위상 필터를 이용한 초점 범위 향상 광 프루브 설계 및 제작

Abstract

There is a trade-off between depth of focus (DOF) and spot size. It can limit the performance of optical systems. Various methods have been proposed to overcome this limitation. However, many of them are difficult to implement in endoscopic optical probe because of the space limitations. In this study, we designed and fabricated an optical probe to extend depth of focus using binary phase spatial filter (BPSF). This optical probe has a diameter of 1 mm and the BPSF was fabricated at the distal tip of the probe using replica molding soft lithography method. We optimized the BPSF to minimum the spot size, enhance the depth of focus and light efficiency through simulation. We measured the three-dimensional point spread function to evaluate the performance of this BPSF probe. The BPSF probe can provide a spot diameter of 3.69 µm and a depth of focus of 199.7 µm. The depth of focus was extended by a factor of 2.7 compare with the probe without BPSF. We anticipate that this BPSF endoscopic probe can be applied in biomedical applications, such as optical imaging or optical trapping.