Why Does The Laser Have Different Colors？

The color of light depends on its wave length and frequency. Certain wave length presents certain color. The wave length of the sun light is between 0.4 and 0.76 micrometers and it has in total 7 colors. Additionally， apart from having many colors， laser excels in terms of direction， monochromatity， intensity and coherence.

To help more people know about “International Year of the Light”， “Workshop of Science Dreams” gave a lecture with the theme of “Optics promotes global progress” on Jan. 24th， 2015. Zhongxiu Yu， Professor of the State Key Laboratory of Information Phonics and Optical Communications of Beijing University of Posts and Telecommunication， and Defu Chen， Assistant Research Fellow of the General Hospital of Peoples Liberation Army， were invited to share with us how light changes the world.