| 主权项 |
1. A method for designing an off-axial optical system with freeform surface, the method comprising:
step (S1), establishing a first initial system, wherein the first initial system comprises a plurality of initial surfaces, and each of the plurality of initial surfaces corresponds to one freeform surface of the off-axial optical system; step (S2), a Nth freeform surface of the off-axial optical system that need to be solved is selected, wherein N=1, keeping the plurality of initial surfaces unchanged, selecting a plurality of feature rays Ri(i=1, 2 . . . K), calculating a Nth plurality of intersections of the plurality of feature rays Ri(i=1, 2 . . . K) with the Nth freeform surface point by point based on a given object-image relationship and a vector form of Snell's law, wherein the Nth plurality of intersections are a Nth plurality of feature data points Pi(i=1, 2 . . . K) of the Nth freeform surface; and obtaining a Nth equation of the Nth freeform surface by surface fitting the Nth plurality of feature data points Pi(i=1, 2 . . . K), wherein the Nth equation of the Nth freeform surface comprises a Nth base conic term and a Nth freeform surface term; step (S3), keeping all the Nth freeform surface obtained in step (S2) and some of the plurality of initial surfaces that does not corresponds to the Nth freeform surface unchanged, and selecting N as N=N+1; step (S4), repeating the step (S2) to step (S3) until all freeform surfaces of the off-axial optical system that need to be solved are obtained, and obtaining a before-iteration off-axial optical system; and step (S5), taking the before-iteration off-axial optical system obtained in step (S4) as a second initial system for an iteration process, and obtaining an after-iteration off-axial optical system by multiple iterations. |
