Diffractive retarders fabricated from gratings in isotropic materials are analyzed by rigorous coupled wave analysis. Calculations show it is difficult to obtain substantial retardance with isotropic phase gratings. Even for an aspect ratio of two, diffractive retarders have a small retardance, < λ/12. Thus it is generally impractical to fabricate quarter wave retarders, much less half wave retarders in plastic or molded glass for example. The dispersion of these gratings is compared to the conventional materials used in the majority of retarders and is found to be very similar. Thus these gratings add little in terms of helping to achromatize retarders
We report on an axially asymmetric beam shaping optical system including a diffraction grating. This optical system
compensates the astigmatism introduced by change in wavelength of a light source or change in ambient temperature.
The phase function of the diffraction grating is determined to minimize the astigmatism by equalizing variation in
distance from a light source to an image point on xz plane and variation in that distance on yz plane. This beam shaping
optical system relates to a laser printer having an axially asymmetric profile.
Recent improvements of plastics optics performance and manufacturing technology of plastics lenses have resulte din rapid applicationfo plastics otical elements. On eof the factors indelyaing the applications of the plastics oticalelements is the existence of birefringence in palstics lenses. It gives us a challenge to resolve th proboem so that the plastics oticalelements can achieve much higher levels of performance. It is generally recongized that the mechanism of birefringence generation is relevant to the resin behaviors during the injection molding process. If this mechanism is fully understood by flow analysis, it may be a great contribution to the fabrication of plastics optical elements. However, convetnioanl two-dimensional flow anlaysis on onjection molding fails to graps th ephenomena of birfringence. in this paper, we have successfully indentified some phenomena on onjection molding that are closely related to the gneratioof birefringence.We anlayzed th ephenomean in detial sin filling pakcing, and colling processes durin th einjection modlin process using tthree-dimensional CAE system, called 3D TIMON. The anlayzed rsults were confirmed experimentally and theyenabled us to predict the generation of birefringence by CAE analysis.