Research On Key Technology Of Surgical System For Femtosecond Laser Cataract Surgery

Femtosecond laser technology has been widely used and developed in the field of ophthalmology,especially the success of femtosecond laser assisted cataract surgery,which is considered a major breakthrough in the medical field.The core technology of femtosecond laser cataract surgery system is to realize the control and processing of femtosecond laser beam.In this paper,the key technology of femtosecond laser cataract surgery system is studied,and some research results of the key technologies of laser beam focusing and scanning control have been made.Focusing is that focusing on the laser beam emitted by the femtosecond laser,enabling laser energy to accumulate in small laser spots,and achieving "sharp operation of the laser knife".Scanning control is that achieving the motion control of laser beam,so that the laser can be controlled in three-dimensional space,and moving according to the designed trajectory,thus achieving the precise cutting path of laser.In this paper,the femtosecond laser assisted cataract surgery system was designed,which laid the foundation for the subsequent research of the key technology of femtosecond laser cataract surgery system.Based on the theoretical analysis of femtosecond laser cataract surgery system,the whole system is designed in a modular way,and the optical control system of the surgical system is designed.Finally,an eyeball fixation device was designed,the contact surface of device and the eye is spherical,and the negative pressure was used to fix the eyeball,furthermore,the experimental was conducted to verify that the device designed in this paper could be used to observe and fix the eyeball object.Based on the above,the analysis shows that the most important part of the optical system is to achieve the focus of femtosecond laser and scanning movement in space,thus the accurate and efficient surgical operation on the eyeball of cataract patients can be achieved.So,in this paper,a laser scanning platform was designed.The work of specific program design,work space determination,selection and structural design etc.were achieved and completing the software and hardware design of scanning platform control system,thus providing a perfect hardware and software equipment basement to achieve the motion control of beam.Again,the study of the aspheric lens design method was conducted for the realization of the laser beam of small spot and long focal length focusing.The aspheric lens design methods based on the principle of optical path length and ZEMAX design ware studied respectively,and examples of aspheric lens design was given.Then,the scheme based on the ZEMAX design was selected and achieved the processing of the aspheric lens,also the focusing effect of the designed lens on the femtosecond laser was verified by experiments.Finally,according to the needs of femtosecond laser assisted cataract surgery incision,the surgical incision trajectory was designed.A spiral-shaped laser-assisted scissor nucleus trajectory is proposed,which can achieve different cutting effects by changing different helix parameters,and thus avoiding the trouble of choosing different methods.A "Jagged"self-closing cornea incision was proposed,which was better than the traditional cornea incision.The corresponding trajectory parameter expression was solved by the proposed trajectory,and the mathematical model was established,and the validity of the trajectory parameter equation was verified by MATLAB and the trajectory was verified.Finally,atrajectory ablation experiment of the scanning platform was carried out by wavelength 532nm laser,which verified the feasibility of the scanning platform designed in this study.