US Patent 11408032 Tube lens design for improved depth-of-field

Imaging systems and methods comprising imaging a first interior surface and a second interior surface of a flow cell are described. In some embodiments, the imaging systems may comprise: a) an objective lens; b) at least one image sensor; and c) at least one tube lens disposed in an optical path between the objective lens and the at least one image sensor; wherein the at least one tube lens is configured to correct imaging performance such that images of the first interior surface of the flow cell and the second interior surface of the flow cell have substantially the same optical resolution.