Four kinds of laser source are used to measure the diffractive efficiency of Fresnel lens.

使用四种不同光源，对菲涅耳透镜的衍射效率进行测试。

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There are four types of subtle traps in Gaoyou sag, Which is fault-lithologic trap, sandstone up pinchout trap, lens trap and stratigraphic onlap trap.

高邮凹陷的隐蔽圈闭主要有四种类型，即断层岩性圈闭、透镜体圈闭、砂岩上倾尖灭圈闭和地层超覆圈闭。

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There are four kinds of lens shapes, which do you like best?

我们有四种镜片形状，您最喜欢哪种？

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Olympus also introduces an intriguing new lens for its Micro Four Thirds line.

ENGADGET: Olympus E-PL5 and E-PM2: Micro Four Thirds cameras with OM-D-like focusing, performance boosts (hands-on)

The design is very similar to Blackmagic's larger Cinema Camera launched at last year's NAB, with the same Micro Four Thirds lens mount.

ENGADGET

What the combination of this giant lens and Dr Gwinn's computers provides is not so much magnification (the gaseous lens magnifies the pulsar only four times) as resolution the ability to discriminate between objects that are close together.

ECONOMIST: Pulsars: In a wink | The