Assertion: beam's surface | /r/HasAspect | parabolic shape
Facets:
Source sentences:
text: The modes of an optical resonator with the lowest order in the transverse direction (called TEM 00 or fundamental transverse modes) are Gaussian modes, if the resonator is stable, all optical media in the resonator are homogeneous, and all surfaces between media are either flat or have a parabolic shape.