title: Extension of focal depth by using an encoded source.
abstract: An idea for extending the focal depth by using an encoded source is presented, and the principle is explained by investigating the clarity of the defocus image. By using partial coherence theory, we show that not only the resolving power can be improved but also the focal depth. We correct the conventional conclusion that focal depth is dependent only on the numerical aperture.
authors: B J
authors: BJ
authors: Guo
authors: S L
authors: SL
authors: Zhuang