Patent ID: 8231222

Claim:
A heliostat, comprising: a mirror ( 11 ); a frame structure ( 12 ) for supporting said mirror ( 11 ), wherein said frame structure ( 12 ) is adapted to be pivotable about at least one axis of rotation; a liquid ballast system ( 20 ) mounted on a side of said frame structure ( 12 ) that is remote from a reflective surface of said mirror ( 11 ), wherein said liquid ballast system ( 20 ) is comprised of at least two tanks ( 22 ; 23 ), wherein said frame structure ( 12 ) includes a first support ring ( 15 ) that is pivotable about a first axis of rotation, and a second support ring ( 16 ) for supporting said mirror ( 11 ), further wherein said second support ring ( 16 ) is pivotably supported on said first support ring ( 15 ) so as to be pivotable about a second axis of rotation that is perpendicular to said first axis of rotation, further wherein said liquid ballast system ( 20 ) is mounted on a side of said second support ring ( 16 ) that is remote from the reflective surface of said mirror ( 11 ), further wherein said liquid ballast system ( 20 ) is comprised of four tanks ( 22 , 23 ), further wherein an imaginary line between one pair of opposing tanks ( 22 ) is perpendicular to said first axis of rotation, and wherein a further imaginary line between the other pair of opposing tanks ( 23 ) is perpendicular to said second axis of rotation; and an electronically controllable pump system for moving ballast liquid between said at least two tanks ( 22 ; 23 ) in an actively controlled manner.