Assertion: index lens | /r/HasAspect | flat optical surfaces
Facets:
Source sentences:
text: A gradient index lens has flat optical surfaces, but has a radial or axial variation in index of refraction that causes light passing through the lens to be focused.
text: A gradient index lens has flat optical surfaces, but has a radial or axial variation in index of refraction that causes light passing through the lens to be focused.