Simple and bright, heliostats tap sunlight for lighting outdoor and, increasingly, indoor spaces.

The article looks at the use of heliostats in the sustainable design movement. They are mirror arrays that track the sun, following preprogrammed sequencing directions from software or responding to exterior-mounted sensors. Designers James Carpenter and Davidson Norris, of New York's Carpenter Norris Consulting have installed heliostats on a residential tower in Battery Park City. Parans Solar Lighting has developed a range of products that take advantage of heliostats to deliver sunlight via fiber-optic cables to light fixtures in interior spaces.