Ban, N. (2017). A novel design of a miniaturized minimal invasive probe for optical coherence tomography [Diploma Thesis, Technische Universität Wien]. reposiTUm. https://doi.org/10.34726/hss.2017.42885
The aim of this thesis was to develop and implement the first prototype of a novel minimal invasive optical coherence tomography probe with main focus on the proximal scanning setup. The designed side viewing probe consists of three basic parts: 1) an external scanning unit to transfer the rotational torque from the endoscope proximal end to the distal tip, 2) a single mode fiber incorporating pigtailed ferrule paired with a gradient index (GRIN) lens to transmit and focus the incident light and 3) a microprism for a 90° reflection of light to generate a side-viewing beam. The GRIN lens based probe achieves an outer diameter of 4mm being ideal for accessing small tubular organs such as blood vessels and does not require any electrical elements at distal end. Furthermore, the OCT probe was designed to achieve a working distance of 6mm and a beam spot size with transversal resolution of 15.6µm. The proximal scanning setup is located at the proximal end of the beam delivery media, outside the body of the imaging subject such that the strict requirements of size for endoscopic application does not need to be considered. The designed external scanning scheme is equipped with a sensorless brushless direct current (BLDC) motor to acquire rotational movement and a precise stepper motor in combination with a single axis translation stage to realize translation movement. OCT A-scan are combined with a rotational scan to generate 2D images, consecutively a translational scanning is applied in order to generate 3D images. By the combination of the fast rotational and the slow translational movement, a spiral scanning pattern is generated, which is ideal for scanning tubular organs and body cavities. The performance of the designed probe was tested for 3D imaging, where real time imaging was conducted using a swept-source OCT (SS-OCT) system which operated at 1300nm center wavelength and a sweeping rate of 100kHz.755