Webster’s Revised Unabridged Dictionary · 1913
Plane-parallel
Plane′-par′al·lel (·păr′al·lĕl), a. (Optics) Having opposite surfaces exactly plane and parallel, as a piece of glass.
Webster’s Revised Unabridged Dictionary · 1913
Plane′-par′al·lel (·păr′al·lĕl), a. (Optics) Having opposite surfaces exactly plane and parallel, as a piece of glass.