Fitting an IR filter?

[bbshamsa]

Hey guys.

I just got a cheapo 10mW pointer for sky pointing, and also had a broken webcam lying around.

I know the pointer doesn't come with an IR filter, so thought I'd remove the one in the webcam and fit that.

I also know that at 10mW some might say that an IR filter isn't really necessary, but I think that if I have it and it doesn't affect the brightness of the beam that much, then I may as well fit it.

My question is, does it matter which way around you fit it?

I mean, it's coated on one side and common sense would tell me to fit it so that the coated side faces in, towards the laser diode and the non-coated side towards the outside of the laser (to protect the coating from scratches); but would it still work?

I ask because when it was fitted, the coated side face in towards the camera's CCD and that was to stop IR light coming in; so, if I turn it around to protect the coating from getting scratched during use, will that make a difference?

Thanks in advance for any help.

 

[SenKat_Stonetek]

If you have a power meter, you could measure the difference between mounting it one way or the other...since it sounds like you don't - I would mount it so that the filter is protected from scratches, etc - the only reason I can see for mounting it one way versus the other is possibly an AR coating on the filter ? At 10mw, it won't make TOO much difference if the AR coating is not facing in - not enough power to really cook the MCA from reflections, IMO.

SteveTexas posted a thread about how to install an IR filter using a TOOTHPASTE cap ! you should check it out - if it would fit on your laser, it could be an excellent aperture cover as well (and minty-fresh laserbeams, too !)