Jump to content
SubSpace Forum Network

Laser Pointers and Camera Lenses

rootbear75

By rootbear75
in General Discussion

 Share

Recommended Posts

rootbear75 Newbie

rootbear75

Posted
Posted (edited)

What exactly happenes to a camera if you point a laser into it..

well i tried that with my webcam, and i got a strange picture...

it was all white (that was expected) but, a purple dot appeared in the middle... what is that from?

Picture_9.jpg

 

EDIT: before u ask: i was using a <5mW Green laser pointer

Edited by rootbear75
L.C. Newbie

L.C.

Posted
Posted
Your webcam is fading into heaven, just like in Halo (when the screen fades to white with some motion as if you crashed and passed out).
2pac Newbie

2pac

Posted
Posted
stop making useless !@#$%^&*, this crap does not belong here, and someone ban this mofo ffs. The dudes spamming with topics and its pissing everyone off, if you mods did something about this fat kid then there wouldn't be a problem.
Samapico Newbie

Samapico

Posted
Posted
you have no idea how pissed off the ss community is getting 'cause of rootbear

You have no idea how pissed off I am hearing you guys arguing like that. You're all worse than 5 years old kids... "HEY LOOK WHAT HE DID, WAAN!! WAAN!!" "HEY HE'S RUINING MY INTERNETZ! WAAAAN!! WAAAN!!" "BAN HIM!! HE DOESN'T AGREE WITH ME!!" "I DON'T LIKE HIM, SO I'LL JUST ACT TOUGH AND MAKE UNORIGINAL INSULT REPLIES!"

Lynx Newbie

»Lynx

Posted
Posted
Well here my PROFESSIONAL answer.. Well you see I think KNOW that the obvious reason here is the Dilithium Crystals.. Basicly root - When placed in a high frequency electromagnetic field, magnetic eddies are induced in its structure which keep charged particles away from the crystal lattice. This prevents it from reacting with antimatter when so energized, because the antimatter atoms never actually touch it. This causes the blue to become green - duh.. whistle.gif
Samapico Newbie

Samapico

Posted
Posted

Oh didn't see it was a green laser... never seen a green laser pointer either blum.gif

 

And what Lynx said makes sense... Anything from Star Trek cannot be refuted anyway.

Blocks Newbie

»Blocks

Posted
Posted
My guess is that you're saturating the charge sensors in that area blarghargharghargh and they're going whack. Or something like that. CMOS sensors work by light building a charge across a photodiode and then sensing that charge with some fancy transistors. There's multiple sensors that are sensitive to different wavelengths. Lasers emit light in a very narrow range of frequencies (your green is ONLY green). Or I could be making all of this up.
rootbear75 Newbie

rootbear75

Posted
  • Author
Posted
My guess is that you're saturating the charge sensors in that area blarghargharghargh and they're going whack. Or something like that. CMOS sensors work by light building a charge across a photodiode and then sensing that charge with some fancy transistors. There's multiple sensors that are sensitive to different wavelengths. Lasers emit light in a very narrow range of frequencies (your green is ONLY green). Or I could be making all of this up.

even if you werent making it up, it wouldnt explain why the green laser appeared purple on the camera

 

also, this is what happened when i pointed it DIRECTLY at the lens

pointing it off camera, its green.

Samapico Newbie

Samapico

Posted
Posted
Photographing Laser Beams

Taking photos of diffuse reflections of a laser beam that aren't intense enough for you to turn away will not damage a camera. Aside from the possibility of there being invisible IR (as with some cheap green laser pointers) or UV, if it doesn't annoy you, it won't annoy the camera. But where there may be an invisible beam lurking within the visible one, precautions like IR-blocking filters must be taken for the safety of both you and your camera.

And photographing the beam scatter of even a high power laser from the side, even *almost* head-on is generally safe as long as the actual beam doesn't enter any of the optics (including our eyes!). Add some dust, smoke, or fog to make it stand out.

 

But, you've seen those photos apparently shot directly into a laser beam. My recommendation is to NOT try to reproduce them with a digital camera unless you won't mind ruining it. The CCD or CMOS sensor is the heart of your camera. Any damage to even a small number of sensor elements (pixels) will render the camera useless for most purposes.

 

A direct hit from a laser of less than 1 mW may damage the sensor since it can focus to a micron-size spot there. Using a fast shutter speed won't necessarily help since digital cameras don't have real shutters - the sensor is always exposed and a narrow laser beam may get through even a stopped down aperture in its entirety. Some guidelines:

 

 

Don't shoot directly into the beam.

If you must, defocus the camera. This will spread the spot on the sensor and decrease the power density.

Limit the laser to an actual output of 1 mW or less using whatever means at your disposal (adjustment, filter, etc.).

Film cameras aren't as susceptible to damage from the laser beam but limiting the power to 1 mW is still a good idea.

 

WARNING: If your camera has an optical viewfinder, take special care that your vision isn't damaged should the beam enter it directly!

 

Unfortunately, low power laser beams don't look like Star Wars light sabers so some !@#$%^&*istance is needed to make decent photographs.

 

(From: Joe Smiley (cadcoke3@yahoo.com).)

 

One technique to help catch the beam is to use two exposures, and combine them in something like Photoshop. One of the exposures, is done in complete darkness (except for the laser) and is timed to capture the beam itself, and the glow it has on the surrounding areas. Then, the next is done is subdued light (you can still have the laser on) to get the surroundings.

 

Another approach (which I've never tried) is to use a flash and an exposure time longer than the 1/60 second the flash requires. The flash itself will occur as soon as the shutter opens, but the longer exposure time will keep the shutter open after that and allow the light from the laser beam to ac!@#$%^&*ulate.

 

Of course, if you want to see the beam, you must have something in the air to catch the beam, like smoke or dust.

 

If it is the intense light where the beam is hitting, I've not tried that. But, I figure the double exposure idea could be used there as well. However, in this case, the exposure for the laser is fast with a small aperture. Then the laser is turned off, and a second pictured done to catch the surrounding areas.

http://www.laserfaq.org/sam/laserioi.htm

 

That page is HUGE... The answer to your question must be somewhere in there... But according to that passage I quoted, camera sensors don't really like direct laser beams. I'll pull a theory out of my butt: The intense laser light heats up the sensor, making it shift toward red-ish light. Yeah it's a !@#$%^&*ty theory blum.gif

Blocks Newbie

»Blocks

Posted
Posted
even if you werent making it up, it wouldnt explain why the green laser appeared purple on the camera
My guess is that you're saturating the charge sensors in that area blarghargharghargh and they're going whack.
Photographing Laser Beams

A direct hit from a laser of less than 1 mW may damage the sensor since it can focus to a micron-size spot there.

http://www.laserfaq.org/sam/laserioi.htm

I'll pull a theory out of my butt: The intense laser light heats up the sensor, making it shift toward red-ish light. Yeah it's a !@#$%^&*ty theory blum.gif

Guest
This topic is now closed to further replies.
 Share
Go to topic listing
×
×
  • Create New...