lens

a transparent optical device used to converge or diverge transmitted light and to form images

genus of small erect or climbing herbs with pinnate leaves and small inconspicuous white flowers and small flattened pods: lentils

(metaphor) a channel through which something can be seen or understood; "the writer is the lens through which history can be seen"

biconvex transparent body situated behind the iris in the eye; its role (along with the cornea) is to focuses light on the retina

electronic equipment that uses a magnetic or electric field in order to focus a beam of electrons