Extender high-light folding feedback displacement measuring system

Abstract

An expansion strong light collapsing feedback displacement measuring system belongs to laser measuring technology field. It relates to applied Zeeman double-refraction double-frequency laser, beam of light collimating spread implement, empty pyramid prism, variable attenuator and feedback mirror with strong reflectivity. When object moves each one forth light wave, the intensity of laser will bring seasonal fluctuate. There are four polarization sections in one period, o light section, coexist section of o light and e light, e light and non-light section, and each of them corresponds one sixteenth light wave of object. Detect the number of the polarization section to get the displacement mete of the object. When the motion direction changes, the appearance order of the four polarization sections in each period changes too, and distinguishes the displacement direction of object.

Description

technical field [0001] The invention belongs to the technical field of laser measurement. Background technique [0002] With the rapid development of modern information technology, sensing technology, one of the three pillars of modern information technology, is the foundation of information technology. Its performance determines the function and quality of information system, and its role is becoming more and more important. Displacement is a basic physical quantity in nature, and displacement measurement is widely used in chip manufacturing, automobile industry, biomedicine, aerospace and other fields. In recent years, laser feedback sensing technology and its application have aroused widespread interest of experts and scholars at home and abroad. Laser feedback means that in the laser application system, after the output light of the laser is reflected by an external object, part of the light is fed back to the laser resonator. The feedback light carries the information ...

AI Technical Summary

Problems solved by technology

The inclination direction of the sawtooth wave is easy to judge the displacement direction from the senses, but it is not easy to realize on the hardware, and at the medium feedback level, the feedback signal will appear hysteresis, which will bring errors to the counting and seriously affect the accuracy of the system measurement. and linearity

When using this method, the feedback signal must be at least one complete cycle before the inclination direction of the feedback waveform can be determined, which limits the resolution of the system measurement to half an optical wavelength, making it impossible to achieve high-precision displacement measurement

At the same time, this type of system has high requirements on the collimation of the feedback cavity and poor ability to resist external interference

Second, it is not possible to subdivide the feedback signal

However, this feedback signal is very unstable and easily becomes a sawtooth-like shape. At the same time, the feedback measurement system can only obtain one optical signal, which makes electronic subdivision difficult to achieve.

The resolution of the system is generally half an optical wavelength, and the system performance is greatly limited

Third, the feedback external cavity has high requirements for collimation and poor ability to resist external interference

Due to the detuning of the external cavity feedback mirror, not only the light reflected once by the feedback mirror can return to the laser resonator to interact with the light in the cavity, but the light reflected twice or even multiple times by the feedback mirror may also return to the laser resonator, modulating the laser. Output, at this time the feedback signal of the system is more complicated, and the measurement system cannot work normally

At the same time, due to the detuning of the external cavity feedback mirror, part of the light cannot return to the laser resonator, which makes the system feedback level drop

Under different feedback levels, the system feedback signals are different, the measurement system cannot obtain the expected feedback signal, and measurement errors occur

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