Forest Green
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Solid State Laser News
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Interesting for applications in space, but not in the atmosphere since such small masses would either slow down very quickly or vaporize in the atmosphere at those speeds due to friction and aero-heating.
Forest Green
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Unless nanotechnology allows them to withstand very high temperatures for short periods. At 4,500km/s, resistance only needs to last ~0.022s
New record set for world's most heat resistant material | Imperial News | Imperial College London
Researchers have discovered that tantalum carbide and hafnium carbide materials can withstand scorching temperatures of nearly 4000 degrees Celsius.
www.imperial.ac.uk
Light alone can levitate some substances
www.nature.com
I was thinking multiple beams--so as to pantograph a "sky cursor" around.
Light-induced levitation of ultralight carbon aerogels via temperature control - Scientific Reports
We demonstrate that ultralight carbon aerogels with skeletal densities lesser than the air density can levitate in air, based on Archimedes' principle, when heated with light. Porous materials, such as aerogels, facilitate the fabrication of materials with density less than that of air. However...
www.nature.com
I was thinking multiple beams--so as to pantograph a "sky cursor" around.
Perhaps.Unless nanotechnology allows them to withstand very high temperatures for short periods. At 4,500km/s, resistance only needs to last ~0.022s
New record set for world's most heat resistant material | Imperial News | Imperial College London
Researchers have discovered that tantalum carbide and hafnium carbide materials can withstand scorching temperatures of nearly 4000 degrees Celsius.
However, the 4500 km/s velocity was for the 0.0001 g projectiles, which would be too small and lightweight to maintain speed and would quickly slow down in the atmosphere before heating up enough to vaporize.
Furthermore, the article talks about withstanding heating for over Mach 5 speed, which is only 1.7 km/s. They mention possible use for leaving and re-entering the atmosphere in space travel. The velocity to reach low earth orbit or re-enter from low earth orbit is about 7.8 km/s. Those velocities are far below the 100 km/s to 4500 km/s velocities you were speculating about with 0.2 g to 0.0001 g projectiles, respectively.
Perhaps, the new materials could reduce the size and mass necessary to survive the heating for velocities on the order of tens of km/s from about centimeters diameter and tens of grams mass to millimeters diameter and tens of milligrams mass, which might be heavy enough to not slow down too much in the atmosphere.
Another option might be to design the projectile such that the core can withstand the very high temperatures and have an outer layer that starts vaporizing at a slightly lower temperature than the core material so that in flight through the atmosphere to the target, the outer layer generates a plasma sheath around the front of the projectile. Perhaps that plasma sheath around the front of the projectile would enhance the lethality over just the impact of the projectile.
By the way, thermal time constants are usually on the order of milliseconds, so 0.022 s = 22 ms is probably too long a time to expect the tiny 0.0001 g projectile to survive the heating at 4500 km/s, but the point is moot since such a small low mass projectile would likely slow down very rapidly due to the atmospheric friction if it did not vaporize.
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Interesting idea.Light alone can levitate some substances
Light-induced levitation of ultralight carbon aerogels via temperature control - Scientific Reports
We demonstrate that ultralight carbon aerogels with skeletal densities lesser than the air density can levitate in air, based on Archimedes' principle, when heated with light. Porous materials, such as aerogels, facilitate the fabrication of materials with density less than that of air. However...
I was thinking multiple beams--so as to pantograph a "sky cursor" around.
By heating the whole aerogel "puck" you can only control its vertical motion because the buoyant force is always upward. Perhaps with multiple beams with spot sizes at the aerogel puck that are smaller than the diameter of the aerogel puck, you could make one part heat up more than another part to tilt the puck and induce a lateral component to the motion, but you might only be able to set it rotating instead of translating laterally, but perhaps the right aerodynamic shape of the puck might enable tilting it to generate lateral translation instead of rotation.
Also, in the lab setup they did not have to contend with winds and air currents which can flow vertically as well as horizontally in the open air where a "sky cursor" would be operated. The wind and air currents might produce vertical and horizontal forces that overcome the buoyant forces generated by the beam heating and carry away such a lightweight structure. In addition, convective cooling from the airflow around the puck due to winds and air currents may necessitate using more power for the heating beams than would be required under static air conditions.
What would be the advantage of such a system over using a small radio controlled quad copter with a laser or other light beam reflecting off of it to act as a sky cursor? Drawing on a touch screen or using a joystick or other motion controller could generate the control signals to synchronize the pointing of the light beam and the motion of the quad copter to move in synchrony such that the light beam is always pointing at the quad copter and both follow the path the user designates with the controller.
Forest Green
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Cool video.
It took a dwell time of about 20 seconds to disrupt the drone. That does not bode well for the use of CLaWS to defend against a swarm of drones. According to https://defence-industry.eu/boeing-...ystem-clws-successfully-downs-group-3-drones/ , the output power is only 5 kW, so it is not too surprising that such a long dwell time was required.
If total energy on target were the only factor (I know it isn't, but it is a major factor), then to get the dwell time down to a couple of seconds or so to be practical against multiple targets such as in a drone swarm, would required at least 50 kW or so of laser output power. Other factors not considered in this simple scaling might drive that laser output power up by a factor of two or three, so that a range of 50 kW to 150 kW laser output power may be required to be effective against swarms of drones.
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I guess it might disrupt the drones feed/vision much earlier though. Shame we can't see it from the drone operator's persepective.
Probably if the drone's vision system has the laser source in its field-of-view, but not necessarily if the laser is attacking the drone from the side or rear of the drone.
Also, it depends on the waveband of the drone's vision system. If the drone's vision system operates in the visible, mid-infrared or far infrared, then it is relatively easy to make a filter that passes light in the drone's operational band and reflects light in the operational band of the laser, which for currently fielded weapon lasers are wavelengths in the near infrared to short wavelength infrared, with the exception of laser dazzlers, which usually operate in the visible band, or sometimes in both the near or short wave infrared and visible bands.
Although it is straight forward to add an optical frequency shifter to the laser to get output in another wave band, the optical output power in the new band will be about 30% to 60% lower depending on the starting and ending wavelengths and the type of optical frequency shifting device used.
Even with a protection filter, the HEL may destroy the protection filter or other optical or electrical components of the drone's vision system, but not necessarily in any less dwell time than for a hard body kill.
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I was thinking that if it aimed for the props rather than the CoM, it might down it quicker.
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Anti-Drone System Concept Revealed - Defense Advancement
Laser Photonics Corporation and Fonon Technologies have released a visual concept of the Laser Shield Anti-Drone System (LSAD) – a joint development by the two companies to create a laser defense system for use against unauthorized drone activity. Following the successful early testing of...
www.defenseadvancement.com
I'm not sure since some of the laser energy would be transmitted through the spaces between the propeller blades depending on aspect angle, and convective cooling by the air flow across the spinning blades may dissipate some to the energy deposited by the laser beam causing the temperature to rise more slowly in the props than other parts of the drone. On the other hand, the materials that the props are made of may melt at a lower temperature than other materials in other places on the drone.
I would expect that the scientists and engineers working on the demo would have tested the laser on various parts of the same model drones to find the most vulnerable spots prior to the demo so they could target those during the demo. Anyway, I would have included such pre-demo testing in the development and testing plan if I had been the project leader.
A lot of marketing verbiage in that article, but no actual technical description of the system concept.Anti-Drone System Concept Revealed - Defense Advancement
Laser Photonics Corporation and Fonon Technologies have released a visual concept of the Laser Shield Anti-Drone System (LSAD) – a joint development by the two companies to create a laser defense system for use against unauthorized drone activity. Following the successful early testing of...
It's not clear if the beams overlaid on the photo in the article represent multiple simultaneous beams or positions of a single beam as the transmitter optics scan it around.
No laser output power is given in the article.
Here is a link to an article that has a video illustrating the concept of operations: https://laserphotonics.com/news/pre...a5I7i2xf5gyEEsvdk5ryTfDNeJiM32H-px68yvhw_yIIu
The video shows multiple beams pointed upward to act like a barrier that destroys drones flying through a beam. The drones are destroyed in transit through the beams, in under a second or two. These devices would need to be deployed around the target being protected at some standoff distance. Still no details on the required laser power output for each laser beam.
No technical details at this site either: https://www.fonon.us/products/laser-shield-anti-drone-defense-system But it does have lots of marketing photos and verbiage.
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