When light inputs the surface of optical elements, there is reflection as well as refraction, so ghost light come into being, its focus is called ghost image.
光学元件表面在折射时都存在反射，从而存在设计意图之外的杂散光，其会聚点即所谓鬼点。
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Note: the "ghost" refers to the working voltage Angle of 60 degrees (to display the surface as the base) should not be displayed on the LCD display Dan vaguely.