In contrast , the following methods are unsafe in one way or the other : directly looking at the sun with naked eyes ; looking at the sun through a pair of sun glasses , exposed films , smoke - darkened glass or small sun filter placed closed to the eyepiece ; looking at the reflection of the sun from a pool of water or dark ink 以肉眼直接观看太阳透过太阳眼镜完全曝光底片俗称盲片熏黑的玻璃或摆放在目镜上的小型太阳滤镜观看太阳观看太阳在水中或墨水中的倒影。
How to improve the three primary colors led light source cavity , polarizing beam splitter system of civil lcos hmd is discussed in this paper . in addition , a new eyepiece optical system with wide fov ( field of view ) 、 big exit pupil 、 long eye relief is also designed by an optical design program named zemax . the result is very successful 本文对民用lcos头盔微显示器的led三基色光源及其腔体、偏振分光系统进行了改进,借助zemax光学设计软件辅助设计出了大视场、大出瞳直径、长出瞳距离的目镜放大光学系统,获得了十分理想的效果。
This microscope is provided with achromatic objectives , wide field eyepieces , abbe condenser , adjustable built ? in light source , and coaxial coarse and fine adjustment with focus stop . . this microscope with his wide field eyepiece gives a nice and sharp image and is designed in a very modem way , it is designed for clinical experiments and classroom demonstration in medical and hygienic establishments , chemical laboratory , agricultural scientific research nets , research institutes and colleges as well as for the routine examination and research purpose in bioloy , bacteriology , cytology and pharmaceutical chemistry 本显微镜采用消色差物镜、广角目镜、阿贝聚光镜，连续可调的人工光源及带有限位置的同轴粗微动机构，视场广阔、成象清晰、设计先进，可供医疗卫生机构、化学试验室、农业科研系统、研究所及高等院校临床试验和教学示范，以及在生物学、细菌学、细胞学和药物化学等领域作常规检查和研究。
Perhaps for such reasons , the term " prime focus " is increasingly being used in a more general manner : in systems in which there is only one place where there is a focuser - - where an image is formed and you can get at it with an eyepiece or some other equipment - - that location is called the " prime focus " 可能出于这些原因， “主焦点”一词正逐渐被人们以一种更宽泛的方式使用：在只有一个聚焦装置的光学系统中，那个成像的、可以用目镜或其他装置摄取像的位置，就叫做“主焦点” 。
The system is of some sense of stereovision and can emancipate the operators from the shackles of microscope eyepieces . flicker is a fatal drawback of the system . based on the analysis of the whys of the flicker phenomenon a kind of flicker - free three - dimensional imaging system based on frequency duplication is then designed 从模拟时分立体成像系统到基于倍频的无闪烁立体成像系统，再到带视频信号处理功能的无闪烁立体成像系统，围绕着实现立体、消除闪烁、增强图像显示效果等三方面对时分式立体显示系统进行了深入的研究。
