光栅在超短脉冲激光照射下的塔尔博特效应

首先导出了光栅在短脉冲激光照射下的菲涅耳衍射光场的方程 ,利用该方程分析了一个开口比为 1∶4的光栅的衍射光场。数值计算结果表明当激光脉冲的半极大值全宽 (FWHM)Δτ在皮秒数量级时 ,可以得到塔尔博特自成像。当激光脉冲的 Δτ从皮秒逐渐减小时 ,塔尔博特自成像现象逐渐消失。而当激光脉冲的Δτ小于几十个飞秒时在第一个塔尔博特距离处光栅的衍射光强的最大值随Δτ的减小而减小

Talbot Effect of a Grating under Ultrashort Pulsed-Laser Beam Illumination

An equation for calculating the Fresnel diffraction field of agrating under short-pulsed light illumination is derived. As an example, the equation is used to analyse the diffraction field of a rectangular grating with the opening ratio 1/4. The following results are found: Talbot self-imaging effect will appear when the full width at half-maximum of the incident short-pulsed light (FWHM) Δτ is within picoseconds and it will be gradually diminished at Δτ becomes small. When Δτ is within a few decade femtoseconds, the maximal intensity of the diffraction field at the first Talbot distance decreases along with the decrease of Δτ.