In optical astronomy, using a telescope and observing the stars that way, we rely on visible light waves.

在光学天文学中，在用望远镜观察恒星时，我们依靠的是可见光波。

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Stereo line-in and out ports, plus optical in and outs, should allow you to connect this PC with your stereo system and other stereo components.

FORBES: Magazine Article

They are the first planets discovered by the enormous Keck telescope in Hawaii, the sharpest optical telescope in the world.

CNN: Astronomers spy new neighbors outside solar system

Another impressive feature is the unit's reported ability to play back DVDs via the built-in optical drive (while in park, obviously), or you can hookup the forthcoming Wii or PlayStation 3 to the dual video inputs fpr keeping you and your co-riders entertained should you hit a traffic jam (or LA stoplight).

ENGADGET: Chrysler to offer hard drive-base MyGIG head unit