Image restoration for optical zooming system based on Alvarez lenses

Abstract

Alvarez lenses are known for their ability to achieve a broad range of optical power adjustment by utilizing complementary freeform surfaces. However, these lenses suffer from optical aberrations, which restrict their potential applications. To address this issue, we propose a field of view (FOV) attention image restoration model for continuous zooming. In order to simulate the degradation of optical zooming systems based on Alvarez lenses (OZA), a baseline OZA is designed where the polynomial for the Alvarez lenses consists of only three coefficients. By computing spatially varying point spread functions (PSFs), we simulate the degraded images of multiple zoom configurations and conduct restoration experiments. The results demonstrate that our approach surpasses the compared methods in the restoration of degraded images across various zoom configurations while also exhibiting strong generalization capabilities under untrained configurations.

A varifocal augmented reality head‐up display using Alvarez freeform lenses

“…The phase distributions of the basic paraxial form of Alvarez lenses are given by Equations () and (). Figure 2A depicts the fundamental faceted shape 29 where Z is the surface sag of the lens; A is the coefficient that determines the ratio of displacement to optical power when the lenses move laterally; D is the tilt term that minimizes the surface sag; and E represents the center thickness of the lens, which is employed to ensure the thinnest portion to have sufficient mechanical strength.…”

“…Unlike the traditional zoom lens, Alvarez lenses adjust the focal length by sliding two lenses perpendicular to the optical axis. [27][28][29][30] The phase distributions of the basic paraxial form of Alvarez lenses are given by Equations ( 1) and (2). Figure 2A depicts the fundamental faceted shape.…”