Aviation Week & Space Technology - 30 March-12 April 2015

T

wo German teams are working on a military-funded pro-

gram that could lead to a world first: an operational air-de-

fense laser. Whether one or both succeed depends on which

of two concepts works well enough to
earn a place on the front line.
While Rheinmetall and MBDA Ger-
many use some of the same technology
(both companies featured their laser
work at February’s IDEX defense show
in Abu Dhabi), they take dissimilar
approaches to one of the fundamen-
tal challenges of using the laser as a
weapon: putting a tightly focused dot

of energy on target. It is easy
to concentrate on the output
power of the laser, and many
current and historic projects
are aimed at new technol-
ogy for beam-generation
(AW& S T Feb. 16-March 1, p. 30).
But getting enough heat on a target
to damage it means having high power,
focusing it on one spot and keeping it
there as the target moves. Good per-
formance means the weapon can be
efective at lower power levels. That is
the goal of German research, because
it offers the prospect of a true laser
weapon using inexpensive and reliable
commercial laser sources.
This development parallels another
trend: the emergence of a serious mili-
tary threat that may be vulnerable to
a laser weapon. Mini unmanned aerial
vehicles (UAVs) provide real-time tar-
get tracking, location and strike dam-
age assessment for artillery or rocket
attacks, and can act as precision-guided
weapons against high-value targets. Not
only are they hard to hit with missiles

or gunfire, but using missiles against a

mini-UAV is expensive.

That is why one Rheinmetall laser

engineer uses a €1 coin ($1.05) to make

a point about the company’s weapon.

“This is the size of the beam on the tar-

get at 1,000 meters (3,300 ft.), and it’s

also what one shot costs.”

Both companies base their systems

on commercial fiber-laser modules.

These are used in manufacturing for

metal cutting and welding, and are ef-

ficient, inexpensive and reliable. The

laser energy passes through a fiber-

optic cable from the beam-former to

the optical unit, a good factor for vi-

bration and shock resistance. Germany

also leads the industrial laser market.

Today, standard laser modules come

in 10- and 20-kw versions, which are

not enough for a weapon, so the key is

the use of optical systems to combine

and focus multiple lasers on one spot.

The main difference between the

MBDA and Rheinmetall approaches is

that MBDA uses reflective optics and

Rheinmetall uses lenses.

The advantage of mirrors, MBDA

argues, is they absorb less energy than

lenses, so the optical system can be

Bill Sweetman Abu Dhabi

Focus on Reality

Mini-UAV threat creates need for practical lasers

driven to high power levels without fun-

damental change. Although tests in 2012

and 2013 used four 10-kw laser modules,

the current system easily could go to 80

kw with standard modules. “We are

also working with industry on alternate

source technologies,” says one engineer,

adding that with the right coating tech-

nology, “100-150 kw is not a problem.”

Rheinmetall accepts the power limi-

tations of lenses (although its optical

system could run to twice its current

power) but says the lens-based optical

system is easier to focus and adjust.

In its fixed-site/naval demonstrator

system, using the same mount as the

Mantis counter-rocket, artillery and

mortar gun system, three laser projec-

tors are fixed to the trunnion in place of

a gun barrel. Internal movements of the

optics are used for fine aiming, to focus

beams on target and converge the three

beams on the same spot at the target’s

exact range.

This has an incidental advantage:

The beams diverge beyond the target,

so the eye-safety range (the distance be-

yond the target that has to be confirmed

free from people or manned aircraft)

is shorter. The potential is also there

to use multiple laser turrets against a

single target to gain range or achieve

a quicker kill.

The 20-kw ceiling on commercial la-

sers is economical as much as techni-

cal. Industrial users are not calling for

greater power, and the defense market,

so far, is tiny.

Solutions to engineering challenges

—packaging the system and providing

power and cooling—also are underway.

MBDA is considering flywheels as alter-

natives to batteries: The key in either

case is to provide instant full power.

Executives note that the laser ofers

a graduated response against a loiter-

ing UAV: damaging the sensor, dazzling

(which, because of the potential to blind

a pilot, is not a legal option against a

manned aircraft) or destruction. Sen-

sor, dazzling can be effective at very

long range. The optics also can be used

for long-range identification, comple-

menting the weapon’s ability to deliver

a discriminating response.

A Rheinmetall engineer says mini-

UAVs are also a concern for event

protection, and a laser can disable or

destroy a threat within a 1-km (0.6-mi.)

radius. c

DEFENSE ANALYSIS

MBDA’s proposed laser weapon

could deliver more than 100 kw on

target from multiple fiber lasers.

BILL SWEETMAN/AW&ST

Gallery See photos of new and notable

IDEX exhibits at AviationWeek.com/IDEX

DTI6 MARCH 30 -APRIL 12, 2015 AVIATION WEEK & SPACE TECHNOLOGY DEFENSE TECHNOLOGY INTERNATIONAL AviationWeek.com/dti