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Dispersion Phase Compensation Method for Laser Frequency Scanning Interferometer Based on Focusing Definition Evaluation Function

A technology of frequency scanning interference and focusing definition, which is applied in the direction of instruments, optical devices, measuring devices, etc., can solve the problems of low measurement resolution and measurement signal influence, and achieve the effect of large-scale high-resolution measurement

Active Publication Date: 2017-10-03
HARBIN INST OF TECH
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  • Application Information

AI Technical Summary

Problems solved by technology

[0003] The present invention aims to solve the problem that the existing method has low measurement resolution and the influence on the measurement signal needs to be compensated, and provides a laser frequency scanning interferometer dispersion phase compensation method based on the focusing definition evaluation function

Method used

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  • Dispersion Phase Compensation Method for Laser Frequency Scanning Interferometer Based on Focusing Definition Evaluation Function
  • Dispersion Phase Compensation Method for Laser Frequency Scanning Interferometer Based on Focusing Definition Evaluation Function
  • Dispersion Phase Compensation Method for Laser Frequency Scanning Interferometer Based on Focusing Definition Evaluation Function

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specific Embodiment approach 1

[0022] Specific implementation mode one: the dispersion phase compensation method based on the focusing sharpness evaluation function, which is implemented in the following steps:

[0023] (3) Establish the beat frequency model of the measurement signal under the fiber dispersion condition of the high-resolution laser frequency scanning interferometer;

[0024] (4) Compensate the optical fiber dispersion of the beat frequency model of the measurement signal by using the phase method:

[0025] (1) The measured signal is multiplied by the complex phase compensation item, and the dispersion phase distortion in the measured signal is compensated by adjusting the dispersion compensation coefficient. When the dispersion phase distortion of the measured signal is compensated, the full width at half maximum of the frequency spectrum of the signal will be narrowed;

[0026] (2) The focusing sharpness evaluation function is proposed as a criterion for judging whether the phase distortio...

specific Embodiment approach 2

[0031] Specific implementation mode two: the difference between this implementation mode and specific implementation mode one is: step (1) is specifically:

[0032] (1) The beat frequency ω formed by the auxiliary interferometer of the high-resolution laser frequency scanning interferometer aux Expressed as formula (6):

[0033]

[0034] Among them, the τ aux Indicates the time delay corresponding to the length difference of the two fiber arms in the auxiliary interferometer, μ is the frequency modulation slope, β 2 =-20ps 2 / km represents the group velocity dispersion of single-mode fiber, υ g Indicates the group velocity, t indicates the frequency modulation time of the laser;

[0035] (2) Since the beat frequency of the measuring interferometer and the auxiliary interferometer is directly proportional to the time delay, after sampling the measurement signal using the frequency sampling method, the delay ratio between the measuring interferometer and the auxiliary int...

specific Embodiment approach 3

[0044] Specific implementation mode three: the difference between this implementation mode and specific implementation mode one or two is: step (2) (1) is specifically:

[0045] (1) indicates that after adjusting the phase compensation factor each time, calculate the S value to see if it reaches the maximum value, and when the S value is the maximum, it is considered that the dispersion compensation is completed. However, in this process, a fixed step size is usually set to change the phase compensation factor, and the S value is judged each time until the S value reaches the maximum, and the compensation speed is relatively slow. And (2) the method of thirds avoids setting a fixed step size, and the maximum value of S can be found through fewer calculation times. Therefore, the method of thirds improves the efficiency of compensation.

[0046]Dispersion compensation is realized by calculating whether the S value of the focusing sharpness evaluation function reaches the maximu...

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Abstract

The invention relates to a laser frequency scanning interferometer dispersion phase compensation method based on a focusing definition evaluation function, and the invention relates to a high resolution laser frequency scanning interferometer dispersion compensation method. The invention aims to solve the problem that the existing method has low measurement resolution and needs compensation for the influence on the measurement signal. Establish the measurement signal beat frequency model under the fiber dispersion condition of the high-resolution laser frequency scanning interferometer; use the phase method to compensate the fiber dispersion of the measurement signal beat frequency model: (1) multiply the measurement signal by the complex phase compensation item, and adjust The dispersion compensation coefficient compensates the dispersion phase distortion in the measurement signal; (2) A focus sharpness evaluation function is proposed as a criterion for judging whether the phase distortion of the beat frequency model of the measurement signal is compensated; (3) The method of thirds is used to find the best dispersion compensation The coefficient compensates for fiber dispersion in a high-resolution laser frequency scanning interferometer. The invention is applied to the field of high-resolution laser frequency scanning interferometer.

Description

technical field [0001] The invention relates to a dispersion compensation method of a high-resolution laser frequency scanning interferometer. Background technique [0002] Laser frequency scanning interferometers play an important role in the fields of industrial parts measurement, aircraft surface processing, and three-dimensional shape modeling of objects. As production progresses, higher resolution frequency scanning interferometers are required. The key to improving the measurement resolution is to increase the sweep bandwidth. However, as the sweep bandwidth increases, the fiber dispersion of the auxiliary interferometer used to correct the beat frequency nonlinearity of the measurement signal increases accordingly, and the measurement signal is corrected by the auxiliary interferometer. After nonlinearity, the target spectrum is broadened and the measurement resolution is reduced. Therefore, the influence of the fiber dispersion of the auxiliary interferometer on th...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01B9/02
Inventor 刘国栋甘雨刘炳国许新科陈凤东庄志涛
Owner HARBIN INST OF TECH
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