Ocular in this context means eyepiece - the piece that is closest to the human eye that is watching.
The periscope has several parts: the ocular lenses, the mirror or prism, inversion/reversion prisms, relay lenses, another mirror or prism, and objective lenses.
Why don't micorscope makers use 100x ocular lenses?
ya mum
YES
Ocular scale
ocular lens
The word "periscope" is a noun. It refers to a device used for seeing over obstacles or around corners, typically by the use of mirrors and lenses.
The ocular and objective
The ocular lenses is the eyepiece the viewer looks through on a microscope. The compensation ring allows the viewer to adjust the focus.
The ocular and objectives
Detector Condensing lenses Ocular lens Electron beam
The ocular and objectives