"OIL LENS: hufhuf oil held in static tension by an enclosing force field within a viewing tube as part of a magnifying or other light manipulation system. Becau

"OIL LENS: hufhuf oil held in static tension by an enclosing force field within a viewing tube as part of a magnifying or other light manipulation system. Because each lens element can be adjusted indivually one micron at a time, the oil lens is considered the ultimate in accuracy for manipulating visible light." -Dune, Frank Herbert, 1965