IR Filter at surplussheld.com

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#3
karrock said:
That's a hot mirror (reflects infrared, transmits visible), and in a projector, I'd expect that you'd want a cold mirror (reflects visible light, transmits infrared)? [/QUOTE

You can use both, cold mirror is a relective filter at 45deg while the heat filter glass is pass through and reflects the ir rays back to its source, they also run at 0deg.

Trev🙂
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#4
hot mirrors

I have read that you can just put 4 rectangular pieces of hot mirror in a diy metal frame to hold them together. Then stick it between your condenser lens and lamp. The author claimed he couldn't see any artifacts of the edges in the final image. (Of course, don't frame each piece like a stained-glass window!)

It will have a reddish tinge at some angles. When that wears out, you need to replace it.

I think it would be a lot more fun to work out a water-filled IR absorber: Never wears out, and it can be self-cooled if you can use a thermal-siphon to a radiator.
 
#5
Re: hot mirrors

Good idea... the closer to the lamp, the higher the temperature. Will the IR filter get melt if I put it colse to the lamp? Can the IR filter be placed close to a 400W MH, 250 MH or 125 MH?


Guy Grotke said:
I have read that you can just put 4 rectangular pieces of hot mirror in a diy metal frame to hold them together. Then stick it between your condenser lens and lamp. The author claimed he couldn't see any artifacts of the edges in the final image. (Of course, don't frame each piece like a stained-glass window!)

It will have a reddish tinge at some angles. When that wears out, you need to replace it.

I think it would be a lot more fun to work out a water-filled IR absorber: Never wears out, and it can be self-cooled if you can use a thermal-siphon to a radiator.
Click to expand...
 
#6
I have read that you can just put 4 rectangular pieces of hot mirror in a diy metal frame to hold them together. Then stick it between your condenser lens and lamp. The author claimed he couldn't see any artifacts of the edges in the final image. (Of course, don't frame each piece like a stained-glass window!)
Click to expand...

Without a doubt that causes scatterd light issues giving you a more blury image. Also i might add a higher risk of the ir filters breaking due to uneven presure when they exspand. The only way to use a ir filter is to have the right sized peice first off, that goes for any optics.

Trev🙂
 
#7
Good idea... the closer to the lamp, the higher the temperature. Will the IR filter get melt if I put it colse to the lamp? Can the IR filter be placed close to a 400W MH, 250 MH or 125 MH?
Click to expand...

It comes in different grades, the stuff from surplus shed is rated at 150w, if you run a higher wattage and depending on the distance from the lamp, the filter will explode into smitherines. You need to find the right filter for the lamp wattage, it boils down to the rating of glass used.

Trev🙂
 
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