Coloured-resist flat lenses focus 550 nm light to a 1.1 µm spot without etching
What was demonstrated
Flat Fresnel zone plate lenses were patterned from coloured photoresist on 8-inch glass wafers using an i-line stepper, with no etching step. At a 550 nm design and test wavelength, they focused light to a spot about 1.1 µm in diameter. Measured focusing efficiency was 7.2%, counted within 3 times the full width at half maximum. Simulation gave 7.3%. The lenses imaged features down to 1.1 µm on a USAF 1951 target.
Why it matters
The result suggests that conventional lithography tools and a single coated resist layer may be enough to make flat lenses for visible light. Efficiency is low, so the work shows a fabrication route rather than a lens ready to replace existing optics.
Caveats
- The 7.2% efficiency is low. The authors say it is lower than other metalens types but comparable with other amplitude-type Fresnel zone plates.
- The outermost resist edges were 1.1 µm wide against a 0.8 µm design. The 10.9% monochromatic figure is a simulated prediction, not a measurement.
- The device is a diffractive Fresnel zone plate, not a metasurface. It is included here because it is a flat optic in the same family.
- Performance falls away from the design wavelength. For the 550 nm lens, the focal spot full width at half maximum was 1.2 µm at 450 nm and at 650 nm.
Technology profiles
Sources
- peer reviewed paper
Optical Fresnel zone plate flat lenses made entirely of colored photoresist through an i-line stepper
Ryohei Yamada, Hiroyuki Kishida, Tomohiro Takami et al.. Light: Science & Applications, 16 Jan 2025. DOI: 10.1038/s41377-024-01725-6.
Last reviewed 21 Oct 2026.