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Metasurfaces, Then and Now
Published in Costantino De Angelis, Giuseppe Leo, Dragomir N. Neshev, Nonlinear Meta-Optics, 2020
Sébastien Héron, Patrice Genevet
An aplanatic lens is a lens corrected for both spherical aberrations and coma; this type of lens is widely used in microscope objectives and condenser lenses [23]. Following the approach developed by Murty [84] for Fresnel zone plates, it is possible to design an aplanatic lens based on a metasurface. The Abbe sine condition establishes that an optical system corrected for spherical aberrations will also be free from coma if the ratio between the sine of the angle traced by a ray as it leaves the object and the sine of the angle traced by the same ray as it reaches the image plane is constant for all the rays. It has been shown that it is possible to design an aplanatic lens by patterning the metasurface on a spherical interface. From the generalized law of refraction for spherical interfaces, the phase gradient required for an aplanatic meta-lens reads: () dφdθ=−n2πλsin(θ)
Some Designs of Image-Forming Concentrators
Published in Roland Winston, Lun Jiang, Vladimir Oliker, Nonimaging Optics, 2020
Roland Winston, Lun Jiang, Vladimir Oliker
There are image-forming systems that satisfy the Abbe sine condition and have large relative apertures. The prototype of these is the Schmidt camera, which has an aspheric plate and a spherical concave mirror, as shown in Figure 3.20. The aspheric plate is at the center of curvature of the mirror, and thus the mirror must be larger than the collecting aperture. Such a system would have the ideal concentration ratio for a restricted exit angle apart from the central obstruction, but there would be practical difficulties in achieving the theoretical maximum. In any case a system of this complexity is clearly not to be considered seriously for solar work.
Curved holographic optical elements and applications for curved see-through displays
Published in Journal of Information Display, 2019
Kiseung Bang, Changwon Jang, Byoungho Lee
The graph shows that the curved HOE has the least aberration when the radius of curvature is 7.92 cm. Note that the optimal radius of curvature is found near the focal length of the 7.5 cm signal wave. This coincides with the result of the previous research on the curved on-axis lens HOE using the Abbe sine condition [43].