A Multi-Resolution Foveated Laparoscope

Abstract

Laparoscopic surgery or minimally invasive surgery has great advantages compared with the conventional open surgery, such as reduced pain, shorter recovery time and lower infection rate. It has become a standard clinical procedure for cholecystectomy, appendectomy and splenectomy. The state-of-the-art laparoscopic technologies suffer from several significant limitations, one of which is the tradeoff of the limited instantaneous field of view (FOV) for high spatial resolution versus the wide FOV for situational awareness but with diminished spatial resolution. Standard laparoscopes lack the ability to acquire both wide-angle and high-resolution images simultaneously through a single scope. During the surgery, a trained assistant is required to manipulate the laparoscope. The practice of frequently maneuvering the laparoscope by a trained assistant can lead to poor or awkward ergonomic scenarios. This type of ergonomic conflicts imposes inherent challenges to laparoscopic procedures, and it is further aggravated with the introduction of single port access (SPA) techniques to laparoscopic surgery. SPA uses one combined surgical port for all instruments instead of using multiple ports in the abdominal wall. The grouping of ports raises a number of challenges, including the tunnel vision due to the in-line arrangement of instruments, poor triangulation of instruments, and the instrument collision due to the close proximity to other surgical devices. A multi-resolution foveated laparoscope (MRFL) was proposed to address those limitations of the current laparoscopic surgery. The MRFL is able to simultaneously capture a wide-angle view for situational awareness and a high-resolution zoomed-in view for fine details. The high-resolution view can be scanned and registered anywhere within the wide-angle view, enabled by a 2D optical scanning mechanism. In addition, the high-resolution probe has optical zoom and autofocus capabilities, so that the field coverage can be dynamically varied while keep the same focus distance as the wide-angle probe. Moreover, the MRFL has a large working distance compared with the standard laparoscopes, the wide-angle probe has more than 8x field coverage than a standard laparoscope. On the other hand, the high-resolution probe has 3x spatial resolution than a standard one. These versatile capabilities are anticipated to have significant impacts on the diagnostic, clinical and technical aspects of minimally invasive surgery. In this dissertation, the development of the multi-resolution foveated laparoscope was discussed in detail. Starting from the refinement of the 1st order specifications, system configurations, and initial prototype demonstration, a customized dual-view MRFL system with fixed optical magnifications was developed and demonstrated. After the in-vivo test of the first generation prototype of the MRFL, further improvement was made on the high-resolution probe by adding an optical zoom and auto-focusing capability. The optical design, implementation and experimental validation of the MRFL prototypes were presented and discussed in detail.