借助于等效光子近似，讨论了双光子过程的一般特征，给出了虚光子谱、光子亮度的表达式和不同末态的截面公式。
The general features of the process are discussed , and the expressions for photon spectrum , photon luminosity , and cross sections for various final states are given based on the Equivalent Photon Approximation .
光子亮度