Demodulation system of optical fiber pressure sensor
By combining optical path and circuit structure, the optical wedge is used to realize the correlation interference signal processing of the fiber optic pressure sensor. Combined with temperature compensation, the problem of low demodulation accuracy in the existing technology is solved, and high-precision pressure demodulation is achieved, which is suitable for medical testing.
Patent Information
- Application Number
- CN202520170359.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-25
- Publication Date
- 2026-01-16
- Estimated Expiration
- 2035-01-25
AI Technical Summary
Existing fiber optic pressure sensor demodulation systems have low accuracy and require dedicated spectral analysis equipment, which is bulky and expensive.
By combining optical and electrical structures, relevant interference signals are generated through FP cavity interference and optical wedge refraction. Signal conversion and demodulation are performed using a CCD module, ADC module, and main control module, and temperature compensation is performed in conjunction with a temperature acquisition module to achieve high-precision pressure demodulation.
It achieves high-precision pressure demodulation, avoids direct analysis of interference optical signals, reduces equipment size and cost, and is suitable for medical testing scenarios.
Smart Images
Figure CN223808003U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of optical fiber sensing, in particular to a demodulation system of an optical fiber pressure sensor. BACKGROUND
[0002] In recent years, optical fiber sensing technology has developed rapidly, and optical fiber pressure sensors are used to realize pressure measurement. As a type of optical fiber pressure sensor, the Fabry-Perot (F-P) optical fiber pressure sensor has the advantages of small size, high sensitivity, and anti-interference compared with other types of optical fiber sensors.
[0003] The output signal of the optical fiber pressure sensor is an optical signal. When the pressure to be measured changes, the change is reflected in the change of the sensor cavity length, and the change of the cavity length further causes the change of the optical signal. The demodulation system is used to demodulate the optical signal output by the optical fiber pressure sensor to obtain pressure data. Therefore, a high-precision demodulation system is urgently needed. SUMMARY
[0004] The purpose of the embodiment of the present application is to provide a demodulation system of an optical fiber pressure sensor to realize high-precision pressure demodulation. The specific technical solution is as follows:
[0005] In the first aspect, the embodiment of the present application provides a demodulation system of an optical fiber pressure sensor, which comprises an optical path structure and a circuit structure. The optical path structure comprises a light source, a coupler, an F-P cavity, a cylindrical lens, and a light wedge. The circuit structure comprises a CCD module, a CCD acquisition module, an ADC module, and a master control module. Wherein:
[0006] The optical signal emitted by the light source is transmitted to the F-P cavity through the coupler, and interference is formed in the F-P cavity. The interference light signal after interference is transmitted to the cylindrical lens through the coupler. The cylindrical lens converts the interference light signal into a linear light beam. The linear light beam enters the inside of the light wedge for refraction, deflection, and transmission attenuation, and outputs a related interference signal.
[0007] The related interference signal is irradiated on the CCD module, and the CCD module converts the irradiated related interference signal into an analog electric signal. The analog electric signal is transmitted to the ADC module through the CCD acquisition module. The ADC module converts the analog electric signal into a digital electric signal and transmits it to the master control module. The master control module demodulates the interference displacement value in the digital electric signal and converts the interference displacement value into a corresponding pressure.
[0008] In one embodiment of the present application, the above-mentioned circuit structure further comprises a temperature acquisition module, wherein:
[0009] The temperature acquisition module acquires temperature data in a related module, and transmits the temperature data to the main control module, wherein the related module is a module of a space region composed of a cylindrical mirror, a light wedge and a CCD module.
[0010] The main control module reads the temperature value acquired by the temperature acquisition module, determines a pressure compensation value corresponding to the temperature value, and performs temperature compensation on the initial pressure value obtained by demodulation to obtain a final pressure value.
[0011] In one embodiment of the present application, the above-mentioned circuit structure further comprises a light source driving module, wherein:
[0012] One end of the light source driving module is connected with the main control module, and the other end is connected with the light source, and the main control module controls the light source to work through the light source driving module.
[0013] In one embodiment of the present application, the chip in the above-mentioned light source driving module is an adjustable PWM control LED constant current driving chip, and the driving voltage of the light source driving module is an adjustable switching voltage, and the driving voltage is 5V or 12V.
[0014] In one embodiment of the present application, the above-mentioned CCD acquisition module comprises a differential amplification circuit, a same-phase amplification circuit and a voltage follower, wherein:
[0015] The input end of the differential amplification circuit is connected with the CCD module, and the output end is connected with the input end of the same-phase amplification circuit; the output end of the same-phase amplification circuit is connected with the input end of the voltage follower; and the output end of the voltage follower is connected with the ADC module.
[0016] In one embodiment of the present application, the above-mentioned circuit structure further comprises a CCD driving module, wherein:
[0017] The input end of the CCD driving module is connected with the main control module, and the output end is connected with the CCD module; the main control module drives the CCD module to work through the CCD driving module.
[0018] In one embodiment of the present application, the above-mentioned CCD driving module comprises a level conversion driving chip, wherein:
[0019] The level conversion driving chip is used for converting the voltage of the level of the three-way clock control signal output by the main control module into a target voltage, and the target voltage is the voltage of the input power supply of the CCD module.
[0020] In one embodiment of the present application, the above-mentioned demodulation system is integrated in a ventricular assist device for detecting blood pressure of a patient, and the ventricular assist device comprises a ventricular catheter pump and an intra-aortic balloon counterpulsation device.
[0021] From the above, the application provides a demodulation system, the demodulation system is divided into an optical path structure and an electrical circuit structure, the light signal emitted by the light source is analyzed by F-P cavity interference and light wedge refraction, forming a related interference signal, the electrical circuit structure collects, converts and demodulates the related interference signal, compared with the prior art, the direct analysis of the interference light signal is avoided, the related operation of the interference signal is realized by the light wedge, and high-precision pressure demodulation of the demodulation system is realized.
[0022] Of course, implementing any product or method of the present application does not necessarily require all the advantages described above. BRIEF DESCRIPTION OF DRAWINGS
[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other embodiments can also be obtained by those skilled in the art based on these drawings.
[0024] Figure 1a A structure diagram of a first optical fiber pressure sensor demodulation system provided by the present application is shown in the figure.
[0025] Figure 1b A model diagram of a light wedge provided by the present application is shown in the figure.
[0026] Figure 2a A structure diagram of a second optical fiber pressure sensor demodulation system provided by the present application is shown in the figure.
[0027] Figure 2b A circuit structure diagram of a temperature acquisition module provided by the present application is shown in the figure.
[0028] Figure 3a A structure diagram of a third optical fiber pressure sensor demodulation system provided by the present application is shown in the figure.
[0029] Figure 3b A circuit structure diagram of a light source driving module provided by the present application is shown in the figure. DETAILED DESCRIPTION
[0030] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art based on the present application belong to the scope of protection of the present application.
[0031] The demodulation system provided in the application can be a demodulation system of an optical fiber F-P (Fabry-Perot) pressure sensor, and the optical fiber F-P pressure sensor refers to an optical fiber pressure sensor with a F-P cavity structure in a sensing part.
[0032] The optical fiber sensor and the demodulation system can be integrated in a ventricular assist device for detecting blood pressure of a patient. Specifically, the sensing part, i.e., the F-P cavity, is located in the blood of the patient, and the demodulation system is integrated in a control circuit of the ventricular assist device. The ventricular assist device includes a ventricular catheter pump and an intra-aortic balloon counterpulsation device.
[0033] Referring to Figure 1a , Figure 1a FIG. 1 is a structural schematic diagram of a first optical fiber pressure sensor demodulation system provided in an embodiment of the application. The system includes an optical path structure and a circuit structure. The optical path structure includes a light source 111, a coupler 112, a F-P cavity 113, a cylindrical lens 114, and a optical wedge 115. The circuit structure includes a CCD module 121, a CCD acquisition module 122, an ADC module 123, and a main control module 124. Wherein:
[0034] 1. The light signal emitted by the light source 111 is transmitted to the F-P cavity 113 through the coupler 112.
[0035] 2. The light signal forms interference in the F-P cavity 113, and the interference light signal after the interference is transmitted to the cylindrical lens 114 through the coupler 112.
[0036] The F-P cavity is the sensing part of the optical fiber pressure sensor. The measured pressure affects the cavity length of the F-P cavity, and the change of the cavity length acts on the light signal. The interference light signal after the interference of the F-P cavity carries the pressure signal.
[0037] The coupler 112 includes two light paths. A light path A connects the light source and the F-P cavity, and a light path B connects the F-P cavity and the cylindrical lens. The light signal emitted by the light source reaches the F-P cavity through the light path A, and the interference light signal after the interference of the F-P cavity reaches the cylindrical lens through the light path B, so as to realize subsequent demodulation of the light signal.
[0038] 3. The cylindrical lens 114 converts the interference light signal into a linear light beam.
[0039] The interference light signal is in the form of a spot when it is output through the light path B. Due to the influence of the divergence angle of the emitted light, the spot becomes larger and larger, the interference of stray light becomes larger, and the edge definition of the spot decreases. The cylindrical lens converts the interference light signal into a linear light beam, which can avoid the above problems.
[0040] 4. The linear light beam enters the inside of the optical wedge 115 for refraction, deviation, and transmission attenuation, and outputs a related interference signal.
[0041] The optical wedge is a key demodulation optical component in the demodulation system, and is similar to the F-P cavity in that interference is formed by reflection between two optical planes with a small distance. The difference is that the distance between the two planes of the optical wedge is larger and the two planes are not parallel, and an included angle of the wedge angle is formed between the two planes.
[0042] After the incident light reaches the optical wedge 115, refraction and transmission attenuation are performed inside the optical wedge to form an interference signal, as shown in FIG. 3. Figure 1b Figure 1b FIG. 4 is a schematic model diagram of the optical wedge, an included angle of the wedge angle is formed between the two non-parallel planes, and the incident light is interfered by the optical wedge.
[0043] Since the optical signal incident to the optical wedge is also an interference signal formed in the F-P cavity, the interference signal is interfered again inside the optical wedge to realize correlation operation of the optical signal, and therefore, the signal emitted from the optical wedge is referred to as a correlation interference signal.
[0044] 5. The correlation interference signal is irradiated on a CCD (Charge Coupled Device) module 21, and the CCD module 121 converts the irradiated correlation interference signal into an analog electrical signal.
[0045] In an embodiment of the present application, the circuit structure further includes a CCD driving module, an input end of the CCD driving module is connected to the master control module, and an output end of the CCD driving module is connected to the CCD. The master control module drives the CCD to work through the CCD driving module.
[0046] The CCD driving module includes a level conversion driving chip, which is used to convert the voltage of the level of the three clock control signals output by the master control module into a target voltage. The target voltage is the voltage of the input power supply of the CCD.
[0047] 6. The analog electrical signal is transmitted to an ADC module 123 through a CCD acquisition module 122.
[0048] The CCD acquisition module acquires the analog electrical signal captured by the CCD module and transmits the analog electrical signal to the ADC module.
[0049] In an embodiment of the present application, the CCD acquisition module 122 includes a differential amplification circuit, a same-phase amplification circuit, and a voltage follower. An input end of the differential amplification circuit is connected to the CCD, and an output end of the differential amplification circuit is connected to an input end of the same-phase amplification circuit. An output end of the same-phase amplification circuit is connected to an input end of the voltage follower. An output end of the voltage follower is connected to the ADC module.
[0050] The differential amplification circuit has an amplification factor of 1, and is configured to control the output level of the analog electrical signal output by the CCD so as not to exceed the voltage input range of the ADC module.
[0051] The in-phase amplification circuit amplifies the signal by 3 times. In order to improve the signal-to-noise ratio, a first-order filter circuit can also be designed in each set of amplification circuits to filter the signal.
[0052] 7. The ADC module 123 converts the analog electrical signal into a digital electrical signal and transmits the digital electrical signal to the main control module 124.
[0053] The main control module 124 can only process the digital electrical signal, and therefore needs to convert the analog electrical signal into a digital electrical signal.
[0054] 8. The main control module 124 demodulates the interference displacement value in the digital electrical signal and converts the interference displacement value into a corresponding pressure.
[0055] The pressure demodulation algorithm can be any low-correlation interference algorithm in the prior art, and the interference displacement value in the digital electrical signal is demodulated. The interference displacement value is the displacement value of the change in the F-P cavity length caused by the pressure to be measured. The interference displacement value is converted into a corresponding pressure as the pressure to be measured.
[0056] It should be further noted that common pressure demodulation usually directly analyzes the interference light signal after F-P cavity interference to realize pressure demodulation. However, this demodulation method has low demodulation accuracy and needs to use a special spectrum analysis device, which is large in size and high in cost.
[0057] As can be seen from the above, the demodulation system provided in the embodiment is divided into an optical path structure and a circuit structure. The light signal emitted by the light source is analyzed by F-P cavity interference and by refraction of the optical wedge to resolve the interference fringes, forming a correlation interference signal. The circuit structure collects, converts, and demodulates the correlation interference signal. Compared with the prior art, the demodulation system avoids directly analyzing the interference light signal and realizes correlation operation of the interference signal through the optical wedge, thereby realizing high-precision pressure demodulation of the demodulation system.
[0058] In addition, the modules other than the F-P cavity in the optical path structure and the circuit structure can be integrated in the circuit board in a small size, meeting the requirements of more extensive application scenarios such as medical detection scenarios.
[0059] In the foregoing Figure 1a In the corresponding embodiment, the circuit structure can further include a temperature acquisition module. Based on this, referring to Figure 2a , Figure 2aA second structure diagram of a demodulation system of a fiber pressure sensor is provided in the embodiments of the present application, and the system includes an optical path structure and a circuit structure. The optical path structure includes a light source 211, a coupler 212, an F-P cavity 213, a cylindrical lens 214, and a light wedge 215. The circuit structure includes a CCD module 221, a CCD acquisition module 222, an ADC (Analog-to-Digital Converter) module 223, a main control module 224, and a temperature acquisition module 225. Wherein:
[0060] The light signal emitted by the light source 211 is transmitted to the F-P cavity 213 through the coupler 212, and interference is formed in the F-P cavity 213. The interference light signal after interference is transmitted to the cylindrical lens 214 through the coupler 212. The cylindrical lens 214 converts the interference light signal into a linear light beam. The linear light beam enters the interior of the light wedge 215 for refraction, deflection, and transmission attenuation, and outputs a related interference signal.
[0061] The related interference signal is irradiated on the CCD module 221, and the CCD module 221 converts the irradiated related interference signal into an analog electric signal. The analog electric signal is transmitted to the ADC module 223 through the CCD acquisition module 222. The ADC module 223 converts the analog electric signal into a digital electric signal and transmits it to the main control module 224.
[0062] The temperature acquisition module 225 acquires temperature data in the related module and transmits the temperature data to the main control module.
[0063] The related module is a module of a spatial region constituted by the cylindrical lens, the light wedge, and the CCD module. The related module is a module with a certain spatial region in the demodulation system, and the spatial region includes the cylindrical lens, the light wedge, and the CCD module.
[0064] A top thermistor is arranged in the related module in the temperature acquisition module, and the external negative line of the thermistor is connected to the circuit. After voltage division, the resistance change value caused by the temperature is read by the ADC port of the main control module to detect the temperature data in real time. An example of the circuit structure of the temperature acquisition module is shown in Figure 2b .
[0065] The main control module 224 demodulates the interference displacement value in the digital electric signal, converts the interference displacement value into a corresponding pressure, takes the interference displacement value as an initial pressure value, reads the temperature value acquired by the temperature acquisition module 225, determines a pressure compensation value corresponding to the temperature value, and performs temperature compensation on the initial pressure value to obtain a final pressure value.
[0066] One implementation of the temperature compensation of the main control module is to calculate the sum value between the initial pressure value and the pressure compensation value to realize temperature compensation as the final pressure value.
[0067] From the above, the application of the demodulation system provided by the embodiment, because the circuit structure also includes a temperature acquisition module, using the temperature data collected by the temperature acquisition module, the temperature compensation of the pressure value is realized, and the accuracy of the demodulation system is further improved.
[0068] In the foregoing Figure 1a In the corresponding embodiment, the circuit structure can also include a light source driving module, based on which, referring to Figure 3a , Figure 3a The third optical fiber pressure sensor demodulation system provided by the embodiment of the application is shown in the structural schematic diagram, the system includes an optical path structure and a circuit structure, the optical path structure includes: a light source 311, a coupler 312, an F-P cavity 313, a cylindrical mirror 314, and a light wedge 315, and the circuit structure includes a CCD module 321, a CCD acquisition module 322, an ADC module 323, a main control module 324, and a light source driving module 325; wherein:
[0069] One end of the light source driving module 325 is connected with the main control module, and the other end is connected with the light source, and the main control 324 module controls the light source 311 to work through the light source driving module 325.
[0070] The chip in the above light source driving module is an adjustable PWM (Pulse Width Modulation, Pulse Width Modulation) control LED constant current driving chip, the driving voltage of the light source driving module is an adjustable switching voltage, and the driving voltage is 5V or 12V.
[0071] The main control module controls the PWM dimming through the setting pin, ensures the service life of the light source in the case of controlling the light source constant current driving, and makes the light source replaceable type in the external interface and the light source structure part, enhances the reliability of the demodulation system. An example of the circuit structure of the light source driving module is shown in Figure 3b .
[0072] The light signal emitted by the light source 311 is transmitted to the F-P cavity 313 through the coupler 312, and interference is formed in the F-P cavity 313. The interference light signal after interference is transmitted to the cylindrical mirror 314 through the coupler 312; the cylindrical mirror 314 converts the interference light signal into a linear light beam; the linear light beam enters the inside of the light wedge 315 for refraction, deflection and transmission attenuation, and outputs the related interference signal;
[0073] The relevant interference signals are irradiated on the CCD module 321, the CCD module 321 converts the irradiated relevant interference signals into analog electric signals; the analog electric signals are transmitted to the ADC module 323 through the CCD acquisition module 322; the ADC module 323 converts the analog electric signals into digital electric signals and transmits them to the main control module 324, the main control module demodulates the interference displacement values in the digital electric signals and converts the interference displacement values into corresponding pressures.
[0074] As can be seen from the above, the demodulation system provided by the embodiment is applied, the circuit structure further comprises a light source driving module, the light source driving module is used for controlling the light source to work, and effective utilization of the light source is improved.
[0075] It should be noted that, in this document, the terms such as first and second are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "contain" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or equipment. Without more limitations, the element defined by the statement "including a" does not exclude the presence of other identical elements in the process, method, article or equipment including the element.
[0076] The above only describes the preferred embodiments of the present application and is not used to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Claims
1. A demodulation system for a fiber optic pressure sensor, characterized by, The system comprises an optical path structure and a circuit structure, the optical path structure comprises a light source, a coupler, an F-P cavity, a cylindrical lens and a light wedge, and the circuit structure comprises a CCD module, a CCD acquisition module, an ADC module and a master control module; wherein: The light signal emitted by the light source is transmitted to the F-P cavity through the coupler, and interference is formed in the F-P cavity; the interference light signal after interference is transmitted to the cylindrical lens through the coupler; the cylindrical lens converts the interference light signal into a linear light beam; the linear light beam enters the inside of the light wedge for refraction, correction and transmission attenuation, and outputs a related interference signal; The related interference signal is irradiated on the CCD module, and the CCD module converts the irradiated related interference signal into an analog electric signal; the analog electric signal is transmitted to the ADC module through the CCD acquisition module; the ADC module converts the analog electric signal into a digital electric signal and transmits it to the master control module; the master control module demodulates the interference displacement value in the digital electric signal and converts the interference displacement value into a corresponding pressure.
2. The system of claim 1, wherein, The circuit structure further comprises a temperature acquisition module, wherein: The temperature acquisition module acquires temperature data in the related module, and transmits the temperature data to the master control module, wherein the related module is a module of a space region composed of the cylindrical lens, the light wedge and the CCD module; The master control module reads the temperature value acquired by the temperature acquisition module, determines a pressure compensation value corresponding to the temperature value, and performs temperature compensation on the initial pressure value obtained by demodulation to obtain a final pressure value.
3. The system of claim 1, wherein, The circuit structure further comprises a light source driving module, wherein: One end of the light source driving module is connected with the master control module, and the other end is connected with the light source; the master control module controls the light source to work through the light source driving module.
4. The system of claim 3, wherein, The chip in the light source driving module is an adjustable PWM control LED constant current driving chip, and the driving voltage of the light source driving module is an adjustable switching voltage, which is 5V or 12V.
5. The system of claim 1, wherein, The CCD acquisition module comprises a differential amplification circuit, a same-phase amplification circuit and a voltage follower, wherein: The input end of the differential amplification circuit is connected with the CCD module, and the output end is connected with the input end of the same-phase amplification circuit; the output end of the same-phase amplification circuit is connected with the input end of the voltage follower; and the output end of the voltage follower is connected with the ADC module.
6. The system of claim 1, wherein, The circuit structure further comprises a CCD driving module, wherein: The input end of the CCD driving module is connected with the master control module, and the output end is connected with the CCD module; the master control module drives the CCD module to work through the CCD driving module.
7. The system of claim 6, wherein, The CCD driving module comprises a level conversion driving chip, wherein: The level conversion driving chip is used for converting the voltage of the level of three clock control signals output by the master control module into a target voltage, and the target voltage is the voltage of the input power supply of the CCD module.
8. The system of any one of claims 1-7, wherein, The demodulation system is integrated in a ventricular assist device for detecting blood pressure of a patient, and the ventricular assist device comprises a ventricular catheter pump and an intra-aortic balloon counterpulsation device.