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Safe IR Laser for Trip Wire Set Up

perfo

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Hello all, I have a sort of safety type question to run past you…

I have displays set up at Christmas and Halloween that require triggering when someone enters my gates, but not when they are leaving. I’ve tried a couple of things including PIR’s, ultra-sonics, IR LEDS etc with none really working that well especially in high winds and a bit of drizzle etc. The simplest way I can think off would be to have two beams that get broken as some one walks past and by looking at which one breaks first work out if they are entering or leaving. I know this can false trigger if multiple people, but I can live with the few error s that’ll cause.

My gateway is around 5-meter width so round trip of 10 meters. It would be simple to use a cheap red laser and bounce it off a reflector but as it’s visible it would attract attention and possibly cause people to look into the beam (especially kids) . IR diodes aren’t powerful enough or maybe if I could collimate them but that doesn’t seem easy to do. So, is there an IR laser module that is 100% guaranteed eye safe? As it would be hidden and an invisible beam someone looking into the beam would be unlikely but still, I’d want to be sure. Is there such a thing? I have another project on the back burner of a wall writer with the wall being coated in IR excited paint, but this too would need 100% guaranteed eye safe laser…Thanks for reading
 



perfo

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No views on this my lasing buddies ?

I've found things lke this

IR laser Module

It states it is class 1 and 0.4mw so should be completely safe? Right?

If I understand it right one of the problems of cheap red (or other colour) lasers are, they also give out IR and you don't really know the true power. The risk of IR is it won't trigger the blink reflex so you could be getting and eyeful of bounced IR radiation and not know it until things go wrong. A proper manufactured laser correctly stamped as class one should be safe no matter of frequency, I guess. but it's this dip in IR that I'm not sure about and would like a bit of advice / guidance/ suggestions etc...
 
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Unown (WILD)

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Hmmm must have upset someone I guess...
Na don't say that. Wish I could help you out but I have no idea.
Actually come to think about it when my father installed a door to his garage there was an IR sensor to stop and retract the door to prevent coming down should an object be in the way.
Setting up two of those with a circuit should do it
 

kecked

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That’s what I was thinking too. I didn’t comment because I don’t know. I think the garage door source is led. Light remote control. For 5 feet led would work…but. Not for two close beams. You’d need laser for that. Or use two different wavelengths and filters over the detectors. Nevermind here’s solution. Shoot one to the left and one to the right. Now they won’t see each other. Offset one low one higher up. Using leds no eye issues either.
 

Sowee7

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No views on this my lasing buddies ?

I've found things lke this

IR laser Module

It states it is class 1 and 0.4mw so should be completely safe? Right?

If I understand it right one of the problems of cheap red (or other colour) lasers are, they also give out IR and you don't really know the true power. The risk of IR is it won't trigger the blink reflex so you could be getting and eyeful of bounced IR radiation and not know it until things go wrong. A proper manufactured laser correctly stamped as class one should be safe no matter of frequency, I guess. but it's this dip in IR that I'm not sure about and would like a bit of advice / guidance/ suggestions etc...
a lot of distance sensors use ir lasers (VCSEL) you can buy one of those and use it as a trigger (instead of measuring distance)
 

Commander J. Bloodmaker

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A 5-10mw 808nm could work. They are so bright in night vision it's like the sun!!! They can be focused or spread, only a slight pink color if the beam is focused ( some can see it as a tiny pinkish/red dot or whatever the beam shape is, I can see it. They call it the red bomb). Or a little higher in the red/ir scale, they become completely invisible. Just keep the power down to 5-10mw and you shouldn't have any probs.

Oh an your cameras on phones and stuff can see the beam. While we cannot, Even with smoke or something to help.
 
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Lifetime17

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Hi,
Just buy a driveway alarm iWorks the same way to alert you when the gate is opened. cameras work well also
Rich:)
 

perfo

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Wow thanks for the reply chaps.. I was thinking that maybe I'd asked a very stupid question and that's why no one had replied.. Good to know it wasn't :)

A complication I'd not thought to mention. One side of the gate way is a building, so not prob with power and or mounting positions. The other side is a gate post and bushes, so though quite possible to run a cable to the other post, ideally I would like this all happening from one side..
Gate openers ... I need to know the direction of travel ie coming in or going out. I did get some of those gate opener detector things to trial. They use LEDs and big lenses.. They are quite chunky and needed power to both ends. Anyway using two of them and a cable between my gate posts I did get them to work but wasn't entirely happy. If it was a permanent installation and warranted running the cables and doing a proper job then this maybe the way to go. But as it is I had to mount them on a make shift stand (which has to be rock steady or the beam moves in the wind) and run a cable across the road, it looked naff and was prone to being fiddled with. So yep works but not ideal...

TOF sensors... I looked at
VL53L0X VL53l1X VL6180X
and went for the VL53L1X in long range mode. I couldn't get a reliable ping from anything greater than about 3m as the targets are all different colours , shapes and materials etc. The manufacture state 4m in ideal conditions so I can't complain really. They are cracking little sensors though I can see myself using these on other things.. Shame they didn't do one that measured 6m (or one with 0.1 mm accuracy for another project I'm doing) .. I am actually keeping this as my back up as I'm thinking for the duration I need it I may just put a big concrete bollard on my drive restricting it to 3m and this should work then :). I did also find this module TF-Luna LiDAR but it was £30 and I'd need 2 and that was too much for an experiment for me...

Cameras I have some already and they can detect motion but not reliably and no way of them reporting a direction. I could set up a pi cam and see if I can program it to track targets and directions and notify my display system over the network. Whilst my skill level is possibly stretchy enough to do this . it would be a decent sized project..

PIRs As with cameras. I hooked up a couple of the PIR modules to an Arduino and spaced them out to try and detect which one goes first... Again it does work but not reliable over 5m in different weather conditions, possibly due to detection angle though putting them in a box with little windows cut in didn't really fix it..

All of the above lead me up the path of ... a beam one side to the other that is either broken or not has to be the most simplest and fool proof idea. If it can be done from one side and just a reflector placed on the distant post then what can go wrong :)?

LED beams A little bit of mystery I here. I know some remotes easily do more than 5m and I guess they are running them way over their rated current but for very short duration's.. IR detectors for normal IR control can be got in different frequencies so it is possible to have two LED's modulated at different frequencies and detect them separately even though the beams overlap .. This works.. butt hmmm not over 10m (well I haven't managed it) maybe it would with a decent set of lens but again a lot more difficult to set up and a lot more prone to something going wrong. It is probably how the gate opener does it but even that won't do it off a target at 5m.

I'm waiting for some of these to arrive
RCWL-0516 microwave detector- they look good and state up to 7m so should cover my gate area. They may even be able to be mounted inside my building and work through the concrete block which would be super. I'm not sure about the detection width though. So maybe trial and error to see if I can get them to trigger one at a time (one first then the other) dependent on target direction. No probs close up but maybe more tricky at the 5m mark.. still looking forwards to given them a bash.. Again they look like a non nonsense can't get it wrong type set up..which I need..The good thing is if they will work through the wall then I can mount them quite far apart. One will be looking across a small road (which is only possible if there is nothing on the outside on show ) but as you can't get to my drive without going down this road it maybe possible. I'll let you know how I get on.


So back to IR lasers. The link I listed above

It states class 1 and 0.4mw . If that is right then that should be totally safe ? Shouldn't it ? Do I believe the rating ? Is there any simple tests I can do to prove it is safe (bar the obvious :) ) . I've sent an email to the company asking where I can get one but they haven't replied yet....

Thanks all
 
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perfo

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Aug 9, 2012
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Got a reply from the company. £12 a laser and £40 delivery. So hmmm £65 (I need two) is too much for an experiment and I don't know if I can trust their label of class 1.

The microwave things have turned up and darn sensitive things they are. I'm not sure if I'm getting false triggers or genuine ones to something I'm not seeing. I'll put it in a metal box and try and get it more directional then possibly test it through my walls..
 




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