Researches On Parallel Confocal Imaging System With Micro-lens Array

Higher measurement accuracy, wider measurement range, and higher measurementefficiency, are always the Olympic goal pursued by engineers and technicians. As awidely used3-dementional microscopic measurement, confocal microscopy technologyhas been booming for decades, its accuracy and measurement range have made aconsiderable development, but when to complete a3-D measurement, traditionalconfocal microscopy needs to scan a large space point to point, it leads to that theimaging speed of traditional confocal is much slower than other3-D measurementmethod. To cover those problems, parallel confocal imaging technology with micro-lensarose. However, there are still some problems in parallel confocal imaging system,which includes:1st) it is easy to be interference by drift of the incident beam orchanging of specimen’s reflectivity, which restricts confocal microscopy’s widespreadapplication.2nd) in the current workmanship of micro-lens, it faces a bottleneck thatimproving the density of micro-lens with good optical properties. Problems list abovehave been becoming a considerable issue in parallel confocal measurement system.The subject“research on parallel confocal imaging system with micro-lens”,according to the problems proposed above, this paper by means of theoretical modeling,computer simulation and building the experiment setup and other research methods,aims to cover the problem1by changing the detection method and the problem2bychanging the illumination method. The research of this dissertation could providecertain reference to develop the parallel confocal imaging system, and provided with awide application prospects in life sciences, semiconductor industry and micro-electronicmechanical system.The major research contents in this dissertation are as follows:1.2-zone pinhole detection method has been proposed. Take the maximum of thespot as the center, the method marks the detection optical spot into the central zone andannulus zone, instead of the central optical intensity, taking the ratio of the opticalintensity in the two zones as the output of the confocal detector. This dissertationanalyze the feature of the2-zone pinhole detection method in theoretically, through thecomputer simulation, it shows that the2-zone pinhole detection method has morenarrow full width at half maximum of axis response, especially, near the focal plane, itcould provide with higher axis detection sensibility compare to traditional pinholedetection method, which makes it more precise to find the position of focal plane.Meanwhile, the output is independent of the incident beam and the specimen’s reflectivity, so2-zone pinhole detection method could suppress the influence of the laserintensity drift or changing of specimen’s reflectivity.2. The method which takes the1/2fractional Talbot image plane as theilluminated plane has been proposed. As a typical object with periodic transmittance,the micro-lens, under the illuminate of a coherent-light, some position behind it willappear spot array in sequence. By means of the features that the period of1/2fractionalTalbot image plane is half of that in focal plane of micro-lens, this method takes the1/2fractional Talbot image plane as the illuminated plane instead of the focal plane ofmicrolens, to achieve a4times illumination density higher than that with focal plane.Finally, an experimental setup has been built to validate the methods and theory.By means of several experiments, some tests and researches of the experiment platformwere conducted. the experiment results show that:1) in2-zone pinhole detectionmethod, under the same experiment conditions of NA=0.45for the detected objective,NA=0.1for the collector, illuminated wavelength λ=632.8nm, and CCD as the detector,in the200nm nearby the focal plane, the2-zone pinhole detection method couldachieve10nm resolution in axis which cannot be achieved by traditional pinhole outputway.2) The same experimental condition, the FWHM in axis response of2-zonepinhole detection method could reach2μm minimum, which is44%narrower than thatin traditional pinhole output,3.6μm.3) The2-zone pinhole could suppress theinfluence of the laser intensity drift or changing of specimen’s reflectivity.4)thismethod takes the1/2fractional Talbot image plane as the illuminated plan, the period ofthe spot array becomes1/2of which use the focal plane of the micro-lens, the densityincreases to4times, meanwhile, the consistency of the axis response in spot array alsogets improved，it is also shows that the FWHM of the axis response can be improvedby2-zones pinhole detection method when using the1/2fractional Talbot image plane asthe illuminating source.