Fast filter system of digital speckle pattern interferometric fringes

Abstract

The invention provides a fast filter system of digital speckle pattern interferometric fringes. The fast filter system comprises a background light removing module, an extreme value cutting module, a signal decomposing module, a bi-dimensional intrinsic mode functions (BIMFs) grouping module, a denoising fidelity module and a rectifying module. Digital speckle pattern interferometry (DSPI) fringe signals are decomposed through a fast bi-dimensional ensemble empirical mode (FBEEMD) method, a group of BIMF components distributed with the frequency ranging from high to low are obtained, each BIMF is a subsignal which is locally narrow-band and has signal characteristics, a BIMF energy curve of corresponding pure noise signals can be evaluated according to a BIMF energy curve of real signals, noises can be separated from an information area by comparing the two curves, useful information is maintained, and the filtering process can be finished. Through the filtering of the fast filter system, signal to noise ratio of fringe signals can be greatly improved, the visual effect is good, and the fast filter system is fast and real-time. The DSPI non-destructive testing technology combined with the fast filter system can be directly used in real projects for detecting whether damages to parts exist.

Description

Technical field [0001] The invention relates to the field of laser non-destructive testing, and in particular, to a digital speckle interference fringe fast filtering system. Background technique [0002] Digital Speckle Pattern Interferometry (DSPI) is a full-field, non-contact, real-time measurement method used to accurately measure the off-plane displacement. Compared with Holographic Interferometry (HI), DSPI has the advantages of simple operation and strong anti-interference ability. However, due to the lack of camera resolution, the quality of the fringe signal of DSPI is very poor, which is far from being comparable to HI. Therefore, in order to improve the signal-to-noise ratio of fringe signals, filtering technology has become an important topic in the development of DSPI. The existing technologies based on Fourier transform and wavelet transform have poor processing effect or poor adaptability, which are not satisfactory. [0003] Although the noise-assisted data analys...

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Problems solved by technology

The leaky wave phenomenon can be explained as that components that should belong to one BIMF may appear in other frequency band BIMFs, or different frequency components appear in one BIMF component, which makes the decomposition incomplete and cannot form a single BIMF component. which affects the filtering effect

The filtering method based on BEEMD proposed by Y. Zhou et al., although the effect is very good, but the requirement for computing power is too high, and the disadvantage of time-consuming makes it impossible for DSPI technology to do online diagnosis and real-time detection

[0005] Compared with the previous contact sensor testing, although DSPI non-destructive testing technology has many advantages, if the signal-to-noise ratio of the fringe signal cannot be improved and the technical bottleneck cannot be broken through, then the application prospect of this measurement technology will be extremely dim

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