Analysis on Effect of Birefringence in an Image Forming Lens of a Laser Scan Unit on Optical Characteristics

In most cases of molding process with glass or optical polymer, it is inevitable to avoid birefringence arisen due to residual internal mechanical stress in a molded material. Even though distribution of the residual stress can be annealed by slow cooling, it has a disadvantage on shape accuracy and manufacturing time. This study mainly analyzes variation in optical performance considering optical phase delay and difference in orientation angles between two principal optical axes due to birefringence. And the simulated optical characteristics are compared with experimental spot profiles from the image forming lens of a laser scan unit, which has specific degree of generation of birefringence. Through this study, we are going to clarify birefringence condition of the image forming lens for a LSU (Laser Scan Unit) to induce degradation in optical performance.