Design and performance of an endoscopic OCT system for in vivo studies of human mucosa

Summary form only given. A key problem for endoscopic application of optical coherence tomography (OCT) is to provide a reliable and convenient access of probing low-coherence radiation to the surface of internal organs. Here, the authors describe the design and performance of their OCT systems integrated in standard endoscopes, operating in parallel with them and thus enhancing essentially the capabilities of endoscopy as a whole. Implementation of an extended flexible arm of the OCT interferometer to provide access to the studied tissue is based on the usage of polarization maintaining fibers for transportation of the low coherence light. The sampling arm of the fiber interferometer is terminated by a newly developed miniaturized electro-mechanical unit that controls the lateral scanning process. The probe beam swinging on the tissue surface approaches 2 mm. As a source of radiation the authors employ a superluminescent diode with a central frequency of 830 nm, bandwidth of 30 nm, and power of 1.5 mW. In-depth scanning is performed with an integrated piezo-optical modulator that introduces the difference in the length arms of the interferometer. With a scanning rate of 30 cm/s and an image depth of 3 mm, an OCT picture is acquired in approximately 1 s. This rate is sufficient to eliminate the effect of internal organ movement on the image quality. The electro-mechanical scanner has a size that fits the diameter and the curvature radius of an endoscope biopsy channel.