A Solar Concentrator is a device that focuses and concentrates sunlight in such a manner that its thermal energy may be extracted for useful purposes. Usually a parabolic reflector is employed to focus and concentrate sunlight. The Pond Science Institute has endeavored to create such a device pictured below.
Solar Concentrator - Prototype
(courtesy Pond Science Institute)
(click to enlarge)

Solar Concentrator - Frame
(courtesy Pond Science Institute)
(click to enlarge)
See Also
Solar Energy
HEAT FROM VIBRATION
heat multiplication
Law of Heat
Radiant heat
WHAT IS HEAT
12.29 - Origin and Nature of Heat
12.31 - Heat Generated Through Resistance to Compression
7B.19 - Light and Heat