noncaustic
/ˌnɒnˈkɔːstɪk/Definitions
1. adjective
Lacking the property of a caustic, especially in optics.
“The noncaustic lens was used in the telescope to focus the light accurately.”
2. noun
A noncaustic point or curve is a point or curve where the light rays converge without being focused to a point.
“The study of noncaustic points is crucial in the design of optical systems.”