nubie question on focusing laser

[pullbangdead]

You can worry less about the size of the beam if you can make the displacement of the beam larger. Rig up a device to make the beam movement larger, and your precision can be ok even with the larger dot. Make the displacement of the dot big enough, and you'll no longer need a 50ft length, you can do it in 5 or 10 feet max.

I have some ideas, such as one little rig I've seen a long time ago in school, one that could make a dot at 10 feet move by three or four feet, just by the force of one person pushing on a cinder block wall.

You'll need to do math to map the displacement of the wall if you do something to amplify the movement of the laser dot, but it's very doable.

Want me to make a diagram of how we amplified the movement of the beam relative to the movement of the wall? I'm sure there are several ways to do it well.

 

[SuicideKing]

Since the laser will be mounted in a static location and the movement of the objective is all lateral, then a simple focusable Axiz or Sure module with a red laser diode should work just fine. (didn't realize the laser wasn't going to be moving around)

I purchased a couple from HighTechDealz.com in the past and they always delivered fast shipping with good prices.

The Sure module would be better for you, since it has a longer focusing range than the Axiz.
Both the Sure and the Axiz are very easy to focus and come with quite nice lenses for the the money.

http://hightechdealz.com/index.php?main_page=product_info&cPath=1&products_id=12

 

[80cj]

ok, so i didnt tell you the entire story.... the target isnt really on the wall of the house, it is up under the overhang of the roof and the lasers are on the ground aiming up. this way i can measure movement in both direction as well as twisting with just 2 lasers. but it also means that i can't shorten the distance. (the 2 lengths are different and are somewhere between 30 and 50 feet)

so the sure module can be focused to give me ~1/8" dot? do you know where else to get them? hightechdealz is sold out.

thanks
shawn

 

[Tw15t3r]

Is HighTechDealz sold out? I just checked, and it says that those modules are in stock.

Well, anyway, if it's sold out, you can also buy them from SureElectronics.net

I hope you can solve the mounting problem. I typically use a retort stand, but that's because I'm doing my experiments in the physics lab in my school. At the moment, for your situation, I can only think of using a camera tripod to mount the laser. Such a tripod is very flexible in terms of the direction that in can point in, and also very stable, since it has a low surface area.

 

[rog8811]

I dont know how tight the line is but Aixiz do a line generator and I believe a cross hair module...
Would that make life any easier? Crosshairs lined up on a crosshair target sort of thing.... :-/

Regards rog8811

 

[80cj]

thanks, i just checked again and they do have them now, (were sold out last night) so i ordered some.

the mounting problem is really with how hold the laser housing securely. not only does it need to be robust, but it needs to LOOK robust (if this goes to court). i have cemented 4x4's in the ground with only about 6" sticking out, so a tripod is not needed. i welded up the actual holders from pipe and angle iron, but physically holding the housing i'm using a bolt and jam nut to press it against the side of the pipe. i think it is ok once i get it where i want it, but it is kinda finiky.

as far as crosshairs or lines, that would work as long as they are thin and still bright enough to see in day light.

thanks
shawn

 

[Tw15t3r]

I'm not sure if a crosshair would be too dim a beam, but DealExtreme has one similar to the SURE module, except with a lens that produces a cross. At 5mW, its pretty cheap: http://www.dealextreme.com/details.dx/sku.5942

I can't really picture what you are using to hold the laser. Maybe some pictures might help, but it looks like you don't have a problem with mounting, since you got that figured out already.

Oh, and since you mentioned visibility, green lasers are the best at that. The only unfortunate part is that green lasers are difficult to manage since they are more complicated, and usually do not have adjustable focus.

 

[SuicideKing]

Sounds like you need a starfinder type mount they use on telescopes. You can get them at telesocpe dealers/websites or make your own out of PVC pipe. Step by step Instructions can be found here:

http://www.rainydaymagazine.com/RDM2007/RDMHomeNov2007.htm#LaserSightProj

 

[80cj]

fluff post

 

[80cj]

10 posts!  now i can post pics! (i think)

SuicideKing,
the setup that i have is very much like what you showed, except a bit more crude looking.  although that is a good idea if i need mine to be more easily aimed.  mine is the same concept except that instead of 3 bolts there is just one and i use a 3/4" pipe (and it is all metal b/c i like to weld).

here is a sketch.  (hopefully)

thanks
shawn

 

[SuicideKing]

Ahhh, well, if you can weld, then weld on a 3/8" inch nut, in the center of the pipe holding the laser and then you can attach it to a cheap camera tripod.

Once on a tripod, you can move the laser in any direction and axis and lock it into whatever setting you want.

 

[80cj]

i've got tripods. (i play with photography too) but the downside of a ball head is that it can move too easily. this is a longterm project, so it will be mounted outsid ein the elements for several months, so i really want/need a rigid mount. but i agree that for most applications, that would be a better option.

are you confident that the Sure laser will get me an 1/8" dot, or am i going to have to build one from the radio shack microscope?

thanks
shawn

 

[Tw15t3r]

I really have no idea whether it will get u the 1/8" dot you are looking for, but it's the best bet you can get for suh a price. If you cant, get the microscope. After all, the SURE laser module is pretty cheap, so it won't be pain even if it doesn't work.

Btw, that tripod's not what I'm talking about. Those are mini tripods. Get something like the one below. More sturdy, and usually comes with a spirit level to help in precision. All movements are locked in place individually by screws. (i.e. left-right, up-down are seperate and not in one "ball" like the mini tripods)

 

[80cj]

i am not looking to just throw money away, but given that my house is at stake, i'm not opposed to spending more than $3 on a laser.

how much would i have to spend to get ~1/8" dot? will one of the handheld laser pointers with an adjustable focus get me there? isn't that what i would be trying to buils anyway?

thanks
shawn

 

[Tw15t3r]

I really would not have a very good idea of whether u can get he 1/8" dot. The only way is to try it out.

isn't that what i would be trying to buils anyway?

Well, in certain cases, the lasers with in built adjustable focus may not be enough, hence you will have to "add on" optics. So, you are not trying to build a handheld laser pointer with adjustable focus, but one with a good focus.