No IR Filter?

Okay, after a few tries, for some reason the beam shows-up on screen, but not in the picture itself. So I used a second camera to get this picture, so bear with me on the quality:

ok ... its collimated thats strange, are you shining it through any mediums, eg cola ?

Diachi said:

ok ... its collimated thats strange, are you shining it through any mediums, eg cola ?

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No,that's just shining it on a wall across the room. I have also taken pictures of the IR with the green filtered out be two layers of floppy discs(I heard that can be used to check for IR) if you would like me to post those, let me know.

hmm, can you give me pictures of the IR dot ?

Diachi said:

hmm, can you give me pictures of the IR dot ?

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Which dot? the dot with the green filtered out via floppy disc, or the dot from the original picture?

Well you would need a LOT of IR to produce a beam, so I am not completely convinced that this thing is outputting +50mW of IR.

It is possible it could be:
The camera is adjusting from low light to normal lighting (low light when laser is off, more light when laser is turned on) which means the sensetivity will be much higher when you first turn on the laser. This would explain how the IR beam fades away (as the camera adjusts to lighted conditions, the sensetivity will decrease and it will look normal once it is adjusted)

OR

Sometimes, my camera creates a purplish pinkish streak across the screen that appears vertical and centered on the source of the light until it auto adjusts to the lighting conditions. It resembles what you show in your picture.

I have tried to produce a beam of IR on my camera, and the only way I can do that is with some fog and a sheet of red plastic that blocks green light.

I removed the IR filter on my X105 and tested IR.
I would estimate that it outputs only 5-30mW of IR MAX. I tried to burn electrical tape with just the IR (green blocked) but it didnt do anything, even when focused.
These photos were taken with the aperture cover removed to allow more IR to pass.
For the photos, collimation was set at optimum for green (to focus the IR, the collimating lens has to be adjusted)
With the divergence set at <1mrad for green, divergence for IR was ~3.6mrad. With IR divergence set at ~1.8mrad (lowest I could get), the green diverged at ~2.5mrad.

4mm beam diameter at 6 inches


9mm diameter at 5 feet


As you can see, there is not much IR that spills, and even with the aperture cover removed, most of it is blocked by the collimating lens nut.

Personally, I think that the green beam is much more dangerous than the excess IR. A DPSS laser outputting more than 100mW of green will not output +30mW of IR. And the IR that does spill will be mostly blocked by the optics and the aperture. It will also diverge more and will be emitted in oblong blobs due to the nature of multimode diodes, so the threat of IR is very low.

RA_pierce said:

Well you would need a LOT of IR to produce a beam, so I am not completely convinced that this thing is outputting +50mW of IR.

It is possible it could be:
The camera is adjusting from low light to normal lighting (low light when laser is off, more light when laser is turned on) which means the sensetivity will be much higher when you first turn on the laser. This would explain how the IR beam fades away (as the camera adjusts to lighted conditions, the sensetivity will decrease and it will look normal once it is adjusted)

OR

Sometimes, my camera creates a purplish pinkish streak across the screen that appears vertical and centered on the source of the light until it auto adjusts to the lighting conditions. It resembles what you show in your picture.

Click to expand...

Hmm, that would make sense. It sounds a lot like what my camera is picking up, so I guess I don't really need to worry about IR with this laser. I do uderstand laser safety (don't stare at the dot too long,don't shine it in you eyes, ect.) and I'm always VERY careful when using my laser.   Anyway, thanks for the help, much apreciated.   and sorry to bug everyone with this.

Oh, and here's the picture I took with the green filtered:

There isnt much coming from that laser by the looks of things, I think its like RA_pierce says, its just your camera.