Method and Equipment Based on Multi-Core Fiber Bragg Grating Probe for Measuring Structures of a Micro Part

摘要

A method and equipment based on multi-core fiber Bragg grating (FBG) probe for measuring structures of a micro part are provided. The provided method relates to how to accomplish measuring structures of a micro part by transforming two or three-dimensional contact displacements into spectrum shifts of the multi-core FBG probe, and to reconstruct the structure geometry of a micro part. The provided equipment can be used to bring the spherical tip of the multi-core FBG probe into contact with a micro part, to determine coordinates of contact points, and to reconstruct the structure geometry of a micro part. The provided method and equipment feature high sensitivity, low probing force, high inspecting aspect ratio and immunity to environment interference.

主权项

1. A method based on multi-core FBG probe for measuring structures of a micro part includes following steps:
Step 1. Providing a multi-core FBG probe, which comprises a spherical tip and a multi-core fiber stylus inscribed FBGs in its cores; the multi-core fiber stylus, cantilevered at one end and with the spherical tip fixed on the other, serves as the multi-core FBG probe; the multi-core fiber utilized to fabricate the multi-core fiber stylus should have one or more cores located out of the center of the multi-core fiber; Step 2. Providing a photoelectric probing system, which consists of the multi-core FBG probe mentioned in step 1, an optical path for the operation of the multi-core FBG probe, and an interrogation unit (consisting of a demodulation unit and a signal processing unit) for detecting and processing the sensing signal of the multi-core FBG probe; when a micro part is measured, the spherical tip of the multi-core FBG probe is brought into contact with a micro part and the spectra of FBGs comprised in the multi-core fiber stylus shift accordingly; the optical path supplies the multi-core FBG probe with energy and ensures the sensing signal containing spectrum shifts of FBGs in the multi-core fiber stylus and the reference FBG can reach the interrogation unit; the interrogation unit detects the sensing signal, transforms it into spectrum shifts of FBGs, and then calculates contact displacements of the spherical tip of the multi-core FBG probe relative to its zero-force position; Step 3. Combining the photoelectric probing system mentioned in step 2 with a coordinate measuring instrument system to form an equipment based on multi-core FBG probe for measuring structures of a micro part, contact displacements of the spherical tip of the multi-core FBG probe and coordinates of the multi-core FBG probe relative to the coordinate measuring instrument system are acquired in real time and are processed by a measurement computer, wherein coordinates of contact points can be calculated from coordinates of the multi-core FBG probe relative to the coordinate measuring instrument system and contact displacements of the spherical tip of the multi-core FBG probe relative to its zero-force position measured directly using the photoelectric probing system; Step 4. A micro part measured is fastened to a measurement table of the equipment based on multi-core FBG probe for measuring structures of a micro part mentioned in step 3; the motion of the measurement table and the multi-core FBG probe fixed on the sleeve of the equipment is controlled by manual operation or a measurement program; relative motion between the multi-core FBG probe and a micro part occurs and the motion track is accurately designed to bring the spherical tip of the multi-core FBG probe into contact with a certain point of a micro part, coordinates of a contact point can be calculated in the measurement computer mentioned in step 3; Step 5. Repeat the measurement process in step 4 to obtain coordinates of more contact points and the structure geometry of a micro part measured can be reconstructed from coordinates of these contact points.