Ray Tracing Simulation Software Research Articles

Hyperspectral camera as a compact payload architecture for remote sensing applications.

Monitoring and observation over the surface of the Earth have been a matter of global interest. In this path, recent efforts aim to develop a spatial mission to perform remote sensing applications. Mainly, CubeSat nanosatellites have emerged as a standard for developing low-weight and small-sized instruments. In terms of payloads, state-of-the-art optical systems for CubeSats are expensive and designed to work in general use cases. To overcome these limitations, this paper presents a 1.4 U compact optical system to acquire spectral images from a CubeSat standard satellite at the height of 550 km. To validate the proposed architecture, optical simulations using ray tracing simulation software are presented. Because the performance of computer vision tasks is highly related to data quality, we compared the optical system in terms of the classification performance on a real remote sensing application. The performances of the optical characterization and land cover classification show that the proposed optical system achieves a compact instrument, operating at a spectral range from 450 nm to 900 nm discretized on 35 spectral bands. The optical system has an overall f-number of 3.41 with a ground sampling distance of 52.8 m and a swath of 40 km. Additionally, the design parameters for each optical element are publicly available for validation, repeatability, and reproducibility of the results.

Variation of Flux Reflected in Solar Parabolic trough Collectors with Rim Angle

A wide range of solar energy applications can benefit from the parabolic collector, including power generation, heating, and cooling. One of the most important parameters that affect the performance of a parabolic trough collector is its rim angle. This study examines how to rim angle affects the intensity of incoming photons reflected from the collector surface to the receiver. Flux distribution was simulated employing Ray tracing Simulation software. Out of 3000 photons employed in the experiment, 126 to 1608 photons were reflected from the collector to the receiver. A narrower rim angle results in a greater number of photons reflected per aperture width. A smaller aperture width also produces more photons for the focal length range studied.

EXPERIMENTAL AND NUMERICAL INVESTIGATIONS OF SOLAR FLUX DENSITY DISTRIBUTION OVER FLAT PLATE RECEIVER OF MODEL HELIOSTAT SYSTEM

The flux density distribution and the temperature of the receiver are important parameters to assess the net thermal energy of any Solar Power Concentrator. In the present work, a heliostat field utilizing ganged type of heliostats for process heating application has been designed. A prototype model of the central receiver system consisting of ganged heliostats has been constructed and installed at Pune, Maharashtra, India. A thermocouple method was used to evaluate the total energy focused by the model heliostat system on a flat receiver. The flux density distribution was validated with the ray tracing simulation software ‘SolTrace’. The simulated flux density distribution was found to be in agreement with the measured one for a surface normal error of 10 milliradian. A heliostat field having 100 m2 total mirror area was designed in the north south cornfield layout. This heliostat field was simulated in ‘SolTrace’ software by considering the surface normal errors as 10 milliradian and the total energy gain was estimated. For the purpose of simulation to investigate the solar flux falling on the receiver, four days of the year were selected. It includes the March equinox, summer solstice, September equinox, and winter solstice.

Prompt Gamma Shielding of Neutron Guides from Ray-Tracing Monte Carlo Simulations

This communication provides a brief overview of an efficient, fast, and computationally inexpensive method for evaluating the contribution of prompt gamma rays to dose rate around shielded neutron guides. Parameterized probabilities for neutron absorption in the materials of the neutron guide coatings during reflection were implemented in McStas ray-tracing simulation software together with analytical formula and tabular data necessary for a numerical evaluation of a dose equivalent. This allows evaluating the dose rate beyond the lateral shielding upon simulation of the guide ray-tracing.

Assessment of tomography signals in view of neural network reconstruction at ISTTOK

The detector measurements that serve as a basis for the tomographic reconstruction of plasma radiation profiles can be affected by a number of issues. In this work, we are especially concerned about reflections inside the vessel that appear as direct incidences, when in fact those contributions come from points that are outside the line of sight of a detector. This problem occurs in devices such as ISTTOK, where the surface of the inner vessel acts as an optical system capable of reflecting light. To assess the contribution of those reflections to the detector signals, we used an experimental setup comprising a cylindrical gas-discharge lamp placed at several radial and angular positions inside the vessel. As detectors, we used two photodiode arrays, one placed on the equatorial plane and the other at the top of the vessel. At the same time, we modelled this experimental setup in a ray-tracing simulation software so that, once the experimental data agrees with the simulation data, we can use this simulated environment to study the effect of reflections in realistic plasma profiles. When properly calibrated, such simulated environment can be used to generate large volumes of high-quality data to train a neural network for plasma tomography.

Recent developments of MCViNE and its applications at SNS

MCViNE is an open source, object-oriented Monte Carlo neutron ray-tracing simulation software package. Its design allows for flexible, hierarchical representations of sophisticated instrument components such as detector systems, and samples with a variety of shapes and scattering kernels. Recently this flexible design has enabled several applications of MCViNE simulations at the Spallation Neutron Source (SNS) at Oak Ridge National Lab, including assisting design of neutron instruments at the second target station and design of novel sample environments, as well as studying effects of instrument resolution and multiple scattering. Here we provide an overview of the recent developments and new features of MCViNE since its initial introduction (Jiao et al 2016 Nucl. Instrum. Methods Phys. Res., Sect. A 810, 86–99), and some example applications.

Parametric analysis of thin multifunctional elastomeric optical sheets

Abstract Flexible optical sheets are thin large-area polymer light guide structures that can be used to create innovative passive light-harvesting and illumination systems. The optically transparent micro-patterned polymer sheet is designed to be draped over arbitrary surfaces or hung like a curtain. The light guidance sheet is fabricated by bonding two or more micro-patterned layers with different indices of optical refraction. By imprinting micro-optical elements on the constituent layers, it is possible to have portions of the optical sheet act as a light concentrator, near ‘lossless’ transmitter, or diffuser. However, the performance and efficiency of the flexible optical sheet depends on the overall curvature (κ) of the optical sheet and the relative orientation of incident light source. To illustrate this concept, the impact of key design parameters on the controlled guidance of light through a two-layer polydimethylsiloxane (PDMS) concentrator-transmitter-diffuser optical sheet is investigated using ray tracing simulation software. The analysis initially considers a flat (κ=0) PDMS optical sheet exposed to a collimated light source. The impact of sheet curvature (κ>0) on both system efficiency and illumination uniformity is then briefly explored. Critical design guidelines for creating multifunctional monolithic optical sheets are also summarized.

Overcoming Systematic Photocurrent Calculation Errors in Ray Tracing Simulations

The calculation of photo-generation current densities jPh by means of Monte-Carlo ray tracing combined with Fresnel's equations for thin films is a common method in opticalsimulation of solar cells. We identified a reproducible and inherent error in ray tracing simulation software leading to systematic errors in jPh calculation in the order of 0.1 to 0.4mA/cm2 when using defined textures like upright, inverted and in some cases random front side pyramids in combination with pyramidal or planar rear sides with the use of Fresnel's equations applying the transfer matrix formalism as physical interface model. It is argued that this error emerges from coupling effects of the front and the rear side interfaces, leading to regular and “dragon-back” shaped oscillations in the calculated jPh when plotted as a function of the solar cell thickness. The amplitudes and frequencies of these oscillations correspond to the width of the pyramids used for the simulation. We show that reducing the base width of the pyramids is a simple way to solve this problem by reducing the amplitude to values where it meets the size of simulation-inherent statistic noise caused by the Monte-Carlo approach, without affecting other simulation parameters.

Determination of the overlap factor and its enhancement for medium-size tropospheric lidar systems: a ray-tracing approach

The problem of overlap factor (OVF) computation and its near-range sensitivity for medium-size aperture (f/10 , f/11 ) bi-axial tropospheric lidar systems using ray-tracing simulation software is presented. The method revisits both detector and fiber optics coupling alternatives at the telescope focal-plane along with the insertion of a field lens. A sensitivity analysis is carried out as a function of laser divergence, field lens, and detector/fiber positions, detector size, and the fiber’s core diameter and numerical aperture. The ray-tracing approach presented here is straightforward and a comparatively much simpler solution than analytical-based methods. Parametric simulations are carried out to show that both approaches are coincident. Insertion of a field lens proves to be an elegant and low sensitivity solution for OVF enhancement, particularly, in the near-range of the lidar.

무선통신과 임베디드 제어시스템 통신환경의 채널특성 알고리즘에 관한 연구

무선통신 임베디드시스템 및 MIMO 전파특성 예측을 위해 실내 및 실외 전파 예측 프로그램을 통합하여 하나의 시뮬레이터를 통해 실내 외 전파 예측이 가능하다. 이러한 해석 기법 개발을 통하여 여러 송신기간의 간섭 문제 및 최대 송신거리 문제, 주파수 이용 효율 등 여러 가지 문제에 대한 분석 및 예측이 가능해진다. 본 예측 기술 개발에서는 기존의 Walfish-Ikegami 방법 등 간략화된 모델보다 정확도 높으면서도 환경적 특성을 잘 고려 할 수 있는 광선추적법을 구현한 모의해석 소프트웨어를 개발하고 효율적인 광선 추적이 가능하도록 고안된 광선 추적 기법과 추적된 광선 정보를 이용하여 전파 특성 해석 기술을 접목시켜 효율적이면서도 이론적 특성을 잘 반영한 전파 특성 예측 기술을 확보하였다. 또한 주파수 확보를 위한 국내 임베디드시스템 및 IMT-Advanced용 신규대역 확보를 위한 주파수 특성 및 IMT-Advanced용 주파수인 3-5GHz대역 전파특성을 규명하여 국내 무선통신 기술 개발에 필요한 기반 기술 확보 및 전파간섭등 주파수 관리 기술 확보를 위하여 검증 및 실험을 통하여 확인 하였다. MIMO wireless communication embedded systems, and for propagation prediction for indoor and outdoor propagation prediction program incorporates an indoor/outdoor propagation through the simulator can be predicted. This analysis technique developed by the interference between multiple transmitters and a maximum transmission distance issues, the frequency utilization efficiency for a variety of issues, including analysis and prediction becomes possible. Development of the prediction of the conventional methods, but I can consider the environmental characteristics of the ray tracing simulation software to develop and implement an efficient ray tracing, ray tracing techniques and are designed to enable tracked beam analysis of propagation characteristics using information technology by combining the theoretical characteristics of an efficient and well-reflected propagation prediction technique was employed. The frequency of domestic embedded systems, ensure the frequency characteristics and frequency of 3-5GHz band for propagation to investigate the development of local wireless communication technology-based skills needed for securing and jeonpaganseopdeung frequency management techniques to ensure the verification and verified through experiments.

R&D of Ray Tracing Simulation Software and Fabrication Technologies Based on VCAD (Volume-CAD) Concept for GRIN Lens

We have been developing an intellectual manufacturing process applying IT (V-Cam system fabrication processes) based on Volume-CAD (VCAD) system which can express internal information of materials. This paper introduces the ultra-precision grinding, ray tracing (optical path) simulation software ‘V-Opt’ and the measurement of actual optical functions in the development of optical element taking gradient refractive index (GRIN) lens with functionally graded material properties as a model. In finish ground GRIN lens using SD#8000 wheel, the P-V (Peek to Value) of 27.07 nm, surface roughness (Ra) of 1.83 nm is obtained. ‘V-Opt’ developed for GRIN lens have two main functions; one is the visualizations of ray tracing and the other is the evaluation of spot diagram and focal length.

Fast-polarization-hopping transmission diversity to mitigate prolonged deep fades in indoor wireless communications

Fast-polarization-hopping (FPH) transmission diversity is herein proposed to mitigate prolonged deep fades at the mobile receiver in, for example, the indoor propagation environment. Even if the individual multipaths are each sufficiently strong for detection, deep fades may occur due to the multipath signals' destructive summation at the receiver. The relative immobility of the transmitter, the propagation environment, and the receiver in the indoor environment means that a deep fade may last for a very long duration, dropping calls or severing links. By rapidly hopping the transmission polarization (say, alternating transmission between a vertically-polarized-dipole antenna and a horizontally-polarized-dipole antenna - or between two X-oriented dipoles), the effective propagation channel experiences consecutive polarization modes (each involving a different multipath summation), all within the duration allowed by the channel-coder's interleaving depth. This scheme is usable for either frequency-shift keying (with incoherent demodulation), or for channel-coded phase-shift keying (with differential coding, or with pilot-symbol phase synchronization). This scheme requires no change in the mobile receiver (which does not need to be dual polarized). The base station also needs no spatially separated antenna array, nor any other additional hardware, no mechanical movement of the transmitting antenna(s), and no sophisticated signal processing (such as channel estimation or closed-loop feedback) nor any additional software. The proposed scheme's cost - relative to using antenna arrays at the base station and/or the mobile - is a potentially doubling of the transmission bandwidth. The proposed scheme's potential is illustrated by limited computer simulations using CINDOOR, a polarization-sensitive indoor wireless-propagation ray-tracing simulation software package based on geometrical optics and the uniform theory of diffraction (GO/UTD)

Miniaturization and module integration of an infrared spectrometer

When designing a miniaturized optoelectronic module, modeling of the system allows us to optimize structures, materials, and components to achieve optimal performance and cost effectiveness of the final product. We have used an approach in which an analytical model and simulation model support each other to speed up and enhance the system's development process. Our system integration approach includes analytical modeling and raytrace simulation modeling of the system, system realization, and system characterization. Our pilot miniaturized system is comprised of three silicon micromachined devices: an electrically modulated thermal infrared emitter, an electrically tunable Fabry-Perot interferometer (FPI), and a photodetector. The analytical modeling of the system was verified by optical raytracing simulation software. The simulation results were verified by experiments thus enhancing the development of the simulation model.

Comparison of laboratory and simulated data for radar image interpretation

It has been shown that the output from in-house ray-tracing simulation software provides a means by which the impulse radar response of a structural system can readily be simulated. Radar simulations were undertaken of re-bar targets in a tank. A 900 MHz commercial antenna was simulated. The simulations undertaken have shown the effects that target spacing and depth have on the radar signature shapes and the results compare well with real-case survey plots. Simulation data have been used to assess the output specification from a commercial antenna, with interesting findings. It is expected that simulation will allow the interpretation of actual surveys to be more readily understood, which will in turn allow a better engineering assessment to be made of a structure under investigation.