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Method of Determining the Main Value of Phase Shift by Light Intensity Map in Three-dimensional Shape Measurement

A technology of three-dimensional shape and phase shift, applied in the direction of measuring devices, optical devices, instruments, etc., can solve the problems of expensive PZT system and cannot be widely used, and achieve the goal of eliminating the influence of calculation accuracy and improving measurement accuracy Effect

Inactive Publication Date: 2017-12-08
NANJING NORMAL UNIVERSITY
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Problems solved by technology

However, the high-precision PZT system is expensive and requires frequent recalibration, which cannot be widely used

Method used

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  • Method of Determining the Main Value of Phase Shift by Light Intensity Map in Three-dimensional Shape Measurement
  • Method of Determining the Main Value of Phase Shift by Light Intensity Map in Three-dimensional Shape Measurement
  • Method of Determining the Main Value of Phase Shift by Light Intensity Map in Three-dimensional Shape Measurement

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Embodiment

[0064] right figure 1 The cantilever shown, four interferograms ( Figure 2-5 ). Take a straight line at the same position in the four interferograms, see Figure 2-5 As shown by the white line in , the light intensity at the line in the four interferograms is as follows Figure 6 As shown, the curves 1, 2, 3, and 4 marked in the figure correspond to Figure 2-5 The light intensity at the line shown in . The background light intensity at the straight line calculated by the method proposed by the present invention is as follows: Figure 7 , the main values ​​of the phase shift are Δψ 21 =52.55°, Δψ 31 =130.37°, Δψ 41 =-175.69°. From Figure 7 It can be seen that the high-order harmonics in the background light intensity are not filtered out, but from the theory of Fourier transform, high-order harmonics do not affect the calculation of the fundamental wave phase, and also do not affect the measurement accuracy of the main value of the phase shift . Since the phase sh...

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Abstract

The invention discloses a method for determining the main value of the phase shift amount from a light intensity map in three-dimensional shape measurement, which can directly determine the main value of the phase shift amount between light intensity maps (at least three) from multiple light intensity maps ( That is, angle values ​​between ‑180° and +180°). The present invention utilizes the characteristic that the background light intensity in each light intensity map is the same, based on the fast Fourier transform (FFT), utilizes an iterative method to calculate the background light intensity, and simultaneously obtains the main value of the phase shift amount (the background light intensity converges The corresponding phase shift is the desired phase shift or the main value of the phase shift). Utilizing the method of the present invention, the main value of the phase shift can be directly and quickly calculated from the light intensity map without introducing complex systems such as PZT, and the influence of the background light intensity on the calculation accuracy can be eliminated, and the measurement accuracy of the main value of the phase shift can be significantly improved , is a simple and feasible method.

Description

technical field [0001] The invention relates to a method for directly determining the main value of the phase shift between light intensity maps (that is, the angle value between -180° and +180°) from light intensity maps in three-dimensional shape measurement, which belongs to optical three-dimensional The field of shape measurement technology. Background technique [0002] Whether it is a macroscopic object or a microscopic object, the measurement of its three-dimensional shape is becoming increasingly important. The optical phase shift three-dimensional shape measurement method (referred to as the phase shift method) is an important method for measuring the three-dimensional shape of an object. The basic principle is to take multiple light intensity maps (at least three) by introducing phase shift, and The size of the phase shift and the light intensity value are used to calculate the three-dimensional shape of the object. The precise introduction of the movement amount...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01B11/24
Inventor 戎华陈玺
Owner NANJING NORMAL UNIVERSITY
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