Can someone help me pick lasers?
rwgast_logicdesign
Posts: 1,464
ok so ive been really intrested in using the ir wiicam, i found this thread from a guy named garreth who doesnt seem to be around anymore
http://forums.parallax.com/showthread.php?129652-The-quot-Lassiter-quot-inexpensive-(LIDAR)-Distance-Detection-amp-Ranging-Propeller-WiiMote/page2
he also has another project where hes using a laser to draw a ring on the floor around his chasis and using the wiicam cam to detect breaks in the ring for object detection. pretty ingeanous..
anyways this gave me an idea to get 4 lasers (wiicam detects 4 points) put them on indavidual x,y pulse them at different frequencys for identification and run scan patterns on objects. and maybe even use the cam to track ir beacons when its not scanning objects.
so the thing is idk much about the details of ir or anything about lasers. ive been looking on ebay and finding cheap 5 packs of lasers and indavidual lasers up to about 20 with focus lenses at higher wattages.
the first thing i dont understand is, the wiicam detects IR. well garreths projects are using visible red lasers, why does this work, can u use any color laser? im thinking i want to use 800-1000nm ir lasers so the beams are not visible, but im wondering if this will have problems outside like ir leds, does using a colored laser eleminate the ambient light issues? the next thing is wattage. i have no idea what a wiicams detection distance is either. so the lasers on ebay in my price range go from a few millawatts to 3 or 5 watts i think. how do i associate power with distance? this will be fairly important if i go with invisible ir as ill have no visual frame of reference. anf finally when one types in ir laser module on ebay the cheapest ones say blah nm blah wattage burning ir laser! does that burning mean something, i know lasers can screw your eyes up im tryin to be safe and the word burning is kinda makin me leary of them.
http://forums.parallax.com/showthread.php?129652-The-quot-Lassiter-quot-inexpensive-(LIDAR)-Distance-Detection-amp-Ranging-Propeller-WiiMote/page2
he also has another project where hes using a laser to draw a ring on the floor around his chasis and using the wiicam cam to detect breaks in the ring for object detection. pretty ingeanous..
anyways this gave me an idea to get 4 lasers (wiicam detects 4 points) put them on indavidual x,y pulse them at different frequencys for identification and run scan patterns on objects. and maybe even use the cam to track ir beacons when its not scanning objects.
so the thing is idk much about the details of ir or anything about lasers. ive been looking on ebay and finding cheap 5 packs of lasers and indavidual lasers up to about 20 with focus lenses at higher wattages.
the first thing i dont understand is, the wiicam detects IR. well garreths projects are using visible red lasers, why does this work, can u use any color laser? im thinking i want to use 800-1000nm ir lasers so the beams are not visible, but im wondering if this will have problems outside like ir leds, does using a colored laser eleminate the ambient light issues? the next thing is wattage. i have no idea what a wiicams detection distance is either. so the lasers on ebay in my price range go from a few millawatts to 3 or 5 watts i think. how do i associate power with distance? this will be fairly important if i go with invisible ir as ill have no visual frame of reference. anf finally when one types in ir laser module on ebay the cheapest ones say blah nm blah wattage burning ir laser! does that burning mean something, i know lasers can screw your eyes up im tryin to be safe and the word burning is kinda makin me leary of them.
Comments
Oh this is easy as I have used a IR laser to trigger a WiMote on my mac ......
You want 808 nm or 1064 nm .. and no not watts Please the specular reflections alone can blind you ..... 5 mw is a TON 10 mw max .
remember a wemote blackboard uses a IRLED that has to Bounce off the board to the Wiimote ..... loads of losses there. so a laser is going to bounce better however please keep in mind that the serface you use is a huge factor .
if you Really want to do this I will need more info . and no outside is not as big of a issue as it seams .
Peter.
EDIT thsi is a load of reading but
http://www.repairfaq.org/sam/lasersaf.htm#saftoc
I highly recommend you read that entire chapter ....
Peter
I'd strongly suggest using red lasers. It's nice to be reminded that lasers are bright and plus red lasers look much cooler than IR (at least the light does).
Come on, you know you want to see those laser dots! IR dots aren't fun to look at.
Use IR when you don't want humans to see the light (like with a Wii Mote white board).
Deal Extreme has all sorts of lasers. Use one of those (or some other cheap source).
I'm not sure but I don't think you need to worry about extra IR in a red laser like you do with green lasers. Maybe Peter knows if there is any harmful amount of IR light in red lasers?
BTW, I've tested the Wii Mote camera with red, green, and violet lasers. No surprise but it could see the red laser much easier than the others.
When I did my wii glove . I used a 532 nm Green as a alwas on beam and then used the 808 to trigger the Wiimote .. worked well and I know of a qurik in the wiii SW that makes it not easy to use a single laser as a tracking and a mouse click ! the light IS the click . and that was a Huge issue..
when Iam at the lab on wed Ill do a responce trace on the sensor .
take in to account the surface you are going to bounce off of .. absorption is a issue .
as far as what ill material the laser will bounce from its veryied. my projects kind of ambitious, i want to use 4 lasers with independent accesses and different pwm rates to do average distance and object detection. but i also wanna "scan" objects, i.e cups, chairs, dogs (without hitting there eyes maybe impossible) using 2 lasers horizontally and two vertically to try and create a height map and maybe image them. kind of like a SAR continous wave radar. i figured i could move to two wiicams and 8 lasers at a later point. this would be a very good way to fill in the gaps of plain old machine vision. if i were able to scan an object and use the height coordinates to make a 3d model that would be usefull in art applicarions well outside of robotics!
no matter what i will be starting with visible lasers but would like invisible ir once i know what im doin and not shooting laser all over the house and gods creation sporaticaly
Peter, you lost me. What's loading that has issues?
Assuming "SW" is software, what software where you using? Is this on a PC? I think rwgast is planning on only using the camera from a Wi Mote and using a Propeller to interface with the camera.
Your Wii glove sounds cool. Do you have it documented anywhere?
Will you be able to test the Wii mote camera without the filter? I'm pretty sure the dark plastic on the front end of the Wii Mote filters out a lot of the visible light.
Another reason to use a red laser so you can "see" how well it's reflecting.
You're correct. The numbers Peter is using are the wavelengths. I minored in physics but I still call a red laser "red" instead of "650nm" (though there are good reasons to use the wavelenth when identifying a laser).
I think your plan to start with visible lasers before using invisible ones is a good one.
BTW, Deal Extreme has lasers that will output as a line or a cross. I doubt they'd be useful with a Wii camera but they could come in handy with other machine vision applications.
Red 660 is OK .
http://farm9.staticflickr.com/8185/8129002717_27b7d7567a_k.jpg
the Laser on the left the one in the blue case is a 660 ish Diode at 31 mw..
again the WL of the laser is gonna effect the reflectivity and there for you Dont necessarily want red , but green or blue or UV who knoews .
just cause you can see red dose not make it better . IR does depending again materials better then green lets say one material X so you really cant choose a " color" till after you choose the surface ..
Are you sure it's a neutral density filter? That surprises me. I'd think they'd want to block all but IR for the Wii Mote.
Okay, I need to know, does the laser light look like that picture to the human eye? If so that's intense.
Peter, you are so wrong!
I'm betting rwgast doesn't have a single material in mind. He (and I) would like to use a Wii camera/laser combo on all sorts of household and natural materials.
Peter, I'm still curious about the Wii software you've used. Was it PC software? Have you used a Wii camera outside of a Wii Mote?
looking cool at the espenmse of performande is not a good idea .. If the laser is gonna wortk in the Visible spectrum then that is great but you may suffer large losses that may not be aissue in the UV or IR range ...
again sheer power not optic finesse can over come these losses . but it may put the laser in to a high class 3B range to get usefull results and I dont want to see any one here out side of a lab( home or work ) with a 100mw Green in a public space .. one wrong move and you can have a blind spot .
By ND ment that the sensor is not very wide on its dynamic range .,
Quote Originally Posted by Peter KG6LSE View Post
http://farm9.staticflickr.com/8185/8...b7d7567a_k.jpg
the Laser on the left the one in the blue case is a 660 ish Diode at 31 mw..
Okay, I need to know, does the laser light look like that picture to the human eye? If so that's intense.
that is what it looks like in person . I did a longer Exp to make up for the fact that my SLR wantrs to do a short EXP and not a true to how I see it EXP.......
31 mw is 6 X that of a Legal off the rack pointer , the CRDH states it is not legal to sell or use a "pointer" greater then 5 mw ,. al of mine are not pointers but lab lasers . the green is 15 mw and the orage red is a 7.5 mw HeNe
as for the glove . I just took the IR/Green module on a drivers glove and put a tact switch on the inside of the pointer finger . I never really bothers to docuemtn t as it was a " i wonder what this does " test and I was really just dinking around ..
perhaps I sould make a new one and use a flex sensor .
the SW was Wiimotewhiteboard. for mac.... my Proff in IHCC made a smart board outta a Wiimot and I was hot in his heels to make my own .
Peter...
.. maybe someones already done some diy projects using alternatives
I have permanent "floaters" in both of my eyes from experimenting with early IR diode lasers back in the 1980s. The damage actually took several months to fully manifest. Unless our IR lasers are used in sealed environments they really aren't all that safe, even a fairly low power one.
5mW to 10mW
invisinle - 808 or 1064nM
visible - 660nm will be the best choice with wiicam, ie most accuracy and safe brightness for wii cam?
also i want to put each laser and cam on its own pan tilt, what would be the best way? im thinking 3 dollarvmicro servos or steppers from ebay but those may be a bit bulky... maybe theres a better way than 5 mini pan tilts for indavidual diode and cam motion?