No IR filter in your pointer? Here's a solution

[iemand]

All you need to do is find is a crappy digital camera and remove the IR filter that is covering the CCD or CMOS. You can cut a lot of laser filters from one typical camera filter.

 

[SenKat]

All you need to do is find is a crappy digital camera and remove the IR filter that is covering the CCD or CMOS. You can cut a lot of laser filters from one typical camera filter.

EXCELLENT idea ! Thanks for the hint !

 

[FNinjaP90]

Make sure the IR filter is very very clean. Any scratch, fingerprint, or speck of dust will cause the laser beam to diffuse resulting in a "dirty" beam.

 

[The_LED_Museum]

I'm going to add this thread to the "Master Stickies" list at the top of this forum.

 

[stevetexas]

I haven't seen this type of filter. Is it thin plastic "sheeting". How easy is it to cut? Any pictures?
Thanks, Steve

 

[ted_park]

All you need to do is find is a crappy digital camera and remove the IR filter that is covering the CCD or CMOS. You can cut a lot of laser filters from one typical camera filter.

I think you can also get ém out of webcams.

I've modified webcams, replacing the IR blocking filter with an IR passing one (easy IR webcam!) but I don't know how good the IR filter was.

--Ted.

 

[FNinjaP90]

If it's a dark plastic filter, the energy from the laser could possibly damage and melt the filter.

 

[iemand]

Steve,

It is not a plastic sheeting. It is a thin glass rectangle the same size as the CCD/CMOS. Its color is light bluegreen, or cyan.

Like Ted_Park writes, you can also get 'm from dead webcams. I guess those are about the appropiate size for in a GLP.

And off course, do not touch it with anything but a pincette.

 

[SenKat]

I had no luck removing the ir filter from a webcam yesterday (waaaaaaa !) I still have it - but it is STUCK but good on there ! Any ideas ? i do not have a heat gun...

 

[iemand]

How about a hobby knife? Some small jewellers screwdrivers might help, too.

 

[chimo]

I have an IR filter from an old camcorder. It's about 12x13mm (I chipped a corner).

I was just about to ask if it would be sufficient to filter a 30mW green pointer but I checked the "stickies" first.

I gave it a quick test (to ensure it was the IR filter) with a remote and a webcam. It completely blocks the IR from the remote (probably not a huge feat).

I also checked with a red pointer. It attenuates the output somewhat and reduces the "splash" when viewed up close by a CCD/CMOS sensor.

 

[Confederate]

How About a Hole Punch

How large do these cut-outs have to be? Can they be cut with a large hole puncher?

 

[dr_lava]

Re: How About a Hole Punch

this thread has applicable information :

http://www.candlepowerforums.com/vb/showthread.php?t=131448

 

[robo21]

What is the reason(s) that IR is undesireable in a pointer? Wouldn't IR make the beam generate higher temps in the target, e.g. a ballon?

Also, would filtering out the IR diminish the power of the beam in the more desireable wavelengths?

Thanks in advance.

 

[chuck]

One reason it's undesirable is that it's invisible. Let's take a green pointer as an example.

A 5mw pointer may have a 100mw IR diode in it, and 5mw of green comes out the end. Now...what if 20mw of IR also came out the same place, by leaking around the side of the crystal? Being invisible, that *could* pose a risk to your eyes.

Additionally, the total output power of that LASER would be 5mw + 20mw. Now, turn that logic around... A 50mw greenie, without an IR filter, may produce only 5mw of green and 45mw of IR. Its total output is 50mw...not false advertising. But, not 50mw of green...

As to the higher temperatures...not really. It's more a matter of what frequencies are absorbed by the material. It's why it's hard to pop a red balloon with a red pointer...it just bounces off. 50mw is 50mw...

-- Chuck Knight

 

[robo21]

Thank you for the great explanation. That makes a lot of sense. I'd like to get a green laser that would be safe yet have the ability use as an astronomical pointer and pop an occasional balloon, perhaps.

I've looked at some of the lower priced units at DX but they seem to be cheap and possibly the type that would have misleading ratings. On the other hand, the prices are seductive. Yet they apparently have no IR filter. I hope someone can make a few recommendations.

 

[nero_design]

I can certainly recommend Canon chips for this job since Canon actively reject the use of their cameras for IR photography and have stated this in writing. This is because of the use of IR filtration on many of their cameras which prevents unnecessary light from 'interfering' with the sensor. Some models do allow for limited IR photography but most (up until recently at least) did not.

Guess you need to find a broken one though since not many of us want to go and cut up a functional camera.

 

[TKA]

And how do you actually go about installing the filter? How do you remove the diode?

 

[The_LED_Museum]

You need not actually disembowel your laser to the point of exposing the diode; just place the IR filter anywhere in the optical train past where green laser radiation is produced; you can even carefully glue it into the inside of the laser's end cap (covering the hole) so you don't have to mess with the optics at all.

 

[steve2004]

I haven't seen this type of filter. Is it thin plastic "sheeting". How easy is it to cut? Any pictures?
Thanks, Steve

Also when taking appart a DVD or CD-RW there is a little piece of glass
that is cyan color, could this be an IR filter?