Three-dimensional endoscopic imaging system based on micro-lithography mask structured light projection

To achieve effective in-situ endoscopic diagnosis and treatment, the measurement of the size of lesions (such as tumors) and the characterization of their shape are important. However, the application of binocular endoscopy is still limited due to issues such as the lack of texture in some scenes, difficulty in matching, and large computational load. To address this, we have developed a 3D endoscopic imaging system based on micro-lithography mask structured light projection to measure the shape and size of targets within the endoscopic view. Firstly, a brand new mechanical design was implemented for the endoscope tip to integrate both white light and structured light channels. Then, a projection lens based on Q-type aspheric design and a micro-lithography mask based on the M-array were designed to achieve high contrast and high-resolution structured light projection in the endoscopic scene. Finally, by identifying feature points in the target and reference images, pixel matching and disparity calculation were achieved, allowing for 3D reconstruction. Our proposed 3D endoscopic imaging system was validated in a gastric model and a cervical model, where the model was reconstructed and compared with the ground truth, yielding mean RMSE of 0.20–0.31 mm at a working distance of about 40 mm, thus confirming the effectiveness of our system.