Study Of Interference Microscopic Imaging Technology With Two-window

With the development of technologies such as micro-electronics,micro-optics,micro-mechanics and bioengineering,higher requirements are demanded for 3D microscopic imaging.The traditional contract and high precision 3D measurement technology suffers from problems of slow measurement speed and destruction of surface under test and probe caused by contract force.Although the optical methods such as confocal microscopy can achieve non-contract measurement,problems of slow measurement speed and complication of system are still exist for the point scanning is adopted to improve the measurement precision.With the advantages of whole-filed,quantitative and non-contract measurement and no special treatment to specimen,interference microscopic imaging technology has been applied to rapid 3D microscopic imaging as an extremely important test and analysis tool,However,studies on improving system stability,real-time ability and so on are still hot topics in interference microscopic imaging field at home and abroad,and have important academic and practical values.The subject "Study of interference microscopic imaging technology with two-window" is to develop new interference microscopic imaging techniques with good stability and high real-time ability based on two-window common-path interferometry.Quantitative interference measurements are achieved by introducing high speed temporal phase-shifting,simultaneous phase-shifting and carrier phase-shifting interferomtries.And the measurement efficiency,utilization of field of view and spatial bandwidth of camera are taken into consideration.Furthermore,microscopic imaging technique is adopted to improve the lateral resolution of system.Thus,it provides new techniques for interference microscopic imaging with high efficiency,high resolution and good stability.The application of this study in micro surface topography,micro optical elements and biological cells is prospective.The main contents of this study are as follows:With the aim of achieving high precision and rapid measurement,this paper presents a two-window temporal phase-shifting technique based on DMD(Digital micromirror device)with the analysis of working principle of two-window common-path interferometry.It can ensure the utilization of field of view and spatial bandwidth of camera.At the same time,with the ability of high speed spatial light modulation of DMD,it can implement high precision and rapid phase-shifting when translating the grating.With the analysis of interference characteristics of different grating diffraction orders,this paper presents a two-window beam-splitting simultaneous phase-shifting technique based on beam-splitting of "grating + non-polarizing beamsplitter" and polarizing phase-shifting.The spectrum of incident light,including object and reference waves,is diffracted into 0 and ±lorders by the grating.Then,with the beam-splitting and polarizing phase-shifting,four phase shifted interferograms with uniform contrast can be obtained in one camera shot.So,the real-time measurement can be achieved while the spatial bandwidth utilization of camera can be ensured.To reduce the complication of system,this paper presents a tri-window simultaneous phase-shifting technique based on two-window common-path interferometry.By changing two-window aperture into tri-window aperture and adjusting the parameters,three phase shifted interferograms can be obtained in one camera shot.There is no other elements of beam-splitting and phase-shifting required,so,the system structure is greatly simplified,while the spatial bandwidth utilization of the camera and real-time ability can be ensured.To compromise the system real-time ability and field of view utilization of camera,this paper presents a two-window two-shot phase-shifting technique based on comparative analysis of temporal and simultaneous phase-shifting.Two polarizer with angle difference 45° are used to modulate interferograms in the output plane.Two phase shifted interferograms are obtained in the first shot,then,an unknown phase shift is introduced by translating the grating,and another two phase shifted interferograms are obtained in the second shot,thus,the phase under test can be retrieved using the phase retrieval algorithm from four phase shifted interferograms.So,it provides an effective tool for interference microscopic imaging with high speed and high utilization of field of view and spatial bandwidth of camera.With the analysis of two-window carrier interferometry,this paper presents a two-window parallel two-step carrier phase-shifting technique.Combining polarizing phase-shifting,this technique can obtain two carrier phase shifted interferograms in one shot,and eliminate the dc term of interferograms using subtraction process.So,the spatial bandwidth of camera can be optimized while the real-time ability of system is ensured.Finally,based on studies on techniques presented above,the microscopic imaging system is introduced to improve the lateral resolution of system,and corresponding experimental setups are build to implement whole-field 3D measurements of several different types of phase object.