Large-scale achromatic flat lens by light frequency-domain coherence optimization

Abstract

Flat lenses, including metalens and diffractive lens, have attracted increasing attention due to their ability to miniaturize the imaging devices. However, realizing a large scale achromatic flat lens with high performance still remains a big challenge. Here, we developed a new framework in designing achromatic multi-level diffractive lenses by light coherence optimization, which enables the implementation of large-scale flat lenses under non-ideal conditions. As results, a series achromatic polymer lenses with diameter from 1 to 10 mm are successfully designed and fabricated. The subsequent optical characterizations substantially validate our theoretical framework and show relatively good performance of the centimeter-scale achromatic multi-level diffractive lenses with a super broad bandwidth in optical wavelengths (400–1100 nm). After comparing with conventional refractive lens, this achromatic lens shows significant advantages in white-light imaging performance, implying a new strategy in developing practical planar optical devices.

Revolutionary meta-imaging: from superlens to metalens

“…To further increase the DoF in design, a new class of diffractive lenses, denoted free-form MDLs, has been proposed in recent years [185][186][187][188][189][190][191][192][193][194][195][196][197] . The height profile of the free-form MDL is irregular and quite different from that of conventional diffractive lenses, as shown in Fig.…”

“…21(j)] or at several discrete wavelengths with the same interval [red line in Fig. 21(j)] [185][186][187][188][189][190][191][192][193][194][195][196][197] . The free-form MDL is designed by inverse design as introduced in Section 3.4.…”

Perspectives on Imaging with Diffractive Flat Optics

“…Note that R is simply the radius in the focal plane that is used to compute focusing efficiency. false⟨ S false⟩ R = ∫ 0 R S ( r ) I d ( r ) r nobreak0em0.25em⁡ normald r ∫ 0 R I d ( r ) r nobreak0em0.25em⁡ normald r = η ( R ) η d ( R ) S ( 0 ) ≤ false⟨ S false⟩ R ≤ 1 The latter is proved in the Supporting Information, and it readily shows that high strehl ratio, S (0) inevitably implies high focusing efficiency, η( R ). Unfortunately, there have been some reports in recent literature, which claim high strehl ratio and relatively low efficiency, , and we believe many of these measurements have been misinterpreted. Often, the strehl ratio is computed using only a small range of the recorded PSF, and as a result, it is highly overestimated.…”

Advance of large-area achromatic flat lenses

“…In 2022, Tao Li from Nanjing University and Guixin Li from Southern University of Science and Technology worked together to propose and experimentally realize non-ideal achromatic flat lenses for a large-scale diameter of up to 10 mm 23 . They solved the issues in two steps.…”

“…The realization of large-area flat lens applications 23 successfully displays excellent potential and perspective of the achromatic flat lens. True color and continuous wide-band are primary for optical imaging.…”