The Process of Interior Progressive Addition Lens
The characteristics of Progressive addition lens (PAL) are described in this paper. Theoretical analysis of advantages of Interior PAL is put forward, and the measurement results of Interior PAL are given. Theoretical and measurement results are consistent by comparing Interior PAL and Exterior PAL. Then the working procedures of freeform CNC machine of making Interior PAL are introduced concisely. Also, the experiments were carried out to analyzing the processing results in turning and polishing. From the results, it is explicit that the lens’ form accuracy is controlled in turning and lens’ better surface finish can be obtained in polishing. The factors affecting surface roughness are discussed explicitely based on experiment. The effects of lens material and cutting speed on surface roughness in turning were investigated. The experimental data show that better surface finish can be obtained by using lens material with higher rigidity and using higher cutting speed. Polishing time and pressure influence surface roughness signally in polishing. The reasonable ranges of polishing parameters which could bring about better surface finish are obtained in the experiment. The ranges of polishing time and polishing pressure are 50s—100s and 0.3bar—0.6bar (1bar=0.1MPa) respectively.
Guo Fan JIN, Wing Bun LEE, Chi Fai CHEUNG and Suet TO
L. L. Qin et al., "The Process of Interior Progressive Addition Lens", Key Engineering Materials, Vols. 364-366, pp. 1054-1060, 2008