infrared digital camera - the real way

Step 7 Install congo blue filters

Now we want to install a filter that will block out all the light of the visible spectrum, only allowing infrared to reach the CCD. We do this by putting 6 layers of the Congo Blue filter gel behind the lens. Cut the filter gel into a bunch of little squares that will fit snugly inside the lens assembly. Pick out the 6 best ones, and install them inside lens before mounting it back in place in front of the CCD.

The material the filter gel is made out of is kind of fragile, and has a tendency to pick up scratches and dust. In my experience it's also really static sensitive, which is annoying. I wore a pair of latex gloves to avoid getting any fingerprints on it, and I handled the squares with tweezers. Even so, it took 15 minutes to wrestle them into place.

Another point here, with some cameras (especially nicer onces that have zoom), removing the IR-blocking filter can mess up the autofocus. Other sets of instructions I have seen recommend installing a piece of ordinary glass about the same thickness as the IR-blocking filter that you removed. I didn't do that, since my camera was fixed focus and not very good to begin with. But if you want to, the easiest way is to cut a microscope slide with a glass cutter to the right size, and install that behind the lens.

Comments

[rafikiand3601]

is there an advantage to using multiple filters?