Conventional Optical Coherence Tomography (OCT) probes usually require complex optics at their tips for focusing the incident light on the measured samples and for scattered light collection. Such complexity is not compatible with the common-path OCT architecture, in which the reference arm is replaced by partial reflection from the probe fiber-air interface. This necessitates close proximity between the measured sample and the fiber tip to have sufficient measurement depth inside the sample within the coherence length of the light. Indeed, separating the light injection and collection paths simplifies the design of the OCT heads and allows the easy integration of a MEMS scanner within the head. In this work, we propose a new OCT probe configuration that allows for such separation. To this end, a swept source OCT setup was built using a tunable laser connected to the single-mode fiber of the probe and the scattered light from the measured sample was collected using another Multi-Mode Fiber (MMF). The usage of the MMF in the reception enables higher power-collection efficiency and transfers the reference position to be at the first layer of the sample under test, which further extends the maximum depth analyzed by the OCT system and overcomes the restriction of the close proximity mentioned above. This simple concept is validated by experimental measurements carried out on 1 mm-thick sheets of glasses with and without an integrated MEMS scanner on-chip.

Date Published: 4 March 2014
PDF: 6 pages
Proc. SPIE 8934, Optical Coherence Tomography and Coherence Domain Optical Methods in Biomedicine XVIII, 89343J (4 March 2014); doi: 10.1117/12.2036485

Published in SPIE Proceedings Vol. 8934:
Optical Coherence Tomography and Coherence Domain Optical Methods in Biomedicine XVIII
Joseph A. Izatt; James G. Fujimoto; Valery V. Tuchin, Editor(s)