Precision Injection Molding And Form Compensation Of Optical Freeform Element For Laser Scanning System

Laser scanning system can convert light high-speed rotation quantities to motion quantities of image plane.It is widely used in electronics,communication,medical treatment and other fields.Laser scanning optical system generally consists of many polymer optics components,and it adopts optical free-form surface devices to guarantee precise control and focus of light.F-theta scanning lens is the core optical component of a laser scanning unit.It needs high form accuracy to meet performance requirements of laser scanning systems.So far,Precision injection molding is the most effective method for polymer optical component mass production.However,errors from geometrical modeling,mold tool insert machining and shrinkage of injection molded part will result in F-theta lenses form accuracy not meeting the design requirements.Thus it is necessary to guarantee a high optical quality,a form accuracy and low residual stress optics in precision injection molding process.In this paper,we discuss the optical design of laser scanning system with overall structure and the precision injection molding techniques in the significant optical component,namely F-theta lenses and its compensation of form accuracy.The research contents are listed as follows:1.The work investigates the latest progress of laser scanning system and precision injection molding technology,and then improves the design of laser scanning system.The design lays special stress on core optics F-theta lens which affect the laser scanning unit optical performance,including surface selection and surface’s mathematical model.Then it designs the mold for injection molding combining with structural characteristics of F-theta lenses.2.The main molding process parameters influencing the F-theta form accuracy is obtained by simulation and analysis of F-theta lens precision injection molding process which is carried out by using Moldex3 D.And through the injection molding experiment,optimization parameters are verified.3.The work analyzes the form error of F-theta lenses in precision injection molding process and three form compensation methods are proposed: Change of the F-theta lenses material;3D volume compensation based Moldex3D;form compensation based on measurement and data fitting.