Centering process 1: Optical axis and radius of curvature of lens surface

Lenses whose surface is polished to the specified radius of curvature
It is necessary to attach it to the lens frame (lens barrel) and assemble it as a lens system.

Since the outer diameter of a lens whose surface is only polished is usually made larger than the specified size, it cannot be attached to the lens barrel with the same shape and dimensions.
Therefore, it is necessary to grind the outer diameter of the lens to the specified dimensions according to the shape of the lens barrel.

At this time, it is necessary to grind to the specified outer diameter with no eccentricity and one side with respect to the optical axis of the lens.
The optical axis is the line connecting the centers of curvature on both sides of the lens as shown in the above figure.

The eccentricity is the geometrical numerical value of the runout of the facing surface when one lens surface is used as a reference. There are the amount of center runout and the amount of outer diameter runout.
This is the process of forming a lens with no shoulder flesh and eccentricity with respect to the optical axis, and grinding the outer diameter of the lens so that the optical axis coincides with the central axis of the lens system when assembled as a lens system.