The only hope for avoiding a grueling six month wagon journey was to travel the narrowest portion of the continent— the 48-kilometer Isthmus of Panama.

避免六个月的艰苦旅行的唯一希望是穿越大陆最狭窄的部分——48 公里的巴拿马地峡。

The light travels to the laser cavity, a portion of the fiber optic cable that's doped with rare earth elements where broad spectrum light is transformed into that of a single wavelength.

光传播到激光腔，光纤电缆的一部分掺杂了稀土元素，在那里广谱光被转化为单一波长的光。