title: Quasi-needle-like focus synthesized by optical coherence tomography.
abstract: It is known that lateral resolution and depth of focus (DOF) in an optical imaging system are coupled, and a compromise between them has to be made. In this Letter, we propose to resolve the trade-off between lateral resolution and the DOF by a synthetic effective point spread function in optical path length (OPL) domain. A quasi-needle-like focus is synthesized by optical coherence tomography. We demonstrate that the synthesized quasi-needle-like focus provides a four-fold extension of a conventional DOF, while maintaining a high lateral resolution of 2.5 μm over a depth range of approximately 240 μm. The focal range can be further extended with more optical path length coded beams for synthesis involved.
authors.forename: Wen
authors.initials: W
authors.lastname: Bao
authors.forename: Zhihua
authors.initials: Z
authors.lastname: Ding
authors.forename: Jianrong
authors.initials: J
authors.lastname: Qiu
authors.forename: Yi
authors.initials: Y
authors.lastname: Shen
authors.forename: Peng
authors.initials: P
authors.lastname: Li
authors.forename: Zhiyan
authors.initials: Z
authors.lastname: Chen