[Laser] Filter Material.

[KD7JYK DM09]

This is the closest group I can think of for this request.

I have a passive IR motion sensor.  The filter is a sheet of black looking 
plastic about as thick as a sheet of paper.  It does not have a lens molded 
or etched into it.  The material is VERY soft and scars easily when cleaned. 
The ability for the sensor to detect has dropped off considerably, probably 
due to scratching of the filter.

I am looking for a source of IR filter material for replacement.  I expected 
this to be easy, I found one piece, in the UK, about $20USD, about 2 square 
inches.  I don't need much, but the price seems high and the material close 
to non-existent outside that one piece.

I'd prefer glass, up to 1mm thick, but thicker plastic would work just as 
well.

Any ideas on sources?  Certainly this is common material?

Thanks.

Kurt