We study the formation of caustic surfaces produced by convex conic lenses, considering a linear set of point sources displayed on a plane, this linear array is placed at arbitrary position along the optical axis. The caustic surface can be defined as the envelope for either reflected or refracted rays propagating through an optical system. Implementing an exact ray trace, we have obtained an analytic equation that describes a parametric family of refracted rays propagating through a convex conic lens and by computing its envelope, we provide an exact equation for the caustic surface as a function of all the parameters involved in the process of refraction. Considering the geometric center of a conic surface, we have located the parabasal image for each point source produced by refraction, and by extending this concept for a set of point sources placed along a linear array, we obtain the image surface which is the locus where the succession of paraxial images are located. Finally, using a commercial 3D printer, we have fabricated a convex conic lens along with its image curved surface to implement a preliminary test to study the image formation for extended objects, with potential applications in uniform illumination systems.
In this work we propose a procedure to divide a regular off-axis conic surface, which defines the parent surface represented by a parametric equation, in order to describe the optical surface for an off-axis Fresnel-type reflector, in such a way that this mathematical representation allows us to implement an exact ray trace considering a plane wavefront incident on the surface. Additionally, we can simulate the performance of a preliminary prototype proposed for designing a solar collector.
Traditionally, the Fresnel-type lens design often assumes thin lenses, since lenses of finite thickness cannot be completely described in analytical terms, then a numerical solution has to be found. We implement an exact ray trace considering a plane wavefront incident by reducing as much as possible the area of light concentration, while increasing the concentration ratio of energy. In such a way that we have mathematically determined a function to compute groove angles, to refract a bundle of rays from each planar echelon, which are propagated into a predetermined area of energy collection. In addition, we can evaluate the performance of the Fresnel-type lens design for a solar collector. Thus, an analytical formula to calculate the optical efficiency is obtained, in terms of the geometrical losses widely studied for nonimaging systems, such as blocking losses. Finally, the proposed aspherical Fresnel lens design is fabricated using a commercial 3D printer and subsequently polishing the surface for better performance. In this fashion we could test the performance of the manufactured prototype.
We study different approaches to describe the evolution of wavefronts refracted through two simple lenses forming an achromat separated by finite distance (dialyte for short), assuming a plane wavefront incident propagated along the optical axis impinging on the optical system. This allows us to quantitatively evaluate the best optical design containing the minimum amount of spherical aberration produced by the optical system under test. Based on this study, we have implemented an interferometric array for testing a dialyte placing a reference mirror at predefined position along the optical axis, which permits to compensate the optical phase and properly produce a null interferogram to evaluate the performance for this kind of optical systems.
We have designed a Linear Fresnel-type Reflector (LFR) to reduce the area of light concentration based on the caustic surfaces produced by reflection. The LFR is designed by a set of planar mirrors, which appropriately have slopes in such a way that input energy can be focused at predefined absorber area. Also, losses due to riser steps were obtained from a geometrical point of view, to reduce and reconfigure the LFR shape in order to facilitate its manufacture. Finally, a LFR prototype will be fabricated on a single aluminum sheet where their grooves will be molded through CNC machine.
We design two different Hartmann type null screens based on an exact ray trace for testing a fast plano-convex aspherical condenser. The first null screen is designed for testing the external convex surface or periphery area for the condenser by reflection. We have implemented an exact ray trace assuming a point source placed along the optical axis, emitting a bundle of rays, which are reflected by the surface under test, to obtain a non-uniform array of spots, which are printed on paper sheet and wrapped on a plastic cylinder fabricated by using additive manufacture. Subsequently, by reversibility Principle’s after by reflection we obtain a uniform array pattern displayed at the detection plane. Alternatively, to evaluate the whole area for the condenser, the second null screen is designed for testing the central convex area for the condenser by refraction. Thus, we have implemented an exact ray trace assuming an incident plane wavefront, these rays are refracted through the lens under test, to obtain a non-uniform array of drop spots, which are printed on plastic sheet and placed in front of the lens under test. Finally, assuming the reversibility Principle’s after by refraction we obtain a uniform array pattern displayed at the detection plane. For this method, we have called Hartmann type hybrid null screens.
We study the propagation of wavefronts refracted through separated doublet lenses (SDL), considering a plane wavefront propagating parallel to the optical axis. We provide formulas for the zero-distance phase front refracted through SDL by using Huygens’s principle. Additionally, we obtain formulae to represent the shape of refracted wavefronts propagated at arbitrary distances along the optical axis, as a function of all parameters involved in the process of refraction. Finally, some examples for commercial SDL showing the evolution of the wavefronts arbitrary distances are presented, assuming different wavelengths for the refractive indices of the lenses, displaying dispersion effects produced through SDL.
We have designed a Linear Fresnel Reflector (LFR), with potential applications for solar concentration, by using an exact ray tracing. We have mathematically parameterized the slopes of LFR to provide predefined areas of light concentration. LFR planar mirrors were calculated in such a way that an incident plane wavefront can be focused at minimum absorber area. Finally, prototypes of LFR were manufactured by using a 3D printer, considering a set of small sized mirrors to join up with the aim of producing a linear focus.
A method to design Ronchi-Hartmann screens for testing a fast plano-convex aspherical Fresnel lens is presented. We design null screens that produce either aligned straight fringes or quasi-angular spots arrays for observed patterns. The designs of these null screens are based on knowledge of the caustic by refraction through arbitrary curves. A qualitative test for a Fresnel lens is presented.
We design Fresnel mirrors by using an exact ray tracing considering an incident plane wavefront propagating along the optical axis, impinging at arbitrary reflective surfaces, in order to efficiently redirect the light at a predefined area where will be placed the absorber. The solar concentrator consists of a set of planar mirrors, each one has its own slope in such a way that all the rays impinging on it will be focused at a predefined area as a CPC does. Finally, we provide a qualitative test for a commercial FM based on the null screen method.
KEYWORDS: Solar energy, Prototyping, Current controlled current source, Solar concentrators, Photocatalysis, Ray tracing, Compound parabolic concentrators, Glasses, Optical components, Freeform optics
We study the propagation of light in order to efficiently redirect the reflected light on photocatalytic samples placed inside a commercial solar simulator, and we have designed a small-scale prototype of Cycloidal Collectors (CCs), resembling a compound parabolic collector. The prototype consists of either cycloidal trough or cycloidal collector having symmetry of rotation, which has been designed considering an exact ray tracing assuming a bundle of rays propagating parallel to the optical axis and impinging on a curate cycloidal surface, obtaining its caustic surface produced by reflection.
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