Browse Topic: Mirrors
Additive manufacturing (AM) processes facilitate the production of components with high geometrical complexity, presenting substantial opportunities for innovation in demanding sectors such as aerospace and biomedical engineering. A significant challenge impeding their broader application is the characteristic surface roughness of as-fabricated parts, which results from the layer-wise construction and the presence of partially melted powder particles. While electrochemical polishing (EP) represents a viable post-processing technique for achieving a smooth surface finish, a comprehensive understanding of how the non-equilibrium microstructures characteristic of AM materials interact with the EP process remains incomplete. This investigation centers on the electrochemical polishing behavior of Ti-6Al-4V alloy fabricated by direct energy deposition (DED), utilizing a sodium chloride-ethylene glycol electrolyte. The findings reveal that the material's distinct engenders anisotropic anodic dissolution. This behavior is attributed to the differential electrochemical potentials among the constituent phases and their crystallographic orientations, which consequently narrows the operational process window for effective, uniform polishing. This preferential dissolution of certain phases results in the formation of a subtle, micro-scale topographical variation that mirrors the orientation of the original columnar grain structure. Notwithstanding this microstructural influence, the EP treatment proved highly successful in refining the surface finish, substantially decreasing the average surface roughness from 0.350 μm to 0.042 μm. Concurrently, the treatment led to a significant enhancement in the alloy's corrosion resistance, attributed to an oxide layer. These findings underscore the critical necessity of accounting for microstructural characteristics when developing optimized electrochemical polishing protocols for additively manufactured components.
Stoneridge displayed its vision for the future of commercial vehicle technology on the SAE COMVEC 2025 exhibit floor. The Innovation Truck showcases the Tier 1 supplier's next-generation vision and driver-assistance technologies designed to enhance driver safety and fleet optimization. Mario Gafencu, product design and evaluation specialist at Stoneridge, gave Truck & Off-Highway Engineering a tech truck walkaround at the event. The first technology Gafencu detailed was the second-generation MirrorEye camera monitor system that's designed to replace the glass mirrors on the sides of a truck.
In the race toward practical quantum computers and networks, photons — fundamental particles of light — hold intriguing possibilities as fast carriers of information at room temperature. Photons are typically controlled and coaxed into quantum states via waveguides on extended microchips, or through bulky devices built from lenses, mirrors, and beam splitters. The photons become entangled — enabling them to encode and process quantum information in parallel — through complex networks of these optical components. But such systems are notoriously difficult to scale up due to the large numbers and imperfections of parts required to do any meaningful computation or networking.
A new bioimaging device can operate with significantly lower power and in an entirely non-mechanical way. It could one day improve detecting eye and even heart conditions. The device uses a process called electrowetting to change the surface shape of a liquid to perform optical functions. By creating a device that doesn’t use scanning mirrors, the technique requires less electrical power than other devices used for OCT and bioimaging. To test the device’s ability to perform biomedical imaging, the researchers turned to zebrafish. The researchers focused on identifying where the cornea, iris, and retina was from the zebrafish. The two benchmarks that the group hoped to achieve were 10 μm in axial resolution and then around 5 μm in lateral resolution.
In the race toward practical quantum computers and networks, photons — fundamental particles of light — hold intriguing possibilities as fast carriers of information at room temperature. Photons are typically controlled and coaxed into quantum states via waveguides on extended microchips, or through bulky devices built from lenses, mirrors, and beam splitters. The photons become entangled – enabling them to encode and process quantum information in parallel – through complex networks of these optical components. But such systems are notoriously difficult to scale up due to the large numbers and imperfections of parts required to do any meaningful computation or networking.
Sound source identification based on beamforming is widely used today as a spatial sound field visualization technology in wind tunnel experiments for vehicle development. However, the conventional beamforming technique has its inherent limitation, such as bad spatial resolution at the low frequency range, and limited system dynamic range. To improve the performance, three deconvolution methods CLEAN, CLEAN-SC and DAMAS were investigated and applied to identify wind noise sources on a production car in this paper. After analysis of vehicle exterior wind noise sources distribution, correlation analysis between identified exterior noise sources and interior noise were conducted to study their energy contribution to vehicle interior. The results show that the algorithm CLEAN-SC based on spatial source coherence shows the best capability to remove the sidelobes for the uncorrelated wind noise sources, while CLEAN and DAMAS, which are based on point spread functions have definite limitations. Considering the testing car, the main noise source of exterior is from the wheelhouse region, then follows the rearview mirror with much lower sound energy. However, noise from the mirror contributes most to the vehicle interior, while the contribution from wheelhouse region ranks the second place. In addition, windshield wipers and door handle can do perceptible contributions to vehicle interior noise at some characteristic frequency bands.
For years the NVH community has known that openings in the dash sheet metal, such as holes to pass wire harnesses through, creates an acoustical weak point that limits the potential noise reduction of the dash insulation system. These pass-throughs can also be a source of water leaks into the vehicle’s interior. With internal combustion engines and now electric inverter power plants generating significant high frequency sound, the need to seal this area is vital. By molding a lightweight barrier that draws through the fiber/absorber interior decoupler and dash sheet metal which mates to a secondary seal molded into an outer engine dash decoupler, the two opposing molded barriers meet in the engine compartment and compress together forming a seal around the wire harness. This male/female molded seal replaces the conventional snap in grommet and eliminates noise/water leaks. The system Sound Transmission Loss (STL) is equivalent to similarly insulated sheet metal with no holes, increasing sound intelligibility/articulation index in the automotive interior, leading to new levels of occupant comfort and ease of communication. This technology can also be used anywhere in the vehicle where a hole is created in sheet metal and a wire is passed through it (e.g. electric side view mirrors).
Machining metal has its challenges as many shops will attest, but machining glass is another matter – one that Dan Bukaty Jr., President of Precision Glass & Optics (PG&O) is well schooled in. Mr. Bukaty and his 35-person shop manufacture high-end precision glass optics for customers such as IMAX, Intuitive Surgical, Boeing and NASA, to name a few. The products PG&O make can range from the ordinary to the extraterrestrial, such as mirrors that it fabricated for the Hobby–Eberly Telescope to measure dark energy in outer space.
Camera-based mirror systems (CBMS) are being adopted by commercial fleets based on the potential improvements to operational efficiency through improved aerodynamics, resulting in better fuel economy, improved maneuverability, and the potential improvement for overall safety. Until CBMS are widely adopted it will be expected that drivers will be required to adapt to both conventional glass mirrors and CBMS which could have potential impact on the safety and performance of the driver when moving between vehicles with and without CBMS. To understand the potential impact to driver perception and safety, along with other human factors related to CBMS, laboratory testing was performed to understand the impact of CBMS and conventional glass mirrors. Drivers were subjected to various, nominal driving scenarios using a truck equipped with conventional glass mirrors, CBMS, and both glass mirrors and CBMS, to observe the differences in metrics such as head and eye movement, reaction time, and perception of distance. The finds from this study will serve as the baseline measurements for future research regarding off-nominal driving scenarios and hardware failures of CBMS, as well as inform potential future policy regarding CBMS for the use in commercial vehicles in lieu of conventional glass mirrors.
This research explores the use of salt gradient solar ponds (SGSPs) as an environmentally friendly and efficient method for thermal energy storage. The study focuses on the design, construction, and performance evaluation of SGSP systems integrated with reflectors, comparing their effectiveness against conventional SGSP setups without reflectors. Both experimental and numerical methods are employed to thoroughly assess the thermal behavior and energy efficiency of these systems. The findings reveal that the SGSP with reflectors (SGSP-R) achieves significantly higher temperatures across all three zones—Upper Convective Zone (UCZ), Non-Convective Zone (NCZ), and Lower Convective Zone (LCZ)—with recorded temperatures of 40.56°C, 54.2°C, and 63.1°C, respectively. These values represent an increase of 6.33%, 11.12%, and 14.26% over the temperatures observed in the conventional SGSP (SGSP-C). Furthermore, the energy efficiency improvements in the UCZ, NCZ, and LCZ for the SGSP-R are considerable, showing increases of 39.18%, 35.46%, and 39.64%, respectively, when compared to the SGSP-C. The numerical simulations are in strong agreement with the experimental results, exhibiting minimal deviations of less than 5% in both temperature distribution and energy efficiency across all zones. This study underscores the potential of SGSPs with reflectors for enhanced thermal storage performance.
Researchers at the Max Planck Institute for Extraterrestrial Physics have developed a new way to produce and shape large, high-quality mirrors that are much thinner than conventional space-telescope mirrors. The final product is even flexible enough to be rolled up and stored compactly inside a launch vehicle.
The global market for automotive LIDAR is expected to grow from $332 million in 2022 to more than $4.5 billion by 2028. That’s solid market growth, particularly given the decades-old challenges of commercializing LIDAR that would be affordable for automotive designs. We interviewed Eric Aguilar, co-founder and CEO of Omnitron Sensors, Los Angeles, CA, to learn about a new MEMS scanning mirror that could accelerate the market adoption of LIDAR.
On a cold, sunny day, you’re driving on a rural road, surrounded by snow-covered fields. In an instant, your eyes process the scene, picking out individual objects to focus on — a stop sign, a barn — while the rest of the scene blurs in the periphery. Your brain stores the focused and blurred images as a memory that can be pictured in your mind later, while sitting at your desk.
The design and location of rear-viewing mirrors or systems, and the presentation of the rear view to the driver can best be achieved if the designer and the engineer have adequate references available on the physiological functions of head and eye movements and on the perceptual capabilities of the human visual system. The following information and charts are provided for this purpose. For more complete information of the relationship of vision to forward vision, see SAE SP-279.
This SAE Recommended Practice describes methods for determining total and specular reflectance for mirrors with flat and curved surfaces and a method for determining diffuse reflectance and haze for mirrors with flat surfaces.
Optical parametric oscillator (OPO) lasers test optical fibers and components to characterize the spectral response of optical components. OPO lasers are common in sophisticated test and measurement applications such as mass spectrometry, photoacoustic imaging, and spectroscopy. Now, these tunable pulsed lasers are being used to facilitate a range of tests at different wavelengths to qualify and quantify the performance of optical components such as fiber optic strands, filters, lenses, and coated mirrors.
The James Webb Space Telescope’s stunning images showing previously unseen corners of the universe are possible because of the telescope’s 21-foot segmented mirror that had to unfurl on its own after launch and assemble itself in space.
Light detection and ranging (LiDAR) provides the type of velocity data about objects and vehicles that are necessary to enable the type of decision-making necessary for navigation systems in autonomous vehicles. However, most LiDAR sensors that have been used in automotive and other mobility applications have been fragile, expensive and unreliable.
Enriched ventilation and driver assistance systems which plays vital role in human thermal comfort and safety, are now necessities for the whole automotive sector. For faster cabin thermal comfort, air circulation around occupant’s body reveals higher cabin comfort index. In India natural and forced ventilation system is predominantly used in commercial vehicles as an economical solution for achieving interim cabin comfort over air conditioning system. Presently used forced ventilation system consist of electrically driven blower motor to remove stale air around human body which is adding alternator load and thus affects fuel economy. Remarkably, 22% of such auxiliary electrical load is taken by electrical components from engine generated power. In order to enhance cabin thermal comfort and conceivably reduce power usage, an effective air flow control system is need of hour. In the proposed new technology, the ORVM (Outside Rear View Mirror) based air cooling technique is used for cooling ambient air. The concept demonstrates the use of air against vehicle speed is directed through ORVM causing air cooling using direct evaporative cooling techniques. The cooled air is then passed to cabin for occupant's comfort. The concept is validated using virtual analysis tools for air flow analysis and air temperature drop at various vehicle speeds. The prototype model is prepared and tested by running vehicle on highway. The experimental analysis shows a temperature drop between 4.5 °C to 8°C over ambient air temperature and vehicle speed. The concept is also evaluated for drag forces to analyze effect of change in ORVM area on fuel economy. The extreme features of cooling the outside hot ambient air using matured cooling technology and dust filtering inside ORVM casing makes idea innovative and easily adoptable.
Numerical methodologies for aeroacoustic analyses are increasingly crucial for car manufacturers to optimize the effectiveness of vehicle development. In the present work, a hybrid numerical tool based on the combination of a delayed detached-eddy simulation and a finite element model, which relies on the Lighthill’s acoustic analogy and the acoustic perturbation equations, is presented. The computational aeroacoustics is performed by the software OpenFOAM and Actran, concerning respectively the CFD and the FEM. The aeroacoustic behavior of the SUV Lamborghini Urus at a cruising speed of 140 km/h has been investigated. The main aerodynamic noise phenomena occurring in the side mirror region in a frequency range up to 5 kHz are discussed. The numerical simulations have been verified against the measurements performed in the aeroacoustic wind tunnel of the University of Stuttgart, operated by FKFS. The predicted exterior noise propagation into the far field has been validated by comparing the sound pressure level with the experimental data measured by exterior microphones, which were located outside the turbulent region beside the wake of the side mirror. Furthermore, the noise transmission into the cabin through the side window has been modeled. Simulation results have been validated by means of interior microphones installed on the driver seat. Both the exterior and the interior noise predictions show very good correlations with experiments. Lastly, a comprehensive investigation of the most critical aeroacoustic sources has been carried out. The numerical tool has been proven to be in good accordance with the microphone array with respect to the distribution of the sound pressure level in the proximity of the side mirror. Besides, the main vortex structures involved in the generation mechanisms of wind noise have been investigated by a CFD analysis. The entire CAA process has been proven to be accurate and suitable for combined analysis between the generation mechanisms of wind noise and the resulting transfer into the interior cabin to the driver’s ear as well.
Thermal control coatings, i.e. coatings with different visible versus infrared emission, have been used by NASA on the Orbiter and Hubble Telescope to reflect sunlight, while allowing heat rejection via infrared emission. However, these coatings absorb at least 6 percent of the Sun’s irradiant power, limiting the minimum temperature that can be reached to about 200 K. NASA needs better solar reflectors to keep cryogenic fuel and oxidizers cold enough to be maintained passively in deep space for future missions.
A gigantic furnace slowly started spinning underneath the stands of Arizona Stadium at the University of Arizona in March 2021. Fire-engine red, massive in size and resembling a sci-fi version of a Dutch oven, the furnace is the only one of its kind, and its sole purpose is to produce the world’s biggest and most advanced telescope mirrors.
The investigation of vehicle soiling by improvement of vehicle parts to optimize the surrounding airflow is of great importance not only because of the visibility through windows and at mirrors but also the functionality of different types of sensors (camera, lidar, radars, etc.) for the driver assistance systems and especially for autonomous driving vehicles has to be guaranteed. These investigations and corresponding developments ideally take place in the early vehicle development process since later changes are difficult to apply in the vehicle production process for many reasons. Vehicle soiling is divided into foreign soiling and self-soiling with respect to the source of the soiling water, e.g., direct rain impact, swirled (dirty) water of other road users and own rotating wheels. The investigations of the soiling behavior of vehicles were performed experimentally in a wind tunnel and street tests. The investigations of self-soiling are assisted numerically by computational fluid dynamics (CFD) simulations at the early development stage. An investigation of droplet formation behind a side mirror was done with a generic side mirror. These information are important for the simulation of the side window and side mirror soiling to speed up the simulation process and to validate the simulation results. A full-size car was examined in a wind tunnel to achieve an extensive understanding of the processes of droplet formation behind a side mirror. The identification of droplet breakup and detachment processes and the measurement of the resulting droplet sizes are the main goals of these studies. The corresponding experimental measurements of droplet velocity and size were carried out by using high-speed cameras and a shadowgraphy measuring technique. A detailed insight into the physical processes of droplet detachment and breakup behind the side mirror on a complete vehicle is shown, which can be used in the future for the development of soiling countermeasures but especially for the validation and comparison of complex three-dimensional (3D) soiling simulations. The droplet detachment process can be divided into the position and the physical process. The detachment position is velocity dependent. At higher air velocities, the detachment position shifts outwards toward the edge of the mirror housing. Different physical processes can be observed for the different air velocities. At the lower velocity of 80 km/h, a ligament formation process can be observed, which changes to a sheet formation (laminar and later turbulent) with increasing air velocity. The type of secondary breakup processes occurring is independent of the air velocity. In addition, droplet sizes were measured, and the distributions show two main peaks at 35 μm and 55 μm independent of the airstream velocity, which could be attributed to the break-off process and secondary decay.
Conventional dental photography technology has had a limitation in using inconvenient tools such as mirrors and cheek retractors. Dentists require basic teeth images from various angles, such as right/left buccal and maxillary/mandibular occlusal, for dental health inspection. To acquire these images, patients feel discomfort because dentists must put a mirror into the mouth to capture the reflected teeth image through a handheld camera. Information such as tooth arrangement and the location of tooth decay can be obtained through this process. A compact intraoral dental camera can overcome the discomfort and scan the condition of teeth. However, due to the restricted depth of field and field of view, the conventional device has limitations in close-up imaging for observing tooth decay in detail and wide-angle imaging for capturing the entire arrangement of teeth.
The commercial vehicle development process needs to consider the vehicle aerodynamics not only in ideal flow conditions, but also in the turbulent real world environment. The turbulent real world environment includes not only atmospheric turbulence, but also the vehicle to vehicle interactions that happen when driving around other vehicles or into and out of the wake of in/on coming vehicles. A vehicle driving into the wake of an oncoming vehicle not only experiences an increase in the total aerodynamic forces, it also experiences unsteady transient loads over the vehicle components such as windshield, mirror, sunvisor, door and side fairing. To properly design specific components, designers need to understand the magnitude of unsteady forces on various vehicle components, otherwise these components may fail which imposes warranty and safety risks. In this paper, we attempt to understand the various forces acting on the primary vehicle during a passing maneuver. The main purpose is to understand the incremental unsteady forces acting on the major components such as windshield, side door, sunvisor and mirror. Result from this study shows, very large swings in side-force magnitude, which could lead to vehicle stability issues for empty trailers that are subjected to large forces acting on little inertial mass. Local forces on isolated components show very high frequency unsteady load that could lead to component fatigue and failure if these loading conditions are not incorporated as part of the vehicle component design.
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