Contactless displacement control system and displacement control method

Abstract

The application is suitable for the technical field of optical coupling, and provides a non-contact displacement control system and a displacement control method. The system comprises a displacement platform, a spectrometer and a control device, and is applied to displacement control of a light source emitting end and a first port of an optical fiber to be optically coupled. The displacement platform is used for fixing the first port of the optical fiber, the spectrometer is used for connecting a second port of the optical fiber, and the control device is connected with the spectrometer and the displacement platform respectively. The light source emitting end and the first port of the optical fiber form an optical cavity. The spectrometer detects and sends a longitudinal mode spacing of the optical cavity to the control device based on a light signal emitted by the light source emitting end. The control device controls the displacement platform to drive the first port of the optical fiber to move based on the longitudinal mode spacing, and adjusts a distance between the first port of the optical fiber and the light source emitting end. The application can accurately control micron-level displacement changes while ensuring that a contact measurement surface is not damaged or contaminated.

Description

Technical Field

[0001] The present application relates to the field of optical coupling technology, and in particular to a contactless displacement control system and a displacement control method. Background Art

[0002] Optical coupling involves directing light to the device being coupled. The bare fiber end diameters of optical fibers used in optical coupling are typically small, for example, some are only 0.2mm. Even the slightest external force can damage the fiber end, requiring precise control of the distance between the bare fiber end and the light source's emitter. Excessive distances can result in a lack of light coupling, while short distances can damage both the fiber end and the light source. Visually identifying millimeter-level distance variations is difficult.

[0003] At present, the distance measuring instruments at home and abroad are roughly divided into ultrasonic distance measuring, laser distance measuring and mechanical distance measuring based on their principles. Laser distance measuring technology can be divided into two categories.

[0004] Ultrasonic ranging works on a similar principle to first-class laser ranging: both calculate distance by reflecting light (or sound) signals off obstacles. Rangefinders based on this technology have advantages such as low signal source requirements, high speed, and simple structure. However, they are significantly affected by environmental factors such as atmospheric refraction and reflectivity, and their measurement accuracy is limited to meters, making them suitable for long-range distance measurement.

[0005] The second type of laser ranging method uses a phase-based laser rangefinder. This method amplitude-modulates a laser beam and measures the phase delay caused by a round trip of the modulated light. The distance represented by this phase delay is then converted based on the wavelength of the modulated light. Coherent laser rangefinders overcome the large errors inherent in the first type of laser ranging method, enabling millimeter-level distance measurement. However, their drawbacks include complex circuitry and a shorter range.

[0006] Mechanical distance measurement primarily measures physical displacement by identifying changes in pressure or physical vibrations caused by the interaction between the probe and the surface being measured. While mechanical distance measurement can achieve extremely high accuracy, its biggest challenge is damage or contamination caused by contact with the measured surface.

[0007] However, in the field of optical coupling, the above-mentioned technology cannot achieve precise control of micron-level displacement changes while ensuring that the contact measurement surface will not be damaged or contaminated when controlling the distance between the bare fiber end of the optical fiber and the emission end of the light source. Summary of the Invention

[0008] In view of this, the embodiments of the present application provide a contactless displacement control system and a displacement control method, which can realize contactless displacement measurement and precise control of micron-level displacement changes.

[0009] To achieve the above objectives, this application adopts the following technical solutions:

[0010] In a first aspect, the embodiments of the present application provide a non-contact displacement control system, which is characterized in that it is applied to control the displacement of a light source emitting end and a first port of an optical fiber to be optically coupled, and comprises a displacement platform, a spectrometer and a control device.

[0011] The first port of the displacement platform is used to fix the optical fiber, and the spectrometer is used to connect a second port of the optical fiber, wherein the first port is the port of the optical fiber receiving the light signal emitted by the light source emitting end; the control device is connected with the spectrometer and the displacement platform respectively.

[0012] The light source emitting end and the first port of the optical fiber form an optical cavity; the light signal emitted by the light source emitting end is transmitted to the spectrometer through the optical cavity and the optical fiber.

[0013] The spectrometer is used to detect the longitudinal mode spacing of the optical cavity based on the received light signal, and send the longitudinal mode spacing to the control device.

[0014] The control device is used to control the displacement platform to drive the first port of the optical fiber to move, so as to adjust the distance between the first port of the optical fiber and the light source emitting end based on the longitudinal mode spacing.

[0015] Based on the first aspect, in some embodiments, the surface of the light source emitting end is coated with a first reflective film, and the surface of the first port of the optical fiber is coated with a second reflective film.

[0016] Based on the first aspect, in some embodiments, the reflection coefficient of the first reflective film ranges from 0.2 to 0.3, and the reflection coefficient of the second reflective film is greater than or equal to 0.9.

[0017] Based on the first aspect, in some embodiments, the light signal emitted by the light source emitting end is reflected multiple times in the optical cavity, forming multiple parallel emitted light and reflected light.

[0018] Based on the first aspect, in some embodiments, the wavelength of the light signal emitted by the light source emitting end is a gain wavelength, and the wavelength range is 1530nm-1561nm.

[0019] Based on the first aspect, in some embodiments, the control device is specifically used for:

[0020] comparing the longitudinal mode spacing with a preset longitudinal mode spacing threshold value, and controlling the displacement platform to drive the first port of the optical fiber to move in a direction close to the light source emitting end when the longitudinal mode spacing is less than the preset longitudinal mode spacing, so as to reduce the distance between the first port of the optical fiber and the light source emitting end.

[0021] Based on the first aspect, in some embodiments, the longitudinal mode spacing and the distance from the first port of the optical fiber to the emitting end of the light source satisfy a first formula, wherein the first formula is:

[0022]

[0023] Wherein, Δλ represents the longitudinal mode spacing, λ is the wavelength of the light source, n is the refractive index of the medium, and L is the distance from the first port of the optical fiber to the emitting end of the light source;

[0024] The control device is further configured to calculate a preset longitudinal mode spacing threshold based on the first formula and an expected distance from the first port of the optical fiber to the emission end of the light source.

[0025] Based on the first aspect, in some embodiments, an alarm device is further included;

[0026] The alarm device is used to control the alarm device to alarm when the longitudinal mold spacing is greater than or equal to the preset longitudinal mold spacing threshold.

[0027] Based on the first aspect, in some embodiments, when the displacement platform is located at an initial position, an initial distance from the first port of the optical fiber to the emitting end of the light source is greater than the expected distance;

[0028] The displacement platform drives the first port of the optical fiber to move one step each time;

[0029] The displacement platform drives the first port of the optical fiber to move in a step length of less than or equal to 0.1 mm;

[0030] The wavelength resolution of the spectrometer is greater than or equal to 0.1 nm.

[0031] In a second aspect, an embodiment of the present application provides a contactless displacement control method, the method comprising:

[0032] The light source emits a light signal; the light signal passes through the optical cavity and the optical fiber and is transmitted to the spectrometer;

[0033] After receiving the optical signal transmitted by the optical fiber, the spectrometer detects the longitudinal mode spacing of the optical cavity and sends the longitudinal mode spacing to the control device;

[0034] The control device controls the displacement platform to drive the first end of the optical fiber to move according to the longitudinal mode spacing, so as to adjust the distance between the first end of the optical fiber and the emission end of the light source.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] The present application is applicable to the field of optical coupling technology and provides a contactless displacement control system and displacement control method. The system includes: a displacement platform, a spectrometer, and a control device. The system is used to control the displacement of the light source emitting end and the first port of the optical fiber to be optically coupled, wherein the displacement platform is used to fix the first port of the optical fiber, the spectrometer is used to connect the second port of the optical fiber, and the control device is connected to the spectrometer and the displacement platform respectively; the light source emitting end and the first port of the optical fiber form an optical cavity, and the spectrometer detects and sends the longitudinal mode spacing of the optical cavity to the control device based on the light signal received from the light source emitting end. The control device controls the displacement platform to drive the first port of the optical fiber to move based on the longitudinal mode spacing, and adjusts the distance from the first port of the optical fiber to the light source emitting end. The present application can ensure that the contact measurement surface will not be damaged or contaminated while accurately controlling the micron-level displacement changes. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments or descriptions of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0038] Figure 1 This is a schematic diagram of a contactless displacement control system provided by an embodiment of the present application;

[0039] Figure 2 is a spectrum diagram of the spectrometer provided in an embodiment of the present application;

[0040] Figure 3 This is a schematic diagram of a contactless displacement control system provided by an embodiment of the present application;

[0041] Figure 4 This is a schematic diagram of a contactless displacement control system provided by an embodiment of the present application;

[0042] Figure 5 This is a flow chart of a contactless displacement control method provided in an embodiment of the present application. DETAILED DESCRIPTION

[0043] Among them, the accompanying drawings are only for illustrative purposes and represent only schematic diagrams rather than actual pictures, and should not be understood as limiting the present invention. In order to better illustrate the embodiments of the present invention, some parts of the accompanying drawings may be omitted, enlarged or reduced, and do not represent the dimensions of actual products. For those skilled in the art, it is understandable that some well-known structures and their descriptions may be omitted in the accompanying drawings.

[0044] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "left", "right", "front", "back", etc. indicating directions or positional relationships, they are based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operate in a specific direction. Therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting the present invention. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0045] The present application will be described more clearly below with reference to specific embodiments. The following embodiments will help those skilled in the art further understand the function of the present application, but are not intended to limit the present application in any form. It should be noted that those skilled in the art may make a number of modifications and improvements without departing from the concept of the present application. These all fall within the scope of protection of the present application.

[0046] In order to make the purpose, technical solutions and advantages of this application clearer, specific embodiments will be described below with reference to the accompanying drawings.

[0047] It should be understood that the size of the serial numbers of the steps in the above embodiments does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0048] See also Figure 1 The embodiment of the present application provides a contactless displacement control system 10, comprising a displacement platform 101, a spectrometer 102, and a control device 103. The system is applied to the displacement control of a light source emitting end 11 and a first port of an optical fiber 12 to be optically coupled.

[0049] The first port of the optical fiber 12 is fixed on the displacement platform 101, and the second port of the optical fiber 12 is connected to the spectrometer 102. The first port is the port of the optical fiber 12 that receives the optical signal emitted by the light source emitting end 11. The control device 103 is connected to the spectrometer 102 and the displacement platform 101 respectively.

[0050] The light source emitting end 11 and the first end of the optical fiber 12 form an optical cavity; the light signal emitted by the light source emitting end 11 is transmitted to the spectrometer 102 through the optical cavity and the optical fiber 12.

[0051] The spectrometer 102 is used to detect the longitudinal mode spacing of the optical cavity based on the received optical signal, and send the longitudinal mode spacing to the control device 103 .

[0052] The control device 103 is used to control the displacement platform 101 to drive the first end of the optical fiber 12 to move based on the longitudinal mode spacing, so as to adjust the distance between the first end of the optical fiber 12 and the light source emitting end 11 .

[0053] In some embodiments, the surface of the light source emitting end 11 is coated with a first reflective film, and the surface of the first end of the optical fiber 12 is coated with a second reflective film.

[0054] Exemplarily, the reflective film may be any one of the following: a metal reflective film, an all-dielectric reflective film, or a metal-dielectric reflective film, which is not limited here.

[0055] In some embodiments, the reflection coefficient of the first reflection film coated on the surface of the light source emitting end 11 may be in the range of 0.2-0.3, and the reflection coefficient of the second reflection film coated on the surface of the first port of the optical fiber 12 may be greater than or equal to 0.9.

[0056] Optionally, a first reflective film coated on the surface of the light source emitting end 11 and a second reflective film coated on the surface of the first port of the optical fiber 12 form a high-reflective film system. A high-reflective film is an optical element that reflects most or almost all of the incident light energy back. Coating an optical device with a film of a certain thickness such that the optical path difference between two beams of reflected light (or transmitted light) of equal intensity satisfies the interference enhancement and reduction conditions can improve the transmittance or reflectance of the optical device. A film that increases reflectivity (i.e., the optical path difference of reflected light) is a high-reflective film.

[0057] In some embodiments, the optical signal emitted by the light source emitting end 11 is reflected multiple times in the optical cavity to form multiple parallel emitted lights and reflected lights.

[0058] Optionally, the spectrometer 102 is connected to the second port of the optical fiber 12 and the control device 103 respectively. The spectrometer 102 receives the optical signal and detects the longitudinal mode spacing of the optical cavity, and transmits the longitudinal mode spacing to the control device 103 .

[0059] Optionally, the wavelength of the optical signal emitted by the light source emitting end 11 is a gain wavelength, and the wavelength range is 1530nm-1561nm.

[0060] In some embodiments, the gain wavelength range is fixed: the operating wavelength range of the C-band EDFA is 1530 nm to 1561 nm, and the operating wavelength range of the L-band EDFA is 1565 nm to 1625 nm.

[0061] Exemplarily, the light source transmitting end 11 transmits an optical signal with a wavelength of 1550 nm.

[0062] The light signal emitted by the light source 11 undergoes multiple reflections in the optical cavity, generating multiple parallel beams of emitted and reflected light. These parallel beams interfere with each other. A specific set of wavelengths, corresponding to the cavity length, is transmitted and reflected within the optical cavity, passing through the cavity and optical fiber 12 to the spectrometer 12. When resonance occurs, this set of light reaches its maximum intensity, generating a peak in the spectrometer 12. This light is considered the longitudinal mode of the optical cavity.

[0063] See also Figure 2 , Figure 2 This is a spectrum diagram of the spectrometer 102 provided in an embodiment of the present application. A light signal vibrates in an optical cavity, and the longitudinal modes that meet the resonant conditions are filtered out by the optical cavity. When the light signal is transmitted to the spectrometer 102, a spectrum appears. The prominent peaks represent the filtered light signals, and the peaks are separated by a uniform spacing Δλ.

[0064] In some scenarios, the light source emitting end 11 can be a laser emitter. The system is used to optically couple the laser emitter to the end of an optical fiber that receives a light beam. In other scenarios, the light source emitting end 11 can be the end of an optical fiber. The system is used to optically couple the end of one optical fiber (e.g., fiber A) that emits a light beam to the end of another optical fiber (e.g., fiber B) that receives a light beam. In this scenario, the light emitted by the laser emitter is transmitted through fiber A, and the end of fiber A that emits light serves as the light source emitting end.

[0065] In some embodiments, the control device 103 can compare the longitudinal mode spacing with a preset longitudinal mode spacing threshold. When the longitudinal mode spacing is less than the preset longitudinal mode spacing, the control device 103 controls the displacement platform 101 to drive the first end of the optical fiber 12 to move toward the light source emitting end 11 to shorten the distance from the first port of the optical fiber 12 to the light source emitting end 11.

[0066] In some embodiments, the longitudinal mode spacing and the distance from the first port of the optical fiber to the emitting end of the light source satisfy the following formula 4:

[0067] Because the light signal emitted by the light source transmitting end 11 is reflected multiple times in the optical cavity, multiple parallel emitted and reflected lights are formed, and the parallel light interferes. A set of specific wavelengths corresponding to the cavity length is transmitted and reflected in this optical cavity, and is transmitted to the spectrometer 12 through the optical cavity and optical fiber 12. Based on the principle of Fabry-Perot cavity resonance, in this case, the optical cavity length is inversely proportional to the longitudinal mode spacing on the spectrum. For example, taking an optical cavity with air as the medium as an example, when the light source wavelength is 1550nm and the optical cavity L spacing is 1mm, the spectrometer measures the longitudinal mode spacing to be 1.2nm; when the optical cavity L spacing is 0.9mm, the spectrometer measures the longitudinal mode spacing to be 1.3nm.

[0068] Through optical analysis, the above formula 4 can be derived. Specifically, formula 2 can be derived from formula 1, and formula 4 can be derived by combining formulas 2 and 3. Formula 4 shows that the optical cavity length is inversely proportional to the longitudinal mode spacing on the spectrum. That is, as the optical cavity length decreases, the longitudinal mode spacing increases, the distance between peaks increases, and the spectrum becomes sparse.

[0069] Wherein, Formula 1 is:

[0070] Formula 2 is:

[0071] Formula 3 is

[0072] Formula 4 is

[0073] Δλ represents the longitudinal mode spacing, λ is the wavelength of the light source, n is the refractive index of the medium, L is the distance from the first port of the optical fiber to the emitting end of the light source, c is the speed of light, and v is the frequency of light.

[0074] In one possible implementation, the control device 103 may be configured to calculate a preset longitudinal mode spacing threshold based on Formula 4 and an expected distance from the first port of the optical fiber 12 to the light source emitting end 11. The expected distance from the first port of the optical fiber 12 to the light source emitting end 11 may be an optimal distance from a bare fiber port of the optical fiber to the light source emitting end, and the preset longitudinal mode spacing threshold is calculated by substituting this distance value into Formula 4.

[0075] In another possible implementation, the control device 103 may also be configured to calculate a preset distance between the first port of the optical fiber 12 and the light source emitting end 11 based on Formula 4 and the longitudinal mode spacing received from the optical cavity. The distance between the first port of the optical fiber 12 and the light source emitting end 11 is calculated based on the longitudinal mode spacing of the optical cavity and Formula 4, and this distance is compared with an optimal distance between the bare fiber port of the optical fiber and the light source emitting end before proceeding to the next step.

[0076] In some embodiments, the step size of the translation stage controlling the distance between the transmitter and receiver should be no larger than 0.1 mm to prevent the step size from moving too quickly, potentially preventing the transmitter from colliding with the first port of the optical fiber before the alarm is activated. Furthermore, the spectrometer's resolution should be sufficiently low. Based on Formula 4, the spectrometer's wavelength resolution should be no less than 0.1 nm. The higher the spectrometer's wavelength resolution, the more accurately the longitudinal mode spacing of the optical cavity can be measured.

[0077] See also Figure 3 , the figure is a schematic diagram of a contactless displacement control system provided in an embodiment of the present application. Optionally, the contactless displacement control system 10 may further include an alarm device 104, which is connected to the control device 103.

[0078] In some embodiments, the alarm device 104 may include: a buzzer, an indicator light, etc. When the alarm condition is reached, the buzzer of the alarm device sounds, and the indicator light is always on or keeps flashing.

[0079] In one possible implementation, when the longitudinal mode spacing is greater than or equal to a preset longitudinal mode spacing threshold, the alarm device is controlled to sound an alarm.

[0080] In another possible implementation, when the distance between the first port of the optical fiber 12 and the light source emitting end 11 is less than or equal to a preset distance, the alarm is controlled to sound an alarm.

[0081] In some embodiments, the control device 103 can be Labview software on a computer, see Figure 4 The figure is a schematic diagram of a contactless displacement control system provided by an embodiment of the present application. The logical relationship therein is that the displacement platform 101, which is fixed to the first port of the optical fiber 12, is in the initial position. The wavelength of the light signal emitted by the light source emitting end 11 is the gain wavelength. The light signal is screened in the optical cavity, and a group of light with a wavelength matching the cavity length resonates. The wavelength of this group of light is called the longitudinal mode of the optical cavity. The first port of the optical fiber 12 receives the light signal and transmits it to the spectrometer 102. The spectrometer 102 detects and outputs the spacing of this group of longitudinal modes to the Labview software for judgment based on the preset value. For example, the preset longitudinal mode spacing is 1.35nm. If the longitudinal mode spacing is less than 1.35nm at this time, the cycle continues. The displacement platform 101 continues to move one step, and the optical cavity distance is shortened by one step. According to the formula, the longitudinal mode spacing increases accordingly. The spectrometer 102 outputs data, and the software makes a judgment, and this cycle repeats. Until the longitudinal mode spacing is greater than 1.35nm, the cycle ends, the displacement platform 101 fixed to the optical fiber 12 stops moving, and the alarm device 104 starts to alarm, at which point the process is considered complete.

[0082] In some embodiments, the staff controls the displacement platform 101 to reset, uses the light source emitting end 11 to provide a 1.55um light source, and when the optical cavity is in the air medium, the staff substitutes the "target optical cavity measurement distance" into formula 4 to calculate the corresponding "spectrometer longitudinal mode spacing", and then inputs this longitudinal mode spacing into the Labview software as the threshold of the longitudinal mode spacing to start the program. According to formula 4, as the electric displacement stage moves forward, the distance between the two ends of the optical cavity continues to decrease, that is, the distance between the light emitting end and the receiving end continues to close, and the peak longitudinal mode spacing Δλ of the optical signal measured by the spectrometer 102 continues to increase. Here, for example, the target optical cavity length is 0.9mm, and its corresponding longitudinal mode spacing Δλ is 1.35nm. The threshold longitudinal mode spacing Δλ is input into the Labview software as 1.35nm. The judgment logic is that when the longitudinal mode spacing Δλ is less than 1.35nm, the Labview software controls the displacement platform 101 to continue moving forward; when the longitudinal mode spacing Δλ is greater than 1.35nm, the Labview software controls the displacement platform 101 to stop moving forward, and the alarm device 104 starts to alarm. The relationship between the optical cavity measurement distance, the longitudinal mode spacing of the spectrometer, the status of the displacement platform and the alarm status is shown in Table 1.

[0083] Table 1

[0084] Optical cavity measurement distance Spectrometer longitudinal mode spacing Displacement platform status Alarm status 1.0mm 1.2nm near Quiet 0.92mm 1.3nm near Quiet 0.86mm 1.4nm stop Call the police

[0085] In some embodiments, based on the principle of Fabry-Perot cavity resonance, "tiny, difficult-to-identify displacement changes" are converted into "detectable changes in the longitudinal mode spacing of the optical signal," achieving precise control of micron-level displacement changes without contact and without damaging the surface. Based on the precise detection and control of micron-level displacement changes, the present invention uses LabVIEW software, a spectrometer, a displacement platform, and an alarm device to automatically control the device to reach a set distance and set a protective distance warning function, significantly saving manpower and improving R&D and production efficiency.

[0086] In order to make the purpose, technical solutions and advantages of the present invention more clear, specific embodiments will be described below with reference to the accompanying drawings.

[0087] Figure 5 This is a schematic flow chart of a contactless displacement control method provided by an embodiment of the present application, with reference to Figure 5 , the contactless displacement control method is described in detail as follows:

[0088] In step 201, a light source emitter sends out a light signal; the light signal passes through the optical cavity and the optical fiber and is transmitted to the spectrometer.

[0089] The wavelength of the optical signal emitted by the light source transmitting end is the gain wavelength, and the wavelength range is 1530nm-1561nm.

[0090] In some embodiments, the gain wavelength range is fixed: the operating wavelength range of the C-band EDFA is 1530 nm to 1561 nm, and the operating wavelength range of the L-band EDFA is 1565 nm to 1625 nm.

[0091] The surface of the light source's emitting end is coated with a first reflective film, and the surface of the first end of the optical fiber is coated with a second reflective film. The first reflective film has a reflection coefficient in the range of 0.2-0.3, and the second reflective film has a reflection coefficient greater than or equal to 0.9. The reflective film may be a metal reflective film, an all-dielectric reflective film, or a metal-dielectric reflective film.

[0092] The light source emitting end and the first port of the optical fiber form an optical cavity. The light signal emitted by the light source emitting end is reflected multiple times in the optical cavity to form multiple parallel emitted lights and reflected lights.

[0093] In step 202, after receiving the optical signal transmitted by the optical fiber, the spectrometer detects the longitudinal mode spacing of the optical cavity and sends the longitudinal mode spacing to the control device.

[0094] The longitudinal mode spacing and the distance from the first port of the optical fiber to the emission end of the light source satisfy the first formula, where the first formula is:

[0095]

[0096] Wherein, Δλ represents the longitudinal mode spacing, λ is the wavelength of the light source, n is the refractive index of the medium, and L is the distance from the first port of the optical fiber to the emitting end of the light source.

[0097] In some embodiments, the longitudinal mode spacing and the distance from the first port of the optical fiber to the emitting end of the light source satisfy the following formula 4: Formula 4 above derives from Formula 1 to Formula 2, and Formula 4 is obtained by combining Formula 2 and Formula 3. Formula 4 shows that the optical cavity length is inversely proportional to the longitudinal mode spacing on the spectrum, that is, as the optical cavity length decreases, the longitudinal mode spacing becomes longer, the distance between peaks becomes larger, and the spectrum becomes sparser.

[0098] Wherein, Formula 1 is:

[0099] Formula 2 is:

[0100] Formula 3 is

[0101] Formula 4 is

[0102] Δλ represents the longitudinal mode spacing, λ is the wavelength of the light source, n is the refractive index of the medium, L is the distance from the first port of the optical fiber to the emitting end of the light source, c is the speed of light, and v is the frequency of light.

[0103] Optionally, the control device is further configured to calculate the preset longitudinal mode spacing threshold based on the first formula and the expected distance from the first port of the optical fiber to the emission end of the light source.

[0104] Optionally, the control device is further configured to calculate the preset distance from the first port of the optical fiber to the emission end of the light source based on the first formula and the received longitudinal mode spacing of the optical cavity.

[0105] In step 203, the control device controls the displacement platform to drive the first port of the optical fiber to move to adjust the distance from the first port of the optical fiber to the emission end of the light source according to the longitudinal mode spacing.

[0106] Optionally, the control device is further configured to calculate the preset longitudinal mode spacing threshold based on the first formula and the expected distance from the first port of the optical fiber to the emission end of the light source. The control device compares the longitudinal mode spacing with the preset longitudinal mode spacing threshold, and when the longitudinal mode spacing is less than the preset longitudinal mode spacing, the control device controls the displacement platform to drive the first port of the optical fiber to move towards the emission end of the light source to reduce the distance from the first port of the optical fiber to the emission end of the light source.

[0107] Optionally, the control device can be a Labview software on a computer. Labview is a program development environment, which uses graphical editing language G to write programs, and the generated program is in the form of block diagram.

[0108] Optionally, the control device is further configured to calculate the preset distance from the first port of the optical fiber to the emission end of the light source based on the first formula and the received longitudinal mode spacing of the optical cavity, and when the distance from the first port of the optical fiber to the emission end of the light source is less than the preset distance, the control device controls the displacement platform to drive the first port of the optical fiber to move towards the emission end of the light source to reduce the distance from the first port of the optical fiber to the emission end of the light source.

[0109] In some embodiments, the step distance of the displacement platform for controlling the distance between the emission end and the receiving end should be not greater than 0.1 mm, so as to prevent the alarm from not being able to alarm in time when the emission end collides with the first port of the optical fiber due to too fast step distance movement; secondly, the resolution of the spectrometer should be low enough, and according to the inverse deduction of formula 4, it is obtained that the wavelength resolution of the spectrometer should be not less than 0.1 nm.

[0110] Compared with the prior art, the present application has the following beneficial effects:

[0111] The present application is applicable to the field of optical coupling technology and provides a contactless displacement control system and displacement control method. The system includes: a displacement platform, a spectrometer, and a control device. The system is used to control the displacement of the light source emitting end and the first port of the optical fiber to be optically coupled, wherein the displacement platform is used to fix the first port of the optical fiber, the spectrometer is used to connect the second port of the optical fiber, and the control device is connected to the spectrometer and the displacement platform respectively; the light source emitting end and the first port of the optical fiber form an optical cavity, and the spectrometer detects and sends the longitudinal mode spacing of the optical cavity to the control device based on the light signal received from the light source emitting end. The control device controls the displacement platform to drive the first port of the optical fiber to move based on the longitudinal mode spacing, and adjusts the distance from the first port of the optical fiber to the light source emitting end. The present application can ensure that the contact measurement surface will not be damaged or contaminated while accurately controlling the micron-level displacement changes.

[0112] The embodiments described above are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention, and should all be included in the scope of protection of the present invention.

Claims

1. A contactless displacement control system, characterized in that: Applicable to displacement control of a light source emission end and a first port of an optical fiber to be optically coupled, the displacement control system comprising: a displacement platform, a spectrometer and a control device; The displacement platform is used to fix the first port of the optical fiber, and the spectrometer is used to connect to the second port of the optical fiber, wherein the first port is the port of the optical fiber that receives the light signal emitted by the light source emission end; the control device is connected to the spectrometer and the displacement platform respectively; The light source emitting end and the first port of the optical fiber form an optical cavity; the light signal emitted by the light source emitting end is transmitted to the spectrometer through the optical cavity and the optical fiber; The spectrometer is used to detect the longitudinal mode spacing of the optical cavity based on the received optical signal and send the longitudinal mode spacing to the control device; The control device is used to control the displacement platform to drive the first port of the optical fiber to move based on the longitudinal mode spacing and a first formula satisfied by the longitudinal mode spacing and the distance from the first port of the optical fiber to the light source emission end, so as to adjust the distance from the first port of the optical fiber to the light source emission end; Among them, the first formula is ; represents the longitudinal mode spacing, is the wavelength of the light source, is the refractive index of the medium, is the distance from the first port of the optical fiber to the emitting end of the light source.

2. The contactless displacement control system according to claim 1, characterized in that: The surface of the light source emission end is coated with a first reflective film, and the surface of the first end of the optical fiber is coated with a second reflective film.

3. The contactless displacement control system according to claim 2, characterized in that: The reflection coefficient of the first reflection film is in the range of 0.2-0.3, and the reflection coefficient of the second reflection film is greater than or equal to 0.

9.

4. The contactless displacement control system according to claim 1, characterized in that: The optical signal emitted by the light source emission end is reflected multiple times in the optical cavity to form multiple parallel emission lights and reflected lights.

5. The contactless displacement control system according to claim 1, characterized in that: The wavelength of the optical signal emitted by the light source transmitting end is the gain wavelength, and the wavelength range is 1530nm-1561nm.

6. The contactless displacement control system according to claim 1, characterized in that: The control device is specifically used for: The longitudinal mode spacing is compared with a preset longitudinal mode spacing threshold. When the longitudinal mode spacing is less than the preset longitudinal mode spacing, the displacement platform is controlled to drive the first port of the optical fiber to move toward the direction close to the light source emission end, so as to shorten the distance from the first port of the optical fiber to the light source emission end.

7. The contactless displacement control system according to claim 6, characterized in that: The control device is further configured to calculate a preset longitudinal mode spacing threshold based on the first formula and an expected distance from the first port of the optical fiber to the emission end of the light source.

8. The contactless displacement control system according to claim 6, characterized in that: Also includes an alarm device; The alarm device is used to control the alarm device to alarm when the longitudinal mold spacing is greater than or equal to the preset longitudinal mold spacing threshold.

9. The contactless displacement control system according to claim 7, characterized in that: When the displacement platform is located at an initial position, the initial distance from the first port of the optical fiber to the emitting end of the light source is greater than the expected distance; The displacement platform drives the first port of the optical fiber to move one step each time; The displacement platform drives the first port of the optical fiber to move in a step length of less than or equal to 0.1 mm; The wavelength resolution of the spectrometer is greater than or equal to 0.1 nm.

10. A contactless displacement control method, characterized in that: The method is based on the contactless displacement control system according to any one of claims 1 to 9, and the method comprises: The light source emits a light signal; the light signal passes through the optical cavity and the optical fiber and is transmitted to the spectrometer; After receiving the optical signal transmitted by the optical fiber, the spectrometer detects the longitudinal mode spacing of the optical cavity and sends the longitudinal mode spacing to the control device; The control device controls the displacement platform to drive the first port of the optical fiber to move according to the longitudinal mode spacing and a first formula satisfied by the longitudinal mode spacing and the distance from the first port of the optical fiber to the light source emission end, so as to adjust the distance from the first port of the optical fiber to the light source emission end; Among them, the first formula is ; represents the longitudinal mode spacing, is the wavelength of the light source, is the refractive index of the medium, is the distance from the first port of the optical fiber to the emitting end of the light source.

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