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Method for verifying and adjusting grating parallelism based on moire fringe equation

A moiré fringe and grating technology, applied in the field of optical measurement, can solve the problems such as the difficulty of completely parallel grating surfaces and the influence of experimental results, and achieve the effects of low implementation cost, easy operation and high data accuracy.

Active Publication Date: 2021-05-11
NANJING UNIV OF INFORMATION SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, it is difficult to ensure that the two grating surfaces are completely parallel in actual measurement, which will have a certain impact on the experimental results

Method used

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  • Method for verifying and adjusting grating parallelism based on moire fringe equation
  • Method for verifying and adjusting grating parallelism based on moire fringe equation
  • Method for verifying and adjusting grating parallelism based on moire fringe equation

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Embodiment 1

[0052] Embodiment 1: no field to be tested

[0053] In this embodiment, the method for verifying and adjusting grating parallelism based on the Moiré fringe equation includes the following steps:

[0054] S1: the optical path system of the experimental device includes a pair of gratings, respectively grating G 1 and grating G 2 , set the grating G close to the light source 1 For the reference grating, the grating G 2 is the grating to be adjusted;

[0055] S2: Determine the three-dimensional coordinate system

[0056] Such as figure 1 As shown, let the grating G 1 The center of is the origin of the coordinates, the propagation direction of the optical path is the z-axis on the horizontal plane, the x-axis is the direction perpendicular to the z-axis on the horizontal plane, and the y-axis is the direction perpendicular to the horizontal plane;

[0057] S3: setting the directions of the grating lines of the two gratings to form angles of +α / 2 and -α / 2 with the y-axis;

[...

Embodiment 2

[0080] Example 2: field to be tested

[0081] It can be seen from the fringe equation that under the irradiation of a plane wave and in the absence of a field to be measured, if the two grating surfaces are parallel, the fringe pattern is a series of straight Moiré fringes with equal spacing. If the two grating surfaces are not strictly parallel and have a certain angle with the x-axis plane, the inclination of the fringes will not change, but the fringe spacing will change with the angle between the grating surface and the x-axis plane, such as image 3 shown. Therefore, we can verify and adjust the parallelism of the two grating surfaces on the basis of the fringe spacing.

[0082] In the case of the field to be measured, due to the existence of the field to be measured 4, the incident on the grating G 1 The probe light field of the front surface is disturbed. Taking the temperature flow field of a burning candle as an example, the Moiré fringes are as follows: Figure 6...

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Abstract

The invention discloses a method for verifying and adjusting grating parallelism based on a moire fringe equation, which is applied to an experimental device for detecting a flow field based on a moire chromatography technology. The method comprises the following steps: determining included angles between grating line directions of two gratings of the experimental device and a y axis, and calculating a standard stripe spacing when two grating surfaces are parallel; and in actual operation, if the space between the moire fringes on the receiving screen is different from the standard spacing, indicating that the two grating surfaces are not parallel, which means that a certain included angle is formed between the grating surfaces and an x-axis surface. At the moment, the grating is rotated around the x axis, and the stripe spacing is adjusted to be consistent with the standard spacing, which means that the grating surface is parallel. The method is convenient to operate and low in implementation cost, the accuracy of experimental data can be effectively improved, and the method has important significance for applying the moire chromatography technology to the field of flow field measurement.

Description

technical field [0001] The invention relates to a method belonging to the technical field of optical measurement, in particular to a method for verifying and adjusting grating parallelism based on the Moiré fringe equation. Background technique [0002] As a branch of optical computer tomography, Moiré tomography has the advantages of real-time, stability and non-contact, and is widely used in flow field detection. When using Moire tomography to measure key parameters of high-temperature complex flow fields, in order to ensure measurement accuracy, it is necessary to ensure that the two grating surfaces are kept parallel as much as possible. However, it is difficult to ensure that the two grating surfaces are completely parallel in actual measurement, which will have a certain impact on the experimental results. Therefore, finding a simple and accurate method to verify the parallelism of two gratings is of great significance for the application of Moiré tomography in the fi...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01B11/02
CPCG01B11/02
Inventor 陈云云索嘉琦徐梦
Owner NANJING UNIV OF INFORMATION SCI & TECH