Laser Designators (questions)

Apophenia

So, it seems this is the most appropiate forum section for this question...

Can anyone give a simple explanation of the parts that make a laser designating system and how a typical unit works. Also, once a coordinate is established, how does this information get communicated to other systems. (Is it, for example, used with gps and shared via a network of some sort?) What information is shared and how are the coordinates/positioning established.

Example: battlefield lasing where a ground force establishes a coordinate using a laser designator which is relayed to aircraft.


I apologize if this is a little vague but my background is in aerospace and I don't have too much knowledge in optics and networking.
Any recommended texts or sources are appreciated as well.

Chεεrs

Drakkith

Have you read this article?
http://en.wikipedia.org/wiki/Laser_designator

CWatters

The article doesn't say much about airborne designators but I think modern systems allow one aircraft to do the lot. eg pilot points the laser at the target then releases the bomb, then computers linked to gps and the aircrafts systems keep the laser pointed at the target while the aircraft can twist and turn to avoid ground fire.

Apophenia

Thanks, but this article is a little to general; I would like more technical info about it. Perhaps, a better google search or something would do the trick for me.

Apophenia

That is all great but do you know if the position is established using GPS; for instance in the original case I stated: If troops on the ground laser designate a target, how does the aircraft get relayed this position? Is the positioning determined by the laser then transferred to GPS coordinates and sent to the aircraft or is there no mediation as such and all done with lasers somehow?

TO ANYONE: I would like a more technical explanation of how it works exactly as well; the wiki article does not quite cut it.

I appreciate it guys.

Drakkith

Did you read the article? It explains exactly how the aircraft sees the laser. The laser itself has no idea where it is at, it only designates a spot on the ground. The aircraft knows where itself is, and it knows where the target is thanks to the laser designator and can calculate what the location is in GPS coordinates I'm sure. You realize that you can't just point a laser at something and have an aircraft drop a bomb on it unless the pilot already knows the general area of the target right? The laser is simply for pinpoint guidance.

d3mm

You're actually asking how to build a guided missile system. I am not sure that we should be answering this question.

berkeman

That's a fair concern, but in this case I doubt the poster is going to pose a threat.

The laser is aimed by a person, so GPS does not need to be involved. The laser is usually not visible to the naked eye, to help keep the target from knowing that they are being lased. Sensors on a vehicle could detect that they are being lased, however, and vehicles with such equipment may exist already. But there's not much you are going to do in the few seconds that you have that information, other than trying to duck into an alley or something.

The laser will usually be modulated as well, with a code that the seeker head in the ordinance will be looking for. It is not just an IR laser spot -- it will have encrypted information modulated into its intensity to ensure that the ordinance and target are meant for each other...

d3mm

http://en.wikipedia.org/wiki/Shtora-1

berkeman

Very interesting link! Looks like it's mainly for ground-based anti-tank missle defense, and it has some issues, but still it's an interesting approach.

Apophenia

Exactly, I am developing a guided missile system to eliminate endangered tortoise species off the coast of Antarctica. :)

Don't know if you are trolling or serious, although I suppose it is a legitimate concern.

I wouldnt say "exactly" but it still helps; I think I had a misconception with the GPS involvement. The seeker which detects the laser determines the position merely by the reflected signal Im assuming so there is no need for GPS. Right, I think, but the relaying of information seems it may use some gps:

"Northrop Grumman's LLDR (ground laser designator), using an eye-safe laser wavelength, recognizes targets, finds the range to a target, and fixes target locations for laser-guided, GPS-guided, and conventional munitions. This lightweight, interoperable system uniquely provides range finding and targeting information to other digital battlefield systems"

It fixes target locations by what means? GPS coordinates?

Lets say for the case of a laser guided missile: the target is lased by the aircraft and the missile is directed to the lased position using a seeker. No, position coordinates involved correct? and it could also be lased from the ground unit (LLDR for example) and seeked by the missile Im assuming?

Since it could send info for GPS guided munitions then it obviously can determine the position in GPS coordinates (range + current position). I want to know if say a laser guided missile typically recieves GPS coordinates first or direct lasing in the event of a ground lased target.
Why would it use GPS at all? (Perhaps, aerial lasing and laser guided missiles of a GPS established position is more accurate than just dropping a GPS guided missile. I dont know)

d3mm

There's no reason for a laser designator to need GPS. The bomb or missile sees it, and homes in on the reflected laser light. As for 'typical missile' there's so many different types, perhaps if you ask about a specific weapon I will look it up in Jane's.

And now the part you won;t like:
The difference between a laser designator for a ground based system and air lanched one is what? Don't answer this because it leads on to the next point which is ...
You're also asking how to defend against one. The information can be used for either purpose. Let's just say that anyone who *really* knows how these things work is going be silent (or get arrested) or is paid to lie, in order that their own systems don't get rendered obsolete. You aren't realistically going to learn more than wikipedia from asking around in public boards.

berkeman

Damn it! I KNEW it! Oh crap the humanity! The tourtisery! LMAO

Nah, he's just being careful. We take "dangerous and illegal" activity discussions pretty seriously here on the PF, and he's just expressing a valid concern. However, by my posting in the thread (or any Mentor), that's a signal that we are watching the thread and will deal with any safety or national security type of issues. Any user is also free to click the Report button on any questionable post, to submit the post/thread to the Mentors for review.

It sounds like that is a very flexible munitions system, that can use multiple guideance mechanisms to the target. That combination would defeat the IR bloom/masking technology described in the link that I commented on earlier, for example. If the munitions loses the laser spot, it could switch to the last recognized GPS coordinates of the target...

Correct. If laser guidance works, that is more accurate than even military grade GPS guidance.

It doesn't. Munitions can be either laser guided or GPS guided. Some munitions may use a combination or be able to switch from laser guided to GPS or just dumb bomb mode if the other modes are interfered with.

Poor litttle turtles...

Apophenia

So it doesnt really matter the lasing source; the seeking unit will be able to home in on it?
Lasing from completely different angles (between the seeker and laser...ex: ground lasing at horizontal and air seeking) wont matter? <- just shows how ignorant I am with optics; I dont really see a beem of light reflecting in all directions to be received by a seeker but that is probably what is going on....it must be.

True, for the most part.
The interest actually spurred from thinking how to incorporate something to that (laser designating) effect in rifle optics; just a thought. "Dont answer.." -> I dont expect someone to tell me all there is to know so that this type of info is presented to all folk (nuts included) on the internet. Id say the interest lays more in optics than anything else; i.e. weapons and such.

10-4. I more got the impression some people do not like to assist anyone who participates in the development of weapons out of a moral obligation. Im currently unemployed (looking for aerospace) and dont possess either the desire or means to do so (Id prefer space over defense anyway)........unless them turtles are involved; then I shall find a way by any means necessary. Hah.


Thanks guys.

Drakkith

Normally the beam undergoes diffuse reflection and can be seen from any angle. However if your laser is hitting the target at a very high angle, near 90 degrees, it is possible that most of the beam will undergo specular reflection and be reflected in mostly one direction, possibly causing the weapon to lose targeting if the laser is reflected away from it. This depends on the angle and the type of surface. Smooth surfaces are much more likely to undergo specular reflection when the angle increases, while matte and rough surfaces almost always undergo diffuse reflection.

d3mm

LLDR has GPS but is also designed for artillery guns (which require co-ordinates)

http://www.es.northropgrumman.com/so...ldr/index.html

Having said this, certain modern smart bombs have both laser and GPS seekers in the same weapon. JDAM was originally GPS-only.

I guess you are looking for one of these. Now this won't fit on a rifle, but goggles are fairly portable. You can't buy these though.

http://www.globalsecurity.org/milita...nd/an-peq1.htm

Apophenia

Yeah, that's a better explanation; thanks Drakkith. A wikipedia search of diffusion was pretty useful (for me).

Thats getting closer to what I was imagining for some implication.

Some near future stuff:
Any ideas on how to incorporate rifle optics with targeting for communication between individual ground troops? I suppose laser designating would be overkill but I was originally imagining how to get like a graphic in something like an ACOG of a position and that same position being relayed to all scopes. It may not be necessary though; Im not sure how much practical use it would be to troops or how much of a benefit it may have over just vocal communication of position.

A more straightforward way would just be laying an IR beam on the target and having scopes that pick up the wavelength. No relaying of position required. Id imagine that there may be technology so that the scope's traditional function is not affected. (It looks normal through the scope and the IR receiver is more of a secondary function.) I know this is already the case with night vision goggles and laser sights (I believe) but I was thinking of the whole system being within the scope (not necessarily night vision scopes which I assume they already have).