Though invisible in normal light once it has hardened, this adhesive glows yellow when illuminated by a beam of ultraviolet of the sort often used in discotheques.

虽然粘着剂在普通光照下看不见，但一旦变硬便可以在紫外线光束的照射下变成黄色。

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That means the beam produced is of higher quality than other lasers, is extremely straight (even by the exacting standards of a normal laser beam) and can thus be focused onto a small area.

(甚至符合正常激光束的严格标准)这样就能将能量集中传送到一个小的区域范围内。

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The normal sonar system rotates its beam, either continuously or under the operator's control, and the position of maximum response to a particular echo is taken as the bearing of the target.

普通声纳系统旋转它的电波，可连续或根据运营商的控制，以及对特定回波的最大响应状态被记录为与目标间的联系。

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That means the beam produced is of higher quality than other lasers, is extremely straight (even by the exacting standards of a normal laser beam) and can thus be focused onto a small area.

ECONOMIST: Solar power from space

In this, the stream of video and audio data is recorded as a series of minuscule spots on the disc's surface that have been gently fried by a laser beam and turned from their normal crystalline condition to an amorphous state that has different reflective properties.

ECONOMIST: Digital video discs

From a standing start, the reconstructed beam sped back up to the normal speed of light.

BBC: NEWS | Science/Nature | Cool clouds turn light to matter