Common Clear to IR material?

Polyethylene, most likely.

Joe Gwinn

Reference the IR data sheet I posted a link to the other day.

need.

I always used exposed Kodachrome.

I set up mine again. Seems most sensitive dead on. I had to cut down on thevolume after trying duct tape, which does not work very well. Used something like 25k in series with speaker. I'd like another if I could get same channel.

Greg

I need.

The last couple of days with high winds cause cause my unit to trip. First problem, sensor was not mounted tight. It will still trip occasionally. First time I have really played with the thing after owning it for several years.

Greg

I need.

Yes, they are very loud and tape does not work to cut the volume, btdt. I'm using the receiver to trigger a call switch on a walkie talkie. This is so I can be 300 feet away and get an alert. What channel do you have? Mikek

Try a cheap IR thermometer gun and an incandescent light source (mostly heat) to test if it will pass long wave IR.

If you modified the PIR receiver (that's the one with the translucent Fresnel lens) it's likely that your sensor won't work well. The device relies on the Fresnel lens to produce dramatic changes in IR level to the detector as the object passes by. See link below with explanation of how it works. Maybe a different style Fresnel lens?

If you want something that will pass IR and block visible light, it will need to be a germanium or silicon lens. Otherwise, HDPE (high density polyethylene).

Polystyrene will pass the entire IR band. The problem is that it will pass the entire IR band and not just far IR. If you just want a protector, and don't care about passing visible light, try the clear window on a mailing envelope.

The Fresnel lens on your driveway sensor is HDPE. See the list of applications below. Look for something that's sorta translucent and made from a hard plastic. Hard and clear plastic bottle caps for glass bottles would be a good start.

Linear Low Density Polyethylene. If the lids are soft plastic, it probably won't work. I just tried a HDPE cutting board. It passed some IR, but because it was so thick, it was lossy. Look for something made from a similar material.

I just tried a common black plastic trash bag. Not the best but it works.

-- Jeff Liebermann snipped-for-privacy@cruzio.com

I have kept the original Fresnel lens in place, but only because earlier testing showed me I had to! I then found out why.

Maybe the plastic lid I have is HDPE.

I could not make it work with polystyrene, I tried several PS objects and none worked. I was ready to use a CD case.

If the lid I have doesn't pass tomorrow's testing, I'll be searching for HDPE to test. The black bag won't last long outdoors, but as a last resort, it would be easy to replace and stretch a couple rubber bands around every three months. Thanks, Mikek

Garbage bags are almost invisible in the thermal IR.

They'll break down eventually in sunlight. See video at: starting at 2:45. Far IR goes through two layers of black polyetheylene trash bag on a thermal imaging camera.

The rather thin trash bag works well. However, when I tried 4 mil and

I also tried the trash bag directly off the roll, which worked out to

plexiglass is reasonably clear in the near infrared (which is what's used for remote controls)

perhaps you can get a sample of IR reansparent roofing sheeting like Ampelite coolite

On a sunny day (Sun, 20 Jan 2013 19:40:54 -0600) it happened amdx wrote in :

There was a movie on youtube of a guy with a garbage bag over his head, you could stiill see him in IR.

I need.

They look identical to the ones sold in Australia as "Swann" brand.

The channel is set via solder links internally - easy to change to match channels.

Same housing;

Just wondering out loud..... Would a Rosco photography filter work here? One of these might have the curve you're looking for. (??)

Link:

Only $2.50 for the whole book (a couple hundred plastic gel filters, various colors)

-mpm

On motion sensor prototypes at work a layer of 2" wide, inexpensive, thin, clear plastic packing tape was used. . This was to cover a one inch hole on a metal project box. The stuff that is 1.50 a roll at Walmart works fine. They did not even bother to remove the adhesive. Works well on sensing people. The battery powered sensors have been outside for four months now, in a Ohio winter, with no failures.

A overhead transparency of the non inkjet kind would be fine as well. They are a little thick, so you may see some attenuation.

The Roscoe filters are usually gelatin based on a clear substrate. . The water in the gelatin would adsorb at 10 microns, blocking the signal.

Steve

You don't need a far IR bandpass filter. There's already a far IR silicon bandpass filter window on the PIR sensor. No need for a silicon, germanium, or garbage bag filter. Anything that will pass IR, including clear uncoated glass, polystyrene, HDPE, etc should work.

Assumption, the mother of all screwsup.