An equation is obtained to describe two-photon absorption of light beams of variable cross section. It is shown that the experimental values of the two-photon absorption coefficients of focused laser beams, calculated in the plane-wave approximation in the focal waist region and taking into account the variable cross section of the light beam, differ by two orders of magnitude.

中文翻译：

---

可变截面光束的双光子吸收

得到一个方程来描述可变截面光束的双光子吸收。结果表明，在焦腰区平面波近似中计算的聚焦激光束的双光子吸收系数的实验值，考虑了光束的可变截面，相差两个数量级。 .