RGB 레이저 가시화를 위한 축대칭 구면 f-θ 렌즈 설계 및 프로젝션응용

A Study of f-θ Lens Design for Axisymmetric Spherical Surface for RGB Laser Display and its applications

The design of a telecentric f-θ lens with a field of view (FOV) 30° and an effective focal length of 1000㎜ is presented. The optical stop is placed at the front plane and the design is based on a geometric ray tracing technique, and the designed system consists of a series of convex and concave lenses. The designed f-θ lens showed a considerable reduction in weight with a simplified structure and resulted in a good performance in the designated FOV. Detail analysis of rays is also presented. 653㎚ (red laser), 586㎚ (green laser), and 468㎚ (blue laser) were simulated as a light source and image illuminating source. The developed optical design requires 7 pieces of lenses made of SF1, N-FK56, N-LAK33, and BK7 glass materials. With optimal parametric design, the effective focal length was calculated to be 974.839㎜ which is very close to the initial design target. For the manufacturing purpose, the dimensions of lens curvature and thickness were truncated with error ranging 0.1% to 3.2%. As a result, the overall error was calculated to be 3.2% which can be still tolerable for display, laser material, and machining processing.