美国的一个物理学家团队通过将一束紫外激光聚焦于一小块氧分子中，发明了一种聚焦于半空中一点的红外激光束。
A team of physicists in the us has created an infrared laser beam at a point in mid air, by focusing a UV laser onto a tiny volume of oxygen molecules.
房子的设计聚焦于两个主要的点，第一点是水池作为主要焦点。
The design of the house was centered around 2 main points, the first being the pool as the main focal point.
本文给出两种能使平行光严格聚焦于一点的凸透镜。
Two kinds of convex lens which make parallel light rays converge to the focal point are given.
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