I've been thinking about ways to cloak ships in space, since they all are warmer than their background they can be seen in the IR spectrum (given a large enough telescope).
So I was thinking, could you direct the waste heat in one direction, using a laser? For example, drive a heat pump where the hot side is a ruby crystal, which gets hot enough to glow, but not hot enough to melt (say 1700 C). Would this be equivalent to "flashing" the crystal how a normal laser works? Thus allowing you to direct the waste heat while keeping the hull of your ship at the same temperature as space.
Basically, do the crystal still behave in the same way at higher temperatures, and can you use the black body radiation from the crystal itself to drive the laser?