Which laser setup to get for Long run times in Daylight?

[Tbutcher]

Hi,
My Father in law wants me to find him a laser to attach to his Slasher unit on the side of the tractor.
He wants to use it has a guide line to avoid hitting the slasher into the tree trunks.
Please forgive my superior drawing skills

......................|{ } tree
......................|
......................| laser line
.[]===[].........|
...|tra.|............|{ } tree
...|.ct.|............|
...| or |............| laser line
[-]===[-]........|
......||..............|{ } tree
.......^^^^^^^|
......<.slasher..>| laser line
......vvvvvvvvvvv

We would mount it in such a way as for it to point into the ground around 15' in front of the tractor.
Can you please advise what mW and nm I should look at getting and where from?
Also take into account that it has to be used in the Daylight of Summer! And be able to be seen with bright green grass in the background...
And be able to run for hours at a time.
I don't mind if it is not hand held.
I would be happy if we had to power it from a 12v source from the tractor..
Any guidance would be very much appreciated.
Thanks
Haydn

 

[3Pig]

A 100mW green laser is bright enough to see the dot clearly in sunlight, but a line laser has the power much more spread out, which would require absurd amounts of power and be very costly.

You could use 2 laser dots and point them where the start and finish of the lines will be.

Keep in mind 100mW of laser light is no joke, instantaneous eye damage can occur if it hits something reflective or you look into the beam.

 

[Tbutcher]

Sorry should have said.. I would hope that it would be a beam one.
I watch the videos of people with beam ones and they seem very bright.... is this just because they are inside and low light?
Thanks
Haydn

 

[3Pig]

Yeah that's right. It is much easier to see a laser beam in low light than outside in direct sunlight. If you had enough power to see the beam in daylight it would be an extreme fire hazard.

Hope you can find another solution.

 

[Marco Polo]

Is the tractor pulling some sort of brush-clearing device? Or is it basically a wide set of lawn mower blades?

Shouldn't need a line laser, just mount the laser on the tractor and aim it at the ground. Adjust the aim such that the laser dot ends up being the same distance from the tractor's axis of travel as the outer edge of the slasher. As long as the tractor is moving in a straight line, then as long as the dot avoids the trees, the slasher shouldn't hit them either.

You'd want to go for one of the green direct diodes, I would think. Probably the PLP520B since it will give you more power (and thus visibility) without breaking the bank, and you can fit it with as large as a heatsink as necessary to avoid heat issues.

Something like this, you get the idea:

...................... 
......................{ } tree
......................
.................[COLOR="Lime"]*[/COLOR]....
.[]======[]...........
...|trac|.............{ } tree
...| tor|.............
...|    |............. 
[-]======[-]..........
.....||...............{ } tree
......^^^^^^^^^^......
.....<.slasher..>.....
......vvvvvvvvvv......

 

[Tbutcher]

OK Thanks.
What sort of money are they?
Are they a complete off the shelf system? or do I have to "make something up"
Thanks

 

[CheeseHasLeafs]

You can get them off DTR's Laser Shop.
https://sites.google.com/site/dtrlpf/home/diodes/osram-plp520

DTR himself is a member on these forums, and you can shoot him a PM to inquire. You can get the diodes on their own, and press them into a module as well as build a driver yourself, or get it installed in a module with a driver, ready to go. You will, however, have to build a housing (including heatsinking) yourself and find your own power source.

EDIT: Note that the spec sheet for this particular diode puts it at 120mW output, but if you get it with a module from DTR, the lowest current setting is the spec sheet's max, which is 250mA. You can ask for it to be set higher than 250mA, but that comes with the risk of overheating and decreased lifespan, though the risk is fairly minimal at conservative settings.

 

[Tbutcher]

Ok thanks, I will contact him and ask. Thanks for your help everyone. Will post a picture of the setup once installed.

 

[DrSid]

It wont work well .. the laser would be at steep angle .. the way I see it 45 degrees at least. So it will be rather sensitive to banking of the tractor and terrain irregularities. This setup would only work well, if the laser were shining straight down, from some long arm. And in that case, the long arm itself would be good device to estimate the distance.

 

[SilverFire]

Sorry, I drew a seeder instead of a slasher for the tractor attachment. Didn't exactly know what a slasher looked like.