Laser power

[Gil]

I just got this anonymous comment on the "how does the kinect work"
blogpost.

_____________________
I just acquire a Kinect and made some incredible measurements. The
laser output power is about 40mW to 60mW, i.e. it exceeds hundred
times the class 1 limit. Moreover this is an IR light so there is no
blink reflex that could protect the eye. Although the diffractive
optical element - that generate the strutured dot pattern for 3D
measurement- separates the incident laser beam into thousand of low
power beams, at short distance (few centimeters) all this power is
focused on the retina. I've been involved in laser product
certification, and I can't understand how Microsoft got this class 1 .
For me this is a very dangerous device and I would recommand to
certificationnever look at the laser dot pattern at less than 50cm.
Take care with the children.
______________________

Is it one of you guys the poster?

Is this true?

[Joshua Blake]

Below is a snippet from an IRC conversation with Ziv of PrimeSense (nick: Invo), who is the embedded hardware lead at PrimeSense. (I removed a few lines from an overlapping topic.)

 

[14:48] <njbutko> would it hurt your eyes to be staring at it constantly? e.g. if you put it on a comp screen
[14:48] <Invo> no
[14:49] <qDot_> I've been working with LIDAR for years and hasn't had a vision problem. Yet. :)
[14:49] <briangibson> as long as you dont remove the IR diffuser from the laser? ;-)
[14:49] <Invo> DO NOT REMOVE IT
[14:49] <briangibson> hahaa
[14:49] <Invo> it's not safe if you do
[14:49] <Invo> seriously !
[14:49] <njbutko> that's good to know
[14:50] <halfdanj> how many mA is it?
[14:50] <qDot_> http://www.ariven.com/store/ariven/warninglaser
[14:50] <Invo> well we have about 1,000,000 safety protection features
[14:50] <Invo> so it's not risky
[14:50] <Invo> but please don't play with the projector :)
[14:51] <halfdanj> are the dots you project so dimmed that it impossibly can hurt? And how is that messeured?
[14:51] <Invo> after the diffuse you can stick it on your eye 24/7 for 10 years and it's still safe
[14:51] <njbutko> where is the diffuser?
[14:51] <halfdanj> ight at your eye, or at a min distance?
[14:51] <Invo> right in your eye
[14:52] <Invo> it's totally safe
[14:52] <halfdanj> good to know
[14:52] <Invo> without the diffuser the projector would not turn on
[14:52] <Invo> there are lots of safety measures
[14:52] <njbutko> that's good to know also

 

Josh

---
Joshua Blake
Microsoft Surface MVP
OpenKinect Community Founder http://openkinect.org

(cell) 703-946-7176
Twitter: http://twitter.com/joshblake
Blog: http://nui.joshland.org
Multitouch on Windows book: http://manning.com/blake

[Mike Harrison]

Class 1 is specced both as a total power limit, and also a power density.
The latter is hard to calculate, so if you meet the power limit, it avoids the need to do the
complex power-density measuremements.
The diffuser spreads the beam over a very wide area, so at any realistic viewing distance, the power
density is (presumably) at a safe level. I would expect a lot of work has been done on this...

[Gil]

10 years? I spend more than that in front of the computer :P

> OpenKinect Community Founderhttp://openkinect.org

>
> (cell) 703-946-7176
> Twitter:http://twitter.com/joshblake
> Blog:http://nui.joshland.org
> Multitouch on Windows book:http://manning.com/blake
>