focal point

nouns

a point of convergence of light (or other radiation) or a point from which it diverges
focal point, focus
a central point or locus of an infection in an organism
"the focus of infection"
focal point, focus, nidus
the concentration of attention or energy on something
"the focus of activity shifted to molecular biology"; "he had no direction in his life"
centering, direction, focal point, focus, focusing, focussing