Practical considerations for OCT applications

OCT measurements have a fundamental trade-off between the ability to resolve small details and the range over which the measurement is consistent. A measurement which is able to resolve small details is able to do so over a small range. A measurement which is consistent over a larger range is not able to resolve small details. While the axial resolution of the OCT measurement is determined by the optical bandwidth of the source, the lateral resolution (spot size) is determined by the focusing optics and the characteristics of the Gaussian beam. The spot size and the depth of field of a Gaussian beam are directly related in such a way that there is a trade-off between the spot size (details which can be resolved) and depth of field (distance over which the spot size is maintained). In this paper we analyze and discuss in detail the trade-off between the spot size and depth of field in OCT measurements. Some techniques to mitigate this limitation are mentioned and one is applied to measurements of cervical tissue with and without cervical intraepithelial neoplasia (CIN). (paper)