DOWN THIS tiled corridor, light does muscular, noisy work. Lasers dig dirt and weld metal. They pound aircraft parts into shape. In Bob Yamamoto's lab, light devours. He straps on emerald green goggles. A technician stabs a fire button and calls out the computer countdown. "Three ... two ... one ..." Then ... nothing. Just a buzz of electronics and an ephemeral glow in this darkened room at Lawrence Livermore Laboratory. But inside Yamamato's target chamber, a block of steel spits flame and molten metal. In those two seconds, 400 blasts of light poured into slabs of clear, manmade garnet....