Automatic Calibration Design Of Image DNA Chip Scanner

Image DNA chip scanner is a rapidly rising detection technology in the research of biomedical.Compared to the laser confocal method,it possesses advantages of simple and efficient which can be widely used in gene structure exploration,new drug development,disease treatment and other fields.Domestic researches on image DNA chip scanners have been slower and less frequent,resulting in domestic instruments that are not only structurally complex but also costly.Therefore,the research group designed and developed the CCD-based DNA chip scanner which Uses high-power LED as the excitation light source and solves the stray light problem by an appropriate light path design.Aiming at tackled the problem that the instrument is easily out of focus and difficult to focus manually,this paper realized the focusing structure of the scanner and investigated the related algorithms such as Image sharpness evaluation function and Focal length search strategy.The main work of this paper are as follow:(1)This chapter Introduce the principle of DNA chip fluorescence effect and two common scanner detection methods,and then analyze the concepts which are related to focal length calibration,lens imaging model,point spread function and optical transfer function.(2)The overall structure of the scanner was designed,a suitable high-power LED was selected.In addition,99.95%of the stray light in the light path was eliminated through the combination of light entry design,extinction darkroom,aperture and dimmer.Subsequently,this paper designed the image automatic calibration solution according to the advantages and disadvantages of different focusing methods and the actual situation of the scanner.The designed solution Implemented the hardware structure by adding stepper motor and its drive,driving wheel and timing belt On the original basis.(3)In order to select the suitable evaluation function for the designed scanner,The dissertation studied on Algorithms which are relevant to Automatic focal length calibration,and then compared the common seven image sharpness evaluation functions on the basis of its sensitivity,noise resistance and real-time performance.As to the focus search strategy,a focusing step size optimization method was proposed on the basis of improved Hill Climbing.The total number of focusing steps are reduced and the test result shows focusing efficiency is improved 16.8%by using the obtained coarse focusing step.(4)For the sake of measuring the performance of scanner scientifically,the accuracy,repeatability error and real-time performance of the auto-calibration are analyzed,then the detection sensitivity and resolution of the scanner have also been evaluated.Subsequently,this dissertation compares the results of Fluorescence lattice image between designed scanner and Capitalbio scanner,the problems and improvement of the designed scanner are discussed at the end of this chapter.The experimental results show that the accuracy of auto focus calibration is better than the way of manual focusing,the repeatability error is 2.1%and the shortest calibration time is 18.72 seconds.The designed scanner exhibits a detection sensitivity above 1.12 flour/um2.the resolution reaches to 10.05μn and the detection consistency coefficient R2 is 0.95 compared with Capitalbio scanner toward a Fluorescence lattice of the Genetic defect chip.