 Depth of focus

The axial image-side range over which a specified image criterion remains satisfied. Lithographic scaling is often written $\mathrm{DOF}=k_2\lambda /{\mathrm{NA}}^2$; specify whether a quoted range is full width or one-sided.

Depth of focus is a term used in optics that refers to the range of distances over which a lens can create a sharp image of a subject on a sensor or film. It is closely related to depth of field, but the two concepts apply to different aspects of the imaging process. 1. **Depth of Focus**: This is the distance between the nearest and farthest points from the lens at which the image remains in acceptable focus on the imaging plane (like a film or digital sensor).