Study On Method And Technology Of Microscopic Speckle Interferometry

Microscopic speckle interferometry combines electronic speckle interference technology and micro-imaging technology.It is an integrated measurement method that integrates optical,mechanical,electronic,and computer technologies.The research purpose of this dissertation is to use the microscopic speckle interferometry to measure the motion state of micro devices.For different motion modes(such as displacement,deformation,vibration,etc.),we have designed the corresponding microscopic interference dynamic measurement systems to achieve non-contact,fast,real-time,and full-field measurement.These measurement systems have great application potential in the field of microscopic measurement.This dissertation has conducted a comprehensive data review of common measurement methods in the field of microscopy,and studied the development history and research status of micro-interferometry technology.By comparing the advantages and disadvantages of each method,and combining the current measurement requirements,we choose the microscopic speckle interferometry as our research direction.Corresponding studies have been carried out on a variety of key algorithms used in this technology,and four corresponding measurement experiments have been completed by designing optical paths,introducing heterodyne technology,improving optical paths,and proposing vibration measurement algorithms.The main works of this dissertation are as follows:1.The principle of microscopic speckle interferometry is discussed.The structure of the microscopic optical path,the characteristics of speckles,the recording conditions,recording principles,and interference fringe extraction methods of speckle interferograms are introduced.Several key algorithms commonly used in processing interferograms,such as: phase extraction algorithm,phase unwrapping algorithm,image preprocessing algorithm are described in detail.These are the theoretical foundations for the realization of microscopic speckle interferometry imaging.2.Aiming at the problem of real-time measurement of displacement process of micro devices,a set of microscopic speckle interferometry system based on Linnik microstructure is designed.The system is used to measure the single-point displacement and multi-point displacement process of the microcantilever.The displacement information is extracted from the time series speckle interferograms by using algorithms such as image preprocessing,phase information extraction and phase unwrapping.Then,the validity of the measurement results was verified by the grating ruler and the finite element analysis,and finally the real-time,full-field,non-contact measurement of the displacement process of the micro cantilever was realized.3.Aming the anti-interference problem of the microscopic speckle interferometry system,heterodyne technology is introduced into the interferometry system,and a set of heterodyne microscopic speckle interferometry system is built.Through the double transverse electric field effect of the lithium niobate crystal,a stable and adjustable heterodyne carrier frequency is obtained.By loading the measurement signal on the heterodyne carrier frequency,the interference of environmental noise can be effectively avoided,and the noise immunity of the system can be improved.4.Aiming at the problem of the small field of view of the above systems,a large-field microscopic speckle interferometry system based on an improved Mach-Zehnder structure is designed.The new measurement system expands the field of view from a circular with a diameter of 2.4 mm to a rectangular with an area of 6 mm×8mm while ensuring a higher resolution;and the new system can reduce the reflected coherent noise of the system and further ensure the high image quality.5.On the basis of realizing the measurement of the dynamic displacement of the micro device,in order to realize measurement of the micro vibration,the dissertation introduced the orthogonal phase distribution method on the basis of micro-interferometry technology,and proposed the corresponding amplitude algorithm,and a set of microscopic speckle interferometry vibration measurement system is designed.The effectiveness of our method is proved by the vibration measurement of the interference of the mirror surface and the rough surface of the micro-device.Compared with the commonly used vibration measurement methods,the experimental device and calculation process of our method are much simpler,and the measurement process does not need to be scanned,which can achieve full-field measurement.Finally,the main work content and research results of the dissertation are summarized and prospected.