Fresnal Lense

Volhunter

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If I attach the fresnal lense directly to the case, should I put glass in front of it? Its pretty flimsy. I want to mount the lense flush, then hot glue the case of the RS sensor behind it...which leads me to another question. The thickness of the sensor case is a little more than 1/16", will this difference in focal length between the lense and the sensor pose any problem?
 



NC Bowhunter

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Welcome Volhunter,
Don't put glass in front of the fresnal lense because the PIR sensor doesn't work through glass.  You can try it to be sure, but from what I've heard it won't work.  I have my fresnel lense glued to the housing, and it might be a little flimsy, but that isn't really an issue.  The sensor should work fine 1/16" farther away, but again, I would just test it just to be sure.  Maybe someone else can give you more definate answers.  Good luck with your camera.
 

Archilochus

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HI Volhunter,
The Fresnel lenses are made of a special plastic that passes the IR energy.  Glass, plexiglas, and most regular plastics block the IR from reaching the sensor.  The lenses are very thin so that transmission losses are minmized.

Archilochus
 

Rob

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I'm just about to mount my lens.  What I did was leave the lens in the pir and mark the inside all the way around with a marker then i will remove the lens and sand the housing down till i just hit the top of the bend in the housing that way when i mount the lens flat I can glue the plastic housing right behind it.
It will maintain the same distance and allignment and I will still have the slot to hold the board.
 


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