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CN-121995642-A - 90-Degree turning and shaping method and device for sensing optical signals

CN121995642ACN 121995642 ACN121995642 ACN 121995642ACN-121995642-A

Abstract

A90-degree turning and shaping method and device for a sensing optical signal belong to the technical field of optical fiber pressure sensing. The method of the invention forms the light path turning reflecting surface by beveling and plating the high reflecting film on the end surface of the transmission optical fiber, replaces the traditional discrete prism, combines the optical function of the lens group by integrating the turning function of the end surface of the optical fiber, simultaneously solves the problems of the size bottleneck of the discrete prism and the bending loss of the all-optical fiber structure, and realizes the reliable measurement of the pressure of the closed space while ensuring the long-term stability and the signal integrity of the optical system. The device mainly comprises a transmission optical fiber, a packaging shell, a shaping lens and a pressure sensitive structure, wherein an inclined plane reflecting structure is processed at the end part of the transmission optical fiber, which is positioned in the probe, the packaging shell is used for accommodating and fixing an optical component, and the shaping lens is fixedly arranged in an optical path in the packaging shell. The invention can remarkably improve the compactness of the optical fiber pressure sensor structure.

Inventors

  • YANG WEIGUANG
  • WANG LI
  • ZHANG XINYING
  • SUI GUANGHUI

Assignees

  • 中国航空工业集团公司北京长城计量测试技术研究所

Dates

Publication Date
20260508
Application Date
20251218

Claims (10)

  1. 1. A90-degree turning and shaping method for sensing optical signals is characterized in that a high-reflection film is processed and plated on the end face of a transmission optical fiber in a beveling mode to form an optical path turning and reflecting face, a shaping lens group is formed instead of a traditional discrete prism, the radial diameter of a probe is optimized to be less than 1.5mm, a bending channel with the inner diameter being more than or equal to 1.8mm can be adapted, the optical surface of the light emitting side of the shaping lens group and a pressure sensitive film directly form a Fabry-Perot interference cavity, the lens group has dual functions of beam shaping and interference sensing, and pressure measurement of a closed space is achieved.
  2. 2. A90-degree turning and shaping device for sensing optical signals is used for realizing the 90-degree turning and shaping method for sensing optical signals according to claim 1, and is characterized by mainly comprising a transmission optical fiber (1), a packaging shell (2), a shaping lens (5) and a pressure sensitive structure (7), wherein an inclined plane reflecting structure is processed at the end part of the transmission optical fiber (1) positioned in a probe, the packaging shell (2) is used for accommodating and fixing an optical component, the shaping lens (5) is fixedly arranged in an optical path in the packaging shell (2), the pressure sensitive structure (7) comprises a pressure sensitive membrane (6) and is arranged opposite to the optical surface of the shaping lens (5), the inclined plane reflecting structure turns an incident optical path by 90 degrees and guides the incident optical path to the shaping lens (5), and an FP interference cavity is formed by the light-emitting side surface of the shaping lens (5) and the pressure sensitive membrane (6).
  3. 3. The 90-degree turning and shaping device for sensing optical signals is characterized in that the end inclined plane of the transmission optical fiber (1) is preferably a 45-degree inclined plane, and the surface of the end inclined plane is plated with a metal or medium high-reflection film for turning an optical path.
  4. 4. The 90-degree refraction and shaping device for sensing optical signals according to claim 2, wherein the shaping lens (5) set is preferably an aspheric lens or a double-cemented lens set formed by positive and negative lenses, so as to effectively correct aberration introduced by oblique refraction and ensure good parallelism and spot uniformity of output beams.
  5. 5. A 90-degree turn-around shaping device for sensing optical signals according to claim 2, characterized in that the light-exit side optical surface of the shaping lens (5) set is used as a fixed reflecting surface of the FP interferometer cavity, which surface is coated with a partially reflecting film to form an optimized FP interferometer cavity structure with the pressure sensitive membrane (6).
  6. 6. The 90-degree turning and shaping device for sensing optical signals according to claim 2, wherein the transmission optical fiber (1), the shaping lens (5) set and the pressure sensitive membrane (6) are integrally fixed through a high-precision packaging shell (2) so as to ensure the stability of the relative positions of optical elements.
  7. 7. The 90-degree turn shaping device for sensing optical signals according to claim 2, wherein a fixed groove structure (4) for precisely positioning the shaping lens (5) is arranged in the packaging shell (2).
  8. 8. The 90-degree turning and shaping device for sensing optical signals according to claim 2, wherein the pressure sensitive structure (7) is in sealing connection with the packaging shell (2) through high-temperature glue.
  9. 9. The 90-degree turn shaping device for sensing optical signals according to claim 2, wherein the transmission optical fiber (1), the shaping lens (5) and the pressure sensitive structure (7) are sequentially arranged in the packaging shell (2) along the optical path direction to form an integrated sensing probe structure.
  10. 10. A90-degree turning and shaping device for sensing optical signals according to claim 2, wherein the relative positional relationship among the inclined plane reflecting structure, the shaping lens (5) and the pressure sensitive structure (7) enables the optical signals to vertically enter the pressure sensitive membrane (6) after turning and shaping.

Description

90-Degree turning and shaping method and device for sensing optical signals Technical Field The invention relates to a shaping method and device for sensing optical signal deflection, in particular to an optical fiber pressure sensor structure for optical signal deflection of 90 degrees, and belongs to the technical field of optical fiber pressure sensing. Background The optical fiber Fabry-Perot (FP) pressure sensor is an optical fiber sensor for pressure measurement by utilizing an FP interference principle, and the working principle is that an optical signal forms interference after two reflections in a sensor cavity, when external pressure acts on the sensor, the change of the cavity length causes the change of wavelength, and the size of the pressure signal can be calculated. The technical characteristics of the optical fiber FP pressure sensor include high sensitivity, capability of detecting tiny pressure change, good temperature compensation performance and excellent electromagnetic interference resistance. In the current optical fiber FP pressure sensing technology, the application of the technology in a narrow space is significantly limited by the physical dimensions of the technology itself, whether the technology is of the diaphragm type or the all-optical fiber type. When the optical fiber is measured in a narrow space, the optical fiber is often bent and wired to reduce the volume of the sensor, but the problems of sharp attenuation of energy of transmitted light signals, reduction of signal to noise ratio of a system and the like are caused, the membrane type structure is limited by a packaging unit of the membrane type structure, the radial and axial dimensions of the membrane type structure are difficult to be further reduced under the existing process, and the problems caused by the contradiction between the dimensions and the performances directly affect the reliability, the measurement precision and the universality of a sensing system, so that the optical fiber FP pressure sensor is a key common bottleneck for limiting the realization of large-scale industrial application of the optical fiber FP pressure sensor in high-end miniaturized equipment and a closed space. At present, researchers have developed the research on microminiaturization of an optical fiber FP pressure sensor, wang Ruinan et al propose a Fabry-Perot optical fiber pressure sensor based on MEMS micro-nano processing technology, a mode of directly bonding a sensitive diaphragm and a glass substrate is adopted to form a micrometer scale FP cavity, vertical alignment insertion of a single-mode optical fiber is realized in a through hole of the glass substrate, an interference cavity is directly formed by the end face of the optical fiber and the inner surface of the diaphragm, but the structure cannot meet the measurement requirement in a narrow space, and large-angle bending can lead to rapid increase of the energy loss of optical fiber transmission and decrease of demodulation precision. The application number CN201910880584 proposes a miniature diaphragm type optical fiber end FP pressure sensor, which is characterized in that an optical fiber and a hollow tubular structure with the same diameter as the optical fiber are welded together, and then a pressure sensitive diaphragm with the same diameter as the optical fiber is fixed on the other end face of the hollow tube. Sun Xiaojie et al propose a fiber optical path deflection sensing probe based on a prism and a collimator lens, where a transmission fiber is placed close to the collimator lens, and then the collimated optical signal is deflected by the prism, so that deflection of the optical path is realized while avoiding bending of the fiber, however, the right-angle prism itself has a non-negligible volume, and the two-way fiber must maintain a sufficient lateral spacing to accommodate the prism structure, which directly limits compression of the radial dimension of the probe. In addition, the complex assembly relationship between the prism and the two paths of collimating lens groups not only increases the structural size, but also introduces the risk of alignment errors, which is unfavorable for deployment and stable application in extremely narrow space. In the prior art, in order to realize pressure measurement in a narrow space, two technical routes mainly exist, and an inherent bottleneck exists, namely, firstly, a scheme for realizing light path turning based on a discrete prism is limited by the physical size (usually the side length is more than or equal to 1 mm) of the prism and the minimum installation distance of side-by-side optical fibers, and the radial diameter of a probe is difficult to be compressed to be less than 3mm, so that the probe cannot be radially placed in an extremely narrow space with the inner diameter less than or equal to 2 mm. Secondly, in order to avoid the size limitation, an all-fiber structure in which a capillary tube and a tr