Hands-on training in Nonimaging Optics for SME's: the SMETHODS experience

A 5-day training in Nonimaging Optics for European SME’s employees was carried out in June 2012 in the framework of the FP7 funded Support Action "SMETHODS". The training combined theoretical introduction and hands-on practice. The experience was very positive, and the lessons learned will improve the next scheduled sessions. Introduction The FP7 funded Support Action "SMETHODS" [1] is an initiative of seven European academic institutions to strengthen Europe's optics and photonics industry, which has started on 1 September 2011. Participation in training sessions is free for participants, who are selected with priority will be given to employees of small and medium sized European enterprises (SMEs). The consortium in SMETHODS is formed by seven partners that are the most prominent academic institutions in optical design in their countries. Through fully integrated collaborative training sessions, the consortium provides professional assistance as well as hands-on training in a variety of design tasks in four domains: (1) imaging optics, (2) nonimaging optics, (3) wave optics, and (4) diffractive optics. For each of this domains domain, 5-day training sessions are scheduled to be hold in different locations throughout Europe, four times in two years, the teach four times in a 2.5 years period

Freeform optics for photovoltaic concentration

Freeform surfaces are the key of the state-of-the-art nonimaging optics to solve the challenges in concentration photovoltaics. Different families (FK, XR, FRXI) will be presented, based on the SMS 3D design method and Köhler homogenization

Optical design of inhomogeneous media to perfectly focus scalar wave fields

A method to design isotropic inhomogeneous refractive index distribution is presented, in which the scalar wave field solutions propagate exactly on an eikonal function (i.e., remaining constant on the Geometrical Optics wavefronts). This method is applied to the design of ¿dipole lenses¿, which perfectly focus a scalar wave field emitted from a point source onto a point absorber, in both two and three dimensions. Also, the Maxwell fish-eye lens in two and three dimensions analyzed

Single freeform surface imaging design with unconstrained object to image mapping

An imaging design approach which is free of third-order astigmatism for one freeform optical surface and the image is presented in this paper. A set of differential equations is derived from generalized ray tracing. The solution of the above derived equations provides the anastigmatic freeform optical surface, the image surface and the object to image mapping. The obtained design can be used as a good starting point for optimization. As an example, a reflective freeform surface is designed for a single reflective Head Mounted Display (HMD). This example has a 3 mm pupil, 15mm eye clearance, 24-degree diagonal full field of view, and the final design yields an average MTF of 62.6% across 17 field points

Double surface imaging designs with unconstrained object to image mapping under rotational symmetry

In this work, we present a novel imaging design formed by two optical surfaces with rotational symmetry. In these designs, both object and image shapes are given but mapping from object to image is obtained through the design process. In the examples considered, the image from a planar object surface is virtual and located at infinity and is seen from a known pupil, which can emulate a human eye. The differential equation method is used to provide single optical surface imaging designs by considering the local properties of the imaging surface and the wavefronts. In the first introductory part, both the rotational symmetrical and the freeform single surface imaging designs are presented using the differential equation method. In these designs, not only the mapping is obtained in the design process, but also the shape of the object is found. In the second part, the method is extended to two surface designs with rotational symmetry and the astigmatism of the image has been studied. By adding one more optical surface to the system, the shape of the rotational symmetrical object can be designed while controlling the tangential rays and sagittal rays simultaneously. As a result, designs without astigmatism (at the small pupil limit) on a planar object surface have been obtained. © (2014) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only

Extreme super-resolution using the spherical geodesic waveguide

Leonhardt demonstrated (2009) that the 2D Maxwell Fish Eye lens (MFE) can focus perfectly 2D Helmholtz waves of arbitrary frequency, i.e., it can transport perfectly an outward (monopole) 2D Helmholtz wave field, generated by a point source, towards a "perfect point drain" located at the corresponding image point. Moreover, a prototype with λ/5 superresolution (SR) property for one microwave frequency has been manufactured and tested (Ma et al, 2010). Although this prototype has been loaded with an impedance different from the "perfect point drain", it has shown super-resolution property. However, neither software simulations nor experimental measurements for a broad band of frequencies have yet been reported. Here we present steady state simulations for two cases, using perfect drain as suggested by Leonhardt and without perfect drain as in the prototype. All the simulations have been done using a device equivalent to the MFE, called the Spherical Geodesic Waveguide (SGW). The results show the super-resolution up to λ/3000, for the system loaded with the perfect drain, and up to λ/500 for a not perfect load. In both cases super-resolution only happens for discrete number of frequencies. Out of these frequencies, the SGW does not show super-resolution in the analysis carried out

TIR RXI collimator

A metal-less RXI collimator has been designed using the Simultaneous multiple surface method (SMS). Unlike conventional RXI collimators, whose back surface and parts of the front surface have to be metalized, this collimator is completely metal-free, made only of plastic (PMMA). The collimator’s back surface is designed as a grooved surface providing two TIR reflections for all rays impinging on it. One advantage of the design is the lower manufacturing cost, since there is no need for the expensive process of metalization. More importantly, unlike conventional RXI collimators, this design performs good colour mixing, as well as being very insensitive to the source non-uniformities. The experimental measurements of the first prototype show good agreement with the simulated design

The Monge-Ampére equation method in freeform optics design

The Monge-Ampére equation method could be the most advanced point source algorithm of freeform optics design. This paper introduces this method, and outlines two key issues that should be tackles to improve this method

Analytical solution of an afocal two freeform mirror design problem

We investigate a new afocal two freeform mirror design problem in first order optics. The resulting first-order partial differential equations for the freeform two mirror system have an analytic solution with the sole condition that the x-y and x'-y' axes are parallel. Two selected solutions are presented. One of them is emiaplanatic (fulfilling the aplanatic condition only for the x-coordinates), while the other is, to our knowledge, the firstexample of an aplanatic two-mirror system without rotational symmetry

Perfect imaging of point sources with positive refraction

The capability of a device called the Spherical Geodesic Waveguide (SGW) to produce images with details below the classic Abbe diffraction limit (super-resolution) is analyzed here. The SGW is an optical system equivalent (by means of Transformation Optics) to the Maxwell Fish Eye (MFE) refractive index distribution. Recently, it has been claimed that the necessary condition to get super-resolution in the MFE and the SGW is the use of a Perfect Point Drain (PPD). The PPD is a punctual receptor placed in the focal point that absorbs the incident wave, without reflection or scattering. A microwave circuit comprising three elements, the SGW, the source and the drain (two coaxial lines loaded with specific impedances) is designed and simulated in COMSOL. The super-resolution properties have been analyzed for different position of the source and drain and for two different load impedances: the PPD and the characteristic line impedance. The results show that in both cases super-resolution occurs only for discrete number of frequencies. Out of these frequencies, the SGW does not show SR in the analysis carried out