| Author |
Message |
Daniel
Nexus Laser
Joined: 22 Sep 2005
Posts: 123
Location: Manchester, England
|
 Posted: 12/20/05, 3:54 AM Post subject: Do webcam' |
 |
|
I know most of us can see to around about 750 nm, some of us can even catch a glimpse of 810 nm. Beyond about 720 nm, most digital cameras start to interpret colours after that deep red through the red, orange, yellow and a purplish white.
But does anybody have experience with IR lasers with webcams? Are these the same as digital cameras? How strange it would be to point an IR unit in front of your webcam and not see anything directly, but on webcam there's a laser beam. Yeah? |
|
| Back to top |
|
 |
Daniel
Nexus Laser
Joined: 22 Sep 2005
Posts: 123
Location: Manchester, England
|
| Posted: 12/20/05, 7:41 AM Post subject: |
|
|
And why on earth did I post that in the "Red" forum, this should be in General!
Forgive me mods, move this if you can  |
|
| Back to top |
|
|
Cypher
25mW Classic Wicked Laser
Joined: 05 Dec 2005
Posts: 27
Location: Australia
|
| Posted: 12/20/05, 9:03 AM Post subject: |
|
|
I hope my camera can pick up my laser. I haven't taken any shots yet.
_________________
^_^ |
|
| Back to top |
|
|
tz
25mW Classic Wicked Laser
Joined: 05 Dec 2005
Posts: 37
|
| Posted: 12/20/05, 10:40 AM Post subject: WebCams &a |
|
|
The usual problem is an infrared absorbing filter (usually looks like a light cyan glass disc) which covers the lens.
The old Logitec cameras that connected to the parallel port had this, but you could remove it easily (and you could use software for very long exposure times so they were used for astronomy and such).
The Sony Nightshot was intentionally capable of this, and it had a real "infrared" mode. However you could pull the filter out or move the selector so it would pull the filter but not activate the "green screen" effect.
The latter and attempts by Sony to prevent the feature came about after stories appeared about digital cameras that could see through some clothes. Basically, the clothes they could see through were white silky things that appeared opaque white under normal light but didn't reflect in infrared, so you could see through them like you can see through fine black cloth.
I have a camera phone (VX8100) as well as several web cams and they can all see in infrared. A panasonic digital camera/video recorder/player (the one from the movie Tomb Raider) has a red-ir filter which if removed allows infrared, but everything appears with a red cast.
The older webcams tend to balance out, but in dim normal (but high IR) light, the "black" or "dark (congo?) blue" clothes start to appear light gray or even white.
With the camera-phone, it tries to do color balancing. A congo blue filter leaves blue and red and IR-Whites still appear dark. With a commercial plastic IR "flashlight" filter, it becomes monochrome, but the IR-reflective blue and black appear white. With the congo-blue + primary-red fliters it is somewhere between. With a Kodak Wratten 83C infrared filter (Almost no visible light), it is like the flashlight filter, only darker - the IR-whites apparently are white at 720-750nm but darker deeper into the infrared.
I don't know about your particular laser - most webcams can't go very deep, not much more than 1000nm. You can find the spectral response for most CCDs or CMOS on the web, and they tend not to vary that much for consumer products. You would need something special to see much farther into the IR - they exist, but wouldn't be in the mass produced web-cams.
At 650nm, the pulsar is going to be very visible to any standard camera. Most have little trouble at 720nm. IR filters only start to kick in around there. |
|
| Back to top |
|
|
kushy04
Fusion Laser
Joined: 10 Oct 2005
Posts: 355
Picture(s): 1
Location: Clarks Summit, PA
|
| Posted: 12/20/05, 10:53 AM Post subject: |
|
|
| I think all camerass do, but usually the color of the laser (green) is too bright for camera to pick up the IR unless of course you are talking about an IR laser itself... |
|
| Back to top |
|
|
Daniel
Nexus Laser
Joined: 22 Sep 2005
Posts: 123
Location: Manchester, England
|
| Posted: 12/21/05, 3:50 AM Post subject: |
|
|
tz, that's a fantastic answer, thanks for the education. 
And yeah sorry kushy I meant an actual IR laser. |
|
| Back to top |
|
|
kushy04
Fusion Laser
Joined: 10 Oct 2005
Posts: 355
Picture(s): 1
Location: Clarks Summit, PA
|
| Posted: 12/21/05, 12:12 PM Post subject: |
|
|
| then yes, it should... |
|
| Back to top |
|
|
Davidgojr
Wicked Lasers Master
Joined: 13 Oct 2005
Posts: 768
Location: USA
|
| Posted: 12/22/05, 4:30 PM Post subject: |
|
|
Most digital cameras with a CDD array are capable of picking up some light in Infra-red frequencies.
_________________
Click http://freewebs.com/photodavidgojr before buying to view photographs and learn about Wicked Lasers in action!
 |
|
| Back to top |
|
|
spooky
Modified 10mW Greenie
Joined: 21 Nov 2005
Posts: 17
Location: Finland
|
|
| Back to top |
|
|
Daniel
Nexus Laser
Joined: 22 Sep 2005
Posts: 123
Location: Manchester, England
|
| Posted: 12/23/05, 3:32 AM Post subject: |
|
|
| The pics on that webpage are great! Thanks spooky. |
|
| Back to top |
|
|
NairB
Wicked Lasers God
Joined: 11 Dec 2005
Posts: 2006
Location: Scotland
|
|
| Back to top |
|
|
Davidgojr
Wicked Lasers Master
Joined: 13 Oct 2005
Posts: 768
Location: USA
|
| Posted: 12/23/05, 12:39 PM Post subject: |
|
|
Great find, spooky!
_________________
Click http://freewebs.com/photodavidgojr before buying to view photographs and learn about Wicked Lasers in action!
|
|
| Back to top |
|
|
Gadgeteer
Wicked Lasers God
Joined: 30 Jan 2006
Posts: 2304
Location: North Texas
|
| Posted: 2/03/06, 6:08 PM Post subject: Do webcam' |
|
|
I think it's been fairly well covered by TZ. And, that's correct that silicon based sensors (CCD & CMOS) are sensitive up to around the 1um (1000nm) range. B&W cams are typically more sensitive to IR and most don't have the NIR cut filter. I use this type of setup when aligning the crystal on a green pointer and checking for artifacts in the beam and proper rotation.
Try this, take your TV or whatever remote and shine it at the cam or on something the cam can see. It should light up quite well. IR remotes are usually in the range of 900nm or so but some may use 780nm diodes (rare).
JD
_________________
http://gadgeteer.home.pipeline.com/laser/laser.htm
http://new.photos.yahoo.com/gadgeteer_x1/albums |
|
| Back to top |
|
|
|
|
