Ray-tracing Software Research Articles

Optical and thermal performance simulation of a micro-mirror solar collector

Concentrating solar thermal systems are widely used for industrial heat production. The state-of-the-art methods use different concepts among which tracking Fresnel mirrors or parabolic troughs. In the market however there are very few devices operating at intermediate to medium temperatures. In order to fill this gap, an innovative concentrating solar thermal system is studied in the frame of the Hellenic — German cooperation project “SCoSCo”. The proposed device concentrates the solar radiation to the receiver using a micro-mirror array. The scope of this paper is to present the optical simulation results of this innovative reflector, and compare the results obtained by different software packages. The optical performance assessed using Solstice ray-tracing software, yields a theoretical optical efficiency from 0.7 to 0.9. In order to evaluate the annual energy yield of the prototype, solar radiation data measurements in Patras, Greece for 2016 and were used as input. A three dimensional thermal model is developed in the COMSOL software to estimate the temperature distribution at the receiver. It was found that temperatures , ranged from 115 to 225 °C. The annual energy yield, calculated using the CARNOT toolbox ranges from 683 to 729 kWh.

Optimum telescope focal ratios for microlens-to-fiber coupled integral field spectrographs

We describe the optimum telescope focal ratio for a two-element, three surface, telecentric image-transfer microlens-to-fiber coupled integral field unit within the constraints imposed by micro-optics fabrication and optical aberrations. We create a generalized analytical description of the micro-optics optical parameters from first principals. We find that the optical performance, including all aberrations, of a design constrained by an analytic model considering only spherical aberration and diffraction matches within +/-4% of a design optimized by ray-tracing software such as Zemax. The analytical model does not require any compromise on the available clear aperture; about 90% mechanical aperture of a hexagonal microlens is available for light collection. The optimum telescope f-ratio for a 200{\mu}m core fiber fed at f/3.5 is between f/7 and f/12. We find the optimum telescope focal ratio changes as a function of fiber core diameter and fiber input beam speed. A telescope focal ratio of f/8 would support the largest range of fiber diameters (100 to 500{\mu}m) and fiber injection speeds (between f/3 and f/5). The optimization of telescope and lenslet-coupled fibers is relevant for the design of high-efficiency dedicated survey telescopes, and for retro-fitting existing facilities via introducing focal macro-optics to match the instrument input requirements.

Ray Tracing versus Thin-Lens Formulas for IOL Power Calculation Using Swept-Source Optical Coherence Tomography Biometry

PurposeTo evaluate the ray tracing method's accuracy employing Okulix ray tracing software and thin-lens formulas to calculate intraocular lens (IOL) power using a swept-source optical coherence tomography (SS-OCT) biometer (OA2000).MethodsA total of 188 eyes from 180 patients were included in this study. An OA-2000 optical biometer was used to collect biometric data. The predicted postoperative refraction based on thin-lens formulas including SRK/T, Hoffer Q, Holladay 1, and Haigis formulas and the ray tracing method utilizing the OKULIX software was determined for each patient. To compare the accuracy of approaches, the prediction error and the absolute prediction error were determined.ResultsThe mean axial length (AL) was 23.66 mm (range: 19–35). In subgroup analysis based on AL, in all ranges of ALs the ray tracing method had the lowest mean absolute error (0.56), the lowest standard deviation (SD; 0.55), and the greatest proportion of patients within 1 diopter of predicted refraction (87.43%) and the lowest absolute prediction error compared to the other formulas (except to SRK/T) in the AL range between 22 and 24 mm (all P 0.05). In addition, the OKULIX and Haigis formulas had the least variance (variability) in the prediction error in different ranges of AL.ConclusionThe ray tracing method had the lowest mean absolute error, the lowest standard deviation, and the greatest proportion of patients within 1 diopter of predicted refraction. So, the OKULIX software in combination with SS-OCT biometry (OA2000) performed on par with the third-generation and Haigis formulas, notwithstanding the potential for increased accuracy in the normal range and more consistent results in different ranges of AL.

P-TRANS: A Monte Carlo ray-tracing software to simulate phonon transport in arbitrary nanostructures

P-TRANS is a software to simulate phonon transport in arbitrary nanostructures based on the Boltzmann transport theory. The core part of the software is a Monte Carlo ray-tracing solver that uses the stochastic method to sample phonon transport in various nanostructures. The solver is written in FORTRAN with well-organized modules and utilizing the OpenMP and MPI parallelization to achieve high performance. The software can handle a typical calculation of nanostructures with a feature size of ∼1000 nm on a normal PC within seconds, which is useful when exploring the wide variety of structures, for instance for structural optimization or high-throughput screening in material informatics. The software takes the bulk phonon properties obtained from the first-principles anharmonic lattice dynamics calculations as inputs. The database of bulk phonon properties is available on the software webpage, which currently contains more than 60 materials and will increase in the future. We also provide a graphical user interface to design the nanostructures and to run the simulation for non-expert users. In this paper, we introduce the theoretical background, the technical details and implementation, and the applications of the software. Program summaryProgram title:P-TRANSCPC Library link to program files:https://doi.org/10.17632/n76jpj3fnz.1Developer's repository link:https://github.com/TEEL-UTokyo/P-TRANSCode Ocean capsule:https://codeocean.com/capsule/9387119Licensing provisions: GPLv3Programming language: FortranSupplementary material:http://www.phonon.t.u-tokyo.ac.jp/p-trans/Nature of problem: Knowing the effective thermal conductivity of nanostructures is important for numerous applications. Phonons are the dominate heat carriers in dielectrics and their transport is influenced by the voids, grain boundaries, and free surfaces in the nanostructure. Here we are focusing on the effective thermal conductivities of nanostructures with complex geometries and boundaries.Solution method: Monte Carlo ray tracing simulations.

Calculation of View Factors for Building Simulations with an Open-Source Raytracing Tool

Longwave radiative heat transfer is a key determinant of energy consumption in buildings and view factor calculations are therefore required for the detailed simulation of heat transfer between buildings and their environment as well as for heat exchange within rooms. Typically, these calculations are either derived through analytical means or performed as a part of the simulation process. This paper describes the methodology for employing RADIANCE, a command-line open-source raytracing software, for performing view factor calculations. Since it was introduced in the late-1980s, RADIANCE has been almost exclusively employed as the back-end engine for lighting simulations. We discuss the theoretical basis for calculating view factors through Monte Carlo calculations with RADIANCE and propose a corresponding workflow. The results generated through RADIANCE are validated by comparing them with analytical solutions. The fundamental methodology proposed in this paper can be scaled up to calculate view factors for more complex, practical scenarios. Furthermore, the portability, multi-processing functionality and cross-platform compatibility offered by RADIANCE can also be employed in the calculation of view factors.

Modeling and Validating a SuperDARN Radar's Poynting Flux Profile

AbstractWe have developed a model that simulates the Poynting flux profile of the Saskatoon Super Dual Auroral Radar Network (SuperDARN) radar at ionospheric altitudes. The model uses ray tracing software to project the radar system's vacuum Poynting flux profile through the ionosphere, taking into account the influence of the ionospheric medium on the propagation characteristics of the high frequency radio waves. Measurements of the radar's transmissions by the Radio Receiver Instrument (RRI) in low‐Earth orbit are used to validate the model during five experiments which occurred between 4 and 8 August 2017. Comparisons between simulated and measured RRI antenna voltages show good agreement, although there are clear instances in which the model underperforms. Nevertheless, the model demonstrates its utility as a tool for interpreting RRI measurements of SuperDARN radars. The model also helps address a lack of knowledge of a SuperDARN radar's Poynting flux profile at ionospheric altitudes. In particular, we assess the assumption that SuperDARN's scattering volume lies along the great‐circle path of the transmitting beam's bearing. Comparisons between the model and RRI's measurements show that this assumption is reasonable for the five experiments investigated in this work. The model presents a new way of carrying out SuperDARN and high frequency radio science investigations.

Simplified optical model, aiming strategy and partial defocusing strategy for solar Fresnel collectors

This paper presents the development of a simplified analytical optical model, an analysis of aiming strategies and a defocusing strategy for a Fresnel solar collector. The model aims to represent the main components of solar concentration on a Fresnel collector when considering independent rotation on each mirror in order compute the solar radiance flux on the absorber. The model is validated with data from a reference Ray-Tracing software and from experimental data. The model is then used to evaluate three aiming proposals with regards to solar radiance flux over the absorber. Data from the optical model and mirror inclinations proposed by the aiming strategies are used to implement a partial defocusing strategy for Fresnel collectors. The main purpose of this analysis is to assess the possible gains that individual manipulation of each collector mirror can bring to the process. It is shown that all the analyzed aiming methods present similar performances regrading the optical efficiency aspect. Thus, the use of the simplest solar aiming method presents itself as a very effective solution. Results also show the possibility to implement partial defocusing on Fresnel collectors, allowing the use of focus as a manipulated variable for control.

Designing a flat beam-down linear Fresnel reflector

A linear beam-down solar field consists of two reflections that concentrate the solar irradiation on heavy materials located on the ground. Several rows of linear Fresnel reflectors, which have the same width, aim the solar irradiation to a secondary mirror with a hyperbolic shape that redirects the solar concentration towards the ground receiver. This paper overcomes the main limitation of the previously proposed hyperbolic secondary reflector. A new secondary reflector composed by several fixed flat mirrors located at the same height is proposed. A model to calculate the optimal layout of this novel solar field, as well as the efficiency and concentration, is developed and validated against a Monte-Carlo Ray-Tracing software, obtaining relative errors lower than 15%. Two new dimensionless parameters are proposed to facilitate the design of the flat beam-down linear Fresnel reflector. The concentration, optical efficiency and receiver width can be easily obtained, without performing any simulation, as a function of the dimensionless parameters. This novel solar field can achieve concentration ratios of up to 31 and optical efficiencies of up to 60%, obtaining similar concentrations with better optical efficiency than a field using a hyperbolic reflector.

Optical characterization of a funnel solar cooker with azimuthal sun tracking through ray-tracing simulation

Funnel type solar cookers are simple and effective. Most of them rely on a multifaceted reflector to concentrate solar radiation on a cooking pot that is placed inside a transparent enclosure to create a greenhouse effect. The analysis of the resulting optical system is a complex task, as multiple reflections occur. The overall performance of funnel solar cookers is strongly affected by their optical efficiency. There is a lack of information in academic literature about this important research topic. This work aims to fill this gap presenting an optical performance analysis of a funnel solar cooker with only azimuthal sun tracking. Open-source numerical ray-tracing software Soltrace is used to investigate relevant characteristics such as the intercept factor, optical efficiency, dependency on incidence angle, performance of each reflecting surface and irradiation density flux distribution on different surfaces of the cooking pot. Some important results for beam radiation at normal incidence are the intercept factor, determined to be 0.664, and the optical efficiency with realistic optical properties, that turned out to be 0.370. When the incidence of solar beam radiation is not normal, optical efficiency remains above 90% of its normal incidence value, if the alignment errors are less than 10°.

An Empirical Study on Using CNNs for Fast Radio Signal Prediction

Accurate radio frequency power prediction in a geographic region is a computationally expensive part of finding the optimal transmitter location using a ray tracing software. We empirically analyze the viability of deep learning models to speed up this process. Specifically, deep learning methods including CNNs and UNET are typically used for segmentation, and can also be employed in power prediction tasks. We consider a dataset that consists of radio frequency power values for five different regions with four different frame dimensions. We compare deep learning-based prediction models including RadioUNET and four different variations of the UNET model for the power prediction task. More complex UNET variations improve the model on higher resolution frames such as \(256\times 256\). However, using the same models on lower resolutions results in overfitting and simpler models perform better. Our detailed numerical analysis shows that the deep learning models are effective in power prediction and they are able to generalize well to the new regions.

Accuracy of intraocular lens power calculation using Scheimpflug tomography and OKULIX ray-tracing software in paracentral corneal scarring not interfering with postoperative refraction

Purpose The aim of this study was to evaluate the accuracy of intraocular lens (IOL) power calculation using Scheimpflug tomography and OKULIX ray-tracing software in cases of paracentral corneal scarring. Patients and methods The study was conducted on 40 consecutive eyes: 20 with corneal scarring and coexisting cataract and 20 controls with clear cornea, for whom uneventful phacoemulsification and IOL implantation was performed. Preoperatively, Scheimpflug tomography and OKULIX ray-tracing software and third-generation IOL power calculation formulas were used for IOL power calculation. Accuracy of IOL power calculation was evaluated by subtracting the expected and achieved spherical refraction, 3 months postoperatively and was recorded as the mean absolute error (MAE). The distance uncorrected visual acuity for each eye was measured preoperatively and 3 months postoperatively; the visual acuity was scored and converted to the logarithm of the minimum angle of resolution (LogMar) for statistical analysis. Results In cases of corneal scarring, all eyes (100%) yielded a postoperative spherical refraction which differed by less than 1 D from the predicted. In 16 (80%) eyes, the postoperative spherical refraction was within 0.50 D from the expected. The MAE was 0.2 D in cases of corneal scarring, which did not differ significantly from the controls (MAE=0.1 D), P=0.142. In corneal scarring cases, the distance uncorrected visual acuity showed significant improvement from 1.3 LogMar (Snellen’s equivalent 20/400), preoperatively, to 0.5 LogMar (Snellen’s equivalent 20/60), 3 months postoperatively. Conclusion Scheimpflug tomography combined with OKULIX ray-tracing software for the calculation of IOL power provided accurate results in cases of corneal scarring.

Accuracy of intraocular lens power calculation using Scheimpflug tomography and OKULIX ray-tracing software in paracentral corneal scarring not interfering with postoperative refraction

Accuracy of intraocular lens power calculation using Scheimpflug tomography and OKULIX ray-tracing software in paracentral corneal scarring not interfering with postoperative refraction

OKULIX ray-tracing software versus third generation formulas: compatibility or superiority?

Purpose The aim of this retrospective study was to compare the accuracy of intraocular lens (IOL) power calculation using the OKULIX ray-tracing software compared with third generation IOL power calculation formulas. Patients and methods The study included 80 consecutive eyes of 80 patients (26 males and 54 females, with a mean age of 58.8±15.1 years), for whom phacoemulsification and IOL implantation was performed following biometry using the OKULIX ray-tracing software and third-generation IOL power calculation formulas for IOL power calculation. Accuracy of IOL power calculation was investigated by subtracting the attempted and achieved spherical equivalent 1 month postoperatively and was recorded as the mean absolute error. Results OKULIX ray-tracing software calculated IOL power was 17.1±8.5 diopters (D), which was statistically significantly different from Sanders, Retzlaff, Kraff (SRK)-T, Hoffer Q, SRK II, and Holladay formulas (16.7±8.3, 16.6±8.7, 16.8±8, and 16.7±8.5 D, respectively, P<0.001). The OKULIX ray-tracing software mean absolute error was 0.2±0.2 D, which was statistically significantly less than that of the SRK-T, Hoffer Q, SRK II, and Holladay formulas (0.5±0.5, 0.6±0.5, 0.8±0.7, and 0.6±0.5 D, respectively, P<0.001). Conclusions The OKULIX ray-tracing software seems to deliver reliable and more accurate results in comparison to the third generation IOL power calculation formulas.

Assessing Accuracy of Okulix Ray-Tracing Software in Calculating Intraocular Lens Power in the Long Cataractous Eyes.

Purpose:To investigate the accuracy of Okulix ray-tracing software in calculating intraocular lens (IOL) power in the long cataractous eyes and comparing the results with those obtained from Kane, Holladay 1 with optimized constant, SRK/T with optimized constant, Haigis with optimized constant, and Barret Universal 2 formulas.Methods:The present study evaluates the refractive results of cataract surgery in 85 eyes with axial length > 25 mm and no history of ocular surgery and corneal pathology. IOL power calculation was performed using the Okulix software. The performances of Okulix software in comparison with the five other formulas were evaluated by predicted error, mean absolute error, and mean numerical error 6 months after surgery.Results:The mean calculated IOL power by the Okulix software was +13.48 ± 4.19 diopter (D). The mean of the 6-month postoperative sphere and spherical equivalent were +0.18 ± 0.63 and -0.34 ± 0.78 D, respectively. Also, the 6-month spherical equivalent in 56.6% and 80% of eyes were within ±0.05 and ±1.00 D, respectively. The predicted error (P < 0.001) and the mean numerical error (P < 0.001) were different between the six studied methods; however, we were not able to find any significant differences in the mean absolute error among six studied methods (P: 0.211).Conclusion:The present study showed acceptable performance of the Okulix software in IOL power calculation in long eyes in comparison with the other five methods based on the postoperative refractive error, calculated mean absolute error, and mean numerical error.

Intraocular lens power calculation in virgin eyes: Accuracy of the Barrett Universal II formula and a Ray tracing software.

To compare the accuracy of Sirius ray tracing software with the Barrett Universal II formula for intraocular lens power prediction in virgin eyes. Retrospective case series including 86 eyes that have undergone uneventful cataract surgery with SN60WF implantation. The median absolute error, mean prediction error, variance, and the percentage of eyes within ± 0.25 D, ± 0.50 D, ± 0.75 D, and ± 1.00 D of the prediction error in refraction were calculated. The correlation of prediction error with different baseline parameters was investigated. No differences were found between the median absolute error of the Barrett Universal II formula (0.226 D) and the ray tracing software with different intraocular lens centerings; apex (0.331 D), limbus (0.345 D), and pupil (0.342 D) (p = 0.084). The variance, from lowest to highest, was the Barrett Universal II (0.144 D2), ray tracing-limbus (0.285 D2), ray tracing-pupil (0.285 D2), and ray tracing-apex (0.287 D2) (p = 0.027). The Barrett Universal II formula showed a higher percentage of eyes within ± 0.25 D (56.98%), ± 0.50 D (82.56%), and ± 0.75 D (93.02%) compared to ray tracing software (p < 0.01). A significant correlation between the prediction error of the Barrett Universal II formula and corneal diameter (r = 0.322, p = 0.002) and pupil diameter (r = 0.230, p = 0.033) was found. Also, a positive correlation between the prediction error of Sirius ray tracing and axial length (p < 0.001) and pupil diameter (p = 0.01) was found. There is a trend of the Barrett Universal II formula to be more accurate than Sirius ray tracing software for intraocular lens power calculation in virgin eyes. This should be confirmed in future prospective comparative studies.

Colored optic filters on c‐Si IBC solar cells for building integrated photovoltaic applications

AbstractBuilding Integrated Photovoltaic systems can produce a significant portion of the energy demand of urban areas. Despite their potential, they remain a niche technology that architects and project engineers still find esthetically limited. The dark blue or black color of standard photovoltaic panels is considered inappropriate for restoration projects of historic buildings and represents a major constraint on the development of new projects. This work will provide insight into how the use of optic filters can offer new pathways for architectural acceptance of photovoltaic panels. Optic filters selectively reflect or transmit light by interference and can be designed and fabricated using cost‐effective and industrially compatible processes. By using in‐house developed ray tracing software coupled with TCAD Sentaurus, more than 400 colors were obtained, and their impact on the opto‐electrical performance of interdigitated back‐contacted solar cells was studied. Results show a maximum efficiency loss of 1.6% absolute at the perpendicular incidence of light on the range of obtained colors when compared with a standard dark blue solar cell. Simulations for different angles of incidence showed that the current reduction on the standard device could be modeled using a cosine relationship. The colored cells, however, deviated significantly from this relationship. We propose that the angular behavior of any cell (colored or standard) could be simulated by modifying the effective irradiance with scaling factors equal to the ratios of the photogenerated current at any angle with respect to the value at normal incidence. We demonstrate that this approach accurately models the effect of the color filter and allows for an easy transition from a bare cell to an encapsulated one. Due to the spectral effect of the filter, we developed both a spectrally resolved optical model and a two‐dimensional finite volume transient thermal model. In case of the optical model, we demonstrate an accuracy in the prediction of the reflectance produced by the color with values of mean bias error (MBE) between 2.0% and 3.9%. As for the thermal model, it was validated by first analyzing a standard model under conditions of nominal operating cell temperature and then comparing its results with published scientific literature. Later, we compare its prediction against 2 weeks of measurements. In both cases the thermal model proves an adequate accuracy, yielding differences below 1.5°C with respect to other scientific works and an MBE value of 0.89°C as well as a root‐mean‐square error value of 2.10°C for the entire measurement period. With the validated models, we studied the effect of the encapsulation on the color perception. We present two options of color filters. The first one produces relatively low reflectance losses and presents relative annual direct current (DC) energy losses of up to 6.4% for Delft, in the Netherlands, and up to 5.9% for Alice Springs in Australia. However, this first option has very poor color brightness. The second studied filter produces highly saturated bright colors. Improving brightness can increase the annual DC relative losses up to 13.7% and 13.5% for Delft and Alice Springs, respectively. Overall, we demonstrate that colored filters based on multilayer optical stacks are a versatile option for coloring cells that allow a good compromise between esthetics and performance.

Concentrated Solar Power (CSP) for Sustainable Architecture to Supply Domestic Hot Water and Heating Loads of Buildings

Parabolic Trough Concentrators (PTC) are the most common solar concentrators. However, the high cost of production, operation, sun- tracking system, and the environmental sensitivity made them unprofitable for urban contexts. Lenses are more efficient and effective, but the complexity of manufacturing made them less used in sustainable architecture. This research proposes a liquid lens to be integrated into buildings’ envelope and compared with a PTC based on the energy production and reduced CO2 emissions over a year. The output energy, temperature, and efficiency of concentrator are obtained by the physics of light equations, and Ray-tracing software simulation. The results show that water lenses are at least 6% more efficient, their output temperature is higher, their underneath greenhouse effect made them less sensitive to the environment, and are still productive in high latitudes where PTCs are not operative. The paper presents the full result of the research that was registered as a patent.

Collection of dim light for accurate optical polarimetry by a plano-convex spherical lens

High-accuracy optical polarimetry of atomic fluorescence generally requires the use of a collimating collection lens. The orientation of this lens can affect its transmission due to reflective loss, but can also change the polarization state of the light being measured. Current best practices regarding lens orientation are related to minimizing spherical aberration. In this work, we use the ray-tracing software TracePro® to investigate the matter of lens orientation for a plano-convex lens as it relates to light transmission and reflection- and refraction-induced polarization changes. We compare the amount of scattered light for both orientations of the lens with and without anti-reflection coating, and show the effect the lens has on the polarization of the light produced by an unpolarized point-source as well as two point sources simulating highly-polarized atomic fluorescence. We discuss how these effects can be of concern for polarization-sensitive imaging and polarimetry of dim light sources with an accuracy of better than 0.1% of the measured Stokes parameters.

Exact equations to design aplanatic sequential optical systems

We present the exact differential equations to design an aplanatic sequential optical system, a system that is free of spherical aberration and linear coma. We get the exact set of equations from the Fermat principle and the Abbe sine condition. We solve the mentioned set of equations by implementing the Runge-Kutta algorithm. We test the solutions using commercial ray-tracing software and confirm the expected behavior of the optical system.

Aerial Base Station Assisted Cellular Communication: Performance and Trade-Off

The use of Aerial Base Stations (ABSs) has received a great deal of attention in academia and industry as a means to support the cellular communication traffic growth. In this article, we focus on obtaining the optimal altitude of an ABS using two criteria - maximum cell coverage area and minimum Symbol Error Rate (SER). Our study is done by using a probabilistic air-to-ground channel model, developed for low altitude aerial platforms via simulations on a commercial ray tracing software, for different scenarios like Urban High Rise, Urban, and Suburban. The probability distributions of the received power of the ground users and of the power delay profile at optimal ABS altitude are provided as a function of the size of the cell area. For the SER analysis, we present a system model based on Generalized Frequency Division Multiplexing (GFDM), in a time-frequency grid that is compatible with Long Term Evolution, by implementing parameters for low latency communication at the physical layer. The impact of “Better than Nyquist” pulses on the GFDM system is evaluated in terms of SER performance. From the presented results, a significant improvement is demonstrated compared to the traditional Nyquist pulses.