Laser speckle contrast ratio measuring method

A measurement method and laser speckle technology, applied in the field of laser measurement, can solve problems such as the contrast error of the whole frame image and the index error of the laser display system

Inactive Publication Date: 2015-03-25
PHOEBUS VISION OPTO ELECTRONICS TECH
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Problems solved by technology

[0003] Due to the inhomogeneity of the light field itself, there is only one contrast measurement method for the entire speckle image in the prior art, which will cause a large error i

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  • Laser speckle contrast ratio measuring method
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  • Laser speckle contrast ratio measuring method

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Embodiment Construction

[0024] The present invention uses a dynamic method to calculate speckle contrast. The specific calculation method is as follows:

[0025] Step 101: Set template length N T ;

[0026] Among them, the template represents an operation group participating in the operation, and the length of the template is N T Indicates the number of pixels participating in the operation of this algorithm each time, N T The theoretical value range of is from 1 to N, where N represents the total number of pixels in the measured light field, and the pixels are the pixels of the speckle image to be processed detected by the linear array CCD. At this time, N T is the number of pixels in one dimension.

[0027] In this algorithm, a one-dimensional speckle pattern 1*N is set. In the prior art, multi-dimensional speckle patterns N*N are mostly used for calculating speckle contrast, and the contrast algorithm for calculating multi-dimensional speckle patterns is relatively complicated. The present inv...

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Abstract

The invention provides a laser speckle contrast ratio measuring method. The method includes the following steps of setting a template length NT, wherein the template length NT represents the number of pixels participating in calculation of the method each time, the value of NT ranges from 1 to N, and N represents the total number of pixels of a measured laser field; calculating the average laser intensity and variance of pixel positions N(n) within the range of the template length NT, wherein n is equal to 1, 2, ..., N-NT+1, and the value of N(n) ranges from 1 to NT; calculating the dynamic speckle contrast ratio of a speckle image, wherein the speckle contrast ratio of the template length NT is the ratio of the standard deviation of the pixel positions N(n) to the average laser intensity of the pixel positions N(n); moving the position of a template without changing the template length NT, and repeating the steps to obtain a series of speckle contrast ratios. By means of the method, the contrast ratio of the whole frame of image can be dynamically reflected, the characteristics of speckles can be completely presented, and the estimation errors of laser display system indexes can be reduced as well.

Description

technical field [0001] The invention relates to a measurement method, in particular to a measurement method of laser speckle contrast, belonging to the field of laser measurement. Background technique [0002] Laser is a kind of highly coherent light. When it is incident on the surface of a rough object and reflected, the elementary light waves reflected from each small facet of the rough surface interfere with each other in space, forming a granular pattern with random distribution of amplitude, intensity and phase. Speckle, that is, laser speckle. The laser speckle phenomenon is a random process in which a large number of light fields with random phases are superimposed. Generally, the quantity that can be measured is the light field intensity. Therefore, the speckle contrast C can be used to describe the fluctuation of the light intensity of the speckle field, that is, the first-order characteristics of the speckle pattern. Measured, speckle contrast is defined as: whe...

Claims

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Application Information

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IPC IPC(8): G01J1/10
Inventor 王斌毕勇孙敏远
Owner PHOEBUS VISION OPTO ELECTRONICS TECH
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