Convex Mirror Research Articles

Unsupervised Domain Adaptation for Semantic Segmentation of Urban Street Scenes Reflected by Convex Mirrors

Reflective convex mirrors are often used on street corners or as passenger-side mirrors on cars to obtain scene information by reflecting blind spots in the field of view, which can provide safety for pedestrians and drivers on roads, driveways, and alleys that lack of visibility. In recent years, deep learning based scene understanding methods (e.g., semantic segmentation) have been rapidly developed. However, due to gaps in the geometric domain, models trained on normal images are not directly applicable to scenes with convex mirror reflections. In this paper, we propose a novel framework to reduce the domain gap between normal images and convex mirror reflection images. In particular, we geometrically model convex mirrors to obtain a differentiable convex mirror simulation layer, CMSL. With the help of CMSL, we perform adversarial domain adaptation on edges in the input space and semantic boundaries in the output space to reduce the geometric appearance gap between the synthetic and real images. To verify the effectiveness of our algorithm, we construct the first convex mirror reflection scene dataset CMR1K, which contains 268 images with fine annotations. Extensive experimental results show that our algorithm can significantly outperform the baseline and previous methods. For example, our method surpasses the baseline and AdvEnt by 10% and 3% in mIoU, respectively.

Correction of perspective distortion and intensity errors in projected fringe patterns in phase-measuring deflectometry

The relative pose between the projector and screen in a phase-measuring deflectometry (PMD) setup can result in perspective distortion and intensity errors in the projected fringe patterns. These problems degrade the sinusoidal characteristics of the fringe patterns, thus increasing phase, slope, and height errors in the PMD measurement. To overcome these issues, inverse perspective distortion and intensity modification algorithms were developed and applied to computer-generated fringe patterns before projection. The inverse perspective distortion matrices were obtained using a single image of the projected grid distortion target. The pixel intensities in the generated fringe patterns were modified using the relationship between the generated and captured pixel intensity values in grayscale images of uniform intensity. Experiments were conducted to measure the surface topographies of spherical concave and convex mirrors using a monoscopic PMD setup. Based on the experimental results, the root-mean-squared (RMS) intensity and phase errors in the projected sinusoidal fringe patterns were reduced by about 90% after using the modified fringe patterns compared to the original fringe patterns. When comparing the measured and the theoretical heightmaps, the results in PMD measurement showed an 8% and a 14% reduction of the RMS height errors in concave and convex heightmaps, respectively. The effectiveness of the algorithms in improving the accuracy of projector-based PMD measurement was demonstrated successfully.

Ocular morphology of the fruit bat, Eidolon helvum, and the optical role of the choroidal papillae in the megachiropteran eye: a novel insight

This work was designed to provide a morphologic, morphometric and histochemical description of the eye of the African straw-coloured fruit bat (Eidolon helvum). An explanation of the optical role of the choroidal papillae in the vision of megachiropteran bats was provided. Enucleated eyes of captured fruit bats were measured and processed for light microscopy. Typical gross features of the mammalian eye including an anterior transparent cornea, posterior whitish sclera and a golden-brown iris surrounding a round pupil were observed in the eye. Presence of undulating retina typically found in megachiropterans was also seen. The ratio of mean corneal diameter to mean axial eye diameter was 0.58 ± 0.08. The histochemical investigation of the eye indicated the presence of mucins, proteoglycans, hyaluronic acid, glycogen and/or glycoproteins in the corneal, scleral, choroidal and retinal tissues. The presence of reflective materials of the tapetum lucidum on the undulating retina was shown to be a morphological adaptation for increased light sensitivity as each parabolic surface of the choroidal papillae served as a convex mirror, reflecting the light rays to the adjacent parabolic surface, thus sensitising photoreceptors in affected regions. This phenomenon thus empowers megachiropteran bats with improved scotopic visual capability and could explain why most of them are reliant on their vison without the need for echolocation.

Dragging three-point method for measurement of telescope optics

We developed the improved three-point method as measuring machine that is applicable for measurements of various telescope optics, including concave, convex, and off-axis mirrors of high aspheric. The method is small and robust against temperature change and vibration and can extend a conventional machining tool to a measurement tool. We measured the cross section of a flat mirror of ϕ300 mm with this method on an old milling machine. The result was consistent with that obtained with an interferometer with a discrepancy of 5.5 nm (RMS). For the next stage, we executed two-dimensional measurements of a concave spherical mirror of ϕ794 mm. The result showed good agreement with that obtained with an interferometer and the method successfully detected an amplitude of 30 nm of small-scale structure in the lateral direction.

Design of stereo imaging system with a panoramic annular lens and a convex mirror.

Panoramic stereo imaging system can not only provide panoramic images to obtain more information, but also obtain the depth information of the target object, and it has broad application prospects in robot navigation, road planning, and obstacle avoidance. A new panoramic stereo imaging system combined with a panoramic annular lens (PAL) and a convex mirror is proposed. It provides a large panoramic vision up to 360°× (30°∼150°) and, to the best of our knowledge, the entire FOV is the largest in the existing literature. Meanwhile, the stereo field of view is 35°.

Backscattering Estimation of a Tilted Spherical Cap for Different Kinds of Optical Scattering

In many optical engineering applications, a spherical cap shaped optical element is widely used such as concave or convex mirrors in reflective optics. Such an element can also tilt around the vertex which corresponds to an off-axis optical design. The optical backscattering of such an optical element sometimes could be important. For example, in the space-based gravitational wave detection, the backscattering of such an element could be superimposed with the local oscillator and limits the sensitivity of the spacecraft. The scattered contributions depend on the scattering property of the mirror surfaces and the geometrical arrangement including the radius of curvature, the tilt and the interval between the scattering source and detector plane. Based on random estimation method, this paper starts from the radiometry, combines these variables and calculates the theoretical amount of back scattered light for both diffuse and superpolished surfaces. The results are compared with analytical and ray tracing solution. The conclusions can be used to further improve the optical design of the telescope or extended to other cases where the backscattered light should be controlled.

Investigation of trapped charges profile for an irradiated insulated material.

The process of examining and analysing insulating materials using a scanning electron microscope usually accompanied by an important phenomenon called the mirror effect or charging effects. Such effects arise due to the ability of insulators to trapping charges at the sample surface for a period. The accumulation of charges leads to creating an electric potential that may be strong enough to deflect incident electrons in the same way a convex mirror scatters light. The created potential depends mainly on the charge amount, charges accumulation profile and the way by which the charges arranging themselves. Present work aims at exploring the influences of the charges distribution profile and their arrangements. In order to achieve such a goal, the sample-surface potential has theoretically formulated to include various shapes of the accumulated charges. Thereafter, the correspondence expression of the mirror plot curve is defined to link thegeometrical distribution of charges.The resultant formula for the surface potential and mirror plot showed that the point charge approximation is a special case of the presented model. The formulaof mirror-plot curve hasput forward to be a detection tool for the actual build-up form that the electrons accumulating might take on the insulator surface.Simulation results have shown that the presented procedurecould be adopted to search for the optimum distribution profile that may meet an experimental data. It is found that the most probable profile that accumulated electrons might form is the semi-hemispheric one. The surface of this profile is generally an ellipsoid of a variant axis rather a flat one. Results also reveal that, all the multipole-moment typescould be formed for any shape of accumulation, but their weightiness progressively decreases whenever the pole-number increases. Furthermore, the configurations that trapped electrons arrange themselves within each distribution profile can be traced with the variation of scanning potential.

Investigation the effectiveness of light reflectors in transmitting sunlight into the vertical farm depth to reduce electricity consumption

Nowadays, the use of greenhouses and vertical farms has become increasingly commonplace due to compensating the crisis of food scarcity and fertile land for the world's growing population. The lack of free natural sunlight within the floors of such modern farms, however, has led to the application of artificial light as a common strategy to enhance food production. The energy supplied to produce this artificial light has increased the cost of food production. In this regard, the current study seeks to develop a new way to bring sunlight into vertical farms to reduce costs, avoid more energy consumption, and then increase the sustainability of food production. For this purpose, this experimental-applied research based on desk review focuses on the necessity of using sunlight in vertical farms, while adopting drawing and graphical software to illustrate how a variety of mirrors can transmit and distribute sunlight into vertical farms as a concept that applies to different latitudes. The proposed concept was tested quantitatively and qualitatively by constructing a physical model on a scale of one-twentieth at the latitude of 36.46° N, 52.86° E. This experiment showed that, in mentioned geographical position, the ratio of light supplied at a depth of a floor to unobstructed sunlight in the space around a vertical farm. • The free and useful light energy of the sun can illuminate the depths of a vertical farm with the help of reflectors. • Using free sunlight on vertical farms will reduce the cost of food production. • Flat and convex mirrors, as light transmitters and diffusers, make access for sunlight to reach into the vertical farm depth.

Near-infrared spectroscopy using period-chirped Si/SiO/SiO2-based guided mode resonance filter.

We demonstrate a Si/SiO/SiO2-based period-chirped guided mode resonance (GMR) filter to discriminate telecom o-band wavelengths by spatially resolved horizontal movement. Continuously period-chirped silicon gratings were fabricated by using a Lloyd's laser interferometer with a convex mirror. Due to the large waveguide effective index, the GMR filter can be realized with a short grating period, thus enabling a slow grating period transition along the sample position and high optical resolution in wavelength discrimination. Depositing a SiO/SiO2 stack on top of silicon gratings enables a narrowband GMR filter with a linewidth of 1-1.5 nm over a wavelength range of 1260-1360 nm. By using the chirped GMR filter as a dispersive device, the optical spectra of a near-infrared broadband light source are reconstructed. An optimized aspheric mirror is proposed to further improve the linearity of chirped gratings. Such a period-chirped GMR filter is promising for compact on-chip spectroscopy and sensing applications.

Interferometer for Testing of Convex Mirrors of Optical and Radio Telescopes Constructed by the Scheme of Orthogonal Rays

Interferometer for Testing of Convex Mirrors of Optical and Radio Telescopes Constructed by the Scheme of Orthogonal Rays

USING OF VIRTUAL REALITY TOOLS FOR THE DEVELOPMENT OF STEAM EDUCATION IN GENERAL SECONDARY EDUCATION

The article researches the use of virtual reality to support STEAM education in general secondary school. To study the impact of STEAM education, the authors proposed a teaching project for the secondary school about convex mirrors and their importance for special visibility and human safety, where the interviewed teachers were able to learn about a real example of the implementation of STEAM education for teaching their disciplines. The purpose of the article is to analyze the meanings and approaches to the use of virtual reality by teachers for organizing the STEAM-oriented learning environment and to identify the basic requirements to VR for supporting the implementation and development of STEAM education. One of the main trends of education modernization is STEAM education, which involves the integration of the natural sciences, the technological sciences, engineering, mathematics and art in the learning process, in particular, at general secondary schools. In light of the findings, researchers indicate that electronic educational resources (including VR & AR) are not only teaching tools for teachers but also a source of inspiration for students, which motivates and stimulates creative thinking. This is an important point considering that creativity is increasingly an important life skill that can help young people cope with the difficulties and uncertainties in their future careers in the fields of STEAM. Prospects for further research are seen in the creation of a model for assessing student performance in STEAM projects. The authors are planning to take into account the differences and features of the use of virtual reality for learning STEAM in schools in different countries, including Ukraine, Spain and Kazakhstan, when creating a multilevel model of STEAM-oriented learning environment using virtual reality tools. The purpose of the model is to evaluate not only the results of tests taken by students after learning this material but also their personal contribution to the final project product, their leadership skills, creative ideas and suggestions, abilities and skills in using ICT and VR in project research. In our next publications, we will focus on several Spanish and Kazakhstani secondary schools to detect the possible differences found in the use of virtual reality to support STEAM education in Ukrainian schools.

Orthogonal ray interferometer: modification for testing convex and concave mirror surfaces

A non-contact optical method for testing of large concave and convex mirrors both spherical and aspheric is presented. It is based on the orthogonal ray interferometer modification. The point source is placed near the testing mirror and the chief ray propagates normally to its axis. The information about a tangential profile of testing mirror is contained in an interference pattern that is a result of superposition between two wavefronts, the first is reflected from the mirror, the second bypasses the mirror. Testing of the entire surface is carried out by rotating the mirror. Interferogram decoding method and algorithm for determination of an error of the testing surface are presented. The proposed method does not require bulky additional optical components what differs it from existing methods and makes promising primary for testing large astronomical mirrors. Furthermore, the method is universal and suited for surfaces with various geometrical parameters. The scheme with some modification of the present method is applied for surfaces without axis of rotational symmetry or freeform surfaces.

Orthogonal ray scheme: a method for processing interference patterns and reconstructing the shape of a test convex mirror

This report is devoted to the processing of the interference pattern of the tested mirror, obtained using the orthogonal ray scheme, where the convex testing surface is illuminated by a collimated beam, which is perpendicular to the optical axis of the surface. The interference pattern is created by two wavefronts, one of which is reflected from the mirror, while the other wavefront bypasses the mirror and travels directly to the detector plane. The result of interference pattern processing is a topography map formed by several tangential profiles. The proposed method is suited for large diameter convex spherical and aspherical mirrors and does not require a priori information of surface under the test, such as the vertex radius of curvature and the conical constant. Theoretical foundation of the data processing method are presented.

Ghost panorama using a convex mirror.

Computational ghost imaging or single-pixel imaging enables the image formation of an unknown scene using a lens-free photodetector. In this Letter, we present a computational panoramic ghost imaging system that can achieve a full-color panorama using a single-pixel photodetector, where a convex mirror performs the optical transformation of the engineered Hadamard-based circular illumination pattern from unidirectionally to omnidirectionally. To our best knowledge, it is the first time to propose the concept of ghost panoramas and realize preliminary experimentations. It is foreseeable that ghost panoramas will have more advantages in imaging and detection in many extreme conditions (e.g., scattering/turbulence and unconventional spectra), as well as broad application prospects.

Augmented Reality Geometrical Optics (AR-GiOs) for Physics Learning in High Schools

This study aims to produce “Augmented Reality Geometrical Optics (AR-GiOs)” as a medium for physics learning for geometrical optics in high school. The method used in this study is the Research and Development method with the ADDIE model (Analyze, Design, Develop, Implement, and Evaluate). AR-GiOs was developed to facilitate students in learning the concept of image formation and image properties of mirrors and lenses. AR-GiOs can display four 3D simulations, including 3D simulations of the image formation process by a concave mirror, a convex mirror, a concave lens, and a convex lens. In addition to AR, in this study, a worksheet was also developed to guide student learning activities and valuable as a marker. The results of product validation covering the material and media aspects got a very good average score (84% and 90%). Based on the results of the expert validation test, it can be concluded that AR-GiOs is suitable for use as a medium for learning physics in high school.

Overtaking Assistance Using Wireless Camera and Sensors (Zenarch Tech)

The major area of concern in the advancement of intelligent vehicles is to improve the safety of driving system. This paper comes up with a new way of using visual system for driving assistance by replacing convex mirror with wireless camera and sensors. The new system uses vehicle-to-vehicle OAS which contains both transmitter and receiver systems. It will assist the driver to avoid accidents during overtaking. This isa driver support system which helps you maintain the correct speed and safe distance from other vehicles. .It helps in reduction of accidents and provides safe journey on all weather conditions.

Precisely Designed and Modeled Double-Clad Fiber Optic Pressure Sensor

In this article, we investigated and designed a double-clad fiber optic pressure (DFOP) sensor, which can acceptably calculate the pressure values using the input and output intensities/powers of light. In order to know the received power, the overlap integral of the emitted light from the core of a double-clad fiber with its reflection from a mirrored diaphragm onto either itself or the inner clad was considered. Also, the diaphragm deflection was approximated as a spherical convex mirror which diverged the received light cone and increased the receiving area albeit for the light Gaussian distribution. In comparison with similar existing setups, this sensor, with its precise calibration, provided a wider range of output normalized power of about 0.3 W (watt). Thus, the sensor can be made more simply and inexpensively since there is no need for very high precision optical time-domain reflectometers (OTDR) or power-meters.

3D Meta‐Prisms for Versatile Beam Steering by Hybridizing Plasmonic and Diffractive Effect in the Broadband Visible Regime

AbstractAs two independent optical sub‐fields, diffraction optics and plasmonics both have been used for wavefront shaping and beam steering. However, the two separate concepts have always been developing as two parallel directions, which have not met for studying their structural hybridization to discover new potentials. For instance of the flat metasurfaces, even though the geometric parameters including shape, size, and periodicity have been studied, it remains mostly unexplored for the 3D spatial height variation. Here, a new type of all‐metallic 3D meta‐prism is proposed and experimentally demonstrated by hybridizing the localized surface plasmonic resonances (LSPR) and the blazed grating diffraction, which enables strong polarization‐dependent behaviors to steer broadband visible light to drastically inverse directions. The nanofabrication of 3D meta‐prism is achieved by nanostencil lithography with electron‐beam evaporation. Such meta‐prism could also enable to split different visible light (green, blue, and red) with high‐efficiency contrast (≈10). By the mirror‐symmetry arrangement, a multifunctional surface is demonstrated with polarization‐/wavelength‐multiplexing wavefront‐shaping functions (concave, convex, or flat mirror). This unique 3D meta‐prism enjoys great simplicity and versatility in broadband beam steering through the incorporation of plasmonic and diffractive effects and can be utilized in various applications including dichroic‐prism splitters, multifunctional meta‐mirrors, etc.

Accident Prevention Road Safety Model with Speed Breaker Power Generation

The implementation of the Collision Avoidance System is aimed to reduce the risks of collisions at the hairpin bend on a Hilly track, Ghats, or other Zero visibility turns The proposed system contains a set of proximity sensors, warning lights combined with a convex mirror is installed by the side of the road. Moreoverthis project is about the design and manufacturing of speed breaker power generator. In this project we are trying to utilize one such source. In this report we explain in detail the various stages of research, design and manufacturing which was involved in the construction of various components such as springs, generator, rack and pinion mechanism.

Implementation of the PIMCA model to learning convex mirror

Learning in the 4.0 era requires various learning models, one of which is the MR-SR based PIMCA learning model (Presentation, Idea Mapping, Conceptualization, Assessment Formative) which presents the same concept in several formats. This study aims to determine the increase in student learning outcomes before and after implementing the MR-SR based PIMCA learning model introduced and developed by Cosmas Poluakan. The research method used of One group pre-test post-test design. This research of conducted in the Department of Physics, State University of Manado, with 29 student respondents. The research process begins with problem formulation, management, analysis of data, and conclusion. The results of the data analysis showed that the average score before the test of 20,69 and the average score after the test is 72,41. With a maximum value of 75, a gain of 0.9 is obtained. This means that there is an increase in learning outcomes in the high category because g > 0,7. The results of this study indicate that the MR-SR based PIMCA learning model can improve student learning outcomes in mastery of physics concepts.