Hmm.. Yes, you are sounding a bit like an..
I see that alot of people explain how to burn a piece of paper. There are always risk involved with using a laser, but I cannot understand that it's not possible to discuss this (if it's being used in a controlled environment).
Let's just say that you have a piece of paper 30 feet away.
If you have a laser that focus to infinity, wouldn't the beam focus when it hits something? So it won't be dangerous for anything behind the object?
A safer way would be to focus the beam on the exact distance. So if you would pass the beam 10 feet from the laser, it would not even sting. If you are 30 feet (focal point) it would sting (and not cut your head off).
I see that lasers can have a focal point 10 feet away. Isn't it possible to make the focal point be 30 feet away?
I am happy that you guys think about safety, and I do take safety very serious. But things can be done to practically achieve something + keep safe.
If it's practically impossible to make a paper burn at 30 feet with a laser that costs less than 1 000 USD, then I will rest my case. But from my understanding this should be possible. I just need some guidance on what tool will be the best for the job.
It's not like I cannot cut the branches with my own hands, but one would never invent anything if one would just say "well, just do it the old fashion way"..
/Hans
Once again, my apologies for wording my reply so harshly.
Well here are a few things to consider,
1. The main problem you would encounter if you tried making a laser tree cutter is Power-at-distance. Currently the most powerful single laser diode available is a 7 watt blue laser diode. Sadly, its also the most diverging laser diode available. Meaning, you would have to either use a large collimating lens or beam shaping optics to obtain a small focal point at a distance. Large diameter collimating lens and Cylindrical lens pairs are both costly parts. Implementing those things into your laser would also take a significant amount of time.
2. You could use multiple smaller lasers and try to blast all of them into the branch at once, but you would have to aim and focus each smaller laser unit individually, which takes a long time.
3. You might consider using 100 watt laser diode arrays to overcome the low power issue, but those arrays have piss poor focus, and will not work well at range. Even if good focus can be achieved, you then have to deal with a 100 watt death ray.
4. Yes a laser will diverge and spread out after reaching the focal point, and its true that it will not burn well after the focal point. But any living thing that has eyeballs would probably have their retinas' nuked if they go into the beam of the laser, because the lens in their eyes will act as the collimating lens.
5. Lasers with >5mW of output power can damage eyes. In order to cut branches, you would need at least a couple watts. Any mishaps here and boom, permanent blindness.
6. Its gonna be a lot of trouble if you disturb/accidentally blind some neighbours. All it takes is someone walking into the path of the laser by accident.
7. Law enforcement won't be happy.
Lets just put it this way, is it possible to build the device you proposed? Yes, with a lot of engineering and effort.
There isn't anything wrong with the core concept, but in terms of safety and general practicality, its not quite worth it.
