Gradient-index Alvarez lenses

Lippman, David H.; Schmidt, Greg; Bentley, Julie; Moore, Duncan T.; Akhavan, Hooman; Harmon, John W.; Williams, G. M.

doi:10.1364/ao.487089

Cited by 6 publications

(3 citation statements)

References 31 publications

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“…Specifically, as shown on the left of Figure 2A, Alvarez lenses suffer from freeform aberrations induced by the non‐negligible spacing between the two freeform surfaces, which is, however, indispensable for surface clearance upon translation 28 . In our AR‐HUD scenario, the necessity for large‐aperture lenses leads to considerable variation in the surface sag.…”

Section: Methodsmentioning

confidence: 96%

“…Specifically, as shown on the left of Figure 2A, Alvarez lenses suffer from freeform aberrations induced by the non-negligible spacing between the two freeform surfaces, which is, however, indispensable for surface clearance upon translation. 28 In our AR-HUD scenario, the necessity for large-aperture lenses leads to considerable variation in the surface sag. Consequently, the spacing introduced by placing the two lenses with their curved surfaces facing each other makes optical design and compact volume more difficult.…”

Section: Z X Ymentioning

confidence: 98%

“…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.…”

Section: Basic Principlementioning

confidence: 99%

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

Liu,

Qiu,

Dong

et al. 2024

J Soc Info Display

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A crucial requirement of augmented reality head‐up displays (AR‐HUDs) is continuously adjustable virtual image distance (VID), which allows adaptation to various depths in road environments and thereby avoids visual fatigue. However, usual varifocal components for near‐eye displays are unavailable because AR‐HUDs require the varifocal component's aperture to be larger than 10 cm. This study considers the Alvarez lenses, which change the optical power by in‐plane sliding two freeform lenses. Under the paraxial assumption, classic Alvarez lenses can create a quadratic wavefront profile, but the large aperture and extensive diopter variation range required by AR‐HUDs lead to significant aberrations. Thus, the classic paraxial Alvarez lens design is extended by co‐optimizing Alvarez lenses with high‐order surface profiles and a primary freeform mirror. Therefore, a novel varifocal AR‐HUD containing Alvarez lenses with apertures larger than 15 cm is proposed. The AR‐HUD generates a varifocal plane whose VID can be continuously adjusted between 2.5 and 7.5 m, and another focal plane with a fixed VID at 7.5 m. In addition, merely one display panel is used for compactness. Finally, an AR‐HUD prototype with a reduced volume of 9.8 L was built. The expected varifocal performance and qualified imaging quality were experimentally verified through the field of view, VID, and image sharpness.

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Section: Methodsmentioning

confidence: 96%

Section: Z X Ymentioning

confidence: 98%

See 1 more Smart Citation

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

Liu,

Qiu,

Dong

et al. 2024

J Soc Info Display

View full text Add to dashboard Cite

show abstract

Shift-photography-assisted image super-resolution for optical zooming system based on Alvarez lenses

Yan,

Li,

Zhou

et al. 2024

Optics Communications

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Increased degrees of freedom afforded by 3D freeform gradient index optics

Williams,

Akhavan,

Harmon

2023

Digital Optical Technologies 2023

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Traditional approaches to satisfying optical performance requirements within application constraints leverage the degrees of freedom (DOF) provided by multiple surface shapes distributed among lenses composed of materials with different dispersion properties. Using homogeneous-index lens materials, the radius, conic constant, or higher order aspheric surfaces provide the DOF necessary to provide optical power and address certain geometric aberrations, while using lens materials with different dispersion properties provides the DOF necessary to compensate for chromatic aberrations. Nevertheless, to achieve the DOF necessary to achieve the performance required of compact head-mounted and mobile camera imaging systems, lens stacks must be composed of a significant number of complex shaped optical elements, resulting in undesirable size, weight, and cost.Recent advancements in inkjet print manufacture of three-dimensional (3D) freeform gradient-index (GRIN) optical materials have increased available design DOF by integrating volumetric index gradients within the bulk of the optical material. The 3D index gradients achieve optical power while reducing aberrations. Moreover, when the refractive index spectra of the optical feedstock are precisely formulated, dispersion may be independently controlled within the lens. The 3D GRIN optical materials may be machined and polished with aspheric or freeform surface shapes that further increase the DOF and provide lens designer unprecedented flexibility in lens designs with reduced lens counts.The performance benefits and applications of 3D GRIN optical elements are demonstrated, showcasing their potential to reduce size, weight, and cost in optical systems.

show abstract

Gradient-index Alvarez lenses

Cited by 6 publications

References 31 publications

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

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

Shift-photography-assisted image super-resolution for optical zooming system based on Alvarez lenses

Increased degrees of freedom afforded by 3D freeform gradient index optics

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