Reflection-type optical fiber vibration frequency measuring device

Abstract

The utility model belongs to the technical field of physical measurement devices, and particularly relates to a reflection-type optical fiber vibration frequency measurement device. Comprising a transmitting optical fiber, a light-emitting diode, a reflecting surface, a receiving optical fiber, a photoelectric receiver, a blocking circuit, an amplifying circuit and a frequency detection module, one end of the transmitting optical fiber and one end of the receiving optical fiber are installed in parallel to serve as a detection end, and the other ends of the transmitting optical fiber and the receiving optical fiber are bifurcated; the other end of the emitting optical fiber is arranged opposite to the light-emitting diode and is used for transmitting light emitted by the light-emitting diode; light output by the light-emitting diode is coupled to the emitting optical fiber, and the light intensity is constant; the other end of the receiving optical fiber is opposite to the photoelectric receiver; the photoelectric receiver is sequentially connected with a blocking circuit, an amplifying circuit and a frequency detection module; the reflecting surface is rigidly connected with a to-be-measured vibrating body, the reflecting surface is perpendicular to the vibration direction, and light emitted by the emitting optical fiber can be reflected back to the receiving optical fiber after irradiating the reflecting surface; the utility model has the advantages of novel design, simple structure and convenience in use.

Description

TECHNICAL FIELD

[0001] The utility model belongs to physical measuring device technical field, concretely relates to a device of reflection type optical fiber measurement vibration frequency. BACKGROUND

[0002] The traditional method of measuring the vibration frequency of an object generally uses a transducer to convert mechanical energy into electrical energy for measurement. This method requires the transducer to be in close contact with the vibrating surface and the electrical signal is input to the instrument host through a cable. It is a contact type measurement method. However, the transducer and the cable itself have a large mass, which may affect the vibration frequency of the object. The reflective optical fiber sensor is a non-contact method for detecting mechanical parameters on the surface of an object. Its measurement principle is as follows: light is coupled from a light source to a transmitting optical fiber, transmitted through the optical fiber, reflected to a receiving optical fiber, and finally received by a photoelectric receiver. The light intensity received by the photoelectric receiver is related to the surface properties of the reflecting surface and the distance from the reflecting surface to the optical fiber probe. When the light intensity of the light source is constant and the surface properties of the reflecting surface are fixed, the light intensity received by the photoelectric receiver is only related to the distance from the reflecting surface to the optical fiber probe. By detecting the light intensity, the distance between the reflecting surface and the optical fiber probe can be obtained. The utility model also uses the same characteristics to extract the alternating component of the signal obtained by light intensity detection, which is used to reflect the vibration state of the measured vibrating body, and then measure the vibration frequency. The method has the advantages that the reflecting surface can be very thin and has a very small mass. Even the original surface of the object can be used as the reflecting surface, so that the measurement has little or no effect on the vibration frequency of the object. SUMMARY

[0003] The utility model discloses a structure is simple, and the device of reflection type optical fiber measurement vibration frequency convenient to use.

[0004] The device of reflection type optical fiber measurement vibration frequency provided by the utility model, including: transmitting optical fiber, emitting diode, reflecting surface, receiving optical fiber, photoelectric receiver, direct current separation circuit, amplification circuit and frequency detection module, wherein:

[0005] One end of the transmitting optical fiber is parallelly installed with one end of the receiving optical fiber as a detection end, and the other end of the transmitting optical fiber and the other end of the receiving optical fiber are bifurcated.

[0006] The other end of the transmitting optical fiber is opposite to the emitting diode and is used for transmitting the light emitted by the emitting diode. The light output of the emitting diode is coupled to the transmitting optical fiber, and the light intensity is constant.

[0007] The other end of the receiving optical fiber is opposite to the photoelectric receiver and is used for measuring the light intensity of the reflected light.

[0008] The photoelectric receiver is connected with a direct-current separation circuit, an amplification circuit and a frequency detection module in sequence.

[0009] The direct-current separation circuit is connected with the photoelectric receiver through a cable, receives the light intensity signal measured by the photoelectric receiver and removes the direct current component, and only outputs the alternating current component of the light intensity signal.

[0010] The amplification circuit is connected with the direct-current separation circuit through a cable, and the alternating current component of the light intensity signal is amplified in amplitude so that the signal amplitude is easy to identify.

[0011] The frequency detection module is connected with the amplification circuit through a cable, and the periodic change of the light intensity signal is converted into a frequency reading by using the alternating current component of the light intensity signal amplified in amplitude and an internal timer, and the frequency reading is the vibration frequency of the vibrating body.

[0012] The reflecting surface is rigidly connected with the vibrating body to be measured, and the reflecting surface is perpendicular to the vibration direction; the reflecting surface is vertically arranged on the detection end and is spaced apart from the detection end by a distance, and the light emitted by one end of the transmitting optical fiber can be reflected back to one end of the receiving optical fiber after irradiating the reflecting surface.

[0013] When the utility model is used, because there is an optimal distance range between the detection end of the transmitting optical fiber and the receiving optical fiber and the reflecting surface, the sensitivity of the light intensity change amount received by the photoelectric receiver to the distance change amount between the detection end and the reflecting surface is the highest, so the detection end needs to be adjusted to the optimal distance range and fixed first; when the reflecting surface vibrates with the vibrating body, the distance between the reflecting surface and the detection end changes at any time, so the light intensity received by the photoelectric receiver also changes, thereby forming an alternating current signal, the frequency of the alternating current signal is consistent with the vibration frequency of the vibrating body, and after the alternating current signal is processed by the direct-current separation circuit and the amplification circuit, the frequency detection module detects the frequency, and the vibration frequency of the vibrating body can be known.

[0014] The utility model discloses a clear measurement principle, novel design, simple structure and convenient use. DETAILED DESCRIPTION

[0015] Figure 1 It is the structure diagram of the utility model.

[0016] In the drawing, 1 is a transmitting optical fiber, 2 is a light emitting diode, 3 is a reflecting surface, 4 is a receiving optical fiber, 5 is a photoelectric receiver, 6 is a direct-current separation circuit, 7 is an amplification circuit, 8 is a frequency detection module, and 9 is a detection end fixing device. CONCRETE IMPLEMENTATION

[0017] The utility model will be further described below in combination with the drawings.

[0018] This utility model includes: a transmitting optical fiber 1, a light-emitting diode 2, a reflective surface 3, a receiving optical fiber 4, a photoelectric receiver 5, a DC blocking circuit 6, an amplifying circuit 7, a frequency detection module 8, and a detection end fixing device 9.

[0019] The left ends of the transmitting optical fiber 1 and the receiving optical fiber 4 are parallel to each other and are encapsulated and fixed relative to each other by the detection end fixing device 9. The detection end fixing device 9 can be a prefabricated silicone block with two holes. The light emitted by the light-emitting diode 2 is installed at the right end of the transmitting optical fiber 1. The light intensity emitted is constant, coupled into the transmitting optical fiber 1, and exits from the left end of the transmitting optical fiber 1. The reflective surface 3 is rigidly connected to the vibrating body and vibrates together with the vibrating body in the left-right direction. It is installed directly opposite the left ends of the transmitting optical fiber 1 and the receiving optical fiber 4. The light emitted from the left end of the transmitting optical fiber 1 is reflected by the reflective surface 3 and illuminates the left end of the receiving optical fiber 4. The reflected light passes through the receiving optical fiber 4. The signal is transmitted and coupled to a photodetector 5 installed at the right end of the receiving optical fiber 4; the photodetector 5 converts the received reflected light intensity into an electrical signal, which is transmitted to a DC blocking circuit 6 via a cable; the DC blocking circuit 6 removes the DC component of the light intensity signal, retaining only the AC component, and transmits it to an amplifier circuit 7 via a cable; the amplifier circuit 7 amplifies the received signal to make the signal amplitude easily identifiable, and transmits the AC component of the amplified light intensity signal to a frequency detection module 8 via a cable; the frequency detection module 8 has a timer inside, which can detect the period of the input AC signal in real time and convert it into a frequency display.

[0020] When using this invention, there is an optimal distance range between the detection end and the reflective surface of the transmitting and receiving optical fibers. This range results in the highest sensitivity between the change in light intensity received by the photodetector and the change in distance between the detection end and the reflective surface. Therefore, the detection end must first be adjusted to this optimal distance range and fixed. As the reflective surface vibrates with the vibrating body, the distance between it and the detection end changes constantly. Consequently, the light intensity received by the photodetector also changes, thus forming an AC signal. The frequency of this AC signal is consistent with the vibration frequency of the vibrating body. After processing the AC signal through a DC blocking circuit and an amplification circuit, its frequency is detected by a frequency detection module, and the vibration frequency of the vibrating body can be determined.

[0021] This invention is simple in structure, easy to operate, and safe and reliable, as long as it can be used in classroom teaching experiments.

[0022] Although the above methods are illustrated and described as a series of structures for the sake of simplicity, it should be understood and appreciated that these methods are not specifically limited, as some structures may occur in different orders and / or concurrently with other actions from those illustrated and described herein or not illustrated and described herein but which may be understood by those skilled in the art, according to one or more embodiments.

[0023] The previous description of the disclosure is provided to enable any person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein can be applied to other variations without departing from the spirit or scope of the disclosure. Thus, the disclosure is not intended to be limited to the examples described herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A device for measuring the frequency of vibrations by means of a reflective optical fiber; characterized in that, It includes: Emitting optical fiber, light-emitting diode, reflecting surface, receiving optical fiber, photoelectric receiver, direct current isolation circuit, amplification circuit and frequency detection module; wherein: The one end of the emitting optical fiber is parallelly installed with the one end of the receiving optical fiber as a detection end, and the other end of the emitting optical fiber and the other end of the receiving optical fiber are bifurcated; The other end of the emitting optical fiber is oppositely arranged with the light-emitting diode for transmitting the light emitted by the light-emitting diode; the light output of the light-emitting diode is coupled to the emitting optical fiber, and the light intensity is constant; The other end of the receiving optical fiber is oppositely arranged with the photoelectric receiver for measuring the light intensity of the reflected light; The photoelectric receiver is connected with the direct current isolation circuit, the amplification circuit and the frequency detection module in sequence; wherein: The direct current isolation circuit is connected with the photoelectric receiver through a cable; the light intensity signal measured by the photoelectric receiver is received and the direct current component is removed, and only the alternating current component of the light intensity signal is output; The amplification circuit is connected with the direct current isolation circuit through a cable; the alternating current component of the light intensity signal is amplified in amplitude, so that the signal amplitude is easy to identify; The frequency detection module is connected with the amplification circuit through a cable, and the periodic change of the light intensity signal is converted into a frequency reading by using the alternating current component of the light intensity signal amplified in amplitude and an internal timer, and the frequency reading is the vibration frequency of the vibrating body; The reflecting surface is rigidly connected with the vibrating body to be measured, and the reflecting surface is perpendicular to the vibration direction; the reflecting surface is perpendicularly arranged on the detection end with a distance, and the light emitted by the one end of the emitting optical fiber can be reflected back to the one end of the receiving optical fiber after irradiating the reflecting surface.

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