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Analysis of the birefringence distributions in compact discs of polycarbonate
Author(s) -
WimbergerFriedl R.
Publication year - 1990
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.760301403
Subject(s) - polycarbonate , birefringence , materials science , perpendicular , optics , beam (structure) , composite material , position (finance) , zero (linguistics) , physics , geometry , economics , linguistics , philosophy , mathematics , finance
The birefringence distributions in injection‐molded Compact Discs (CD) are determined in radial and tangential cross‐sections and interpreted in terms of the process. The influence of processing conditions is discussed in several examples. It is shown that despite the high birefringence level the retardation of a beam of normal incidence is almost zero due to several compensation mechanisms. One optical axis is almost perpendicular to the surface. The medium, however, is biaxial with the preferential directions depending on the distance from the surface and the radial position. In contrast to a parallel beam, zero retardation cannot be achieved with a convergent beam in injection‐molded polycarbonate disks for that reason.