Study On Rheological Properties Of Optical Micro V-groove Element In Molding Process

Molding of optical element is an effective replication technology which has become a hot research around the world;the molding fabrication of optical aspheric components and microstructure components is the main research field at present.Compared with the optical aspheric elements,there are lot difficulties such as uneven filling and low filling rate during molding of microstructure optical elements due to their uneven shape,the number of arrays,the small size of the structure,and so on.In this paper,the rheological properties of glass during the molding of micro V-groove optical element are studied,and the main research works are following:According to the rheological theory,the constitutive equations and model parameters suitable for describing the rheological model of the molten optical glass are studied.Taking the relaxation time spectrum into consideration,the computational method how to calculate the approximate solution of the relaxation time spectrum through the physical parameters of materials by experiments is obtained,and the time variation curve of the material relaxation time is obtained by static dynamic viscosity and static elastic modulus after linear transform in the case that the material parameters couldn't be obtained by experiments.In order to obtain the static dynamic viscosity parameters of the molten optical glass,the dynamic viscosity-temperature curve and the flow-temperature curve of the material were experimentally investigated.Experimental results show that the dynamic viscosity of the molten glass decreases with increasing temperature;and the flowability of optical glass increases with increasing temperature.The dynamic viscosity curve decreases abruptly when the temperature of optical glass is more than the transition temperature Ts.The experimental method of obtaining the time curve of the relaxation time based on H-QK3L optical glass by using static dynamic viscosity and static elastic modulus is described in detail.Finally,the filling effect of the micro V-groove structure of the array was simulated by using the MSC-Marc finite element software.The simulation results show that the V-groove filling rate is gradually increased with the increase of temperature and the flowability of the molten glass during the molding process.The characteristics of the V-groove filling in the boundary position are mainly carried out.The actual filling profile of micro V-groove structure is obtained by the molding experiment;the uniform filling and the low filling rate occurs in the experiment.The phenomenon of uniform filling and the low filling rate is regarded with relation to the rheological properties of the optical glass;and based on the simulation results;this phenomenon is analyzed from the temperature effect and position effect.