Design And Research Of Refractive Test System Of Refractometer Based On Raspberry Pi

Eyes are the most direct means for human beings to observe the outside world.When there is ametropia,the refractometer refractive detection system is needed for real-time detection to prepare for the subsequent refractive correction.Therefore,the refractive detection system must have the characteristics of high accuracy and high stability.From the current development of optometry,most of the refractive detection systems in the domestic market rely on imports.Although there are domestic companies carrying out independent research and development,there are still some gaps in technology and hardware with foreign products,which can not quickly seize the market.Therefore,it is great significance to study the fast and high-precision refractive detection system.In this paper,raspberry pi is used as the main processing module of the system and combined with image processing technology to optimize and improve the algorithm in the refractive detection system.The research content mainly includes the system’s center positioning of the human eye,the research on focusing algorithm of human eye image,the realization of Automatic eye center alignment and focusing technology,and refractive parameter detection of the human eye,as follows:Positioning the center of the human eye: spot center location algorithm based on the traditional,a method of spot center positioning is proposed that combines double filtering of spots in the image and image space moment algorithm,and use the ellipse fitting algorithm to fit the center point of the target spot,the center of the ellipse is calculated as the center of the human eye.Through the comparative experiment with the traditional center positioning algorithm,it is verified that the eye center positioning algorithm has the advantages of strong anti-interference,higher accuracy and strong real-time performance.Focusing on human eyes: A focusing algorithm based on the target spot gray distribution and edge features of double focusing criteria is proposed.According to the focusing formula derived from the algorithm,the automatic alignment and focusing technology of the optometer to the center of human eyes is realized by using the reliability of the stepper motor with threeaxis linkage.Measure the refractive parameters of the halo image reflected by the human eye: By summarizing the inapplicability of the traditional skeleton extraction algorithm in this paper,an adaptive skeleton point extraction algorithm based on gray transformation is proposed to extract the skeleton points from the measured ring images.And use the ellipse fitting method to fit the skeleton points,then calculate the corresponding refractive parameters.Compared with traditional algorithms,it has more accurate parameter measurement and faster detection speed.The corresponding software design was completed on the main processing module of the system(Raspberry Pi),and the above algorithm was tested on the software,which improved the integrity of the system.which improves the integrity of the system.The results show that the refractive detection system has higher accuracy,faster detection speed and higher automation level for the detection of refractive parameters of the human eye,and meets the needs of computer refractor for detection accuracy and real-time performance.