Research On Differential Confocal Imaging Microscopy And Distortion Correction Methods

Differential confocal microscopy with its output signal stability, wide linearrange, high resolution, which has played a great role in the fields of biology,medicine, microelectronics, detection of ultra-precision machined surfacemeasurement. Scholars have done a lot of research on how to improve and expandthe differential confocal microscopic imaging, and the imaging quality evaluationstandard system has been developed. Although the differential confocal microscopyhas significant advantages, however, because of the imaging three-dimensionaldistortion, error, instrument measurement capability, ultimately affect the imagingquality.Topic ‘Research on differential confocal imaging microscopy and distortioncorrection methods’ mainly refer to solve the above problem, analyze differentialconfocal microscopic imaging theory with three-dimensional imaging capability,conduct analysis of differential confocal imaging characteristics of straight edge,build a mathematical model, and complete differential imaging distortion correctiontechnology research. The main research work is as follows:First of all, based on Fourier optical theory, analyze detecting sensing principleof confocal properties of the Fourier transform lens, analyze confocal technique, thetraditional differential confocal technology and improved differential confocalsensing mechanism. Analysis results show that the signal strength, improveddifferential confocal system is not affected by the reflectivity disturbance, only to bedecided by side distance of focus position.Secondly, analyze the pupil function and the optical transfer function based onthe theory, construct the mathematical model, frequency domain analysis of imagingcharacteristics of straight edge, focus on the edge position determination, step heightand the relationship between defocus detector and straight edge image gradient, anddiscuss the defocus state straight edge imaging confocal system. Analyze differentialconfocal system step edge imaging characteristics, and analysis results show that,the pupil modulation cannot enhance the straight edge of image, edge position asintensity of edge response amplitude of the1/4-1/3, the edge image intensitygradient.Again, using the linear characteristic of differential confocal system, thedifferential confocal sensor based on the principle of spatial phase shifting, relyingon the larger sampling intervals to achieve high axial resolution, and using only onedetector to ensure the consistency of the differential response curve. Theestablishment of mathematical model, and discuss the influence of axial offset on the imaging characteristics of the detector, the simulation results show that, theoptimal axial offset differential confocal pinhole of5.21system.Finally, build the differential confocal microscopy3D measurement system,and conduct related experiments. Applied with measuring grating differentialconfocal system, and the measurement results were compared with the calibration ofatomic force microscopy, analyze and compared with spatial phase shift differentialconfocal measurement method and the centroid measurement results. Experimentresults show that, compared with the centroid method, spatial phase shift differentialconfocal measurement standard deviation is less affected by the sampling interval,and the sampling interval is greater than50nm, the advantage is more obvious.