IR filter

firefly

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Hi
I don't remember where in this site a guy talk about IR filter, because i search a url to find this, could you please help me?
 

yellow

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do, I remember also seeing a link, but was also not able to find it. Hopefully one still knows.

As this title my find some guys who can answer:
Is there an easy way to check any laser if there is an IR-protection built in, say something like: "if You see that black colored window, then its an IR-filter?"

unfortunately black glass is a daylight stopper, so IR will look different. (?)
 

stevetexas

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Yes, Optics online is a decent company - I've bought filters and lenses from them. I use the IRC 21 and IRC 30 filters.

Steve
 

The_LED_Museum

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yellow said:
do, I remember also seeing a link, but was also not able to find it. Hopefully one still knows.

As this title my find some guys who can answer:
Is there an easy way to check any laser if there is an IR-protection built in, say something like: "if You see that black colored window, then its an IR-filter?"

unfortunately black glass is a daylight stopper, so IR will look different. (?)
The IR filter in a visible wavelength DPSS laser (yellow, green, or blue) is a small, thin square piece of blue-green glass.
Here, let's see if I can get a photograph of one...BBS...

filter.jpg


This is the one from my blue DPSS laser pointer.

This filter is *USUALLY* in the optical train, well inside the laser housing itself, and therefore, inaccessible. In such a case, its presence or absence can only be reliably determined through spectroscopy; only rarely is it found on a removeable part of the laser like the example I just photographed for you.
 

firefly

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stevetexas said:
Yes, Optics online is a decent company - I've bought filters and lenses from them. I use the IRC 21 and IRC 30 filters.

Steve

What's the difference between absorptive and reflective?
 

The_LED_Museum

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firefly said:
What's the difference between absorptive and reflective?
Actually, it's fairly self-explanatory. :)

An absorptive filter absorbs radiation at the wavelengths it's designed to filter while transmitting the rest.
A reflective filter reflects the wavelengths it's designed to filter while transmitting the rest.

In either case, the wavelengths it is designed to filter do not make it past the filter, while the rest of wavelengths do.
 

luvlasers

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Normally it's not too hard to see if a laser has an IR filter. Much tricker to determine the quality/rating of the IR filter.

A very high quality filter for example would be one that blocks 99% of IR. As for poor quality, the IR blocked can vary from say 95% to downwards.

An important point to keep in mind with laser safety is that even lasers with IR filters will still give out IR. Possibly depending on the quality of the laser, enough to be dangerous.
 

Ashton

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I was told on another site by a reputable party that IR filters could also be almsot transparent amber-colored glass..? is this correct? (I've got one I'm wanting to use in a DX 100mw greenie, or possibly that otehr 200mw greenie if it turns out to really be ~200mw for ~$200)
 

pseudonomen137

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Ashton said:
I was told on another site by a reputable party that IR filters could also be almsot transparent amber-colored glass..? is this correct? (I've got one I'm wanting to use in a DX 100mw greenie, or possibly that otehr 200mw greenie if it turns out to really be ~200mw for ~$200)

Yes, I don't know the details on this but on some cheap webcams I've seen the IR filter is coated on a lens or a piece of glass/plastic and gives red-ish reflection.
 

Ashton

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I dont know, this info was comming from RR on the WL forums... this one I have was ripped out of my dead DVD-burner
 
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