טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentAbramov Avraham
SubjectMultiple Channel Spectrally Encoded Endoscopy
DepartmentDepartment of Nanoscience and Nanotechnology
Supervisor Professor Yelin Dvir
Full Thesis textFull thesis text - English Version


Abstract

Miniaturization of instrumentation for clinical intervention is a current trend in minimally invasive medicine, pressed forward by the constant advance in science and technology. Fiber bundle endoscopes have made a considerable impact in clinical applications that require imaging through small and flexible probes. Recently, the use of a single optical fiber and a scanning mechanism at the distal end of an endoscope allows one to overcome some of the limitations of fiber bundle technology, at the expense, however, of the bulk of the mechanical scanning apparatus. (no new line here)Spectrally encoded endoscopy (SEE) uses miniature diffractive optics to encode space with wavelength, allowing three-dimensional imaging through sub-millimeter, flexible endoscopic probes which do not require rapid mechanical scanning. In its current mode of implementation, SEE has several limiting factors which need to be addressed before its clinical promise could be realized, including limited fluorescence imaging capabilities, pronounced speckle noise, small depth of field, and poor signal collection efficiency.

 This thesis work will present a new method for spectrally encoded imaging in which the illumination and the collection channels are separated in space, and spectral encoding is present only in one of the channels, allowing variety of channel configurations. Bench-top experiments using spatially incoherent white light illumination reveal significant improvement in image quality and considerable reduction of speckle noise compared to conventional techniques. We demonstrate that the new technique is capable of high sensitivity fluorescence imaging of single cells and show that color imaging is feasible using a simple, slow probe scanning along the wavelength axis. Finally, we demonstrate spectral imaging using multiple channel SEE, i.e. the acquisition of the full spectrum from each point in the image.

The presented variants of spectrally encoded imaging significantly improve image quality and functionality, and could potentially be incorporated into small diameter endoscopic imaging probes for minimally invasive clinical diagnosis.