潛望鏡

潛望鏡（Periscope），是一種利用光線反射原理所製作的光學儀器，最常被用在潛水艇用以在水下觀察水面上的動靜。曾在塹壕戰中被用來從壕溝觀察敵軍動態。

Military handheld periscope optical design.
1 - Eyepiece
2 - Diagonal prism
3 - Handle
4 - 6 - Erecting lenses
5 - Periscope tube
7 - Field lens
8 - Lens
9 - Head diagonal prism
10 - Window

潛望鏡示意圖
Principle of the periscope.
A - Periscope using two plane mirrors.
B - Periscope using two right–angled prisms.
1 - 2 - Plane mirrors.
3 - 4 - Right–angled prisms.
5 - 6 - Observer eye.
7 - 8 - Periscope tube.
H - Periscope optical height.

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.

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  thumb|Submarine monocular attack periscope.

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  Zeiss submarine periscope optical design.

另見

• 望遠鏡
• 內視鏡