A graded-index (GRIN) lens is suitable for developing an ultra-thin endoscope due to its small diameter and simplicity for optics design. A GRIN lens, however, generates intrinsic optical aberration causing low resolution and poor imaging quality. Recently, wavefronts of light can be measured with very high precision and the optical aberration can be corrected in numerical ways even for the case of highly scattering media. In this study, based on the high precision wavefront sensing and numerical image processing techniques, we demonstrate a high-resolution and ultra-thin endo-microscope using a GRIN rod lens as a core imaging optics. We constructed a reflection-type interferometric microscope through a GRIN rod lens using a p-polarized Nd:YAG laser (532 nm) as a light source. By recording and processing blank transmission images as a function of various illumination states, the characteristics of the aberration generated by the GRIN lens were obtained. After this pre-calibration, we could numerically compensate the aberration induced onto a reflection image of an object. Consequently, a diffraction limited lateral resolution as well as improved axial resolution could be achieved. Our approach will fascinate the use of GRIN lenses for compact and high-resolution imaging devices including ultra-thin endo-microscopes.
Hyung-Jin Kim, Changhyeong Yoon, Taeseok D. Yang, Wonshik Choi, Beop-Min Kim, and Youngwoon Choi, "High-resolution and ultra-thin endo-microscopy using a GRIN rod lens (Conference Presentation)," Proc. SPIE 9691, Endoscopic Microscopy XI; and Optical Techniques in Pulmonary Medicine III, 96910F (Presented at SPIE BiOS: February 14, 2016; Published: 27 April 2016); https://doi.org/10.1117/12.2209228.4828146954001.
Conference Presentations are recordings of oral presentations given at SPIE conferences and published as part of the proceedings. They include the speaker's narration with video of the slides and animations. Most include full-text papers. Interactive, searchable transcripts and closed captioning are now available for most presentations.
Search our growing collection of more than 22,000 conference presentations, including many plenaries and keynotes.