Optical fiber online optical path switching system

Abstract

The invention discloses an optical fiber online optical path switching system which is characterized by comprising a spectrograph and an integrating sphere connected with the spectrograph, the integrating sphere is connected with a one-to-many optical fiber and a light source single-core optical fiber isolated from the one-to-many optical fiber, and a light source switching module is arranged between the one-to-many optical fiber and the light source single-core optical fiber. The light source switching module comprises a first collimating mirror arranged corresponding to the light source single-core optical fiber, a spectroscope located at the rear end of the first collimating mirror and a hollow retroreflection assembly located on the side, away from the first collimating mirror, of the spectroscope, and the hollow retroreflection assembly is used for returning light transmitted by the spectroscope along the same path. And the light is reflected by the spectroscope to enter the one-to-many optical fiber. Mechanical switching errors can be eliminated fundamentally, optical signals are homogenized, the signal-to-noise ratio is improved, the structure is compact, and integration is easy.

Description

Technical Field

[0001] This invention relates to the field of optical detection and spectral analysis, specifically to an online optical path switching system for optical fibers. Background Technology

[0002] Near-infrared spectroscopy, due to its advantages of speed and non-destructive testing, is widely used in online detection and quality monitoring in fields such as chemical engineering, agriculture, and pharmaceuticals. In practical applications, it is often necessary to simultaneously perform rapid, alternating measurements on multiple sampling points or various reference samples, requiring the spectrometer to have multi-path switching capabilities. Traditional multi-path switching schemes mainly rely on motor-driven mirrors or fiber optic switchers. However, these existing schemes have inherent drawbacks. Due to the unavoidable backlash, hysteresis error, and slight angular deviations inherent in the reciprocating motion of the motor, the mirror's attitude (tilt, deflection) cannot be completely reproduced after each switch, introducing optical path collimation errors and severely affecting the consistency and accuracy of measurements. Furthermore, the long-term wear of mechanical moving parts exacerbates these errors, reducing the system's long-term stability and increasing maintenance costs. In direct detection, uneven energy distribution or slight positional changes in the light spot can also cause signal fluctuations received by the detector, reducing the signal-to-noise ratio.

[0003] Therefore, there is an urgent need in this field for a highly stable multi-path switching scheme that can eliminate mechanical switching errors, ensure permanent collimation of the optical path, and effectively homogenize the optical signal. Summary of the Invention

[0004] To overcome the deficiencies in the prior art, embodiments of the present invention provide an online optical path switching system for solving one or more of the above-mentioned problems.

[0005] This application discloses an online optical path switching system for optical fibers, including a spectrometer, an integrating sphere connected to the spectrometer, an integrating sphere connected to a multi-fiber optical fiber, a single-core optical fiber for a light source isolated from the multi-fiber optical fiber, and a light source switching module disposed between the multi-fiber optical fiber and the single-core optical fiber for the light source. The light source switching module includes a first collimating lens corresponding to the single-core optical fiber for the light source, a beam splitter located at the rear end of the first collimator, and a hollow retroreflection assembly located on the side of the beam splitter away from the first collimating lens. The hollow retroreflection assembly is used to return the light transmitted through the beam splitter along its original path, and the light is reflected by the beam splitter into the multi-fiber optical fiber.

[0006] Furthermore, it includes a plurality of single-core optical fibers of the light source, which are arranged around the circumference of the light source switching module, and each single-core optical fiber of the light source has a corresponding first collimating lens in the light source switching module.

[0007] Furthermore, it also includes a second collimating lens, which has an input end located on the side of the multi-optical fiber away from the integrating sphere. The second collimating lens is disposed between each input end and the corresponding beam splitter. The second collimating lens is used to couple the light reflected by the beam splitter into the input end.

[0008] Furthermore, the beam splitter is configured to transmit the light from the single-core optical fiber of the light source to the hollow retroreflection assembly, and reflect the light reflected from the hollow retroreflection assembly to the second collimating lens.

[0009] Furthermore, the first collimating lens faces the single-core optical fiber of the light source, and the second collimating lens faces the light-inlet end of the multi-fiber optic cable.

[0010] Furthermore, the hollow retroreflector assembly includes a motor and a hollow retroreflector connected to the motor. The motor can drive the hollow retroreflector to rotate and shift, so as to adjust the alignment of the hollow retroreflector with the beam splitter.

[0011] Furthermore, it also includes a connecting single-core optical fiber, the two ends of which are respectively connected to the spectrometer and the integrating sphere, and the connecting single-core optical fiber is used to transmit the homogenized light in the integrating sphere to the spectrometer.

[0012] Furthermore, the single-core optical fiber of the light source includes a sample light single-core optical fiber and a near-infrared light source for irradiating the sample. The near-infrared light source irradiates the sample to form information-carrying sample light, which enters the sample light single-core optical fiber and is directed by the sample light single-core optical fiber to the first collimating lens.

[0013] Furthermore, the beam splitter is configured to transmit the light from the single-core optical fiber of the light source to the hollow retroreflection assembly, and reflect the light reflected from the hollow retroreflection assembly to the second collimating lens.

[0014] Furthermore, the hollow retroreflector has a cornerstone prism or a cat's-eye structure inside.

[0015] The beneficial effects of this invention are as follows: 1. It can fundamentally eliminate mechanical switching errors. Due to the "self-collimation" characteristic of the hollow retroreflector, even if there is a tiny angular clearance in the motor switching, the reflected light path will always remain strictly parallel to the incident light path, with only a slight parallel shift possible, without causing tilting. This is crucial for optical systems that rely on collimation, ensuring extremely high repeatability of the light path after each switch.

[0016] 2. It homogenizes the optical signal and improves the signal-to-noise ratio. The use of an integrating sphere forms a uniform Lambertian light source after multiple reflections of the non-uniform incident light within the sphere, eliminating the influence of light spot shape and energy distribution fluctuations on the detector, and significantly improving the stability and signal-to-noise ratio of the measurement.

[0017] 3. The system has extremely high stability and reliability. Combining the anti-interference characteristics of the hollow retroreflector with the homogenization advantage of the integrating sphere, the entire system is insensitive to mechanical vibration, motor repeatability errors, etc., and the long-term stability and reliability are greatly improved, reducing maintenance requirements.

[0018] 4. The structure is compact and easy to integrate. The optical module is connected by optical fiber, which realizes the physical separation and flexible layout of the light source, detector and switching module, making it easy to integrate into complex industrial online detection environments.

[0019] To make the above and other objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the structure of an online optical path switching system for optical fibers according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the optical path of an online optical path switching system for optical fibers according to an embodiment of the present invention; The reference numerals in the above figures are as follows: 1. Spectrometer; 2. Integrating sphere; 3. One-to-many fiber; 31. Light input end; 4. Single-core fiber for light source; 41. Single-core fiber for sample light; 5. Light source switching module; 51. First collimating lens; 52. Beam splitter; 53. Hollow retroreflector assembly; 531. Motor; 32. Hollow retroreflector; 6. Second collimating lens; 7. Connecting single-core fiber. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] like Figures 1 to 2 As shown in this embodiment, an online optical path switching system for optical fibers includes a spectrometer 1 and an integrating sphere 2 connected to the spectrometer 1. The spectrometer 1 is used to receive and analyze optical signals, and the integrating sphere 2 is used to homogenize sample light from different optical paths, eliminating spatial inhomogeneities. The integrating sphere 2 is connected to a multi-fiber 3 and a single-core optical fiber 4 for the light source, which is isolated from the multi-fiber 3. A light source switching module 5 is provided between the multi-fiber 3 and the single-core optical fiber 4, i.e., one end of the multi-fiber 3 is connected to the integrating sphere 2, and the other end is adjacent to the light source switching module 5. The light source switching module 5 includes a first collimating lens 51 corresponding to the single-core optical fiber 4 of the light source. The first collimating lens 51 is used to collimate the light from the single-core optical fiber 4 into parallel light. A beam splitter 52 is located at the rear end of the first collimator, and a hollow retroreflection assembly 53 is located on the side of the beam splitter 52 away from the first collimating lens 51. The beam splitter 52 is used to partially reflect or transmit the incident parallel light (according to the design), with one beam pointing towards the hollow retroreflection assembly 53. The hollow retroreflection assembly 53 is used to return the light transmitted through the beam splitter 52 along its original path, and this light is reflected by the beam splitter 52 into the multi-fiber 3.

[0024] Specifically, the light source includes multiple single-core optical fibers 4, which are arranged around the light source switching module 5 in the circumferential direction, so that each single-core optical fiber 4 can emit corresponding sample light with information. Each single-core optical fiber 4 has a corresponding first collimating lens 51 in the light source switching module 5, so that the sample light with information emitted by each single-core optical fiber 4 can be collimated into parallel light by the corresponding first collimating lens 51.

[0025] Specifically, it also includes a second collimating lens 6, which has an input end 31 on the side of the multi-fiber 3 away from the integrating sphere 2. Each input end 31 and the corresponding beam splitter 52 are provided with a second collimating lens 6. The second collimating lens 6 is used to couple the light reflected by the beam splitter 52 into the input end 31. That is, the second collimator can couple the light signal that returns through the hollow retroreflection component 53 and passes through the beam splitter 52 again back to the multi-fiber 3.

[0026] Specifically, the beam splitter 52 is configured to transmit the light from the single-core optical fiber 4 of the light source to the hollow retroreflection assembly 53, and reflect the light reflected from the hollow retroreflection assembly 53 to the second collimating lens 6. Preferably, the beam splitter 52 is a 50 / 50 beam splitter 52.

[0027] Specifically, the first collimating lens 51 faces the single-core optical fiber 4 of the light source, thereby enabling the first collimating lens 51 to have a good collimation effect on the light from the single-core optical fiber 4 of the light source. The second collimating lens 6 faces the light input end 31 of the multi-fiber 3, thereby enabling the second collimating lens 6 to better couple the light from the beam splitter 52 to the light input end 31 of the multi-fiber 3.

[0028] Specifically, the hollow retroreflector assembly 53 includes a motor 531 and a hollow retroreflector 532 connected to the motor 531. The motor 531 can drive the hollow retroreflector 532 to rotate and shift, thereby adjusting the alignment of the hollow retroreflector 532 with the beam splitter 52. The optical characteristic of the hollow retroreflector 532 is that, regardless of the angle at which the incident light enters, its outgoing light is strictly parallel to the incident light and exits in the opposite direction, i.e., it possesses "self-collimation" or "permanent collimation" characteristics. Multiple hollow retroreflectors 532 can be integrated into one hollow retroreflector assembly 53, driven by the motor 531 to rotate or move linearly, in order to select different optical path channels. The motor 531 is preferably a high-precision stepper motor 531 or a servo motor 531.

[0029] Specifically, it also includes a connecting single-core optical fiber 7, the two ends of which are connected to the spectrometer 1 and the integrating sphere 2, respectively. The connecting single-core optical fiber 7 is used to transmit the homogenized light in the integrating sphere 2 to the spectrometer 1.

[0030] Specifically, the light source single-core fiber 4 includes a sample light single-core fiber 41 and a near-infrared light source for irradiating the sample. The near-infrared light source irradiates the sample to form information-carrying sample light. The information-carrying sample light enters the sample light single-core fiber 41 and is directed by the sample light single-core fiber 41 to the first collimating lens 51.

[0031] Specifically, the beam splitter 52 is configured to transmit the light from the single-core optical fiber 4 of the light source to the hollow retroreflection assembly 53, and reflect the light reflected from the hollow retroreflection assembly 53 to the second collimating lens 6.

[0032] Specifically, the hollow retroreflector 532 has a cornerstone prism or a cat's eye structure inside, where the cat's eye structure refers to a structure composed of a lens and a plane mirror.

[0033] In this embodiment, a near-infrared light source (not shown in the figure, integrated in the "illumination" section or introduced through an optical fiber) illuminates the sample, generating "information-carrying sample light." This information-carrying sample light enters the sample light single-core optical fiber 41 and is directed by the sample light single-core optical fiber 41 to the first collimating lens 51. The first collimating lens 51 collimates the light into parallel light, which is then incident on a beam splitter 52 (e.g., a 50 / 50 beam splitter 52). Part of the light is transmitted through the beam splitter 52 and incident on a hollow retroreflector 532. The hollow retroreflector 532 can be moved and rotated under the action of a motor 531 to adapt to the corresponding optical path. The hollow retroreflector 532 accurately returns the light along the original path, and the light is reflected by the beam splitter 52 into a second collimating lens 6. The second collimating lens 6 couples the light and sends it into the light input end 31 of the multi-fiber 3.

[0034] Light entering the fiber 3 through the input end 31 of the multi-fiber 3 enters the integrating sphere 2. The size and inner coating of the integrating sphere 2 can be optimized according to the sensitivity of the near-infrared band. Inside the integrating sphere 2, the light is fully homogenized, forming a uniform diffuse reflection light source. The homogenized light is then guided to the spectrometer 1 for detection and analysis through the connecting single-core fiber 7 at the outlet of the integrating sphere 2.

[0035] When it is necessary to switch sampling points, motor 531 rotates according to the command, moving the hollow retroreflector 532 of another channel to the predetermined working position. Due to the self-collimation characteristics of the hollow retroreflector 532, even if there is a micron-level angular error in the positioning of motor 531, the direction of the returned beam remains unchanged, thus ensuring a high degree of consistency in optical path collimation between different channels.

[0036] With the above structure, this solution has the following advantages: 1. Mechanical switching errors can be fundamentally eliminated. Due to the "self-collimation" characteristic of the hollow retroreflector 532, even if there is a tiny angular clearance during the switching of the motor 531, the reflected light path will always remain strictly parallel to the incident light path, with only a slight parallel offset possible, without causing tilting. This is crucial for optical systems that rely on collimation, ensuring extremely high repeatability of the light path after each switch.

[0037] 2. It homogenizes the optical signal and improves the signal-to-noise ratio. The use of integrating sphere 2 forms a uniform Lambertian light source after multiple reflections of the non-uniform incident light inside the sphere, eliminating the influence of light spot shape and energy distribution fluctuations on the detector, and significantly improving the stability and signal-to-noise ratio of the measurement.

[0038] 3. The system has extremely high stability and reliability. Combining the anti-interference characteristics of the hollow retroreflector 532 and the homogenization advantages of the integrating sphere 2, the entire system is not sensitive to mechanical vibration, repeatability error of motor 531, etc., and the long-term stability and reliability are greatly improved, reducing maintenance requirements.

[0039] 4. The structure is compact and easy to integrate. The optical module is connected by optical fiber, which realizes the physical separation and flexible layout of the light source, detector and switching module, making it easy to integrate into complex industrial online detection environments.

[0040] Specific embodiments have been used to illustrate the principles and implementation methods of this invention. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of this invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this invention. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. An online optical path switching system for optical fibers, characterized in that, The device includes a spectrometer, an integrating sphere connected to the spectrometer, an integrating sphere connected to a multi-fiber optic cable, a single-core fiber optic cable for a light source isolated from the multi-fiber optic cable, and a light source switching module between the multi-fiber optic cable and the single-core fiber optic cable. The light source switching module includes a first collimating lens corresponding to the single-core fiber optic cable, a beam splitter located at the rear end of the first collimator, and a hollow retroreflection assembly located on the side of the beam splitter away from the first collimating lens. The hollow retroreflection assembly is used to return the light transmitted through the beam splitter along its original path, and the light is reflected by the beam splitter into the multi-fiber optic cable.

2. The fiber optic online optical path switching system according to claim 1, characterized in that, It includes multiple single-core optical fibers of the light source, which are arranged around the circumference of the light source switching module. Each single-core optical fiber of the light source has a corresponding first collimating lens in the light source switching module.

3. The fiber optic online optical path switching system according to claim 1, characterized in that, It also includes a second collimating lens, which has an input end located on the side of the multi-optical fiber away from the integrating sphere. Each input end and the corresponding beam splitter are provided with the second collimating lens. The second collimating lens is used to couple the light reflected by the beam splitter into the input end.

4. The fiber optic online optical path switching system according to claim 3, characterized in that, The beam splitter is configured to transmit light from the single-core optical fiber of the light source to the hollow retroreflection assembly, and reflect the light reflected from the hollow retroreflection assembly to the second collimating lens.

5. The fiber optic online optical path switching system according to claim 3, characterized in that, The first collimating lens faces the single-core optical fiber of the light source, and the second collimating lens faces the light-inlet end of the multi-fiber optic cable.

6. The fiber optic online optical path switching system according to claim 1, characterized in that, The hollow retroreflector assembly includes a motor and a hollow retroreflector connected to the motor. The motor can drive the hollow retroreflector to rotate and shift, so as to adjust the alignment of the hollow retroreflector with the beam splitter.

7. The fiber optic online optical path switching system according to claim 1, characterized in that, It also includes a connecting single-core optical fiber, the two ends of which are connected to the spectrometer and the integrating sphere, respectively. The connecting single-core optical fiber is used to transmit the homogenized light in the integrating sphere to the spectrometer.

8. The fiber optic online optical path switching system according to claim 1, characterized in that, The single-core optical fiber of the light source includes a sample light single-core optical fiber and a near-infrared light source for irradiating the sample. The near-infrared light source irradiates the sample to form sample light with information. The sample light with information enters the sample light single-core optical fiber and is directed by the sample light single-core optical fiber to the first collimating lens.

9. The fiber optic online optical path switching system according to claim 1, characterized in that, The beam splitter is configured to transmit light from the single-core optical fiber of the light source to the hollow retroreflection assembly, and reflect the light reflected from the hollow retroreflection assembly to the second collimating lens.

10. The fiber optic online optical path switching system according to claim 1, characterized in that, The hollow retroreflector has a cornerstone prism or a cat's eye structure inside.

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