James,
Another good product for light shades is Reflectix Insulation [1]
Basically Reflectix is bubble wrap with aluminum foil bonded to one or both sides. I have used it to make thermal drapes for my home, and know that it blocks all visible light. You can buy it at most Home Improvement centers. It commonly comes in 25′ rolls that are 16″, 24″, or 48″ in width.
Last winter I bought a 4’x25′ roll and had enough to do my entire house. (9 windows of various sizes) the cost was about $40.
Manufacturers claim that reflects up to 97% of all radiant heat, so not only will you save some energy, I would expect it to be somewhat effective against infrared and thermal imaging.
I know that the temperature in my old Mobile Home came up a good 10 degrees F in just the 45 minutes it took me to put up my blinds.
While I made my blinds so they can be rolled up during the day time, it would be very easy to find some way to anchor them on the sides and at the bottom so they would completely block all light at night.
Thank You JWR for a great site. – Fanderal