Investigation of Polishing Characteristics for Aspherical Lenses Manufacturing

Nerijus Kadzevičius,Mindaugas Jurevičius,Ieva Švagždytė,Artūras Kilikevičius,Justinas Gargasas

doi:10.5755/j01.mech.26.5.24572

Abstract

There were used the spherical lenses in industry conventional for long time, but new types of lenses were created during innovation processes. One type of lenses is aspherical. Two main parameters describing quality of aspherical lenses are accuracy of the form shape and surface roughness. These parameters can be obtained after last operation – polishing. Technical parameters that give the biggest influence to form shape and surface roughness were investigated in this experiment and optimal technical parameters for polishing process were established. Melted quartz ,,UVFS” was used in this research, investigations were carried out according by full factorial design. Five axis CNC machine Schneider SCPA100 was used for polishing and profilometer Nanoscan 855 was used for measurements. After analysis of results it was found out that speed of rotation and penetration depth are the most important factors in polishing process. For getting the best shape it’s necessary to use the smallest chosen values of speed of rotation and penetration depth, for getting the best surface roughness polishing parameters changing conversely. The smallest value of surface roughness Rz was 0.06 µm, and shape deviation was 2.6 µm. Optimal polishing parameters for the best quality of aspherical lenses was provided.

Highlights

Fabrication of optical elements by machining results in surface irregularities and a certain roughness
Any manufacturing inaccuracies damage the entire operation of the optical system due to excessive form deviations, light, or laser beam propagated through a lens, prism or other optical element that can cause distortion, image irregularity, or system damage in the worst case, and this is especially true for high power lasers
Spherical lenses were used in conventional industry for a long time, but new types of lenses have been created during the innovation processes

Summary

Introduction

Fabrication of optical elements by machining results in surface irregularities and a certain roughness. It is important to examine what technological parameters would reduce the resulting inaccuracies during manufacturing, as the most difficult operation in the production of aspherical lenses is polishing. The demand of lenses of this type is constantly increasing (they are used in cameras, lasers and other optical systems); and it is a problem to optimize the manufacturing process for aspherical lenses. Various parameters are important to control the polishing process if it is necessary to get high quality of the optical element. Two main parameters describing the quality of aspherical lenses are accuracy of the form shape and surface roughness. When the polishing pressure increases, the coefficient of friction increases [3]; and when the rotation speed and size of abrasive grains increases, the surface roughness deteriorates [4 – 7]. A research on the polishing characteristics for aspherical lenses from fused quartz manufacturing has been conducted and optimal polishing parameters for the best quality of aspherical lenses are provided in this article

Object of the research

The experimental setup

Results and discussion

Conclusions

Summary