| As an important organ for obtaining external information,eyes receive external radiation and response to the body's multiple tissues.Eyes' measurement can not only find eye diseases,and even some of the disease can be diagnosed early.The precise measurement of pupil diameter and its change is important for the evaluation of ophthalmologic surgery and the diagnosis of various diseases.The traditional detection methods are qualitative testing.The testing steps are complex,and.the subjective influence is larger.It's important technical means to measure pupils' size objectively and accurately with the pupil detector based on optical telecentric imaging and subsequent digital image processing.In this paper,the optical system of the pupil detector with single CCD,prisms and telecentric lens is proposed.The pupil diameter can be precisely detected and analyzed dynamically using a small aperture telecentric optical system and a CCD according to a digital image processing algorithm.The optical system parameters are determined according to the overall scheme.Zemax is used to design the refractive and refractive-reflective optical imaging system.After a comprehensive comparison,the refractive object telecentric optical system is chosen—the scheme of pupils detector.Tolerance analysis is carried out with key criterions MTF and distortion.Finally,a set of system tolerances is determined,which is easy to process.Besides this paper calculates the paraxial model of the lighting path,and simulates the lighting path with Lighttools.The experimental platform is built,and the developed prototype is calibrated by standard circular model.The result of experiment shows that it is suitable for wide range of interpupillary distance(55-75mm).Single pupil imaging distortion is low(less than 0.02%),and diameter measurement accuracy up to 0.05mm.Besides this system ueses only one CCD as imaging device,compared with the apporach of imaging with two CCDs,which greatly reduces the costs. |
PDF Full Text Request