epifocal
/ɛpɪfəʊkəl/Definitions
1. adjective
relating to or situated at a point equidistant from two foci, especially in optics.
“The epifocal point of the lens is crucial for achieving the desired focus.”
2. noun
A point or line equidistant from two foci, especially in optics.
“The epifocal point of the lens was determined to be 5 cm from the mirror.”