All-fiber F-P array integrated three-coordinate probe

Abstract

The application relates to the technical field of measurement, and discloses a full-optical-fiber F-P array integrated three-coordinate measuring head which comprises a measuring rod and a reflecting sleeve, a central through hole is arranged in the middle of the measuring rod along the axial direction of the measuring rod, a flat-end-face optical fiber is arranged in the central through hole, a plurality of grooves are circumferentially arranged on the outer side wall of the measuring rod, the grooves are arranged along the axial direction of the measuring rod, and an inclined-angle optical fiber is fixedly arranged in the grooves; the reflecting sleeve is arranged on the outer side of the measuring rod, a flat-reflection end face is arranged on the inner side of the reflecting sleeve and corresponds to the inclined end face of the inclined-angle optical fiber, the flat-reflection end face is arranged in a spaced mode with the inclined-angle optical fiber, and the flat-reflection end face is used for reflecting the light signal reflected by the inclined end face of the inclined-angle optical fiber back to the inclined end face of the inclined-angle optical fiber; the multiple inclined-angle optical fibers are arranged to realize the measurement of the coordinates, the structure is more simple and reliable, the resolution is higher, the working state is more stable and reliable, and the three-coordinate measuring head is not prone to electromagnetic interference.

Description

Technical Field

[0001] This invention relates to the field of measurement technology, and in particular to a coordinate measuring machine probe integrated with an all-fiber FP array. Background Technology

[0002] The coordinate measuring machine (CMM) probe is the core component of a CMM, and its performance directly determines the measurement accuracy, response speed, and applicability of the instrument. It is widely used in fields such as machinery manufacturing, aerospace, and precision electronics. Currently, traditional contact-type CMM probes mostly employ a mechanical trigger structure, using mechanical displacement when the probe contacts the object being measured to trigger a signal and achieve three-dimensional coordinate detection. However, this type of probe suffers from drawbacks such as complex structure, slow response speed, and susceptibility to mechanical wear affecting measurement accuracy. Furthermore, in scenarios involving minute displacement measurements, mechanical backlash can increase measurement errors, making it difficult to meet the demands of precision measurement. Existing fiber optic sensing probes, on the other hand, suffer from complex structures, high assembly precision requirements, and large dimensions. Electrical probes are susceptible to electromagnetic interference and lack stability. Summary of the Invention

[0003] The technical problem this invention aims to solve is how to improve the interchangeability and stability of the probe while simplifying its structure in the context of achieving three-dimensional displacement sensing. To address this problem, this invention provides a three-coordinate measuring machine probe integrated with an all-fiber FP array, comprising a probe rod and a reflective sleeve. A central through-hole is provided through the probe's central axis, and a flat-end fiber is disposed within the central through-hole. Multiple grooves are circumferentially arranged on the outer wall of the probe rod, extending along the probe's axis. An angled fiber is fixedly disposed within each groove. The reflective sleeve is fitted over the probe rod, and a planar reflective end face is provided inside the reflective sleeve corresponding to the angled end face of the angled fiber. The planar reflective end face is spaced apart from the angled fiber and is used to reflect the light signal refracted and reflected by the angled end face of the angled fiber back to the angled end face of the angled fiber.

[0004] Preferably, the angled end face of the angled optical fiber is tilted at an angle of 45 degrees relative to the central axis of the angled optical fiber, and the angled end face is used to reflect the optical signal so that the reflected light path is emitted along the radial direction of the measuring rod. The planar reflective end face is perpendicular to the radial outgoing light path after reflection by the inclined end face.

[0005] Preferably, three grooves are evenly arranged circumferentially around the central axis of the measuring rod.

[0006] Preferably, the planar reflective end face includes a polished metal surface or an optically coated reflective surface.

[0007] Preferably, the light-emitting end of the flat-end optical fiber is flush with the end of the measuring rod or is disposed in the central through hole and is 0.1 mm to 1 mm away from the end of the measuring head.

[0008] Preferably, both the angled end face of the angled optical fiber and the light-emitting end face of the flat end face optical fiber are provided with an anti-reflection film or a reflective film.

[0009] Preferably, the outer wall of the measuring rod is fitted with a protective sleeve, which is used to press and fix the angled optical fiber in the groove; one end of the protective sleeve is fixedly connected to the reflective sleeve, and the other end of the protective sleeve is fixedly connected to the measuring rod.

[0010] Preferably, a sealing layer is provided between the sheath, the measuring rod, and the reflective sleeve.

[0011] Preferably, the sheath and the measuring rod are fitted with a clearance, and the inner sidewall of the sheath is provided with an auxiliary groove corresponding to the groove, and both the auxiliary groove and the groove are attached to the outer sidewall of the angled optical fiber.

[0012] Preferably, a flange is fixedly provided at the end of the measuring rod away from the beveled end face of the angled optical fiber, and the flange is provided with through holes corresponding to the flat end face optical fiber and the angled optical fiber, and the flange is fixedly connected to the sheath.

[0013] Compared with the prior art, the all-fiber FP array integrated coordinate measuring machine provided in this embodiment of the invention has the following advantages: In this invention, the beveled end face of the angled optical fiber and the planar reflective end face of the reflective sleeve form a FP interference cavity. After the light beam is reflected by the beveled end face of the angled optical fiber, it is transmitted along the radial direction of the measuring rod to the planar reflective end face of the reflective sleeve. Then the light beam is reflected back to the beveled end face of the angled optical fiber and reflected again by the beveled end face before returning to the measuring instrument. The returned transmitted light and the reflected light from the beveled end face form self-interference inside the angled optical fiber. However, when the side of the probe contacts the object being measured, the micro-deformation of the measuring rod causes a change in the cavity length of the FP interference cavity, thereby enabling the acquisition of displacement signals in the xy plane. The flat-end optical fiber, through the FP interference cavity between its light-emitting end and the object being measured, can realize the sensing of the z-axis displacement signal, thereby realizing the measurement of the three coordinates. It only relies on multiple beveled optical fibers to realize coordinate measurement. The overall structure is simpler, the resolution is higher, and the working state is more stable and reliable, and it is not easily affected by electromagnetic interference. Attached Figure Description

[0014] Figure 1 This is a perspective view of the present invention; Figure 2 This is a partial view of the present invention; Figure 3 This is a side view of the present invention; Figure 4 This is a schematic diagram of the beam propagation path of the present invention; Figure 5 This is a schematic diagram of the detection state of the present invention.

[0015] In the diagram: 1. Measuring rod; 11. Central through hole; 12. Flat end face fiber optic cable; 13. Groove; 14. Angled fiber optic cable; 141. Angled end face; 15. Flange. 2. Reflective sleeve; 21. Planar reflective end face; 3. Protective sleeve. Detailed Implementation

[0016] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0017] like Figures 1 to 5 As shown, a preferred embodiment of the present invention provides a coordinate measuring machine (CMM) probe integrated with an all-fiber FP array, comprising a probe rod 1 and a reflective sleeve 2. A central through-hole 11 is provided through the probe rod 1 along its axial direction, and a flat-end fiber 12 is disposed within the central through-hole 11. Multiple grooves 13 are circumferentially arranged on the outer wall of the probe rod 1, extending along the axial direction of the probe rod 1. An angled fiber 14 is fixedly disposed within each groove 13. The reflective sleeve 2 is sleeved on the outside of the probe rod 1. Inside the reflective sleeve 2, a planar reflective end face 21 is provided corresponding to the angled end face 141 of the angled fiber 14. The planar reflective end face 21 is spaced apart from the angled fiber 14, and is used to reflect the light signal refracted by the angled end face 141 of the angled fiber 14 back to the angled end face 141 of the angled fiber 14.

[0018] Specifically, in this embodiment, a flat-end fiber 12 is fixedly installed in the central through hole 11 inside the measuring rod 1. When the probe contacts the object being measured perpendicularly along its axial direction, the light-emitting end of the flat-end fiber 12 and the surface being measured form an FP interference cavity along the axis, thereby enabling the sensing of displacement signals in the z-direction (i.e., the probe axis). For coordinate measurement in the xy (x and y are perpendicular to each other and both are perpendicular to the z-direction) plane, the measurement is performed through an FP interference cavity formed by the beveled end face 141 of the angled fiber 14 and the planar reflective end face 21 of the reflective sleeve 2. The same beam of light is transmitted in the beveled fiber 14 and reflected at the beveled end face 141. The reflected beam of light propagates along the direction of travel of the measuring rod 1 and is transmitted out to the outside of the beveled fiber 14. Then the beam of light is reflected by the planar reflective end face 21 and returns along the original path, forming self-interference with the light reflected by the beveled end face 141 inside the beveled fiber 14. When the side of the end of the measuring rod 1 comes into contact with the object being measured, the measuring rod 1 undergoes a slight deformation, which causes a change in the cavity length of the FP interferometer cavity. This allows the displacement signal in the xy plane to be sensed, ultimately achieving coordinate measuring machine measurement.

[0019] It is understood that in some embodiments, the angled fiber 14 and the flat-end fiber 12 may be single-mode fiber or multi-mode fiber, respectively, to meet different measurement requirements.

[0020] Furthermore, the head of the measuring rod 1 can be hemispherical, conical, or flat-headed, as long as it can make stable contact with the object being measured.

[0021] In some embodiments, the angled end face 141 of the angled fiber 14 is tilted at an angle of 45 degrees relative to the central axis of the angled fiber 14. The angled end face 141 is used to reflect the optical signal so that the reflected optical path is emitted in the radial direction of the measuring rod 1. The planar reflecting end face 21 is perpendicular to the radially emitted optical path after being reflected by the angled end face 141.

[0022] Specifically, in this embodiment, the angled end face 141 of the angled optical fiber 14 is set at 45 degrees. This allows the light beam, after being reflected by the angled end face 141, to propagate in a direction perpendicular to the central axis of the measuring rod 1, that is, to propagate along the radial direction of the measuring rod 1 and exit to the planar reflecting end face 21. The planar reflecting end face 21 is parallel to the central axis of the measuring rod 1, that is, perpendicular to the light path emitted in the radial direction. This allows the light beam, after being reflected by the planar reflecting end face 21, to return along the path to the angled end face 141 and generate self-interference with the original light beam, thereby realizing coordinate measurement.

[0023] In some embodiments, three grooves 13 are evenly arranged around the central axis of the measuring rod 1.

[0024] Specifically, in order to accurately measure the coordinates in the xy plane, at least three angled optical fibers 14 need to be set up. By measuring the changes in the length of the interference cavity corresponding to the three angled optical fibers 14, the displacement signal in the xy plane can be accurately sensed.

[0025] Furthermore, the initial cavity length of the radial FP interferometer cavity is determined by the structural dimensions of the reflecting sleeve 2 and the internal planar reflecting end face 21; the cavity length D of the radial FP interferometer cavity (including the initial cavity lengths a, b, c and the cavity lengths a', b', c' after displacement) can be obtained through interference spectrum demodulation, and its calculation formula is as follows: ; Where D represents the cavity length of the radial FP interference cavity (i.e., the distance between the end face of the 45° angled fiber 14 and the corresponding plane reflection end face 21), and λ? and λ? represent the wavelengths corresponding to two adjacent peaks or troughs in the interference light spectrum; a coordinate system is established with the center of the measuring rod 1 as the origin, and the initial cavity lengths of the radial FP interference cavities with the three angled fibers 14 arranged uniformly at 120° are a, b, and c respectively. After the measuring rod 1 undergoes radial displacement, the three sets of cavity lengths become a', b', and c' respectively. The specific position of the measuring rod 1 in the xy plane can be determined by the changes in the three cavity lengths, and then the displacement of the measuring rod 1 can be calculated.

[0026] In some embodiments, the planar reflective end face 21 includes a polished metal surface or an optically coated reflective surface. Both polished metal surfaces and optically coated reflective surfaces can improve the reflection effect of the light beam and reduce interference, thereby improving the accuracy of coordinate measurements.

[0027] In some embodiments, the light-emitting end of the flat-end fiber 12 is flush with the end of the probe 1 or is disposed in the central through hole 11 and is 0.1 mm to 1 mm relative to the end of the probe.

[0028] Specifically, if the light-emitting end of the flat-end fiber 12 is too close to the outlet of the central through hole 11, the light-emitting end of the flat fiber is easily damaged, resulting in damage to the entire measuring rod 1. In order to balance measurement accuracy and service life, in some embodiments, the light-emitting end of the flat fiber is controlled to be recessed and set inside the central through hole 11, and the distance between the light-emitting end and the end of the measuring head is controlled to be between 0.1 mm and 1 mm.

[0029] Furthermore, in some embodiments, the flat-end fiber 12 is fixed to the central through hole 11 by adhesive.

[0030] In some embodiments, both the angled end face 141 of the angled fiber 14 and the output end of the flat end face fiber 12 are provided with anti-reflection coatings or reflective coatings. The provision of anti-reflection coatings and reflective coatings can improve the reflection efficiency and reflection quality of the beam, thereby improving the contrast of the interference signal of the corresponding FP interferometer cavity, and thus improving the accuracy and precision of coordinate measurement.

[0031] In some embodiments, a protective sleeve 3 is provided on the outer wall of the measuring rod 1. The protective sleeve 3 is used to press and fix the angled optical fiber 14 in the groove 13. One end of the protective sleeve 3 is fixedly connected to the reflective sleeve 2, and the other end of the protective sleeve 3 is fixedly connected to the measuring rod 1.

[0032] Specifically, in order to improve the stability of the position of the angled beam and thus improve the accuracy of the measurement results, in this embodiment, the position of the angled optical fiber 14 is fixed by a sheath 3 fitted outside the measuring rod 1 to prevent the position of the angled optical fiber 14 from shaking, which would cause the interference cavity to change and thus affect the accuracy of the measurement results.

[0033] The sheath 3 and the reflective sleeve 2 are fixed by threaded connection or snap-fit ​​connection.

[0034] Furthermore, a sealant layer (not shown) is provided at the connection gap between the sheath 3 and the measuring rod 1 and the reflective sleeve 2. This sealant layer can prevent dust from entering the interference cavity, thus achieving dustproof and anti-fouling protection for the optical fiber and the interference cavity.

[0035] Furthermore, the sheath 3 and the measuring rod 1 are fitted with a clearance, and the inner side wall of the sheath 3 is provided with an auxiliary groove corresponding to the groove 13. Both the auxiliary groove and the groove 13 are attached to the outer side wall of the angled optical fiber 14.

[0036] Specifically, in some embodiments, the auxiliary groove (not shown) and the groove 13 are both arc-shaped grooves with equal depth and width, and their cross-sections are adapted to the outer diameter of the angled optical fiber 14, so that the angled optical fiber 14 can fit and be positioned with the groove 13 and the auxiliary groove, and the angled optical fiber 14 will not be offset in position.

[0037] In some embodiments, a flange 15 is fixedly mounted on the end of the probe 1 away from the beveled end face 141 of the angled fiber 14. The flange 15 has through holes (not shown) corresponding to the flat end face fiber 12 and the angled fiber 14. The flange 15 is fixedly connected to the sheath 3. The flange 15 also has mounting holes for fixing with the coordinate measuring machine (CMM) fixture bolts, thereby mounting the probe 1 onto the CMM. The tail end of the sheath 3 has a flange, which is fixedly connected to the flange 15 by screws.

[0038] In addition, in one specific embodiment, the measuring rod 1, the sheath 3, and the reflective sleeve 2 are made of stainless steel, hard aluminum alloy, brass, or engineering plastic, depending on the actual needs.

[0039] The above are merely preferred embodiments of the present invention. It should be noted that those skilled in the art can make several improvements and substitutions without departing from the technical principles of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present invention.

Claims

1. A three-coordinate measuring head integrated with an all-fiber FP array, characterized in that, include: The measuring rod has a central through hole extending through its central axis, and a flat-end optical fiber is disposed in the central through hole; the outer side wall of the measuring rod has multiple grooves extending along the axial direction of the measuring rod, and an angled optical fiber is fixedly disposed in the grooves. A reflective sleeve is sleeved on the outside of the measuring rod. Inside the reflective sleeve, a planar reflective end face is provided corresponding to the angled end face of the angled optical fiber. The planar reflective end face is spaced apart from the angled optical fiber and is used to reflect the light signal refracted and reflected by the angled end face of the angled optical fiber back to the angled end face of the angled optical fiber.

2. The all-fiber FP array integrated coordinate measuring machine (CMM) probe according to claim 1, characterized in that, The angled end face of the angled optical fiber is tilted at an angle of 45 degrees relative to the central axis of the angled optical fiber. The angled end face is used to reflect the optical signal so that the reflected optical path is emitted in the radial direction of the measuring rod. The planar reflective end face is perpendicular to the radial outgoing light path after reflection by the inclined end face.

3. The all-fiber FP array integrated coordinate measuring machine (CMM) probe according to claim 2, characterized in that, The grooves are evenly arranged circumferentially around the central axis of the measuring rod.

4. The all-fiber FP array integrated coordinate measuring machine (CMM) probe according to claim 1, characterized in that, The planar reflective end face includes a polished metal surface or an optically coated reflective surface.

5. The all-fiber FP array integrated coordinate measuring machine (CMM) probe according to claim 1, characterized in that, The light-emitting end of the flat-end optical fiber is flush with the end of the probe or is located in the central through hole and is 0.1 mm to 1 mm away from the end of the probe.

6. The all-fiber FP array integrated coordinate measuring machine (CMM) probe according to claim 1, characterized in that, Both the angled end face of the optical fiber and the light-emitting end face of the flat end face optical fiber are provided with anti-reflection coatings or reflective coatings.

7. The all-fiber FP array integrated coordinate measuring machine (CMM) probe according to claim 1, characterized in that, The outer wall of the measuring rod is fitted with a protective sleeve, which is used to press and fix the angled optical fiber in the groove; one end of the protective sleeve is fixedly connected to the reflective sleeve, and the other end of the protective sleeve is fixedly connected to the measuring rod.

8. The all-fiber FP array integrated coordinate measuring machine (CMM) probe according to claim 7, characterized in that, A sealing layer is provided between the sheath, the measuring rod, and the reflective sleeve.

9. The all-fiber FP array integrated coordinate measuring machine (CMM) probe according to claim 7, characterized in that, The sheath and the measuring rod are fitted with a clearance fit. The inner sidewall of the sheath is provided with an auxiliary groove corresponding to the groove, and both the auxiliary groove and the groove are attached to the outer sidewall of the angled optical fiber.

10. The all-fiber FP array integrated coordinate measuring machine (CMM) probe according to claim 9, characterized in that, A flange is fixedly provided at the end of the measuring rod away from the beveled end face of the angled optical fiber. The flange is provided with through holes corresponding to the flat end face optical fiber and the angled optical fiber. The flange is fixedly connected to the sheath.

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