Laser CIWS

"Bjørnar Bolsøy" wrote in message ...
With weight ever decreasing, does anyone know if there has been/is
a project on something like this:


http://members.rogers.com/biglasers/continuous/abl.html


..intended to replace this?


http://www.military.cz/usa/navy/weap...phalanx_en.htm

A more likely scenario is that the big electrical power outputs of
forthcoming hybrid gas turbine/electric power plants will be used to
power 'rail guns', which could electromagnetically hurl projectiles at
several times the velocity of powder guns. It would be logical to
install these in different sizes for different purposes, including
CIWS.

Tony Williams
Military gun and ammunition website: http://www.quarry.nildram.co.uk
Discussion forum at: http://forums.delphiforums.com/autogun/messages/

"B2431" wrote in message
...
From: "Bjørnar Bolsøy" am
Date: 1/2/2004 5:42 PM Central Standard Time
Message-id:

(B2431) wrote in
:
From: "Bjørnar Bolsøy" am
Date: 1/2/2004 1:15 PM Central Standard Time
Message-id:


With weight ever decreasing, does anyone know if there has
been/is a project on something like this:


http://members.rogers.com/biglasers/continuous/abl.html


..intended to replace this?


http://www.military.cz/usa/navy/weap...phalanx_en.htm




Regards...

Not likely. The ABL is designed to be fired in the clear air at
altitude. A ship borne version would face problems with smoke,
fog and sea spray interferance.

Dan, U. S. Air Force, retired


But impossible to overcome? I think there are som arguments
in favor:

1. A ship is a more stable platform than an airplane
2. The ABL's targets are houndreds of miles away, while
CIWS operate in less than a mile
3. More powerful lasers and advances in adaptive optics will
compensate for air distortions

For ship use it's not so much air "distortions" you have to
worry about as air "absorption." The wrong wave lengths
will be expend their energy quite quickly heating the air
instead of the target.

Good points.

I have no idea how die lasers work but I wonder how long they shelf life
of the
chemicals are. In the case of the airborne version they can be prepared
just
prior to flight. Again not an insoluable problem for boats.

Depends on the specific chemistry of laser.
However, solid state lasers are fast approaching the useful
power range and all you have to feed them is electricity.

When I mentioned sea spray I sould also have said rain. I don't know if
they
can be optically corrected for.

There's no amount of optical correction that will deal with absorption.
You simply have to have a laser wave length which is not too badly
absorbed in that environment. This in turn means that a weapons grade
laser at 30000ft may be totally unsuited for a surface combatant.

Weapons grade power levels out of lasers are hard, weapons grade
power levels at wave lengths chosen for reasons other than they
are easy to produce is much harder.

(B2431) wrote in message ...


I have no idea how die lasers work but I wonder how long they shelf life of the
chemicals are. In the case of the airborne version they can be prepared just
prior to flight. Again not an insoluable problem for boats.

When I mentioned sea spray I sould also have said rain. I don't know if they
can be optically corrected for.

Dan, U. S. Air Force, retired

Diode lasers would probably be the way to go for a CIWS system, just
because small size and no fuel requirements. The latest ships have
large amounts of electricity for a bunch of reasons, but including DEW
weapons. There are a bunch of problems with a laser CIWS though. One,
most modern lasers need a large amount of time to kill a missile. ABL
uses a three second burst and ABL is a lot more powerful than a diode
laser (megawatt class for ABL v. 100kw for Diode lasers). That may be
a problem, but maybe not, considering it would have a line of sight
range and the horizon distance is about 8 nm at 50 ft. That gives 22
sec against the fastest antiship missiles. The other power is
attentuation. Diode pumped lasers are all in the IR range which
happens to have problems with water vapor absorption. Ironically, the
lasers used to measure water vapor in the atmosphere are almost the
exact same as those produced by the most powerful diode pumped lasers.
In fact, almost all High Energy Lasers are in the IR range, except for
excimer lasers. That is in addition to the previously mentioned
problem of particulates getting in the way of the beam.

No Spam! wrote:

One of the issues is the lasers produce toxic gases. On the ABL, they
are vented outside the plane and are dispersed in the slipstream.

On ships it could be a more significant problem to get rid of them
without endangering the crew.

On the other hand, a ship could carry more laser fuel and heat
dispersion is easier to solve.

The lasing chemicals used in weapons like ABL are not really considered safe
for shipboard use. For example, one part of a COIL's typical fuel is
high-test hydrogen peroxide, the same stuff that blew up Kursk. So you
almost certainly will not see high-energy chemical lasers aboard ship.

Naval laser applications are pretty much focused (no pun intended) on lasers
that run on electricity from the ship's power system instead. (Such as the
all-electric propulsion system planne for DD(X)) There are a couple of
candidates -- free-electron lasers are promising these days (seppite a poor
hsitory back in the 1980s). So are solid-state lasers. There's been a lot
of research on these two in the last couple of years, from all of the
services. (The Army is looking at a solid-state laser to replace the
chemical laser in the THEL anti-artillery system, to make it usefully
portable. The Air Force thinks it can put a solid-state laser in the
lift-fan bay of a JSF.)

People have taked about absorption problems, which are certainly a real
issue. The shipboard environment is about the worst possible for a weaopn
laser, with salt spray, fog, mist, haze, etc. ABL gets to operate above all
this stuff and thus can be comparatively simple. But it's still dependant
on adaptive focusing to get through the thin, dry air where it would be
shooting.

That's one thing making free-electron lasers of particualr interest to the
Navy. An FEL can be tuned across a wide range of frequencies, letting it
pick the optimium one for good propagation under prevailing conditions.

http://www.jlab.org/news/articles/2003/navy.html

--
Tom Schoene Replace "invalid" with "net" to e-mail
"If brave men and women never died, there would be nothing
special about bravery." -- Andy Rooney (attributed)

There's also an expendable laser weapon in development. See:

http://weekendpundit.blogmosis.com/l...nd/013094.html