…a heliostat is a device for tracking the sun, which can be used to maintain the light intensity of a solar lighting system.
i'm not sure if there is a special name for a device that orientates a mirror to reflect the sun onto a fixed point, but here are some links about them anyway:
(with an emphasis on ones that have been made non-professionally)
appears to use a mechanical arrangement to keep the mirror pointing at a point halfway between the sun and the fixed collector. clever idea. it think it would work better with two trackers mounted this way, one of each rotational axis of the mirror. although it seems that one of their axes rotates, rather than tilts, the mirror. this might be the reason why they can't do it with two detectors.
uses a cute solution of putting the sunlight detector in the path between the mirror and the collector. then the control is essentially the same as with a non-reflective heliostat. this leaves a small shadow in the light hitting the collector, but if you were using a mirrored collector like the http://sunlight-direct.com
one, then the centre of the collector isn't used anyway.