Operating microscope eyepiece heaters.
Precipitation of water vapour from expired air on to exposed eyepiece lenses of operating microscopes can seriously interfere with the surgeon's view. By  warming these optical surfaces to temperatures well above the dew point of expired air this problem is eliminated. A pair of small heaters were designed to clamp over the eyepiece tubes of a standard operating microscope and their effectivity assessed.
D006361:Heating / Q000295:instrumentation; D006801:Humans; D007909:Lenses; D008853:Microscopy / Q000295:instrumentation*; D008866:Microsurgery / Q000295:instrumentation*