#metamaterials

[materialsscienceandengineering]

Scientists uncover light absorbing properties of achiral materials

Researchers at the University of Ottawa have made a discovery that changes what we know about light and materials. They found that engineered achiral (symmetric) materials, called achiral plasmonic metasurfaces, can absorb light differently depending on the handedness of the wavefront of light. This was surprising because, for years, such materials were found to be indifferent to any optical probes and do not show such selective absorption. The research, conducted over the past year at uOttawa's Advanced Research Complex (ARC), was led by Ravi Bhardwaj, Professor, Department of Physics at the University of Ottawa and Ph.D. student Ashish Jain. Collaborators include Howard Northfield, Research Engineer, and colleagues Ebrahim Karimi, Canada Research Chair in Structured Light and Associate Professor of Physics, and Pierre Berini, University Research Chair in Surface Plasmon Photonics and Professor of Electrical Engineering.

Read more.

[cassiachloe]

Did you know there are currently smart materials and technologies, as well as active comouflage methods, in use and under research that can render objects, vehicles or persons invisible: not only to the naked eye, but also to security cameras?

This is especially concerning when dealing with corruption, fascism, other developments in military technologies this could be cross applied with, or covert operations involving human victims or sex traffick and other criminal government operations.

Here's a few examples:

"Next-gen Military Uniforms: Various military research programs are exploring smart uniforms that incorporate these technologies. For example, DARPA has been involved in developing "invisibility cloaks" that use smart fabrics to reduce the visibility of soldiers on the battlefield."

"MIT's Electromagnetic Metamaterials: Research at MIT has explored using metamaterials to create a "cloaking" effect in the electromagnetic spectrum. Although these are primarily experimental, they could eventually lead to applications where objects or people are rendered invisible to certain detection methods."

"BAE Systems' Adaptiv: This is a military camouflage technology developed for vehicles. Adaptiv uses hexagonal tiles that can change temperature to blend into the infrared spectrum of the background. While primarily developed for vehicles, the concept could theoretically be miniaturized for use on smaller objects or individuals."

"Duke University and University of California, Berkeley: Researchers at these institutions have been working on invisibility cloaks using metamaterials that can bend electromagnetic waves around an object, effectively making it invisible. Although this technology is currently limited and works mainly at specific wavelengths or in laboratory conditions, it demonstrates the potential for future applications."

"Invisibility Cloaks Based on Transformation Optics: This research area involves designing materials that guide light around an object, making it invisible. Companies and military research labs are exploring this, but practical, deployable versions are still speculative."

"Quantum Stealth by Hyperstealth Biotechnology Corp: This Canadian company has developed a material they claim can bend light around an object, rendering it invisible. The technology is said to work without cameras, batteries, or mirrors, and it could be used to conceal objects or people from view by manipulating light waves. However, the actual effectiveness and deployment status of this technology remain largely unverified in the public domain."

Ultimately, how these technologies, or other advanced weapons, can impact civilian populations left in the dark is a huge concern. There are multiple methods of intercepting or undermining the purpose of security cameras, this is one of many potentials.

Fox Badge The Steel Yard

[realcleverscience]

Pretty awesome

"The sensor works purely mechanically and doesn't require an external energy source. It simply utilises the vibrational energy contained in sound waves," Robertsson says. Whenever a certain word is spoken or a particular tone or noise is generated, the sound waves emitted -- and only these -- cause the sensor to vibrate. This energy is then sufficient to generate a tiny electrical pulse that switches on an electronic device that has been switched off. The prototype that the researchers developed in Robertsson's lab at the Switzerland Innovation Park Zurich in Dübendorf has already been patented. It can distinguish between the spoken words "three" and "four." Because the word "four" has more sound energy that resonates with the sensor compared to the word "three," it causes the sensor to vibrate, whereas "three" does not. That means the word "four" could switch on a device or trigger further processes. Nothing would happen with "three." Newer variants of the sensor should be able to distinguish between up to twelve different words, such as standard machine commands like "on," "off," "up" and "down." Compared to the palm-​sized prototype, the new versions are also much smaller -- about the size of a thumbnail -- and the researchers are aiming to miniaturise them further.

[whatsissue]

China Unveils Cutting-Edge Stealth Coating That Redefines Anti-Stealth Radar Evasion

China Unveils Cutting-Edge Stealth Coating That Redefines Anti-Stealth Radar Evasion In a significant advancement in military technology, the Chinese military has announced the development of a groundbreaking radar-defeating coating designed to conceal targets from anti-stealth radars. This innovative coating, which is paper-thin yet highly effective, can absorb low-frequency electromagnetic waves (EM), marking a remarkable leap in stealth technology. Transforming Stealth Aircraft Detection This breakthrough has the potential to revolutionize how stealth aircraft evade radar detection, particularly against EM waves emitted from various angles. Historically, radar-absorbing materials have had limited success in countering radar systems, a costly lesson highlighted by the detection and subsequent downing of an F-117A "Nighthawk" during the late 1990s in Yugoslavia. Developed by researchers at China's National University of Defence Technology (NUDT), this new material can absorb wavelengths ranging from 70 to 20 cm, which are primarily used by anti-stealth P-band and L-band radars. These frequency bands are critical in detecting stealth aircraft, making this coating a vital development for military applications. Unique Properties of the Coating What distinguishes this stealth coating is its lightweight and flexible nature, allowing for large-scale production that is economically viable for military use. Composed of metamaterials, the coating exhibits extraordinary properties not found in natural materials. When low-frequency EM waves strike the surface, these metamaterials convert the incoming energy into heat, dissipating it quickly and thereby significantly reducing the radar signature. Strategic Implications Chinese researchers have indicated that this development is crucial for enhancing future warfare strategies, potentially providing the country with a competitive edge on the global stage. As advancements continue in stealth technology through innovative materials like this, the balance of military capabilities worldwide may begin to shift. The Ongoing Technological Arms Race With China's persistent advancements in anti-stealth technology, this new coating represents more than just a military upgrade; it signifies a strategic shift in defense capabilities. It underscores the growing importance of metamaterials in modern military applications and reflects the ongoing technological arms race among global powers. Conclusion This latest innovation in stealth technology could have profound implications for global military dynamics, setting a new standard for what stealth technology can achieve in contemporary warfare. As nations race to enhance their defense systems, China's development of this advanced stealth coating may redefine the future of aerial combat and radar evasion. Read the full article

[mybam2u]

Afterlife/Otherside Ghostface projection experiment # 282

[dnieperrobot69420]

Status Update: Generalized Lorentz-Drude model of Dielectrics.

This week I continued to venture into the realm of nonlinearities by learning about the Lorentz model followed by the Drude model for metals.

It was fun employing the whole "statistical ensemble" trick to relate the microscopic dipole moments of individual atoms being subjected to an applied Electric Field to the macroscopic property of Material Polarization and further towards the Electric Flux Response of a material.

Once again, complex numbers rear their heads and there's growing pains in understanding the physical significance behind "complex dielectric" with the "real permittivity" all while trying to connect it with notions of conductivity in terms of both free space responses and material responses contributing to the total Electric Flux.

It is kinda neat how the complex refractive indexes extinction coefficient can be used to ??? Let us see where a materials absorption is highest near points of resonance?

And furthermore, a interesting connection to metamaterials was established when I realized that if the resonances of our doped elements are in frequencies way below our materials resonances, we do some cool stuff with the maths.

Something something we can use the dielectric permittivity at DC and at very high (infinity) to calculate the plasma frequency of a metal.

Now my plan is to deep dive into crystal anisotropy, do some numerical examples of tensor rotation, and hopefully that will help me better understand optical components like quarter wave plates and all that stuff.

And before anyone asks, no, Optical Rectification, the second order chi nonlinearity is NOT the mechanism of solar panels, that's the photoelectric effect 😉

[jcmarchi]

An endless domino effect - Technology Org

New Post has been published on https://thedigitalinsider.com/an-endless-domino-effect-technology-org/

An endless domino effect - Technology Org

If it walks like a particle, and talks like a particle… it may still not be a particle. A topological soliton is a special type of wave or dislocation which behaves like a particle: it can move around but cannot spread out and disappear like you would expect from, say, a ripple on the surface of a pond. In a new study published in Nature, researchers from the University of Amsterdam demonstrate the atypical behaviour of topological solitons in a robotic metamaterial, which may be used to control how robots move, sense their surroundings and communicate.

Topological solitons can be found in many places and at many different length scales. For example, they take the form of kinks in coiled telephone cords and large molecules such as proteins. At a very different scale, a black hole can be understood as a topological soliton in the fabric of spacetime. Solitons play an important role in biological systems, being relevant for protein folding and morphogenesis – the development of cells or organs.

The unique features of topological solitons – that they can move around but always retain their shape and cannot suddenly disappear – are particularly interesting when combined with so-called non-reciprocal interactions. “In such an interaction, an agent A reacts to an agent B differently to the way agent B reacts to agent A,” explains Jonas Veenstra, a PhD student at the University of Amsterdam and first author of the new publication.

Veenstra continues: “Non-reciprocal interactions are commonplace in society and complex living systems but have long been overlooked by most physicists because they can only exist in a system out of equilibrium. By introducing non-reciprocal interactions in materials, we hope to blur the boundary between materials and machines and to create animate or lifelike materials.”

The Machine Materials Laboratory where Veenstra does his research specialises in designing metamaterials: artificial materials and robotic systems that interact with their environment in a programmable fashion. The research team decided to study the interplay between non-reciprocal interactions and topological solitons almost two years ago, when then-students Anahita Sarvi and Chris Ventura Meinersen decided to follow up on their research project for the MSc course ‘Academic Skills for Research’.

Solitons moving like dominoes

The soliton-hosting metamaterial developed by the researchers consists of a chain of rotating rods that are linked to each other by elastic bands – see the figure below. Each rod is mounted on a little motor which applies a small force to the rod, depending on how it is oriented with respect to its neighbours. Importantly, the force applied depends on which side the neighbour is on, making the interactions between neighbouring rods non-reciprocal. Finally, magnets on the rods are attracted by magnets placed next to the chain in such a way that each rod has two preferred positions, rotated either to the left or the right.

The robotic metamaterial with a soliton and anti-soliton lying at the boundaries between left- and right-leaning sections of the chain. Each blue rod is connected to its neighbours with pink elastic bands, and a little motor under each rod makes the interactions between neighbouring rods non-reciprocal. Image credit: Jonas Veenstra.

Solitons in this metamaterial are the locations where left- and right-rotated sections of the chain meet. The complementary boundaries between right- and left-rotated chain sections are then so-called ‘anti-solitons’. This is analogous to kinks in an old-fashioned coiled telephone cord, where clockwise and anticlockwise-rotating sections of the cord meet.

When the motors in the chain are turned off, the solitons and anti-solitons can be manually pushed around in either direction. However, once the motors – and thereby the reciprocal interactions – are turned on, the solitons and anti-solitons automatically slide along the chain. They both move in the same direction, with a speed set by the anti-reciprocity imposed by the motors.

Veenstra: “A lot of research has focussed on moving topological solitons by applying external forces. In systems studied so far, solitons and anti-solitons were found to naturally travel in opposite directions. However, if you want to control the behaviour of (anti-)solitons, you might want to drive them in the same direction. We discovered that non-reciprocal interactions achieve exactly this. The non-reciprocal forces are proportional to the rotation caused by the soliton, such that each soliton generates its own driving force.”

The movement of the solitons is similar to a chain of dominoes falling, each one toppling its neighbour. However, unlike dominoes, the non-reciprocal interactions ensure that the ‘toppling’ can only happen in one direction. And while dominoes can only fall down once, a soliton moving along the metamaterial simply sets up the chain for an anti-soliton to move through it in the same direction. In other words, any number of alternating solitons and anti-solitons can move through the chain without the need to ‘reset’.

Motion control

Understanding the role of non-reciprocal driving will not only help us better to understand the behaviour of topological solitons in living systems, but can also lead to technological advances. The mechanism that generates the self-driving, one-directional solitons uncovered in this study, can be used to control the motion of different types of waves (known as waveguiding), or to endow a metamaterial with a basic information processing capability such as filtering.

[embedded content]

Future robots can also use topological solitons for basic robotic functionalities such as movement, sending out signals and sensing their surroundings. These functionalities would then not be controlled from a central point, but rather emerge from the sum of the robot’s active parts.

All in all, the domino effect of solitons in metamaterials, now an interesting observation in the lab, may soon start to play a role in different branches of engineering and design.

Source: University of Amsterdam

You can offer your link to a page which is relevant to the topic of this post.

[kenleephotography]

AI's crystal ball: Predicting future camera features in 2034

What features will cameras have ten years from now that cameras do not have now? I asked Gemini AI. Here are the answers. AI’s Crystal Ball – Predicting future camera features in 2034. Image by Justin Clark from Unsplash. I don’t know that AI – our new buzzword for what is largely machine learning – has a crystal ball. But Google’s Gemini is pretty good at scraping the internet for information…

[vnetwork]

Not Science Fiction: Scientists Around the World Shocked by Self-Healing in Metal

[irradiate-space]

How long before I can replace my roof with this?

New material lets through 95% of visible light (compared to 91% for ordinary glass), but still blocks infrared (so has a strong cooling effect) and is opaque:

It's also superhydrophobic so is essentially self-cleaning.

[materialsscienceandengineering]

Novel framework allows for tunable ultrasound propagation in microscale metamaterials

Acoustic metamaterials—architected materials that have tailored geometries designed to control the propagation of acoustic or elastic waves through a medium—have been studied extensively through computational and theoretical methods. Physical realizations of these materials to date have been restricted to large sizes and low frequencies. "The multifunctionality of metamaterials—being simultaneously lightweight and strong while having tunable acoustic properties—make them great candidates for use in extreme-condition engineering applications," explains Carlos Portela, the Robert N. Noyce Career Development Chair and assistant professor of mechanical engineering at MIT. "But challenges in miniaturizing and characterizing acoustic metamaterials at high frequencies have hindered progress towards realizing advanced materials that have ultrasonic-wave control capabilities."

Read more.

[jonfazzaro]

"Optical metamaterials, which are designed to manipulate light, possess structures with repeating patterns at scales that are smaller than the wavelengths of light they influence."

[realcleverscience]

fascinating

[themultiuniversal]

To add to this, structural colour also have the unique advantage of being resistant to fading; while pigments may fade over time due to chemical reactions with sunlight and the environment, as structural colour is from the structure of the object it doesn't fade over time unless damaged!

Structural colour also contributes to the study of metamaterials - intentionally changing the structures of objects to manipulate the way light go through it. It's a currently researched area with potential future applications including more efficient solar power system (using metamaterial so the object is better at absorbing light) and metamaterial cloaking (using metamaterial to bend light around an object so it looks like it isn't there)

Bonus: if you change the refractive index of the medium around an object with structural colour then you can change the colour of the object! An example is dropping ethanol on a blue morpho butterfly wing!

44?

44. RANDOM FACT

In terms of animal coloration, here is a difference between color produced by pigmentation and color produced by physical structures. Colour from physical structures are a sort of optical illusion caused by refracting light, and disappear when the structure is damaged. Colour from pigmentation, however, is chemical, and does not go away when physically damaged.

Knowing this, there are no *actually green* birds- birds with green pigmentation- except for the Turaco, which is native to sub-saharan Africa. All other birds technically only appear green.