Anaya-Vera S, García-Martínez L, Rosete-Aguilar M, Bruce N C, Garduño-Mejia J
J Opt Soc Am A Opt Image Sci Vis. 2013 Aug 1;30(8):1620-6. doi: 10.1364/JOSAA.30.001620.
We study femtosecond pulses at the focal plane of a perfectly conducting spherical mirror which is a dispersionless system, that is, it introduces no group velocity dispersion and no propagation time difference to the pulses after reflection. By using the scalar diffraction theory we will show that the neglected terms in the diffraction integral, when using the approximation of the bandwidth being smaller than the frequency of the carrier, have a significant influence on imaging if a laser pulse of a few femtoseconds is used in time-resolved imaging. The neglected terms introduce temporal spreading to extremely short pulses of a few optical cycles incident on the mirror, which avoids a fully compensated pulse, i.e., a one optical cycle pulse, at the focus of the mirror. The study in this paper also applies to refracting optical systems such as microscope objectives or lenses.
我们研究了在完全导电球面镜焦平面处的飞秒脉冲，该球面镜是一个无色散系统，也就是说，它在反射后不会给脉冲引入群速度色散和传播时间差。通过使用标量衍射理论，我们将表明，在使用带宽小于载波频率的近似时，衍射积分中被忽略的项，在时间分辨成像中使用几飞秒的激光脉冲时，会对成像产生显著影响。被忽略的项会给入射到镜面上的几个光学周期的极短脉冲引入时间展宽，这避免了在镜面焦点处出现完全补偿脉冲，即一个光学周期脉冲。本文的研究也适用于折射光学系统，如显微镜物镜或透镜。
