingly, the laser voltage driving signal comprises a first reference light driving section, a second reference light driving section, a third reference light driving section and a detection light driving section; the first reference light driving section is a direct current voltage signal corresponding to the low current section, and the third reference light driving section is a direct current voltage signal corresponding to the high current section; the second reference light driving section is an alternating voltage signal generated by superposing the medium current section and the modulation signal; the detection light driving section is a voltage signal generated by superposing the ramp current section and the modulation signal; the first reference light driving section, the second reference light driving section and the third reference light driving section drive the wavelength output by the laser to be in a non-absorption region of the gas to be detected; the detection light driving section drives the laser to output a wavelength in the absorption region of the gas to be detected.
2. The laser modulation driver according to claim 1, wherein the dc driving signal is a trapezoidal wave driving signal.
3. The laser modulation driver according to claim 2, wherein the frequency of the trapezoidal wave driving signal is 1-100 Hz.
4. The laser modulation driver according to claim 1, wherein the modulation signal is a sine wave modulation signal.
5. The laser modulation driver according to claim 4, wherein the frequency of the sine wave modulation signal is 1KHz to 1 MHz.
6. A method for removing background noise is applied to a gas detection system based on TDLAS technology, and comprises the following steps:
driving a direct current signal generator to output a direct current driving signal according to a preset scanning range;
driving a modulation signal generator to output a modulation signal according to a preset frequency, so that the direct current driving signal generates a voltage driving signal for driving a laser under the modulation of the modulation signal, wherein the voltage driving signal comprises a reference photovoltage driving signal and a detection photovoltage driving signal;
receiving a reference signal of the laser after the laser emits laser light to pass through the gas to be detected under the drive of a reference photocurrent drive signal, wherein the reference photocurrent drive signal is obtained by converting the reference photocurrent drive signal;
receiving a detection signal of the laser after the laser emits laser light to pass through the gas to be detected under the drive of a detection photocurrent drive signal, wherein the detection photocurrent drive signal is obtained by converting the detection photocurrent drive signal;
carrying out differential operation on the reference signal and the detection signal to remove background noise in the detection process of the gas to be detected;
the reference photocurrent driving signal drives the laser to output a wavelength in a non-absorption region of the gas to be detected; the detection photocurrent driving signal drives the laser to output a wavelength in an absorption region of the gas to be detected, and is used for detecting the concentration of the gas to be detected;
the direct current driving signal consists of a first current segment, a second current segment and a third current segment; the first current segment is a direct current voltage signal; the second current segment is superposed with the modulation signal to generate an alternating voltage signal; the third current segment is superposed with the modulation signal to generate a detection voltage signal; the direct-current voltage signal and the alternating-current voltage signal drive the laser to output a wavelength in a non-absorption region of the gas to be detected; the detection voltage signal drives the laser to output a wavelength in the absorption region of the gas to be detected; or
The direct current driving signal consists of a low current section, a medium current section, a high current section and a slope current section; the slope current section is a current value corresponding to the high current section and is uniformly reduced to a current value corresponding to the low current section along with time, and correspondingly, the laser voltage driving signal comprises a first reference light driving section, a second reference light driving section, a third reference light driving section and a detection light driving section; the first reference light driving section is a direct current voltage signal corresponding to the low current section, and the third reference light driving section is a direct current voltage signal corresponding to the high current section; the second reference light driving section is an alternating voltage signal generated by superposing the medium current section and the modulation signal; the detection light driving section is a voltage signal generated by superposing the ramp current section and the modulation signal; the first reference light driving section, the second reference light driving section and the third reference light driving section drive the wavelength output by the laser to be in a non-absorption area of the gas to be detected; the detection light driving section drives the laser to output a wavelength in the absorption region of the gas to be detected.
7. The method of claim 6, wherein the differentiating the reference signal and the detection signal to remove the background noise during the detection of the gas to be detected comprises:
averaging the alternating current reference signal, and then adding and averaging the alternating current reference signal and the direct current reference signal to serve as the reference signal;
carrying out differential operation on the reference signal and the detection signal to remove background noise in the detection process of the gas to be detected;
the direct current reference signal is a direct current reference signal after the laser is emitted to pass through the gas to be detected under the drive of the direct current reference photocurrent driving signal; the alternating current reference signal is the alternating current reference signal after the laser is received and emitted to pass through the gas to be detected under the driving of the alternating current reference photocurrent driving signal.
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| CN108872146B (en) * | 2018-06-22 | 2020-11-24 | 中国科学院长春光学精密机械与物理研究所 | Laser driving device based on TDLAS and laser generating device based on TDLAS |
| CN108872147B (en) * | 2018-06-22 | 2020-07-24 | 中国科学院长春光学精密机械与物理研究所 | Laser generating device and gas concentration detection device based on TD L AS technology |
| CN110057778A (en) * | 2019-03-13 | 2019-07-26 | 武汉信达易通科技有限公司 | A kind of gas concentration detection apparatus and method |
| CN110231313B (en) * | 2019-04-25 | 2022-07-29 | 光力科技股份有限公司 | Online zero calibration method and device for laser gas analyzer |
| CN110470622B (en) * | 2019-08-28 | 2020-09-08 | 中国科学院长春光学精密机械与物理研究所 | Gas concentration detection method, device and system |
Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101308089A (en) * | 2008-04-30 | 2008-11-19 | 宁波工程学院 | Ethyne gas optical checking method and apparatus |
| CN102545038A (en) * | 2011-12-29 | 2012-07-04 | 北京农业智能装备技术研究中心 | Distributed feedback laser driving and modulating device and trace gas detection system |
| CN102706832A (en) * | 2012-06-01 | 2012-10-03 | 吉林大学 | Laser infrared gas analyzer based on TDLAS-WMS (tunable diode laser absorption spectroscopy-wavelength modulation spectroscopy) |
| CN102914515A (en) * | 2012-07-29 | 2013-02-06 | 安徽皖仪科技股份有限公司 | Method for extracting low-concentration signals of laser gas analyzer |
| CN104330386A (en) * | 2014-11-04 | 2015-02-04 | 中国科学院长春光学精密机械与物理研究所 | Time division multiplexing-differential modulation laser driving device for detecting drunk driving |
| CN104359857A (en) * | 2014-11-15 | 2015-02-18 | 武汉新烽光电科技有限公司 | TDLAS (Tunable Diode Laser Absorption Spectroscopy) gas monitoring device having time division multiplexing function |
| CN104568834A (en) * | 2015-01-08 | 2015-04-29 | 天津大学 | TDLAS-based ammonia gas detection experiment system |
| CN105891151A (en) * | 2016-04-21 | 2016-08-24 | 中国科学院长春光学精密机械与物理研究所 | Single-light-source laser drive system for reflection type laser drunk driving detection |
-
2017
- 2017-12-28 CN CN201711465520.XA patent/CN108181269B/en active Active
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101308089A (en) * | 2008-04-30 | 2008-11-19 | 宁波工程学院 | Ethyne gas optical checking method and apparatus |
| CN102545038A (en) * | 2011-12-29 | 2012-07-04 | 北京农业智能装备技术研究中心 | Distributed feedback laser driving and modulating device and trace gas detection system |
| CN102706832A (en) * | 2012-06-01 | 2012-10-03 | 吉林大学 | Laser infrared gas analyzer based on TDLAS-WMS (tunable diode laser absorption spectroscopy-wavelength modulation spectroscopy) |
| CN102914515A (en) * | 2012-07-29 | 2013-02-06 | 安徽皖仪科技股份有限公司 | Method for extracting low-concentration signals of laser gas analyzer |
| CN104330386A (en) * | 2014-11-04 | 2015-02-04 | 中国科学院长春光学精密机械与物理研究所 | Time division multiplexing-differential modulation laser driving device for detecting drunk driving |
| CN104359857A (en) * | 2014-11-15 | 2015-02-18 | 武汉新烽光电科技有限公司 | TDLAS (Tunable Diode Laser Absorption Spectroscopy) gas monitoring device having time division multiplexing function |
| CN104568834A (en) * | 2015-01-08 | 2015-04-29 | 天津大学 | TDLAS-based ammonia gas detection experiment system |
| CN105891151A (en) * | 2016-04-21 | 2016-08-24 | 中国科学院长春光学精密机械与物理研究所 | Single-light-source laser drive system for reflection type laser drunk driving detection |
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