Miniaturized and integrated optical fiber sensing signal demodulation circuit system

Abstract

The invention discloses a miniaturized and integrated optical fiber sensing signal demodulation circuit system, which is used for demodulating an amplitude type optical fiber sensing signal, and adopts a constant power source to drive a laser diode to serve as light source signal output, and a single-wavelength laser signal with stable power is sent out and is transmitted to an optical fiber sensor through an optical fiber tail end; an optical signal is output to the photodiode after being modulated by external sensing quantity, the photodiode converts the optical signal into a current signal, the current signal is converted into a voltage signal after being amplified and stably filtered by the transimpedance amplification circuit, and the continuously changing voltage signal is acquired by the data acquisition card to reflect the measured change of the optical fiber sensor. Data waveform signals are output in real time through an upper computer, and small and integrated amplitude demodulation of optical fiber sensing signals is achieved.

Description

Technical Field

[0001] The present invention relates to the field of optical fiber sensing technology, and in particular to a miniaturized and integrated optical fiber sensing signal demodulation circuit system. Background Art

[0002] Fiber optic sensing is a highly sensitive and high-precision sensing technology that can be applied to the measurement of parameters such as temperature, pressure, strain, and refractive index, and has a very broad development prospect. In the actual application of fiber optic sensing, a stable and reliable circuit integration system is one of the key technologies, which can realize the detection, amplification, and digital conversion of sensor signals, ensuring the reliability and accuracy of the system output results. Miniaturized and integrated circuit integration systems are issues that must be solved for the industrialization of fiber optic sensors, and are still in a stage of continuous development.

[0003] The development trend of fiber optic sensor signal demodulation circuit design includes the following directions: (1) Power consumption optimization: With the rising cost of electricity, power consumption optimization has become a basic requirement for circuit design. In fiber optic sensor circuits, power consumption optimization can be achieved by reducing the brightness of the light source, using low-power amplifiers and filters, etc. (2) Integration: With the continuous development of integrated circuit technology, the circuit design of fiber optic sensors also tends to be integrated. Integrated design can improve the reliability and stability of the circuit and reduce the size and cost of the circuit. (3) High-speed transmission: With the continuous increase in data transmission speed, fiber optic sensors require circuit design to have high-speed transmission capabilities. High-speed transmission can be achieved by using high-performance data converters and signal processing chips. (4) Multi-channel: Fiber optic sensor circuits usually need to process multiple input signals, so multi-channel design has become a trend. Multi-channel design can be achieved by using multi-channel amplifiers and cross switches. (5) Adaptive adjustment: The working environment of fiber optic sensors is changeable, so the circuit design needs to be adaptive and can intelligently adjust parameters and working modes according to environmental changes to achieve better performance and stability.

[0004] However, in the existing fiber optic sensor signal demodulation circuit system, the fiber optic sensor is limited by the high price and large size of the light source and spectrometer in the laboratory, and most of the practical application research of fiber optic sensors is still in the laboratory stage. Therefore, how to design a fiber optic sensor signal demodulation circuit system to promote the miniaturization, integration and low cost of fiber optic sensing has become an important and urgent problem to be solved for the practical application of fiber optic sensing technology. Summary of the invention

[0005] In view of the deficiencies of the prior art, the object of the present invention is to provide a miniaturized, integrated fiber optic sensor signal demodulation circuit system for demodulating line-of-sight fiber optic sensor signals in a low-cost, miniaturized, integrated manner.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] A miniaturized, integrated optical fiber sensing signal demodulation circuit system, the key of which is to include:

[0008] A constant power source driving circuit is used to output a driving current signal with constant power;

[0009] A laser diode, configured to emit a laser signal according to the driving current signal;

[0010] An optical fiber sensor, used for importing the laser signal and outputting it after modulation;

[0011] A photodiode, used to sense the laser signal modulated by the optical fiber sensor and convert it into a current signal;

[0012] A transimpedance amplifier circuit, used for converting the current signal into a voltage signal, and amplifying, stabilizing and filtering the voltage signal before outputting it;

[0013] A data acquisition card, used for acquiring the voltage signal output by the transimpedance amplifier circuit, and outputting it to a signal demodulation module;

[0014] The signal demodulation module is used to demodulate and visualize the voltage signal collected by the data acquisition card into an optical fiber sensing signal.

[0015] Furthermore, the laser diode is a laser diode with a PD end as power feedback, and the PD end outputs feedback current to the constant power source driving circuit, and the constant power source driving circuit adjusts the current size of the output driving current signal according to the feedback current negative feedback.

[0016] Furthermore, the constant power source driving circuit includes a first operational amplifier, a transistor S11, a transistor S12, and a voltage regulator S1. The non-inverting input terminal of the first operational amplifier is connected to the PD terminal of the laser diode, the inverting input terminal of the first operational amplifier is grounded via a resistor R12, the output terminal of the first operational amplifier is connected in series with resistors R14 and R16 in sequence and then connected to the base of the transistor S12, the collector of the transistor S11 is connected to the power supply via a resistor R17, and the emitter of the transistor S12 is connected to the emitter of the transistor S 11, the base of the transistor S11 is connected to the power supply through the resistor C14, the emitter of the transistor S11 is grounded, the output end of the first operational amplifier is connected in series with the capacitor C11 and then connected to its reverse input end, the anode of the voltage regulator S1 is grounded, the cathode of the voltage regulator S1 is connected in series with the resistor R15 and then connected to the power supply, the cathode of the voltage regulator S1 is also connected in series with the resistor R13 and then connected to the reverse input end of the first operational amplifier, the reference electrode of the voltage regulator S1 is connected to its cathode, and the anode of the voltage regulator S1 is also connected to its cathode.

[0017] Furthermore, the transimpedance amplifier circuit includes a second operational amplifier, the non-inverting input terminal of the second operational amplifier is connected to the cathode of the Zener diode D2 via a resistor R6, the anode of the Zener diode D2 is connected to a power supply, the inverting input terminal of the second operational amplifier inputs the current signal, and the output terminal of the second operational amplifier outputs the voltage signal.

[0018] Furthermore, the non-inverting input terminal of the second operational amplifier is also grounded via an RC filter circuit, and the RC filter is composed of a resistor R7 and a capacitor C9 connected in parallel.

[0019] Furthermore, the output terminal of the second operational amplifier is also connected to its inverting input terminal via a resistor R5 and a capacitor C8 connected in parallel.

[0020] Furthermore, the cathode of the Zener diode D2 and the common end of the resistor R6 are grounded via the resistor R10 and the light emitting diode LED4, and the cathode of the Zener diode D2 and the common end of the resistor R6 are also grounded via capacitors C12, C11, C7, and C6 which are all connected in parallel with each other.

[0021] Furthermore, the photodiode adopts a PIN photodetector, and the data acquisition card adopts an ADS1115BQDGSRQ1 chip.

[0022] Furthermore, the signal demodulation module is a host computer or a single-chip microcomputer, and when the signal demodulation module is a single-chip microcomputer, it is equipped with a display screen, and the single-chip microcomputer adopts a 51 single-chip microcomputer.

[0023] Furthermore, the system also includes a power supply module, which supplies power to the constant power source drive circuit, the photodiode, the transimpedance amplifier circuit, and the data acquisition card.

[0024] Compared with the prior art, the present invention has the following advantages and effects:

[0025] The present invention discloses a miniaturized, integrated optical fiber sensing amplitude demodulation circuit system, which drives a laser diode to generate laser light by sending a driving current signal through a constant power source driving circuit, and a photodiode detects the light signal, which is amplified, stabilized, and filtered by a transimpedance amplifier circuit and outputs a voltage signal. The detected signal is output in real time through a data acquisition card and output to a signal demodulation module for demodulation and visual display. The circuit system is low-cost and miniaturized and integrated, and is expected to greatly promote the practical application of optical fiber sensors. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a system composition block diagram of the present invention;

[0027] Figure 2 It is the circuit schematic diagram of the constant power source drive circuit;

[0028] Figure 3 It is the circuit schematic diagram of the transimpedance amplifier circuit;

[0029] Figure 4 This is the circuit schematic diagram of the data acquisition card;

[0030] Figure 5 is a circuit schematic diagram of one implementation of a power module;

[0031] Figure 6 is a circuit schematic diagram of another embodiment of the power module;

[0032] Figure 7 It is the circuit schematic diagram of the microcontroller. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] Example

[0035] like Figure 1 As shown, Figure 1The block diagram of a miniaturized, integrated fiber optic sensor amplitude demodulation circuit system disclosed in the present invention is shown, including: a power module, a constant power source drive circuit, a laser diode, a fiber optic sensor, a photodiode, a transimpedance amplifier circuit, a data acquisition card and a signal demodulation module. The circuit structure is simple, and the circuit system can be made into a patch type and a plug-in type. Specifically:

[0036] The miniaturized, integrated optical fiber sensing signal demodulation circuit system comprises:

[0037] The power supply module is used to directly provide power support to the constant power source drive circuit, the photodiode, the transimpedance amplifier circuit, and the data acquisition card, and also to provide power to the entire circuit system, and adopts a 5V single power supply mode, but is not limited to a 5V single power supply mode;

[0038] The constant power source driving circuit is used to output a driving current signal with constant power. The power module directly supplies power. The driving current signal is controlled by a constant power method. The output current is adjusted by negative feedback at the PD end of the laser diode to ensure the constant output optical power and offset the influence of temperature.

[0039] The laser diode is used to emit a laser signal according to the driving current signal;

[0040] In a specific implementation, the laser diode is a laser diode with a PD end as power feedback, which provides a light source for the optical fiber sensor. The LD end of the laser diode is the input end of the current. The input current causes the laser diode to emit laser light. The larger the current, the stronger the output laser power. The PD end is the feedback end. A photodetector is integrated inside the laser diode, which can feed back the current to the PD end according to the strength of the emitted power. Since the laser diode itself is a semiconductor, it is affected by changes in the external environment such as temperature. If the laser diode works for too long, it will generate heat and affect the output stability. There is a disadvantage of temperature drift. The input current is adjusted by feedback from the PD end to avoid the influence of temperature drift, ensure the stability of the output laser power, and reduce the error of the signal demodulation output end.

[0041] The optical fiber sensor is used to import the laser signal and output it after modulation. The optical fiber sensor is any optical sensor that uses optical fiber as the medium for optical signal input and output. The modulation and demodulation parameters of the sensing signal are signal amplitude.

[0042] The photodiode is used to sense the laser signal modulated by the optical fiber sensor and convert it into a current signal, and a PIN photodetector is used, but not limited to a PIN photodetector;

[0043] A transimpedance amplifier circuit is used to convert the current signal into a voltage signal, and output the voltage signal after amplification, voltage stabilization and filtering. That is, the weak current signal emitted by the photoelectric detector after photoelectric conversion is converted into a voltage signal, and the voltage signal is amplified, while taking into account noise suppression and signal-to-noise ratio improvement, thereby ensuring the accuracy of voltage acquisition and reading. The output voltage signal realizes real-time output of the measured signal through a data acquisition card;

[0044] A data acquisition card, used for acquiring the voltage signal output by the transimpedance amplifier circuit, and outputting it to a signal demodulation module;

[0045] The signal demodulation module is used to demodulate and visualize the voltage signal collected by the data acquisition card into an optical fiber sensing signal.

[0046] In this example, the system reserves two optical fiber tail ends for connecting to two tail ends of the optical fiber sensor to achieve access to the optical fiber sensor.

[0047] See attached Figure 2 The constant power source driving circuit includes a first operational amplifier U3.1, a transistor S11, a transistor S12, and a voltage regulator S1. The non-inverting input terminal of the first operational amplifier U3.1 is connected to the PD terminal of the laser diode. The inverting input terminal of the first operational amplifier U3.1 is grounded via a resistor R12. The output terminal of the first operational amplifier U3.1 is connected in series with resistors R14 and R16 in sequence and then connected to the base of the transistor S12. The collector of the transistor S11 is connected to the power supply via a resistor R17. The emitter of the transistor S12 is connected to the transistor R18. The collector of the transistor S11 is connected, the base of the transistor S11 is connected to the power supply through the resistor C14, the emitter of the transistor S11 is grounded, the output end of the first operational amplifier U3.1 is connected to its reverse input end after being connected in series with the capacitor C11, the anode of the voltage regulator S1 is grounded, the cathode of the voltage regulator S1 is connected to the power supply after being connected in series with the resistor R15, the cathode of the voltage regulator S1 is also connected to the reverse input end of the first operational amplifier U3.1 after being connected in series with the resistor R13, the reference electrode of the voltage regulator S1 is connected to its cathode, and the anode of the voltage regulator S1 is also connected to its cathode.

[0048] Through the above circuit, the current size of the driving current signal is controlled in a constant power manner, and negative feedback is generated through the PD end of the photodiode to adjust the output current, ensure the constant output light power, offset the influence of temperature, and reduce the error of the signal demodulation output end.

[0049] See attached Figure 3The transimpedance amplifier circuit includes a second operational amplifier U2, the non-inverting input terminal of the second operational amplifier U2 is connected to the cathode of the voltage zener diode D2 via a resistor R6, the anode of the voltage zener diode D2 is connected to a power supply, the inverting input terminal of the second operational amplifier U2 inputs the current signal, and the output terminal of the second operational amplifier U2 outputs the voltage signal; the non-inverting input terminal of the second operational amplifier U2 is also grounded via an RC filter circuit, and the RC filter is composed of a parallel resistor R7 and a capacitor C9; the output terminal of the second operational amplifier U2 is also connected to its reverse input terminal through a parallel resistor R5 and a capacitor C8.

[0050] from Figure 3 It can also be seen that the cathode of the Zener diode D2 and the common end of the resistor R6 are grounded via the resistor R10 and the light-emitting diode LED4, and the cathode of the Zener diode D2 and the common end of the resistor R6 are also grounded via the capacitors C12, C11, C7, and C6 which are all connected in parallel with each other.

[0051] Through the above circuit, the weak current signal emitted by the photoelectric detector after photoelectric conversion is converted into a voltage signal, and the voltage signal is amplified, while taking into account noise suppression and improvement of the signal-to-noise ratio, thereby ensuring the accuracy of voltage reading. The output voltage signal realizes real-time output of the measured signal through the data acquisition card.

[0052] In this example, the data acquisition card uses the ADS1115BQDGSRQ1 chip, and its circuit schematic is shown in the attached Figure 4 .

[0053] See attached Figure 5 With attached Figure 6 The specific implementation circuit of the power module has two forms as shown in the figure. One is based on the TYPR-C communication interface module, and the other is based on the serial communication module. The specific circuit of the power module is integrated through the power lines of the two modules, so that it has both communication function and single power supply function, so as not to occupy too much circuit board space, realize voltage conversion, high integration and low power consumption.

[0054] In the specific implementation process of this embodiment, the signal demodulation module is a host computer or a single-chip microcomputer, and when the signal demodulation module is a single-chip microcomputer, a display screen is configured. The single-chip microcomputer adopts a 51 single-chip microcomputer. Figure 7 .

[0055] Finally, it should be noted that since the circuit system described in this embodiment can be made into a surface mount type and a direct plug type, it is only necessary to Figure 2-Figure 7 This can be achieved by replacing the corresponding interfaces in the circuit shown without modifying the circuit.

[0056] In summary, the present embodiment discloses a miniaturized, integrated fiber optic sensor signal demodulation circuit system for demodulating amplitude-type fiber optic sensor signals. The circuit system uses a constant power source drive circuit to drive a laser diode, the laser diode is a light source that emits a single-wavelength laser signal, and a photodiode is used for light signal acquisition. The laser diode emits a single-wavelength laser signal with stable power, which is transmitted to the fiber optic sensor through the tail end of the optical fiber, and is output to the photodiode after being modulated by the external sensor quantity. The photodiode converts the light signal into a current signal, which is converted into a voltage signal after being amplified and smoothly filtered by a transimpedance amplifier circuit. The continuously changing voltage signal is used as a collection signal to reflect the changes in the fiber optic sensor being measured. The voltage signal is collected through a data acquisition card, transmitted to a host computer or a single-chip microcomputer, and the collected demodulated signal is displayed visually after demodulation, thereby realizing a miniaturized circuit integrated fiber optic sensor signal amplitude demodulation system, which can help the industrialization of the practical application of fiber optic sensors.

[0057] The technical solution provided by the present invention is described in detail above. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the present invention, the present invention can also be improved and modified in a number of ways, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A miniaturized, integrated optical fiber sensor signal demodulation circuit system, characterized in that: include: A constant power source driving circuit is used to output a driving current signal with constant power; A laser diode, configured to emit a laser signal according to the driving current signal; An optical fiber sensor, used for importing the laser signal and outputting it after modulation; A photodiode, used to sense the laser signal modulated by the optical fiber sensor and convert it into a current signal; A transimpedance amplifier circuit, used for converting the current signal into a voltage signal, and amplifying, stabilizing and filtering the voltage signal before outputting it; A data acquisition card, used for acquiring the voltage signal output by the transimpedance amplifier circuit, and outputting it to a signal demodulation module; The signal demodulation module is used to demodulate and visualize the voltage signal collected by the data acquisition card into an optical fiber sensing signal.

2. The miniaturized, integrated optical fiber sensor signal demodulation circuit system according to claim 1, characterized in that: The laser diode is a laser diode with a PD end as power feedback. The PD end outputs feedback current to the constant power source driving circuit. The constant power source driving circuit adjusts the current size of the output driving current signal according to the feedback current negative feedback.

3. The miniaturized, integrated optical fiber sensing signal demodulation circuit system according to claim 2, characterized in that: The constant power source driving circuit includes a first operational amplifier, a transistor S11, a transistor S12, and a voltage regulator S1. The non-inverting input terminal of the first operational amplifier is connected to the PD terminal of the laser diode, the inverting input terminal of the first operational amplifier is grounded via a resistor R12, the output terminal of the first operational amplifier is connected in series with resistors R14 and R16 in sequence and then connected to the base of the transistor S12, the collector of the transistor S11 is connected to the power supply via a resistor R17, the emitter of the transistor S12 is connected to the emitter of the transistor S11 The collector is connected, the base of the transistor S11 is connected to the power supply through the resistor C14, the emitter of the transistor S11 is grounded, the output end of the first operational amplifier is connected in series with the capacitor C11 and then connected to its reverse input end, the anode of the voltage regulator S1 is grounded, the cathode of the voltage regulator S1 is connected in series with the resistor R15 and then connected to the power supply, the cathode of the voltage regulator S1 is also connected in series with the resistor R13 and then connected to the reverse input end of the first operational amplifier, the reference electrode of the voltage regulator S1 is connected to its cathode, and the anode of the voltage regulator S1 is also connected to its cathode.

4. The miniaturized, integrated optical fiber sensor signal demodulation circuit system according to claim 1, characterized in that: The transimpedance amplifier circuit includes a second operational amplifier, a non-inverting input terminal of the second operational amplifier is connected to the cathode of the Zener diode D2 via a resistor R6, an anode of the Zener diode D2 is connected to a power supply, an inverting input terminal of the second operational amplifier inputs the current signal, and an output terminal of the second operational amplifier outputs the voltage signal.

5. The miniaturized, integrated optical fiber sensor signal demodulation circuit system according to claim 4, characterized in that: The non-inverting input terminal of the second operational amplifier is also grounded via an RC filter circuit, and the RC filter is composed of a resistor R7 and a capacitor C9 connected in parallel.

6. The miniaturized, integrated optical fiber sensing signal demodulation circuit system according to claim 4, characterized in that: The output terminal of the second operational amplifier is also connected to its inverting input terminal via a resistor R5 and a capacitor C8 connected in parallel.

7. The miniaturized, integrated optical fiber sensing signal demodulation circuit system according to claim 4, characterized in that: The cathode of the voltage zener diode D2 and the common end of the resistor R6 are grounded via the resistor R10 and the light emitting diode LED4. The cathode of the voltage zener diode D2 and the common end of the resistor R6 are also grounded via capacitors C12, C11, C7 and C6 which are all connected in parallel with each other.

8. The miniaturized, integrated optical fiber sensor signal demodulation circuit system according to claim 1, characterized in that: The photodiode adopts a PIN photodetector, and the data acquisition card adopts an ADS1115BQDGSRQ1 chip.

9. The miniaturized, integrated optical fiber sensor signal demodulation circuit system according to claim 1, characterized in that: The signal demodulation module is a host computer or a single-chip microcomputer, and when the signal demodulation module is a single-chip microcomputer, a display screen is configured, and the single-chip microcomputer adopts a 51 single-chip microcomputer.

10. The miniaturized, integrated optical fiber sensing signal demodulation circuit system according to any one of claims 1 to 9, characterized in that: The system also includes a power supply module, which supplies power to the constant power source drive circuit, the photodiode, the transimpedance amplifier circuit, and the data acquisition card.

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