短焦距光

Referring to the function of cylindrical lens and the principles of holographic optical elements, we make this holographic element, which can achieve the optical function of cylindrical lens, and have the advantage of large-scale, short focal length and well-distributed light energy, in order to meet the requirements of laser direct writing synthetic holograms.

实验结合激光直写合成全息拍摄时所需柱面透镜的功能，参考全息光学元件的制作原理来制作图像柱面压缩全息光学元件，实现柱面透镜的光学功能，并使元件具有大面积、短焦距、会聚光均匀分布的特点，满足激光直写合成全息拍摄对图像的需求。

In general, for each field stop size, choosing eyepieces with shorter focal lengths and larger apparent fields of view will allow you to see more detail and fainter stars.

通常，针对每一个尺寸的视场光阑，选择短焦距和大表现视场的目镜将允许你看见更多的细节和暗淡的星光。

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。