Principal point - Principal point

Japanese: 主点 - しゅてん（英語表記）principal point

The point on the optical axis that serves as the base point for measuring the focal length of a coaxial spherical system such as a lens, and the distance to an object or image. For a thin lens, it is the center of the lens, and for a spherical mirror, it is the intersection of the spherical surface and the optical axis, but for a thick lens, two points must be considered: the object space principal point and the image space principal point. The surface that contains the principal point and is perpendicular to the optical axis is called the principal plane. When drawing an image formed using a thick lens, it is sufficient to draw pairs of object space focus and object space principal plane, and image space focus and image space principal plane.

Source: Encyclopaedia Britannica Concise Encyclopedia About Encyclopaedia Britannica Concise Encyclopedia Information

Japanese:

レンズのような共軸球面系の焦点距離や，物体および像までの距離などをはかる基点となる光軸上の点。薄肉レンズではレンズの中心，球面鏡では球面と光軸との交点になるが，厚肉レンズでは物空間主点と像空間主点の2つを考えなければならない。主点を含み光軸に垂直な面を主平面という。厚肉レンズを使って結像の作図をするときは，物空間焦点と物空間主平面，像空間焦点と像空間主平面とをそれぞれ対にして作図をすればよい。

出典　ブリタニカ国際大百科事典小項目事典ブリタニカ国際大百科事典小項目事典について　情報

<<: Shuten Doji - Shuten Doji

>>: Sternheim - Carl Sternheim