基于矢量衍射理论,计算了多个可见光波段激光经紧聚焦后在焦点附近的双光子点扩散函数。 计算结果表明,双光子吸收效应的作用区域随着波长的减小而减小。采用多个可见光波段飞秒激光 光源进行了双光子光聚合加工,并对加工分辨率和加工阈值进行了分析。实验结果表明,在每个激光 波长条件下,降低光子流密度能够提高加工分辨率；随着加工波长的减小,双光子跃迁过程逐渐满足 近共振跃迁条件,双光子吸收几率逐渐增大,双光子加工的阈值逐渐降低。

Two-photon point spread functions of several tightly focused visible lasers were calculated based on the vectorial diffraction theory. The calculated result shows that the two-photon absorption region reduces with the decrease of laser wavelength. Femtosecond laser sources with visible wavelengths were employed to perform the two-photon polymerization fabrication, and the fabrication resolution and threshold were analyzed. The experimental results indicate that lower photon flux density leads to the improvement of fabrication resolution. The decrease of laser wavelength causes the two-photon transition to meet near resonance transition condition gradually, which further increases the two-photon transition probability and reduces the fabrication threshold.