太阳 ,是人类观测到的比较大的自然光源 .人们常常利用太阳光进行各种光学研究和实验 ,这是由于太阳光不仅取之方便 ,亮度很高 ,而且它还接近于平行光 .但是 ,很多教辅用书却把太阳光称为“理想的平行光” ,原因是“太阳离地球十分遥远 .”有的甚至还在“理想”二字前面冠以“ The sun is a relatively large natural light source observed by humans. People often use sunlight to perform various kinds of optical research and experiments. This is due to the fact that sunlight is not only convenient and has high brightness, but it is also close to parallel light. However, Many teaching aids use the sun as the “ideal parallel light.” The reason is that “the sun is very far away from the earth.” Some even use the word “ideal” before the word "