Optical Fiber Online High-precision Displacement Measurement Technology For Low Reflectance Surface Objects

With the increasing accuracy of microelectronics,precision instrument manufacturing and even whole product processing and industrial technology,high-precision nanometer measurement technology is becoming more and more important.Displacement,as one of the most basic physical quantities,and the precision measurement of displacement is particularly important,and it also has been used extensively.Among them,Optical interferometry displacement measurement method is widely used in high-precision displacement measurement because of its advantages of high resolution,high accuracy and non-contact.However,the existing optical interferometry method is sensitive to environmental interference,difficult to be measured online,and this method is required for the reflectivity of the measured surface,so it is difficult to measure low reflectance object.Aiming at the shortcomings of the existing optical interferometry displacement measurement methods.in this paper,we propose and test a kind of applicable to all reflection from low to high objects on the surface of the online measurement of optical fiber high precision displacement interference measurement system.The system contains two optical fiber Mach Zehnder interferometers.Two different wavelengths of the two lasers are used to stabilize the Mach Zehnder interferometer and to measure the displacement of the measured object.A wavelength of light through the interferometer form interference signal,the signal through the feedback control system to compensate optical fiber Mach Zehnder interferometer due to affected by the interference of fiber optical path of making the Mach Zehnder interferometer has a strong resistance to environmental disturbance,therefore the system is suitable for on-line measurement.Another wavelength of light is reflected back from the object being measured and re-entered into the interference system to measure the displacement of the object being measured.An interferometer arm of the fiber-optic Mach-Zehnder interferometer is an erbium-doped fiber that amplifies the light reflected from the object being measured.This allows the measurement system to measure not only objects with a high reflectivity surface but also surfaces with low reflectivity.The standard deviation of multiple repeated measurements reached 44.56 nm.