Method and system for improving phase shift error detection precision based on probability density function

A probability density function and error detection technology, applied in measurement devices, instruments, optical devices, etc., can solve problems such as limiting the scope of use, and achieve the effect of improving accuracy and reducing detection errors

Active Publication Date: 2021-07-09
SICHUAN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Among them, although the digital phase shift has no phase shift error, its scope of application is limited due to the need for digital equipment; One of the important factors of measurement accuracy, so obtaining accurate phase shift is of great significance to improve the measurement accuracy of the system

Method used

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  • Method and system for improving phase shift error detection precision based on probability density function
  • Method and system for improving phase shift error detection precision based on probability density function
  • Method and system for improving phase shift error detection precision based on probability density function

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Experimental program
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Embodiment 1

[0028] 1. Phase error caused by inaccurate phase shift

[0029] The ideal fringe intensity is:

[0030]

[0031] Wherein (x, y) is any pixel coordinate, which will be omitted in the following formulas for convenience. A, B are background intensity and modulation degree respectively, is the phase of the fringe, 2πn / N is the phase shift of the nth frame in the N fringe images, n=0,1,...,N-1. Therefore, the ideal phase can be calculated by the following formula:

[0032]

[0033] Due to the fact that in the actual measurement system of the interferometric phase shift method and the mechanical phase shift method, there is inevitably a certain problem of inaccurate phase shift, therefore, the actual fringe intensity can be expressed as:

[0034]

[0035] where δ n =2πn / N+Δδ n Indicates the actual phase shift of the nth fringe pattern, Δδ n is the corresponding phase shift error. From the formulas (2), (3), the actual phase can be calculated as:

[0036]

[0037...

Embodiment 2

[0056] Such as Figure 5 As shown, an electronic device according to an exemplary embodiment of the present invention (such as a computer server with a program execution function), which includes at least one processor, a power supply, a memory and an input / output interface communicatively connected to the at least one processor; The memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor, so that the at least one processor can execute the method disclosed in any of the foregoing embodiments; The above-mentioned input and output interfaces may include a display, a keyboard, a mouse, and a USB interface for inputting and outputting data; the power supply is used for providing electric energy for electronic equipment.

[0057] Those skilled in the art can understand that all or part of the steps for implementing the above-mentioned method embodiments can be completed by hardware related to program instr...

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Abstract

The invention discloses a method for improving phase shift error detection precision based on a probability density function, establishes a phase error model caused by inaccurate phase shift in a measurement system, and provides an algorithm for extracting a phase shift error by using a statistical method. According to the method, the characteristic that the probability density (PDF) of a truncation phase is uniform and consistent under an ideal condition is utilized, different phase shift error combinations are adopted for a stripe to be measured, the STD value of each probability density function curve is calculated,and the corresponding compensation phase shift error combination when the STD value is minimum serves as the real phase shift error of a measurement system. According to the method, the accuracy of phase shift error detection is improved, and the detection error is reduced.

Description

technical field [0001] The invention relates to the field of phase shift interferometry, in particular to a method and system for improving the detection accuracy of phase shift errors based on a probability density function. Background technique [0002] With the continuous development of human society, the three-dimensional topography measurement of the object surface plays an increasingly important role in the production and life of human beings. The common three-dimensional measurement methods of objects can be divided into contact measurement and non-contact measurement. Among the non-contact measurement methods, phase measurement profilometry is widely used in medical treatment, cultural relic protection, industrial manufacturing, intelligent monitoring and other fields due to its advantages of high precision, non-contact and fast measurement. Phase measurement profilometry uses phase shift technology to extract the phase from the fringe pattern modulated by the heigh...

Claims

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Application Information

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Patent Type & AuthorityApplications(China)
IPC IPC(8): G01B11/25
CPCG01B11/2527
Inventor刘元坤于馨陈文静张启灿薛俊鹏王亚军申俊飞
OwnerSICHUAN UNIV