"The US Military Is Making Lasers That Create Voices out of Thin Air"





Non-Lethal Laser Induced Plasma Effect - Generation of Plasmas In-Air 


Combination of femtosecond and nanosecond laser excitations in the so-called "igniter-heater" scheme


Dept. of Defense Non-Lethal Weapons Program | Directed Energy Portfolio: Sound and Light Technology



Transcript (slightly modified): "We have whole propagated weakly-focused laser pulses, one of which is a femtosecond 30 mJoule igniter pulse which creates a very dilute plasma. The plasma is subsequently densified by copropagating a nanosecond pulse with about 3 Joules of pulsed energy.


At this point only a nanosecond pulse is propagating. The femtosecond pulse is blocked. As you can see, although the nanosecond pulse has huge energy, it doesn't have any visible effect and does not produce any amount of plasma except for occasional sparks due to the dust in the lab.


You can see that if I insert different objects in the beam like this piece of paper, then immediately on the surface there is dielectric breakdown (electrical breakdown). This is all left over dust triggering the breakdown.


Depending on the type of materials I put in the beam, dark or light an so forth, the amount of noise that the plasma produces is different, the amount of plasma is different.


This is a blackened foil. Of course immediately the amount of plasma and noise increases.

Now let me turn on the femtosecond pulse. The femtosecond pulse will trigger the plasma formation in the gas and the nanosecond pulse will enhance the plasma, and create another plasma in the air.


Now the igniter and nanosecond pulse propagate together and the level of sound is (...) maybe at about a loud voice level. The plasma is created in the form of a string which expands maybe to a distance of 10 cm.


If I block the igniter femtosecond pulse, the effect disappears even though the Joule pulse is still propagating.


Now I am again opening again the igniter pulse and I see the stable formation of plasma in the air."


Video from Defense One article: https://www.defenseone.com/technology/2018/03/us-military-making-lasers-create-voices-out-thin-air/

Reference: https://jnlwp.defense.gov/Press-Room/Fact-Sheets/Article-View-Fact-sheets/Article/1574157/directed-energy-sound-and-light-technology/



Combinaison de lasers femtosecond et nanosecond en schéma allumeur-chauffage ("igniter-heater" scheme)
Ministère de la Défense des États-Unis - Programme sur les armes non-létales | Portefeuille d'énergie dirigée: Technologie son et lumière
Effet plasma induit par laser non létal - Génération de plasmas dans l'air https://youtu.be/0eJzcPz8ujo?t=159
Transcription (légèrement modifiée): "Nous avons des impulsions laser faiblement focalisées et propagées dans leur ensemble, dont l’une est une impulsion d’allumeur femtoseconde de 30 mJoules qui crée un plasma très dilué. Le plasma est ensuite densifié par copropagation d'une impulsion nanoseconde avec environ 3 Joules d'énergie pulsée.
À ce stade, seule une impulsion nanoseconde se propage. L'impulsion femtoseconde est bloquée. Comme vous pouvez le constater, bien que l’impulsion nanoseconde ait une énergie considérable, elle n’a aucun effet visible et ne produit aucune quantité de plasma, à l’exception des étincelles occasionnelles dues à la poussière du laboratoire.
Vous pouvez voir que si j'insère de différents objets dans le faisceau, comme ce morceau de papier, alors immédiatement en surface, il se produit un claquage. Tout cela provient de la poussière qui déclenche le claquage.
En fonction du type de matériaux que je mets dans le faisceau, qu'il soit sombre ou clair, la quantité de bruit produite par le plasma est différente, la quantité de plasma est différente.
Celle-ci est une feuille noircie. Bien sûr, la quantité de plasma et de bruit augmente immédiatement.
Maintenant, je vais activer les impulsions femtoseconde. L'impulsion femtoseconde déclenchera la formation de plasma dans le gaz et l'impulsion nanoseconde renforcera le plasma et créera un autre plasma dans l'air.
Maintenant, l'allumeur et l'impulsion nanoseconde se propagent ensemble et le niveau sonore est (...) peut-être à peu près au niveau d'une voix forte. Le plasma est créé sous la forme d’une ficelle qui peut s’étendre sur une distance de 10 cm.
Si je bloque l'impulsion femtoseconde de l'allumeur, l'effet disparaît même si l'impulsion Joule continue à se propager.
Maintenant, j'ouvre à nouveau l'impulsion de l'allumeur et je vois la formation stable de plasma dans l'air."



"New Scientist" reports military experimentation with laser weapons for plasma-generated visual effects in the sky (1980s)







"DOD to invest $17M on laser weapons research in New Mexico"


U.S. Air Force Starfire Optical Range at Kirtland Air Force Base: astronomical research and anti-satellite laser weapons


Wired (2007): "Plasma Laser: UFO Maker?"

Cites ultra-quick laser pulses and mid-air plasma bursts. 
(Please use this link for the cited 1997 Air Force paper


Orbs and Radar "ghosts"


An orb is a circular or spherical anomaly due to backscatter (diffuse reflection due to scattering). It appears frequently on photographs (image below) due to reflection of the camera's flash from dust, water droplets and particulate matter in general.
orb (n.) | etymonline.com: "sphere, globe, something spherical or circular"
Generation of visual anomalies/effects of different forms which function as radar "ghosts": they are detected by a radar as actual objects or can be used for camouflage of an object e.g. aircraft (Deception in the fields of defence and security)
Laser Focus World reports in 2013 that work* from the National University of Singapore published in Advanced Functional Materials "can generate ghosts through optical scattering and artificial metallic metamaterials that cause light from an object to behave abnormally, appearing in places different from the actual location of the real object. Most metamaterial-based ghost images appear at the same location as the object, but this work enables more than one virtual ghost to appear, offering a new level of camouflage and cloaking capability."
Freely accessible paper (also mentioned below): https://arxiv.org/abs/1301.3710







Wave-dynamic illusion functionality: Application in camouflage, cloaking, optical and/or microwave cognition, and defense security

Figure 1, "a" shows a metallic object and "b" the same object camouflaged with a ghost device denoted by red lines. Notice how its radar image on the right changes.