Rochester Cloak is an optical device that makes solid objects disappear, similar to the magic power of Harry Potter's 'invisibility cloak' that makes things disappear in front your eyes. Designed by a professor-student team of physics at the University of Rochester, the device uses four standard lenses to render an object invisible by moving the user's point of view a few degrees away from the optimal viewing position. Unlike most other cloaking experiments have relied on high-tech or exotic materials, the Rochester Cloak uses only inexpensive, everyday materials in its unique structure to achieve invisibility.

In order to cloak an object without disturbing the background, the Rochester Cloak uses a combination of lens types, power, and the precise distance between the lenses to hide the object. To construct such a device, the following materials/tasks are needed:

1. 2 sets of 2 lenses with different focal lengths f1 and f2 (4 lenses total, 2 with f1 focal length, and 2 with f2 focal length)
2. Separate the first 2 lenses by the sum of their focal lengths (So f1 lens is the first lens, f2 is the 2nd lens, and they are separated by t1= f1+ f2).
3. Do the same in Step 2 for the other two lenses.
4. Separate the two sets by t2=2 f2 (f1+ f2) / (f1-- f2) apart, so that the two f2 lenses are t2 apart.