Has anyone here made a laser line using a prism?

[Alaskan]

Found this diagram on http://www.opticsjournal.com/MPBexpanders.htm - What do the numbers mean?

Has anyone here experimented with prisms to make a laser line? I've scoured the internet and searched for information and finding some, but not as much as I'd like. Looking for someone with practical experience in this area, trying to see if it is possible to reduce the expansion of a laser line by expanding it through multiple prisms. Is this possible or am I way out in left field?

Is there such thing as a beam expander for laser lines to reduce the divergence of the line in one plane? This is what I am trying to do, so I can use a laser line for long distance signalling from mountain top to mountain top at a great distance, that way, I wouldn't need concern about aiming the laser exactly on a target as well as reduce the amount of light at the same time, fearful of a pilot complaining, although that could happen if close enough anyway, but theoretically, is it possible to reduce the divergence of a laser line? The line need not be extremely wide, just 10-20 degrees wide but with as thin a line for as far as possible is what I am working on.

 

[bloompyle]

It's referring to dimensions of the spot. That circle with the line through it means diameter.

So initially, it is 1mm x 1mm. X-axis vs Y-axis. Then implementing prisms to continue growing one side.

Anamorphic prisms like these are used to take multimode lasers, and turn them into squares.

 

[Alaskan]

Thanks, I found another article, here is a screen print transferred to .jpg:

From http://www.scirp.org/journal/PaperInformation.aspx?paperID=43574&

Thanks for the answer on the numbers... I'm perplexed, I have a set of prisms much like the ones shown here and I cannot see any line, it looks just like a spot to me. I used four prisms too in the same physical arrangement, perhaps the amount of expansion is so small I can't tell the difference with the brightness of the 175mw green laser I am using. My prisms are relatively huge at a couple of inches long each compared to the diameter of the beam. I will find a low power laser and look again, this 175mw is probably just too bright to see the difference. Disappointing to me I can't get the beam to spread out more Guess I will just have to use a cylinder lens but my objective was to have as thin a line as possible with the least divergence, as a beam expander, I was hoping it would do so, that is why I choose prisms. Maybe my whole premise is wrong to begin with on that and this type of beam expander wont do so.

Any laser optic guru's here who can tell me the best way to get the thinnest line possible with the least divergence? My guess, is that you must start out with the least divergence focused to infinity laser beam you can, whether using a cylinder or a prism, but since a "normal" beam expander using a diverging lens with a PCX lens is for a spot, I thought a prism expander would be the thing to use for a line while also reducing the divergence.. True?

Since I have some large right angle prisms, maybe I ought to just expand the beam using a PCX lens etc. and then spot that on to these prisms to make a line with a lower divergence? This is assuming a prism beam expander also reduces the divergence while making the spot more into a line? Right or wrong? Anyone?

Found another article on prism beam expansion: http://preview.tinyurl.com/n6ly3zk

 

[Bionic-Badger]

It'll depend on the angle the prisms are designed for too. Most anamorphic prisms are designed for use as pairs so that you can get a beam out at the same angle it came in, only wider. Those prisms are also designed for a specific ratio of expansion, and to minimize reflections.

If you want to see a "line" try shining the light so that it slightly illuminates the surface the prisms are resting on. Then you can see how the beam is shaped as it goes between prisms.

 

[Alaskan]

Thanks, I tried that and can see it now. The problem is I looked at the diagram and expected huge changes, when working with such a small beam diameter to begin with, doubling or even 10 times bigger isn't that significant when looking at it by eye.

 

[CDBEAM777]

Simple...On the cheap !!! Just shine your beam thru a Rod/Cylinder of Clear
Acrylic !!! You WILL get a line....maybe more line than you want...as in wider !!

Try 1/4" ~ 1" in diameter !!! They have this geometry in B7 glass and IIRC it is called a cylinder lens !!

BUT......Using a Laser...outdoors....with NO beam stop....over 5mw ...off your property...has issues !!!!!!!!!!!!!!!!!!!!

Just noting the legal considerations !!! Maybe you own the mountain tops and the land in between ????

Have fun and watch your eyes !!!

Lite'em Up CDBEAM=======>

Edit...Had a piece of 1" clear Acrylic around ( Doesn't everybody !!)...At 2' from the LD source....with THIS dia...produces a very thin line...about 30 degree spread...a larger dia...OR further from the LD source....will lower your divergence...maybe down to the 10~20 degree range...

 

[Cyparagon]

shallower angle of incidence will get you greater expansion, but also greater power loss. Expect the change to be small - you won't get anything like the line of a line-generator optic.

 

[Alaskan]

Thanks for the help everyone, I was expecting too much from a prism, was thinking I'd get something like a cylinder lens line. I have lots of cylinder lenses and they do the job well but I was hoping using a prism would allow the line to be thinner compared to a cylinder lens, but perhaps that isn't what they can do. It sure takes a lot of prisms to spread the beam very much and the power loss is too high so I will probably abandon the idea of using them. I want to build an IR line generator more than a visible light one so the possibility of interfering with aviation night vision won't happen, although it could flash any CCD camera they might have, something I'm not wanting to do either as they might take it as a laser attack. I will only use such in a remote area anyway, so not likely I will accidentally hit an aircraft using a camera like a police helicopter.