In this sub-class: The following terms are used with the meanings indicated:
"Simple lens or prism" denotes a single lens or prism.
"Compound lens or prism" denotes an optical member, the constituents of which either are close together without air-space or (except in group Fulltext... Hierarchy... Expanded...G02B 11/00) are "in broken contact", i.e. with the air-space between the constituents having no essential optical influence
"Objective" denotes a lens or an optical system designed to produce a real image of a real object.
"Eyepiece" denotes a lens or an optical system designed to produce a virtual image for viewing by the eye or by another optical system.
"Front" and "rear" are determined by looking from the more distant conjugate.
"Optical" applies not only to visible light but also to ultra-violet and infra-red radiations.