The Research Of Key Issues In Speckle Interferometry Measurement And Its Application

Electronic Speckle Pattern Interferometry is an optical, non-contact and full-fieldmeasurement technology for.rough surface. Because of the full-field, non-contact, highaccuracy and high sensitivity measurement characteristics, it is widely used in rough surfacedisplacement and deformation measurement, non-destructive testing and vibrationmeasurement. The method is based on speckle interference fringe pattern shows the mainobject of study to obtain the phase map, and by processing the interference fringe pattern andmeasure the physical quantity. It is significant to extract the phase of the displacement of theobject, strain, vibration and other measurements quickly and accurately. The main works areas follows:1. There is a detailed and in-depth discussion for the time phase shift speckleinterferometry technology firstly in this article. In order to improve the quality of the phasemap in the dynamic and vibration state, produced two new phase extraction algorithms basedon integrating direct-correlation algorithm and the Windowed Fourier transform filtering methodwith5interferogram four steps phase shifting method, respectively.2. Since the Windowed Fourier transform filtering threshold value process uses a fixedthreshold value, which causes the filtered image to generate a ringing, pseudo Gibbsphenomenon. In the proposed adaptive threshold method, the threshold value can be adjustedaccording to the image itself, overcomes the disadvantages of a fixed threshold value, andimproves the filtering effect of the phase diagram.3. With multiple speckle patterns to be collected at different times based on the phase ofthe time phase shift extraction algorithm, it is easily affected by the environment, and thereare also disadvantages in measurement efficiency; Although the phase shift method based onspatial light path can be collected at the same time multiple speckle patterns can improvemeasurement efficiency, but its light path is too complex, the actual application is verydifficult. In this paper, electronic shearing speckle interferometer system.based on spatialcarrier phase shift speckle interferometry and Mach–Zehnder is proposed. Shearographyinterferometer based on Mach-Zehnder interferometer system has a very small angle of view because the field geometry. In order to expand the angle of view, interference system with alarge angle of view based on4f system is proposed and used for non-destructive detection ofdefects. The system comprises a CCD camera, a semiconductor laser, Mach-Zehnderinterferometer and4f system. Phase maps are obtained by the improved sinusoidal-fittingmethod and Fourier transform method, respectively, and is used to contain the spatial carrierfringe interference. The interferometer system can control the amount of shear and the spatialcarrier frequency. In this optical system, the imaging lens is placed in front of the Mach-Zehnder interferometer system. the angle of view may no longer be restricted by the Mach-Zehnder interferometer system, only depends on the size of the sensor and the focal length ofthe imaging lens of digital camera, breaking the traditional Mach-Zehnder electronicshearing speckle interferometry system the angle of view the maximum limit of19°, toachieve a large field angle measurement.4. Mach-Zehnder interferometer optical path only use half of the light energy, lightenergy utilization rate is low, when applied to the light-sensitive material, high lightrequirements, the method has some limitations. In order to improve energy efficiency, thispaper proposes a new electronic shearing speckle pattern interferometry system. The opticalpath can take advantage of all the light energy, utilization problem is solved theoreticallyimproving light energy utilization efficiency has improved significantly.5. With the rapid development of the tire and composite materials, non-destructivetesting techniques proposed new requirements. Electronic speckle pattern interferometry has areal-time, high sensitivity, audience measurement and other advantage, the technology hasbeen widely used in non-destructive testing. Based on electronic shearing speckle patterninterferometry system, based on spatial carrier phase shift, electronic shearing speckle patterninterferometry is builded for Nondestructive Testing. With VC++6.0visual programmingdevelopment software to prepare a set of image acquisition and image processing, phase mapis displayed in real time in one electronic speckle non-destructive testing applications. Andthe use of vacuum load and thermal load, this article study of electronic Shearography ofnon-destructive detection technology, tire and composites NDT validation experiments,acquired defect pictures of tires and composites. The results show that this method can fastand accurate assess the material within the pores, delamination and structural quality. The system can be out of the shock station detects and practical.