Gabor superlens with variable focus
A. Garza-Rivera
1
, J. E. Gómez-Correa
2,
*, F. J. Renero-Carrillo
1
, J. P. Trevino
3
,
and V. Coello
4
1
INAOE, Departamento de Óptica, Tonantzintla, Puebla, 72840, Mexico
2
Catedras Conacyt – CICESE, Unidad Monterrey, PIIT Apodaca, Nuevo León, 66629, Mexico
3
Tecnológico de Monterrey, Campus Puebla, Departamento de Bioingeniería y Ciencias, Puebla, Puebla, 72453, Mexico
4
CICESE, Unidad Monterrey, PIIT Apodaca, Nuevo León, 66629, Mexico
*Corresponding author: jesusg@cicese.mx
Received June 19, 2020; accepted August 11, 2020; posted online Septembe r 30, 2020
In this Letter, a Gabor superlens with variable focus is presented. This configuration uses tunable liquid lenses in
the third microlens array of the Gabor superlens. By applying voltage, the radius of curvature of the micro-
tunable doublet arrays changes, and the Gabor conditions are fulfilled at different focal planes. As a consequence,
the magnification of the image at the focal planes changes, and a zoom effect is observed. The marginal depth
plane for this system goes from 0.86 to 0.89 mm. The optical simulation, calculations, and results of the simulated
optical system performance are presented.
Keywords: Gabor superlens; micro-tunable lens; multi-aperture optics; geometric optical design.
doi: 10.3788/COL202018.122201.
In 1940, Denis Gabor proposed a system that, by using a
set of microlens arrays (MLAs), forms an erect image
whose relative position is a function of the object distance,
i.e., it could be seen as a synthetic superposition com-
pound eye. Such a configuration is currently known as
the “Gabor superlens” (GSL)
[1]
. GSL had been inspired
by multi-aperture optical systems that are present in com-
pound eyes. This kind of eye has the advantage of being
capable of processing a large amount of input information
from the environment, without saturating the neural sys-
tem of the organism. The mechanism by which the small
faceted eyes form the image of an object has sparked the
idea of developing non-conventional optical systems that
will profit from those capabilities. The multi-aperture op-
tical devices could be used in image forming applications,
optical communica tions, and medical instruments, among
others. For instance, in free space optical communication
systems, it is possible to have signal multiplexers, demul-
tiplexers, and switches using a GSL configuration
[2]
. Since
this configuration performs integral imaging, the axes of
bundles of light rays coming from different object posi-
tions intersect. Also, integral imaging is a very promising
technology for three-dimensional (3D) displays. With this
technique, it is possible to form an image by concentrating
light rays through a lens array. It has the advantage that
the viewer does not need to wear glasses required by
ordinary stereoscopic 3D displays, neither does it need
to process a lot of information like in holography
[3,4]
.
On the other hand, a tunable liquid lens, or electrowet-
ting lens, is a lens that changes curvature when a voltage is
applied, whereas a different alternative is a liquid crystal,
which has a short response time and low operation
voltage
[5,6]
. A change like this shifts the focal distance of
the lens
[7]
. This process has several similitudes with the ac-
commodation of the human eye
[8]
due to the fact that the
human crystalline lens adjusts its shape to correctly focus
the eye in response to visual demand
[8–10]
rather than shift-
ing its position as other mechanical systems. For this rea-
son, the tunable liquid lens has been considered as an
option for developing bionic eyes to mimic the function
of the human crystalline lens
[11]
.
In this Letter, for the first time, to the best of our knowl-
edge, a design of a GSL capable of performing a zoom func-
tion and changing its focal distance using an array of
micro-tunable liquid lenses is presented. The use of a
micro-tunable liquid lens array, instead of the conven-
tional MLA basic design, makes it possible to achieve dif-
ferent values of the global focal length and the optical
power of each configuration as a function of the change
of curvature. With a varifocal system, as the one presented
here, the function of focusing a signal with different inten-
sities at different planes will enable the design of more ro-
bust and versatile devices. There are several possible
designs for tunable lenses. Specifically, this work is based
on the research of Kuiper et al.
[12]
, who showed that the
variation of focal length is a function of the radius of cur-
vature of the meniscus of a liquid lens that works by
electrowetting.
The GSL consists of an array of off-axis micro-Keplerian
telescopes (MKTs), in which a beam of light that enters
the system is deflected by an angle t hat changes with
the focal lengths of the lenses and their relative displace-
ment
[13]
. A collimated incident beam would be divided into
arrays of smaller beams, which would converge to a
common point of minimum confusion, producing a finite
conjugate image. The first MLA performs the function of
an objective lens and produces multiple real images that
are transferred afterwards to the image plane by a relay
MLA. At the center of the GSL, three lenses on each
MLA are aligned on a common optical axis. As the
COL 18(12), 122201(2020) CHINESE OPTICS LETTERS December 2020
1671-7694/2020/122201(5) 122201-1 © 2020 Chinese Optics Letters