Have been asked to pertake in Laser trip wire project

[The Lightning Stalker]

You could try the ML101. It might just have the beam quality you're looking for. Nowhere
close to DPSS, but none of the stability issues either. 10-packs are going for $30 on eBay.
650nm is much less visible than 532nm. If you're really worried about it you could probably
go to 780nm at an increased risk of blinding yourself and others.

Each beam should have its own individually adjustable mirrors to make alignment less of a
pain.

660nm 300 400mW CW Red Laser Diode ML101U29 25 10pcs Pak | eBay

 

[irishluck]

Well that listing looks like its for a qty of 10 but still for $30 thats a great deal.

I just checked out the datasheet. Any idea how long these diodes can last?
Im going to go ahead and pick up a box of them though!

But thats my main problem is trying to find any data on roughly the amount of hours diodes will last!

Im going to draw up some schematics of the layout im looking at doing this around and the box I will be putting the lasers in so you and everyone can see what Im looking at.

You could try the ML101. It might just have the beam quality you're looking for. Nowhere
close to DPSS, but none of the stability issues either. 30-packs are going for $30 on eBay.
650nm is much less visible than 532nm. If you're really worried about it you could probably
go to 780nm at an increased risk of blinding yourself and others.

Each beam should have its own individually adjustable mirrors to make alignment less of a
pain.

660nm 300 400mW CW Red Laser Diode ML101U29 25 10pcs Pak | eBay

[/QUOTE]

 

[The Lightning Stalker]

Any idea how long these diodes can last?

They are supposedly good for over 10,000 hours.

 

[irishluck]

They are supposedly good for over 10,000 hours.

That would be very nice!

Only way to find out is get one here and do a duty cycle on it and see how long it would last!

Any idea what type of driver I could use to power it? Would a standard linear driver or x-driver work?

Would the drivers last 10,000 hours or a constant cycle? lol

 

[The Lightning Stalker]

A linear driver would have no problem going 10,000 hours with good heatsinking.

 

[Javalin]

650nm would be a good choice since deer can't see it, but raccoons will. I said that hiding the beam might be a good idea because neither raccoons nor deer are spooked by lasers and in one study deer seemed to be more curious about the laser. Couldn't find a similar study on raccoons, but youtube would suggest that raccoons are drawn to a moving laser, not sure about a stationary one.

300mW is a lot! the beam would be visible at night. Which for deer wouldn't be an issue but you don't want to draw attention to the field from other fauna.

I've been running a really REALLY cheap diode (a 5 pack ran me <$2 free shipping) for over 36 hours straight now off of a wall AC-USB adapter. It isn't fancy, but if this diode could last even half that time it could be worth it. The "driver" is just a simple resistor and is built in so you wouldn't need to build a driver circuit or have to be concerned with heat sinking.

I like the sprinkler system idea, I did a little research about what methods are currently used, and it looks like deer will habituate to most non-kinetic methods. I actually couldn't find any studies done with a kinetic style deterrent system.

 

[BShanahan14rulz]

Why are you suggesting he use a 400mW laser module? He should keep it under 5mW, and probably under 1mW.

And again, I will say this word:
retroreflector.

 

[irishluck]

A linear driver would have no problem going 10,000 hours with good heatsinking.

A linear driver will work you say, but would a x-driver be better?

From what ive read the x-drivers are great with heat and a nicely built.
Of coarse I will be using a decent size heatsink and possible fan for cooling with these. I want the life of them being as long as I can!

Even if the 400mw diodes are to much, ill just use them for myself. I mean 10 for $30 isnt a bad deal!:beer:

A couple of you are talking about using a 400mw vs 30mw vs 5mw.
Now the sensor I will be using for this is a photocell. The basic understanding that I have of a photocell is that once the beam has been broken and the light is no longer shining in the cell, it will trigger the system I will be using.

But how much power will it take for a photocell to activate? Or does that depend on the photocell I use?

At the same time I am asking this question I will probably have to have the diodes tested to see how many watts the diode produces as well.

 

[The Lightning Stalker]

I've been running a really REALLY cheap diode (a 5 pack ran me <$2 free shipping)

Can you post a link? Beamshot or it didn't happen.

Why are you suggesting he use a 400mW laser module? He should keep it under 5mW, and probably under 1mW.

I never said it had to be run at 400mW. 5mW might not be enough to pierce haze or fog.
Either way, there will need to be placard warning signs all around the parimiter.

And again, I will say this word:
retroreflector.

That is impractical for a number of reasons. For one thing, it would quadruple the number
of laser diodes. It would also double the number of "posts" with diodes and detectors. If
the property is not rectangular it will be even worse. Then there would be all the optics
required to split the outgoing and return beams. A dirty retroreflector is much more difficult
to clean than a simple mirror. The list goes on.

 

[irishluck]

Well im going to try out a few different laser diodes to see what may provide sufficient power to the photocell.

I looked up a retroreflector and I don't think its going to work.

There will be warning signs placed around and also glasses will be worn doing the installation.

Right now im trying to determine what driver to use that will last awhile under a constant duty cycle and how to power it.
All I would need to do is find a 3.6v power supply to wire up to the driver right?
Being that most of these run off a 3.6v battery?

 

[Javalin]

Can you post a link? Beamshot or it didn't happen.

https://www.fasttech.com/products/0/10005940/1453713-5mw-650nm-red-laser-diode-module-head-5-pack

It's not fancy by any means, but I've had it running constant for over 60
hours and counting off of a USB wall adapter.

 

[The Lightning Stalker]

 

[irishluck]

https://www.fasttech.com/products/0/10005940/1453713-5mw-650nm-red-laser-diode-module-head-5-pack

It's not fancy by any means, but I've had it running constant for over 60
hours and counting off of a USB wall adapter.

What kind of power is that wall charger using?

That may be a great way for me to test some diodes out but I need to find a PSU that will be waterproof/weatherproof even though it will be in a weatherproof box but will also have a protection circuit that wont let electrical spikes jump through it and destroy the diodes or drivers

 

[Javalin]

That's just running off USB which is 5V. My set up is FAR from weatherproof but it wasn't really meant for this thread, I just happened to be running it to see what would happen. The diode has been on for 97 hours constant so far and it's still going. You could probably use any microUSB style charger and use calk to seal the hole into a weatherproof box. Just a thought. How long do you have until the project starts? - edit - by that I meant until they system needs implemented

 

[CheeseHasLeafs]

While you're talking about whether 1mw would last through fog/be sufficient to trip the photcell:
Have you considered the divergence? From the sound of it, you're building a triangle which covers approximately an acre of land. 1100' (is it feet?) is the distance given.
That divided by three is 366.67 feet, or 111 metres approximately.
And if you're planning to use reflectors to go the whole distance with just one laser, that's a significant increase in spot size.
Which makes me believe that using several lasers for one perimeter is a good idea (an idea which as been stated before, though for different reasons).
If you're going to be using a cheap red laser, the divergence is going to be rather poor at 1100 feet, and if it's only 1mw to start of with, energy density of the spot will really be rather low.
Infrared lasers also have rather worse characteristics in this regard, if I am right?
Anyway, my 2 cents.
Good luck!

EDIT: I did some calculations (which are probably wrong, I'm horrible at this stuff) and it puts the dot size at 5.11cm in diameter at 100 meters assuming a divergence of 1.5 mrad and an initial spot size of 2.5mm. That's what, 0.24mw per square centimetre?

EDIT NO 2: CALCULATIONS ARE ALL WRONG PLEASE DISREGARD I DON'T KNOW WHAT I WROTE

 

[irishluck]

That's just running off USB which is 5V. My set up is FAR from weatherproof but it wasn't really meant for this thread, I just happened to be running it to see what would happen. The diode has been on for 97 hours constant so far and it's still going. You could probably use any microUSB style charger and use calk to seal the hole into a weatherproof box. Just a thought. How long do you have until the project starts? - edit - by that I meant until they system needs implemented

Oh yea that would be a great way for me to test the diodes but would have to have a different power supply used when I actually power it all. I would still need to have some type of circuit protection in it as well.

We actually start the project in march and would like to have it done that summer but the whole project is about 2 years long so we would have a year and a half to test it and watch it in action.