Fiber laser self-mixing interferometer and measurement method thereof

Abstract

The invention discloses a fiber laser self-mixing interferometer and a measurement method thereof and belongs to the field of displacement precision measurement. The interferometer comprises a distributed feedback semiconductor laser, a polarization-maintaining fiber coupler, an intra-line polarizer, a single mode fiber, an electrooptical modulator, an fiber Bragg grating, a gradient refractive index lens, a test piece, an photoelectric detector, a data acquisition and processing system, a fiber holder, one-dimensional guide rails, two-dimensional precision translation platform, a microscope, a base, a support and a signal generator. The fiber Bragg grating and the test piece form a reference outer cavity and a measurement outer cavity with the exit end face of the laser respectively for generating a double outer cavity self-mixing interference phenomenon; and the data acquisition and processing system adopts a self-mixing signal obtained by analysis by orthogonal demodulation technology to calculate the displacement of the test piece. The structure of the fiber interferometer is very suitable for measuring the nanometer displacement and vibration of the micro machines and MEMS devices and is more practical.

Description

technical field [0001] The invention relates to displacement precision measuring instruments, in particular to an optical fiber type self-mixing interferometer for measuring tiny displacements and a measuring method thereof. Background technique [0002] Interferometer systems are often used in the measurement of small displacements in the fields of precision machinery, microelectronics, and microelectromechanical systems (MEMS). For the micro-displacement measurement range from submicron to micron (μm), laser interferometry has been widely used due to its advantages of non-contact, high resolution and high measurement accuracy. Due to the advantages of flexibility, miniaturization and anti-electromagnetic interference, the fiber-coupled semiconductor laser is used in displacement sensors. For example, the MTI-2100 FotonicTM Sensor series optical fiber displacement gauge of MTI Corporation in the United States has an error of 0.01 μm to 0.1 μm in the working range of 1 μm t...

AI Technical Summary

Problems solved by technology

However, these measuring instruments require many optical components and complex optical signal detection devices, so it is difficult to make a compact and inexpensive measuring device

[0003] Traditional interferometric test structures are generally large in structure, complex in optical path, sensitive to collimation, and expensive, so there is an urgent need for a simpler, more compact and stable interferometric system

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