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Dispersion phase compensation method based on peak evolution distortion elimination in high-resolution frequency scanning interferometer

A technology of frequency scanning interference and phase compensation, applied in the field of dispersion compensation of scanning interferometers, can solve the problems of low measurement resolution and large ranging error

Active Publication Date: 2015-10-21
HARBIN INST OF TECH
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] The purpose of the present invention is to solve the problem of low measurement resolution and large ranging error caused by the linear change of the corrected measurement interferometer signal beat frequency as the frequency modulation bandwidth and the measured distance increase caused by the optical fiber dispersion effect of the auxiliary interferometer The problem

Method used

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  • Dispersion phase compensation method based on peak evolution distortion elimination in high-resolution frequency scanning interferometer
  • Dispersion phase compensation method based on peak evolution distortion elimination in high-resolution frequency scanning interferometer
  • Dispersion phase compensation method based on peak evolution distortion elimination in high-resolution frequency scanning interferometer

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specific Embodiment approach 1

[0086] Specific implementation manner 1: A dispersion phase compensation method based on peak evolution and distortion reduction in a high-resolution frequency scanning interferometer includes the following steps:

[0087] The signal after the nonlinearity is corrected by the frequency sampling method of the optical fiber Machzide interferometer can be expressed as formula (14)

[0088]

[0089] Where I b To measure the signal, A T Is the signal energy reflected by the target, A R Is the energy of the local oscillator optical signal; η H Is the interference efficiency, n is the sampling point number; Is the distortion phase of the sampled signal, which is mainly caused by the fiber dispersion of the auxiliary interferometer; σ disp Is the phase distortion coefficient; τ and τ aux Respectively indicate the corresponding time delay of the measuring interferometer and auxiliary interferometer in the high-resolution frequency scanning interferometer;

[0090] Expressing formula (14) as a...

specific Embodiment approach 2

[0099] Specific implementation manner 2: The selected phase compensation coefficient α comp , Make -πσ disp n 2 +πα comp n 2 Minimum, get the measured signal I after dispersion phase compensation b , To complete the compensation for the influence of the frequency scanning interferometer's dispersion; including the following steps:

[0100] Analyze the characteristics of the signal function after sampling, and express the frequency spectrum amplitude square of the sampled signal as formula (17):

[0101] | S I b ( f ) | 2 = 1 8 σ d i s p [ F r e s n e l c ( ξ 1 ) - F r e s n e l c ( ξ 1 + 2 σ d i s p T 2 ) ] 2 + 1 8 σ d i s p [ F r e s n e l s ( ξ 1 ) - F r e s n e l s ( ξ 1 + 2 σ d i s p T 2 ) ] 2 - ...

Embodiment

[0110] The simulation process is as follows: Assume that the beat frequencies of the measurement signal formed by four point targets are 5500Hz, 5800Hz, 5900Hz, 6000Hz, in order to explain the principle and increase the contrast effect, the corresponding maximum distortion coefficients are set to 4.88×10 4 , 5×10 4 , 5.04×10 4 , 5.08×10 4 , The time-domain diagram and frequency-domain diagram of the measured signal are shown in Figure 6(a) and Figure 6(b) respectively. From Figure 6(b), it can be seen that the signal has severe spectral interference and false peaks are generated. Point targets cannot be distinguished and measured. In order to eliminate this effect, the sampled signal and Multiply and set the compensation coefficient α respectively comp = 48800, α comp = 50000, α comp =50400,α comp =50800, and then Fourier transform is performed on the compensated signal, and the frequency spectrum is shown in Figure 7.

[0111] Compared Figure 7(a)-Figure 7(d) As shown in Fi...

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Abstract

The invention discloses a dispersion phase compensation method based on peak evolution distortion elimination in a high-resolution frequency scanning interferometer, which relates to the technical field of scanning interferometer dispersion compensation technology and aims at solving the problems of low measurement resolution and large ranging errors as beat frequency of corrected measurement interferometer signals generates linear changes along with increasing of a frequency modulation bandwidth and a measured distance due to auxiliary interferometer fiber dispersion effects. A fiber Mach-Zehnder interferometer frequency sampling method is used for correcting a nonlinear signal as shown in the description, the signal is multiplied by a complex phase compensation term exp(jphicomp), and a formula as shown in the description is obtained; according to a compensation phase phicomp=pialphacompn<2>, Ib is shown in the description; and a phase compensation coefficient alphacomp is selected, -pisigmadispn<2>+pialphacompn<2> is minimal, a measurement signal Ib through dispersion phase compensation is obtained, and compensation on frequency scanning interferometer dispersion influences is completed. The method is applied to dispersion compensation of the scanning interferometer.

Description

Technical field [0001] The invention relates to the technical field of scanning interferometer dispersion compensation. Background technique [0002] With the development of aerospace, shipbuilding, heavy machinery, power generation equipment and other industries, large-scale and high-precision measurement problems have emerged prominently, such as the measurement of the installation position of large aircraft components, the measurement of the length of the main shaft of the water turbine, and the measurement of the bed of a large precision machine tool. And the measurement of the rotor stator diameter of the generator set of the hydropower station. Traditional large-scale workpiece detection methods such as coordinate machines, theodolites, and visual measurement have the disadvantages of contacting the measured workpiece, low accuracy, high cost, and low efficiency. It is difficult to meet the requirements of large-scale high-precision absolute distance measurement in the manu...

Claims

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Application Information

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