Ultra-thin flat lens has extreme depth of focus
In a paper titled “Extreme-depth-of-focus imaging with a flat lens” published in the OSA Optica journal, the researchers report a very thin lens that does not require refocusing even to capture different object images separated by large distances, removing the need for refocusing mechanisms and drastically simplifying imaging systems.
that exhibits extreme-depth-of-focus (ExDOF)
imaging.
The so-called multi-level diffractive lens (MDL) described in the paper enhances the depth of focus by over 4 orders of magnitude compared to traditional fixed lenses.
a magnified view of the centre of the lens. Focal range is 5 to
1200mm, aperture is 1.8 mm.
In experiments using such a lens, the researchers were able to maintain focus for objects separated by as large a distance as 6 metres. When illuminated by collimated light at 0.85m, a 1.8mm diametre multi-level diffractive lens shaped with a distribution of concentric rings of varying thickness up to 2.6µm maximum, produced a beam which remained in focus from 5 to 1200 mm.
The researchers have founded a startup Oblate Optics in San Diego to commercialize planar optics with large bandwidths and a large depth of field. They are seeking collaboration with strategic partners.
Oblate Optics – www.oblateoptics.com
University of Utah – www.utah.edu
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