Periskopo

Principle of the lens periscope.
A - Periscope using a single lens (L2) to correct image.
B - Periscope which uses two lenses (L2-L3) to correct image.
1-3 - Periscope window.
2-4 - Field stop or reticle.
P - Right–angled prisms (or plane mirrors).
L1 - Objective lens.
L2 - for A - L2 - L3 - for B - Image erecting lens.
L3 - L4 -for A - L4-L5- for B - Eyepiece.
L0 - Field lens.
y - Distant object.
H - Periscope optical height.
A - Periscope using a single lens (L2) to correct image.
B - Periscope which uses two lenses (L2-L3) to correct image.
1-3 - Periscope window.
2-4 - Field stop or reticle.
P - Right–angled prisms (or plane mirrors).
L1 - Objective lens.
L2 - for A - L2 - L3 - for B - Image erecting lens.
L3 - L4 -for A - L4-L5- for B - Eyepiece.
L0 - Field lens.
y - Distant object.
H - Periscope optical height.
Periskopo esas optiko-tubo, uzata dat-unesme da submarnavi, kom aparato qua posibligas vidar dum submerseso.