3D Endoscope Based on the Controlled Aberration Method

Abstract

Surgeons use endoscopes to inspect the cavity of patient’s body in the minimal invasive surgery. However, the conventional 2D endoscopes cannot offer depth information. Surgeons might overshoot the targets due to the lack of depth perception. So, it is essential to develop the 3D endoscopes to overcome this problem. In current 3D imaging technologies, the stereo method and structured light method both require angle diversity. The controlled aberration method is a uniaxial depth measurement method. It only requires the projection pattern and the differential focus to implement depth measurement. It has potential to be applied in the endoscopic system. This research aims to develop a 3D endoscope prototype based on the controlled aberration method and prove it can implement depth measurement. The first part of the work is a simulation study to prove that the controlled aberration method can be scaled down and applied to an endoscopic system for the depth measurement. Then the prototype design was discussed with each element in the projection path and imaging path of the system. Two depth measurement experiments were conducted. One is based on the miniature camera placed next to the projection path, another is based on an on-axis DSLR with diffuser screens. It used diffuser screens as “detector” and DSLR to capture the transmitted image on the screen. These experiement results indicate that endoscope prototype with controlled aberration method can implememnt depth measurement. The mini camera configuration suffers from high distortion. It reduces the measurement accuracy. The DSLR configuration was developed to deal with the distortion problem. But the DSLR camera configuration is not applicable to the actual endoscope. Hence, the future work is to develop a controlled aberration prototype with co-axial projection and imaging path to capture the reflected pattern image of the scene and the optimization of the calibration and measurement processes for more accurate depth measurement.