Switchable pattern projector module with rotational offset of double microlens arrays for 3D endoscopy (Conference Presentation)

Abstract

Three-dimensional (3D) endoscopes provide depth information and help determining the surgical sites more accurately. Among the conventional 3D endoscopic techniques, efforts on implementation of structured illumination method into 3D imaging system was actively made due to the potential of light environmental robustness and miniaturization. However, structured illumination methods are suffering from the low resolution, which is affected by the light patterns density and uniformity with minimized projector. In this work, we demonstrate switchable pattern projector module using rotational offsets of double microlens arrays (MLAs) for 3D endoscopic imaging with structured illumination method. The pattern projector module includes diffractive optical element part of double MLAs with rotational offsets for double diffraction pattern generation and the switchable light source part of fiber bundle comprised of the GRIN fiber for collimating laser at the center and other surrounding fibers for white-light illumination. The double MLAs was fabricated using double-sided photolithography on 4-inch borosilicate wafer, thermal reflow with hydrophobic nano film, and parylene-c coating. The period, curvature and rotational offset angle of double MLAs were determined to have high density and uniformity of the projected dot array patterns. The calculated disparity map of non-textured 3D object showed increase on resolution and robustness on surrounding light environment compared to the disparity map with stereoscopic imaging method. The 3D imaging system using the projector module can provide depth information with miniaturized system and lead to various applications for medical imaging as well as other imaging applications in industrial and military fields.