Refractive-type varifocal liquid-crystal Fresnel lenses for smart contacts

Area of Science:

• Optics and Photonics
• Biomedical Engineering
• Materials Science

Background:

• Smart contact lenses require compact, tunable optical systems for advanced functionalities like variable focus.
• Existing liquid crystal (LC) lenses face challenges in power consumption, profile, and image quality.

Purpose of the Study:

• To demonstrate a low-power, low-profile varifocal liquid-crystal Fresnel lens stack for tunable imaging in smart contact lenses.
• To evaluate the optical performance, power efficiency, and image quality of the proposed lens stack.

Main Methods:

• Implementation of a lens stack comprising a liquid-crystal Fresnel chamber, twisted nematic cell, polarizer, and offset lens.
• Characterization of optical power tunability, wavefront aberration, chromatic aberration, and power consumption.
• Assessment of image quality using the BRISQUE score and comparison with a conventional curved LC lens.

Main Results:

• The varifocal lens stack achieved a maximum optical power change of ~6.5 D with low power consumption (~2.6 µW) at ~2.5 V_RMS.
• The lens stack exhibited a low RMS wavefront aberration error of 0.2 µm and minimal chromatic aberration (0.008 D/nm).
• The Fresnel lens demonstrated superior imaging quality (BRISQUE score 35.23) compared to a curved LC lens (57.23).

Conclusions:

• The demonstrated liquid-crystal Fresnel lens stack is a viable candidate for tunable imaging in smart contact lenses.
• The design offers a compelling balance of low power, low profile, efficient optical power tuning, and high image quality.
• This technology has the potential to enable next-generation augmented reality and vision correction devices.