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Abstract:
In the 20th century, rigid laparoscopes revolutionized surgery such that minimally invasive procedures are now the norm. However, these systems only provide surgeons with a two-dimensional (2D) view of the operative field and are subject to two major optical limitations: (1) the absence of binocular vision results in restricted depth perception and (2) the field of view (FOV) is restricted to the local operating region to ensure high image spatial resolution. Performing surgery through a monitor without depth perception is challenging and requires extensive training. Meanwhile, surgical accidents that occur outside of the limited FOV and have gone unnoticed may cause unnecessary trauma to the patient. In this dissertation, two novel optical designs were developed to address the two limitations and further advance this technology. The conceptualization, lens design, prototyping, calibration, and processed results are discussed for both designs.
The first design is a programmable aperture light field laparoscope. It was used to investigate and explore the requirements of three-dimensional depth information extraction in a monocular form factor. Compared to state-of-the-art dual objective stereoscopic laparoscopes, this form factor preserves more design volume for transmitting more of the object scene’s light field. A programmable aperture is used to preserve the laparoscope’s conventional high resolution 2D imaging and upon demand, capture the light field. The light field information enables this system to view the object scene from different viewing angles, digitally refocus, and generate depth maps for surgical guidance in post processing.
A second-generation design called a tri-aperture monocular laparoscope was then developed to address the depth perception and FOV limitations simultaneously. This system uses two displaced apertures and a custom prism to capture the stereoscopic views simultaneously, which can then be processed to generate absolute depth maps. Meanwhile, a wide FOV for situational awareness is captured via a central third aperture. It provides 2D vision over an area 2x as large as that of the stereoscopic views. Such a system may pave the way towards restoring the binocular and large, foveated FOV qualities of human vision within the minimally invasive surgical setting.