Disclosure of Invention
The invention aims to provide a quasi-distributed humidity online monitoring system to solve the problem that high sensitivity, remote monitoring and distributed measurement of an optical fiber humidity sensor in the prior art cannot be realized simultaneously.
In order to achieve the purpose, the invention provides the following scheme:
a quasi-distributed humidity online monitoring system comprises a system terminal, n probe modules and n transmission modules;
the system terminal comprises a C-band ASE broadband light source, an optical fiber circulator, a first wavelength division multiplexer, a second wavelength division multiplexer, a photoelectric detector array and a data acquisition card;
the C-band ASE broadband light source is connected with the optical fiber circulator; the optical fiber circulator is connected with the first wavelength division multiplexer; the optical fiber circulator is also connected with the second wavelength division multiplexer; the C-waveband ASE broadband light source is used for providing broadband light of a C waveband of optical fiber communication; the optical fiber circulator is used for sending the broadband light to the first wavelength division multiplexer; the first wavelength division multiplexer is used for decomposing the broadband light into multiple paths of narrowband light; the first wavelength division multiplexer is connected with the transmission module; the transmission module is connected with the probe module; the optical fiber circulator is also used for sending the light reflected by the transmission module and received by the first wavelength division multiplexer to the second wavelength division multiplexer; the second wavelength division multiplexer is used for decomposing the light reflected by the transmission module into multiple paths of narrow-band light again; the second wavelength division multiplexer is connected with the photoelectric detector array; the photodetector array is used for converting an optical signal of the narrow-band light into an electrical signal; the photoelectric detector array is connected with the data acquisition card; the data acquisition card is used for carrying out data processing on the electric signals to obtain humidity; the transmission module is used for transmitting light between the system terminal and the probe module;
the probe module comprises a glass right-angle prism and a first optical fiber collimator;
the transmission module is connected with the first optical fiber collimator; the first optical fiber collimator is connected with a first right-angle edge of the glass right-angle prism; the first optical fiber collimator is used for collimating the light output by the first wavelength division multiplexer into parallel light; the glass right-angle prism is used for reflecting the collimated parallel light; the second right angle edge of glass right angle prism is provided with first gold membrane, be provided with the humidity sensitive film on the hypotenuse of glass right angle prism, the humidity sensitive film is used for arousing surface plasma resonance.
Optionally, the system terminal further includes: the system comprises a second optical fiber collimator, an optical power stabilizer, a single-mode optical fiber coupling system and an industrial personal computer;
the C-band ASE broadband light source, the second optical fiber collimator, the optical power stabilizer, the single-mode optical fiber coupling system and the optical fiber circulator are sequentially connected; the industrial personal computer is connected with the C-waveband ASE broadband light source and the data acquisition card respectively;
the second optical fiber collimator is used for converting the broadband light into parallel light; the optical power stabilizer is used for stabilizing the optical power of the parallel light output by the second optical fiber collimator; the single-mode optical fiber coupling system is used for coupling the parallel light output by the optical power stabilizer into the optical fiber circulator; the industrial personal computer is used for controlling the switch of the C-band ASE broadband light source and controlling the data acquisition card to acquire data.
Optionally, the humidity-sensitive thin film includes a first indium tin oxide film, a second gold film, a second indium tin oxide film, a silicon dioxide film, and a copper oxide film;
the first indium tin oxide film is covered on the bevel edge of the glass right-angle prism, the second gold film is covered on the surface of the first indium tin oxide film, and the second gold film is used for exciting surface plasmon resonance; the second ITO film covers the surface of the second Au film; the silicon dioxide film is covered on the surface of the second indium tin oxide film and is used for adjusting the surface plasma resonance condition; the copper oxide film is coated on the surface of the silicon dioxide film and used for absorbing water vapor.
Optionally, the probe module further comprises: a joint and a hard plastic straight pipe; one end of the first optical fiber collimator is connected with the transmission module through the joint, and the other end of the first optical fiber collimator is connected with the glass right-angle prism through the hard plastic straight pipe.
Optionally, the transmission module specifically includes: the optical fiber device comprises an optical fiber reflector, a first conventional optical fiber flange plate, 2 second conventional optical fiber flange plates, a first optical fiber and a second optical fiber;
the joint, the first conventional optical fiber flange plate, the first optical fiber and one second conventional optical fiber flange plate are sequentially connected to serve as a sensing optical path;
the optical fiber reflector, the second optical fiber and the other second conventional optical fiber flange plate are sequentially connected to serve as a reference light path.
Optionally, the first wavelength division multiplexer and the second wavelength division multiplexer have at most 80 channels.
Optionally, the number of photodetectors in the photodetector array is the same as the number of channels of the first wavelength division multiplexer and the number of channels of the second wavelength division multiplexer.
According to the specific embodiment provided by the invention, the invention discloses the following technical effects:
broadband light emitted by a C-waveband ASE broadband light source in the system terminal is decomposed into multiple paths of narrow-band light through a first wavelength division multiplexer, the narrow-band light enters a probe module, surface plasma resonance is generated on the surface of a humidity-sensitive film, and the surface plasma resonance has high-sensitivity response to the change of dielectric constants outside the humidity-sensitive film or the humidity-sensitive film. In addition, multiple paths of narrow-band light enter the probe modules through the transmission modules, and a quasi-distributed sensing network is formed by the probes, so that quasi-distributed monitoring can be realized.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. 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 invention aims to provide a quasi-distributed humidity online monitoring system to solve the problem that high sensitivity, remote monitoring and distributed measurement of an optical fiber humidity sensor in the prior art cannot be realized simultaneously.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
Fig. 1 is a schematic diagram of a quasi-distributed online humidity monitoring system according to the present invention, and as shown in fig. 1, the quasi-distributed online humidity monitoring system includes a system terminal, n probe modules 22, and n transmission modules.
The system terminal comprises a C-band ASE broadband light source 12, an optical fiber circulator 16, a first wavelength division multiplexer 17, a second wavelength division multiplexer 18, a photoelectric detector array 19 and a data acquisition card 20. In practical application, a C-band ASE broadband light source 12 of the combined fertilzier optical and electrical technology Limited with the model of ASE-C-100-T-B, an optical fiber circulator 16 of the combined fertilzier optical and electrical technology Limited with the model of SMCIR-1550nm-311-1, and a wavelength division multiplexer of the deep Shenzhen aerospace optical fiber system Limited with the model of C-band 50GAWG are adopted, wherein the first wavelength division multiplexer 17 and the second wavelength division multiplexer 18 have 80 channels. The method adopts a photoelectric detector array 19 of Sorabo photoelectric technology (Shanghai) Limited company, supports at most 80 DET01CFC, and adopts a data acquisition card 20 of the Shanghai Enai Instrument Limited company, the model of which is USB-6255.
The C-band ASE broadband light source 12 is connected with the optical fiber circulator 16; the optical fiber circulator 16 is connected with the first wavelength division multiplexer 17; the fiber circulator 16 is also connected to the second wavelength division multiplexer 18. The C-band ASE broadband light source 12 is used for providing broadband light of a C-band of optical fiber communication; the optical fiber circulator 16 is used for sending the broadband light to the first wavelength division multiplexer 17; the first wavelength division multiplexer 17 is used to split the broadband light into 80 narrowband lights with different center wavelengths, and to re-couple the light reflected back from the probe module 22 and the reference light path into the fiber circulator 16. The first wavelength division multiplexer 17 is connected with the transmission module; the transmission module is connected with the probe module 22; the optical fiber circulator 16 is further configured to send the light reflected by the probe module 22 and received by the first wavelength division multiplexer 17 and the light reflected by the reference optical path to the second wavelength division multiplexer 18; the second wavelength division multiplexer 18 is configured to re-decompose the light reflected from the probe module 22 and the light reflected from the reference optical path into 80 narrowband lights with different center wavelengths; the second wavelength division multiplexer 18 is connected with the photodetector array 19; the photodetector array 19 is used for converting the optical signal of the narrow-band light into an electrical signal; the photoelectric detector array 19 is connected with the data acquisition card 20; the data acquisition card 20 is used for performing data processing on the electric signals to obtain humidity; the transmission module is used for transmitting light between the system terminal and the probe module 22. The maximum number of the photoelectric detectors is 80, and the number of the photoelectric detectors corresponds to the number of the channels of the wavelength division multiplexer. Therefore, the quasi-distributed humidity on-line monitoring system of the present invention can support 40 probe modules 22 to work simultaneously.
The system terminal further comprises: a second optical fiber collimator 13, an optical power stabilizer 14, a single-mode optical fiber coupling system 15 and an industrial personal computer 21; the C-band ASE broadband light source 12, the second optical fiber collimator 13, the optical power stabilizer 14, the single-mode optical fiber coupling system 15, and the optical fiber circulator 16 are sequentially connected; the industrial personal computer 21 is respectively connected with the C-band ASE broadband light source 12 and the data acquisition card 20. In practical applications, the second optical fiber collimator 13 is an optical fiber collimator of the type CFC11A-C of the songbo electro-optical technology (shanghai), the optical power stabilizer 14 of the type NEL04/M of the songbo electro-optical technology (shanghai), the single-mode optical fiber coupling system 15 of the type MBT613D/M of the songbo electro-optical technology (shanghai), and the industrial personal computer 21 of the type IPC-610MB-BTO of the beijing, chunsheng, electronics technology limited.
The second optical fiber collimator 13 is used for converting the broadband light into parallel light; the optical power stabilizer 14 is used for stabilizing the optical power of the parallel light output by the second optical fiber collimator 13; the single-mode fiber coupling system 15 is used for coupling the parallel light output by the optical power stabilizer 14 into the fiber circulator 16; the industrial personal computer 21 is used for controlling the switch of the C-band ASE broadband light source 12 and controlling the data acquisition card 20 to acquire data.
The optical fiber communication C-band broadband light emitted by the C-band ASE broadband light source 12 enters a second optical fiber collimator 13 through optical fiber transmission, collimated light is output and enters an optical power stabilizer 14, the optical power stabilizer 14 emits broadband light with stable and collimated power, the single-mode optical fiber coupling system 15 is used for coupling the light into an optical fiber circulator 16, the light is output from the optical fiber circulator 16 and enters a first wavelength division multiplexer 17, the light is divided into 80 paths of narrow-band light with different wavelengths and is output from 80 second conventional optical fiber flanges 11, every two adjacent ITU channels are used as a group, one path of light passes through a first optical fiber 9 of a sensing light path and is connected with a first conventional optical fiber flange 8, and the light enters a probe module 22 and is used as incident light of the probe module 22; the other path passes through a second optical fiber 10 of the reference optical path and then enters a fiber reflector 7. In which the first optical fiber 9 of the sensing optical path and the second optical fiber 10 of the reference optical path are turned together while being affected by the outside (fiber stretching and bending). Light reflected by the probe module 22 returns to the first wavelength division multiplexer 17 through the first conventional optical fiber flange 8, the first optical fiber 9 and the second conventional optical fiber flange 11, light reflected by the optical fiber reflector 7 returns to the first wavelength division multiplexer 17 through the second optical fiber 10 and the second conventional optical fiber flange 11, exits from a reflection port of the optical fiber circulator 16, enters the second wavelength division multiplexer 18, exits from the second wavelength division multiplexer 18 and is received by the photoelectric detector array 19, the photoelectric detector array 19 outputs an electric signal which is in a linear relation with light intensity, and the data acquisition card 20 acquires the electric signal. The industrial personal computer 21 controls the data acquisition and signal processing functions of the data acquisition card 20 and has the function of controlling the switching of the C-band ASE broadband light source 12.
Fig. 2 is a schematic diagram of a probe module of a quasi-distributed humidity online monitoring system provided by the present invention, and as shown in fig. 2, the probe module 22 includes a glass right-angle prism 1 and a first fiber collimator 5. In practical application, the glass rectangular prism 1 is a K9 glass rectangular prism with the model of GCL-030101A, manufactured by Dahengjie New epoch science and technology, and the first optical collimator 5 is a single-mode optical collimator with the model of 50-1550A-APC, manufactured by Sorabo photoelectric technology (Shanghai).
The transmission module is connected with the first optical fiber collimator 5; the first optical fiber collimator 5 is connected with a first right-angle edge of the glass right-angle prism 1; the first optical fiber collimator 5 is used for collimating the light output by the first wavelength division multiplexer 17 into parallel light; the glass right-angle prism 1 is used for reflecting the collimated parallel light; the glass rectangular prism 1 provides a coupling condition of Surface plasmon resonance, and the wave vector of incident light is increased to enable the wave vector of the incident light to be matched with the wave vector of the Surface plasmon on the humidity-sensitive film 2, so that Surface Plasmon Resonance (SPR) is excited. The second right angle edge of glass right angle prism 1 is provided with first gold membrane 3, be provided with humidity sensitive film 2 on the hypotenuse of glass right angle prism 1, humidity sensitive film 2 is used for arousing surface plasma resonance. The thickness of the first gold film 3 was 400 nm. The humidity sensitive film 2 adopts an ITO/Au/ITO/SiO2/CuO film.
The humidity-sensitive thin film 2 includes a first indium tin oxide film, a second gold film, a second indium tin oxide film, a silicon dioxide film, and a copper oxide film.
The first indium tin oxide film is covered on the bevel edge of the glass right-angle prism 1, the second gold film is covered on the surface of the first indium tin oxide film, and the second gold film is used for exciting surface plasmon resonance; the second ITO film covers the surface of the second Au film; the silicon dioxide film is covered on the surface of the second indium tin oxide film and is used for adjusting the surface plasma resonance condition; the copper oxide film is coated on the surface of the silicon dioxide film and used for absorbing water vapor.
Wherein, the thickness of the first indium tin oxide film is 5nm, which is used for increasing the adhesive force of the second gold film and the glass right-angle prism 1; the second gold film is 40nm thick and is used for exciting SPR; the second indium tin oxide film is 5nm thick and used for increasing the adhesive force of the second gold film and the silicon dioxide film; the thickness of the silicon dioxide film is about 74nm, one of the silicon dioxide film plays a role in adjusting SPR resonance conditions, and the other silicon dioxide film does not contact with the copper oxide film, namely plays an insulating role; the copper oxide film has a thickness of about 10nm and is used for being sensitive to water vapor, i.e., humidity. Preparing a film sample by using vacuum coating equipment, annealing at 400 ℃ for 60 minutes in an air environment, and naturally cooling to room temperature. The copper oxide film has hygroscopicity, water molecules in the air environment can be adsorbed on the surface of the copper oxide film in a physical adsorption mode, the refractive index of the surface of the copper oxide film is changed, the surface plasma resonance condition is further changed, the reflectivity is changed, finally the light intensity detected by the photoelectric detector array 19 is changed, the electric signals collected by the data collection card 20 are changed, and the sensing function is achieved.
Light emitted from the first conventional optical fiber flange 8 enters the glass right-angle prism 1 from the first optical fiber collimator 5 through the joint 6, surface plasma resonance on the humidity-sensitive film 2 is excited at an incident angle of 45 degrees on the humidity-sensitive film 2, reflected light is normally incident on the first gold film 3 with the thickness of 400nm, is reflected by the first gold film 3 with the thickness of 400nm, enters the first optical fiber collimator 5 after being reflected by the humidity-sensitive film 2 again, is emitted from the joint 6, and is emitted into the second conventional optical fiber flange 11 through the first conventional optical fiber flange 8 and the first optical fiber 9.
The surface plasmon resonance sensing technology is often used for detecting the change of the external refractive index or the change of the refractive index of a medium on the surface of the humidity-sensitive film, and has the characteristic of high sensitivity. The quasi-distributed humidity on-line monitoring system converts the response of copper oxide to water vapor into a light signal capable of being transmitted remotely, can realize remote monitoring and high-sensitivity measurement through selection of a working waveband, and also has the advantage of quasi-distributed sensing.
The probe module 22 further includes: a joint 6 and a hard plastic straight pipe 4; one end of the first optical fiber collimator 5 is connected with the transmission module through the joint 6, and the other end of the first optical fiber collimator 5 is connected with the glass right-angle prism 1 through the hard plastic straight pipe 4. The linker 6 is an FC/APC linker. The hard plastic straight pipe 4 is used for fixing the glass right-angle prism 1 and the first optical fiber collimator 5 and is fixed by ultraviolet curing glue.
As shown in fig. 1, the transmission module specifically includes: a fiber reflector 7, a first conventional fiber flange 8, 2 second conventional fiber flanges 11, a first optical fiber 9, and a second optical fiber 10.
The joint 6, the first conventional optical fiber flange 8, the first optical fiber 9 and the second conventional optical fiber flange 11 are sequentially connected to serve as a sensing optical path.
The optical fiber reflector 7, the second optical fiber 10 and the other second conventional optical fiber flange plate 11 are connected in sequence to serve as a reference optical path. The optical fiber reflector 7 is used for reflecting the reference light, and the second optical fiber 10 of the reference light path forms a reference light path, and is used for reducing the influence of external disturbance on a measurement result, which is suffered by the first optical fiber 9 of the sensing light path in remote sensing monitoring. The first optical fiber 9 and the second optical fiber 10 are used for transmission of light in the sensing optical path and the reference optical path, respectively.
In order to obtain the function of remote monitoring of relative humidity, the quasi-distributed humidity online monitoring system adopts the optical fiber communication C wave band as the working wavelength, and the wave band is the only low-loss wave band of the common single-mode optical fiber.
The quasi-distributed humidity online monitoring system adopts the surface plasma resonance sensing principle, and in order to work in an intensity modulation mode, a probe form of combining an optical fiber and a prism is required, otherwise, the incident angle is difficult to fix to a certain determined value.
In order to obtain the function of quasi-distributed sensing, in combination with a quasi-distributed humidity online monitoring system, a wavelength division multiplexer must be used to decompose broadband light emitted by an ASE broadband light source into multiple narrow-band light simultaneously.
In order to obtain the sensitive response to the relative humidity, the quasi-distributed humidity online monitoring system adopts the CuO film as the sensitive film, which does not exclude that films made of other materials also have the sensitive response to water vapor, but other materials are not in the scope of patent protection.
In order to make the initial reflectivity at 0.5, namely the angle position where the reflectivity changes steepest, the quasi-distributed humidity online monitoring system utilizes a certain thickness of SiO2 film to adjust the resonance condition, and electrolyte films of other materials are not excluded to complete the function, but other materials are not in the scope of patent protection.
Compared with the existing humidity sensing technology, the sensing means provided by the invention has the advantages of higher sensitivity, remote monitoring and quasi-distributed monitoring.
The high sensitivity comes from the application of the probe module 22, the surface plasmon resonance sensing principle of the humidity sensitive film 2. Surface plasmon resonance has a highly sensitive response to changes in the dielectric constant outside or within the thin film, and therefore sensing techniques based on surface plasmon resonance are a hotspot in sensor research in recent years. The quasi-distributed humidity online monitoring system adopts the intensity modulation sensing principle at the C wave band section of optical fiber communication, when the incident angle is fixed, the resonance condition changes along with the change of the dielectric constant of the humidity sensitive film 2, and after the copper oxide film at the outermost layer of the humidity sensitive film 2 is adsorbed by water molecules, the change of the dielectric constant of the humidity sensitive film 2 leads to the change of the intensity of reflected light. The quasi-distributed humidity on-line monitoring system converts the response of the humidity-sensitive film 2 to water vapor into an optical signal for detection by the surface plasma resonance principle. Since the angular spectrum response of surface plasmon resonance at the C-band of optical fiber communication is extremely steep, the sensitivity of intensity modulation sensing is higher than that at a short wavelength.
The introduction originating from the system terminal can be monitored remotely. The working wavelength of the quasi-distributed humidity online monitoring system is selected in an optical fiber communication C wave band, the optical fiber communication C wave band is a low-loss wave band of optical fiber communication, and optical signals can propagate in optical fibers for tens of kilometers, so that the optical fiber communication C wave band can be used for improving the sensitivity of intensity modulation sensing and realizing remote monitoring.
The advantage of quasi-distributed monitoring comes from the system terminals. Incident light of the quasi-distributed humidity online monitoring system is obtained by filtering out the incident light from the C-band ASE broadband light source 12 through the first wavelength division multiplexer 17, at most 40 paths of 80 paths of light with different central wavelengths are used as incident light of the probe modules 22, a quasi-distributed sensing network can be formed, and at most 40 probe modules 22 are supported.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.
The principles and embodiments of the present invention have been described herein using specific examples, which are provided only to help understand the method and the core concept of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.