| Glaucoma is the world’s second blinding eye disease, for a variety of types of glaucoma, there is no prevention method, but if you can treat of early cases reasonable, can save useful visual function. Therefore, early diagnosis is the key to the treatment of glaucoma. Perimeter is the determination of eye vision and medical professional ophthalmic nerve testing instrument. This article mainly aimed at the current advanced projection type automatic perimeter of some of the key technology involved: optical imaging, scanning spherical screen, the cursor area of compensation, the eye fixation monitoring were studied.First, the projection of the perimeter optical imaging system was designed, the characteristics of the optical system presented study is: virtual aperture of the optical distance has a linear relationship with the convertible aperture moved distance; the cursor area has nothing to do with the projection position, the area size depends on the area of the diaphragm and other parameters of the optical system, at the same time the cursor brightness has nothing to do with the size and location of the diaphragm. Validation and optimized using Zemax optical software, finally the optical system imaging quality is better than the eyes inside the perimeter spherical screen cursor identification application requirements.Secondly, the mechanical parts of the optical system used Solidworks2012 to 3D modeling, motion simulation is carried out after completion of the modeling, check whether there is interference phenomenon among the various parts, for interference phenomenon and the special requirement of parts are designed and made mechanical institutions more satisfy the actual needs. Control part used the computer as the upper machine, servo card as lower machine, the application in the control system of step motor, control accuracy to meet the requirements of the project perimeter.Again, for the position of the cursor in the spherical projection screen, position adjustment algorithm is deduced at the same time, in view of the beam in the projected into the spherical screen, the cursor area differ greatly with the theoretical calculation value to study this problem, establish a tapered beam mathematical model of the fellowship with the equation of spherical screen, it is concluded that the cursor in the different position of light spot equation.Finally, the pupil- corneal tracking method is used to establish the pupil solid visual monitoring system, through the system calibration set up the connection between the pupil positions and the spherical screen cursor. In view of the actual vision inspection spherical screen changes occurred in the blind spot coordinate system of two kinds of circumstances, the rotating coordinate system formula derivation and electric bracket was designed.Through the experiment was carried out on the prototype, the vast majority of cursor area control error within 12%, and the most commonly used cursor area error is 7%; The position error in the experiment, the maximum position offset is 0.35 mm, in the cursor illumination experiment, the maximum error is 1.3%, this system meet the requirements of perimeter for vision inspection. |
