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Optimization of angular diffractive lenses with extended depth of focus

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Sánchez Brea, Luis Miguel and Torcal Milla, Francisco José and Hoyo Muñoz, Jesús del and Cuadrado Conde, Alexander and Gómez Pedrero, José Antonio (2020) Optimization of angular diffractive lenses with extended depth of focus. Journal of Optics . ISSN 2040-8978 (In Press)

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Official URL: https://doi.org/10.1088/2040-8986/ab8614




Abstract

Conventional refractive lenses concentrate the incident light at focal distance. A narrow beam waist can be achieved by increasing the lens numerical aperture, but strongly reduces the depth of focus. In this paper, we explore diffractive lenses designs, with fast angular variation of the focal distance, that produce both a narrow beam waist and a long depth of focus. We predict the focusing properties or the diffractive lenses with a simple analytical model based on an incoherent superposition of standard lenses with different focal distances. The histogram of the local focal distances is used to determine the weights in the superposition. Our model optimizes the shape of the diffractive lenses, in order to extend the depth of focus, which corresponds to the lotus lens. We verify our results with numerical simulations based on Rayleigh-Sommerfeld approach. Experimentally, we validate our analytical and numerical solutions with a Spatial Light Modulator are carried out and compared to the analytical and numerical results. We have found configurations for the lotus lens where the depth of focus is significantly incremented with only a slight increment of the focal width. For example, we increased the depth of focus from 7.6 mm to 37.2 mm while the beam waist varied from 35.0 microns to 51.6 microns for a lens with diameter D~=~4~mm, and focal distance f'~=~125~mm. These results may find applications in the design of contact and intraocular lenses with extended depth of focus, laser focus generators, and imaging applications where extended depth of focus is needed.


Item Type:Article
Additional Information:

Received 5 December 2019
Revised 27 March 2020
Accepted 2 April 2020
Accepted Manuscript online 2 April 2020

Uncontrolled Keywords:Diffractive lenses; Diffractive optics; Diffractive optical elements; Extended depth of focus lens
Subjects:Sciences > Physics > Optics
Medical sciences > Optics > Contact lenses
Medical sciences > Optics > Geometrical and instumental optics
ID Code:59982
Deposited On:19 Apr 2020 16:00
Last Modified:20 Apr 2020 07:24

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