文章：Dirk Lorenser, Xiaojie Yang, and David D. Sampson, "Ultrathin fiber probes with extended depth of focus for optical coherence tomography," Opt. Lett. 37, 1616-1618 (2012) 链接：https://doi.org/10.1364/OL.37.001616 实现extend depth of focus的原理：the light travels through two sections of GRIN fibers with different apertures to create two different focal positions, which results in a extended depth of focus. […]