Heliostats are self-adjusting mirrors for the precise transmission of sunlight. The collected sunlight can be used either for the production of energy or for the illumination of windowless areas, for the lighting of shaded objects or as a source of natural light.
Already in the Ancient World people had the idea to use the sun for lighting purposes. It is known that the Old Egyptians illuminated their monumental buildings with the help of bronze mirrors which were manually adjusted to the position of the sun.
In our days collecting and guidance of the sunlight is done by so-called Heliostats (Greek «sun» + «bring to a halt»), this astronomical term describes an instrument with plane mirrors which is moved by a clockwork mechanism. It continually projects the starry sky into a fix-mounted telescope.