Development of a laparoscope with multi-resolution foveation capability for minimally invasive surgery

Abstract

Laparoscope is the essential tool for minimally invasive surgery (MIS) within the abdominal cavity. However, the focal length of a conventional laparoscope is fixed. Therefore, it suffers from the tradeoff between field of view (FOV) and spatial resolution. In order to obtain large optical magnification to see more details, a conventional laparoscope is usually designed with a small working distance, typically less than 50mm. Such a small working distance limits the field of coverage, which causes the situational awareness challenge during the laparoscopic surgery. We developed a multi-resolution foveated laparoscope (MRFL) aiming to address this limitation. The MRFL was designed to support a large working distance range from 80mm to 180mm. It is able to simultaneously provide both wide-angle overview and high-resolution image of the surgical field in real time within a fully integrated system. The high-resolution imaging probe can automatically scan and engage to any subfield of the wide-angle view. During the surgery, MRFL does not need to move; therefore it can reduce the instruments conflicts. The FOV of the wide-angle imaging probe is 80° and that of the high-resolution imaging probe is 26.6°. The maximum resolution is about 45um in the object space at an 80mm working distance, which is about 5 times as good as a conventional laparoscope at a 50mm working distance. The prototype can realize an equivalent 10 million-pixel resolution by using only two HD cameras because of its foveation capability. It saves the bandwidth and improves the frame rate compared to the use of a super resolution camera. It has great potential to aid safety and accuracy of the laparoscopic surgery.