Why don’t we use laser weapons instead of kinetic weapons?

Because, the basic principles are a little different and energy weapons are constrained by other physical limits.These weapons are not and will not be suitable for all weather, but show their best performance under clear skies with dry air.

Projectile weapons such as rifles, missiles, and bombs destroy targets through kinetic effects, including overpressure, projectiles, splinters, chipping damage, and fire effects.The results are structural damage and fire, which can often lead to (lethal) damage. A kinetic weapon thus uses stored chemical energy in propellants and explosive warheads, and delivers that energy to a target by a projectile in some form. Whether the projectile weapon is a catapult that hurls a large rock over 300 meters, or a long-range air-to-air missile equipped with multimode searchers and hitting an aircraft 250 kilometers away – the basic principle is the same, only the Implementation is different.

The most fundamental level of energy weapons shares the concept of providing large amounts of stored energy to a target with the intention of causing structural and fire damage.The most fundamental difference is that energy weapons release their effect at the speed of light instead of the typical supersonic of projectile weapons or subsonic velocity. However, two of the most fundamental problems with projectile weapons, namely: successfully transporting the projectile over a required distance and then hitting the target in order to generate a sufficient amount of damage, have also the energy weapons.

First, a few corrections: There are no laserweapons, but energy weapons (DEW – Directed Energy Weapons).There are currently 4 classes in this category.

  1. High-energy laser (HEL),
  2. High-power microwave (HPM),
  3. Particle beamweapons
  4. laser-induced Plasma ChannelWeapons (LIPC).

The first two of these four classes of weapons are real energy weapons (DEWs).Particle beam weapons are best described as a form of projectile weapon, with atomic or subatomic particles as projectiles, accelerated to relativistic speeds. The LIPC is a hybrid that uses a laser to ionize a path of molecules to the target, causing damage to the target via an electrical charge. Of these four categories, HELs (= high-energy laser effectors) have the greatest potential to produce significant results in the near future.

(Fig.

German mobile HEL effector from 2013, test center Ochsenboden (Switzerland) [1)

HELs have a different number of advantages.What is the reason for the motivation of their development. These include:

  • Speed of light – no bullet flight time.
  • Photons – no muzzle fire, no bullet bang, no recoil.
  • Directly directed – no ballistics, no retention.
  • Electrical excitation possible – no logistics and storage of ammunition.
  • Precision Weapon – Minimal Collateral Damage
  • Non-lethal effect possible – Graduated escalation possible

In the past, therefore, co2 lasers (wavelength 10600 nm) were first experimented with.Later, one switched to chemical lasers (e.g. COIL: oxygen iodine at 1350 nm). These chemical lasers were used in the ground-based Tactical High Energy Laser (2000-2005) and the airborne YAL-1 Airborne Laser (see picture).Both programmes have now been discontinued. At present, a lot is being tested with electric lasers.

(Fig.

airborne HEL effector: YAL-1 Airborne Laser from 2002 to 2014, White Sands Missile Range, New Mexico, USA [2)

In another question I had already answered the highly reflective coatings on a target do not cause the laser beam to be ineffective.

But now to the real problem and the reason why energy weapons, conventional weapons (for the first time) will not replace: the weather, more specifically the atmosphere.A LASER is basically coherent, monochromatic light. This means that all photons have the same wavelength, the same direction of propagation and the spatial and temporal phases are identical. But it’s still light.

Laser beam propagation in the atmosphere therefore reveals expected and unexpected problems: water vapour molecules, water droplets and carbon dioxide molecules “suck” into the beam, creating local warming along the beam path, which causes beam dispersal.This effect is called thermal blooming and worsens when the beam power level (laser power) is increased.A general limitation of all HEL weapons is the inability to penetrate clouds, dust clouds orfog.These scatter and reduce the beam performance very quickly.

Other problems arise as a result of scintillation due to turbulence in the atmosphere, which are characteristically caused by different air layers with slightly different temperature.Small temperature differences mean small differences in air density, which cause the beam to break at each transition between two air layers as it penetrates through them. With thousands of such distortions along the beam, this problem is a difficult obstacle to a useful range, especially at low altitude, where the beam is heavily defocused.

In order to penetrate through the atmosphere without defocusing the beam distortion, the beam itself would have to be “pre-distorted” when it leaves the optics of the HEL weapon, so that the wave front of the beam reaches the target unadulterated and precisely aligned.Although this is in principle a simple idea, it is very difficult to implement in practice. The movement of the HEL platform, the movement of the target and the movement of the air masses make it necessary to continuously change the pre-distortion of the beam. Each solution must therefore include a device for the continuous measurement of distortion on the way to the target and a mechanism to be able to constantly distort the HEL beam.

Two technologies have been developed to solve this problem.

One of these is the adaptive or deformable mirror, which contains up to hundreds or thousands of miniature drives, each of which can elevat itself locally or push into the surface of the mirror to distort the beam in a controlled manner.These rubber mirrors are able to compensate for a distortion of the wave front in a controlled manner, with sufficient accuracy for atmospheric problems.

The second technique is a form of lidar (laser radar), which is used to continuously measure the distortion along the beam path to the target.This system illuminates the target with a lower-power laser with a wavelength similar to but not identical to that of the HEL weapon. This laser illumination is scattered back from the target and then fed into a wave front sensor that measures the distortion over the entire cross-section of the beam to the target.

The most commonly used device鈥?the Hartmann-Shack wavefront sensor鈥攗ses an arrangement of tiny lenslets in front of a imaging device arranged like a CCD.If the wave front is completely flat, a point is centered below each of the lenslets. When part of the wave front is distorted over the position of a lenslet, the position of the point moves in a manner specific to the direction and size of the distortion. In a HEL weapon system, the lidar and the wave front sensor are used to continuously measure distortion along the beam. They then generate correspondence commands to the actuator field, which is used in the deformable main mirror that reflects the high-performance HEL beam on the target.

However, this solution has limitations, the laser beam cannot be distorted at will.

The whole system can only work within a certain bandwidth, and just as light-dense fog cannot penetrate, HEL weapons cannot. This represents a significant restriction on all-weather suitability and is also the reason why energy weapons, which currently only complement conventional weapons, will not replace but not replace. Because projectile weapons don’t matter if there is dense fog or it rains heavily.

(Meaningful question, therefore the answers are almost identical:
Robert P盲tzold’s answer to Laser Weapon Systems Are More Efficient Than Missiles for Air Defense? )

Footnotes

[1 Rheinmetall Defence – HEL on Wheels

[2 A-60 and YAL-1 airborne laser versus F-35.

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