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of an optical semiconductor chip called a digital micromirror device. This device contains Digital movie projectors use three micromirror devices, one for each of the primary colors red, blue, and green, so that movies can be displayed with up to 35 Several movies have been projected digitally to audiences and polls show that 85 percent of the viewers describe the image quality as “excellent.” The first all-digital S E C T I O N 3 5 . 4 • Reflection 1101 Figure 35.8 Applications of retroreflection. (a) This panel on the Moon reflects a laser beam directly back to its source on the Earth. (b) An automobile taillight has small retroreflectors that ensure that headlight beams are reflected back toward the car that sent them. (c) A light ray hitting a transparent sphere at the proper position is retroreflected. (d) This stop sign appears to glow in headlight beams because its surface is covered with a layer of many tiny retroreflecting spheres. What would you see if the sign had a mirror-like surface? Retroreflector (a) (b) (c) (d) Courtesy of NASA George Semple George Semple Figure 35.9 (a) An array of mirrors on the surface of a digital micromirror device. Each mirror has an area of about 16 2 m 2 . To provide a sense of scale, the leg of an ant appears in the photograph. (b) A close-up view of two single micromirrors. The mirror on the left is “on” and the one on the right is “off.” Courtesy T exas Instruments (b) (a) (a) |