Adjustable frequency difference two-frequency laser back-feed nano measuring ruler for frequency stabilizing

Abstract

The nanometer measuring tape comprises a light source, a probe and a target mirror. The light source uses a frequency-stabilized dual-frequency helium-neon laser; the outputted frequency difference of said dual-frequency laser can to continuously tuned from 1MHz to hundreds MHz; when the target mirror or the measured object moves each 1 / 8 optical wavelength along with the surface of the measured target, the polarization state of light outputted from the light source varies once. In the range of one cycle from the traceable source to the natural reference, four different polarization states are sequentially appeared, which are parallel ray independent oscillation, parallel ray and vertical ray commonly oscillation, vertical ray independent oscillation and non oscillation; based on the four different polarization states, estimating the bias size and direction of the measured object.

Description

technical field [0001] The invention relates to a frequency-stabilized dual-frequency laser feedback nano measuring ruler with adjustable frequency difference, which belongs to the technical field of laser measurement. Background technique [0002] Laser feedback effect (also known as self-mixing interference effect) is a basic effect in laser physics. The basic point is that the beam output by the laser is reflected back into the cavity by the reflective surface outside the resonator, and superimposed with the light field in the cavity. In this way, physical quantities such as output light intensity, power, and phase of the laser are modulated. After the laser feedback effect was discovered by King et al. in 1963, researchers at home and abroad have devoted themselves to eliminating the influence of this effect on the output characteristics of lasers. Because of the existence of this "noise", the frequency stabilization of existing lasers Method fails. [0003] With the d...

AI Technical Summary

Problems solved by technology

However, the frequency stabilization problem in the laser feedback effect has always been a bottleneck problem that researchers must face but is difficult to solve. The frequency stability of the feedback system is about s=10-6, which makes the feedback measurement system unable to stabilize Comparable to ordinary interferometers (s<10-7)

In addition, in terms of feedback displacement measurement, researchers generally encounter problems such as the inability to break through the diffraction limit of half the light wavelength, and the inability to accurately determine the displacement direction of the measured object, which makes the research progress of feedback displacement measurement technology slow.

[0004] On the other hand, the traditional Zeeman dual-frequency laser, according to the principle of the Zeeman effect, generally does not exceed 3MHz, which limits the measurement speed of the interferometer using it as a light source (cannot exceed 900mm / s)

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