焦距

Taking the laser diode line generator as the light source, the parallel laser screen unit was formed by using aplanatic cylindrical Fresnel lens with long focal length. By splicing seamlessly with multiple parallel laser-screen units, the large area laser screen can he constructed.

以半导体激光线发生器为光源，用长焦距消球差的柱面菲涅耳透镜形成平行激光幕单元，通过多个平行激光幕单元的无缝拼接可形成大面积靶面。

As substitute for fluorite lens, a double-layer DOE is used in a long focal-length apochromatic objective lens. The modulation transfer function of this hybrid optical system is suggested for evaluating diffraction efficiency of the multilayer DOE. The results show the diffraction efficiency has a wide and symmetrical distribution in the whole waveband.

利用双层衍射光学元件替代萤石透镜校正混合光学系统的二级光谱，设计并制作了一套长焦距物镜，并利用系统调制传递函数评价了多层衍射光学元件衍射效率，测试结果表明衍射效率在整个设计波段内以较高的数值平均分布。

Lunar optical astronomical telescope consists of five parts: long focus telescope, detector, bracket of telescope, control system and appendant equipment.

月基光学天文望远镜由长焦距望远镜、探测器、望远镜支架、控制系统和附属设备五部分组成。

Since however the reticle image at larger distance of the autocollimator develops, as converter optics

然而，随着自准直仪在更远距离产生十字线的像，需要使用长焦距的转换目镜。

They are common optical measurement and their distributions are obtained from the large sample data. Beta distribution is used as a unified distribution to simplify the research of optical measurement distribution.

通过对光学测量中常见的叉线对准以及焦距、曲率半径测量进行大样本数据采集和分析处理，利用实验方法得到常见光学测量数据的分布，并选择Beta分布统示表示多种分布，简化了光学测量中的分布研究。

The bifocus lens could produce images at the two independent focal length respectively and recovery the object's depth information according to the two bifocal images,which is the principle of depth estimating using bifocal lens.

成像物镜具有两个独立的焦距，通过对空间物体成像并进行分析可获取其深度信息，此即双焦测距的原理。

No one before had thought of bifocal glasses.

以前没人想过会有两个焦距的眼镜

Box camera:a simple camera shaped like a box and usually having a fixed focus and a single shutter speed.

盒式照相机：一种形似盒子的简易照相机，通常只有一个固定焦距和单一快门速度。

From the results of ultimate stress, breaking energy and relaxation, there were no significant differences between transverse and longitudinal direction.

同时在考虑角膜外形和焦距对视网膜的作用时，特别是经过放射状角膜切开术后，角膜的力学特性将是重要的研究课题。

You must bring the object into focus if you want a good photograph .

如果你想拍出好的照片，你必须给特调好焦距。

I didn't watch TV last night, because it .

昨晚我没有看电视，因为电视机坏了。

Since this year, in a lot of villages of Beijing, TV of elevator liquid crystal was removed.

今年以来，在北京的很多小区里，电梯液晶电视被撤了下来。