3D endoscope system using DOE projector.

For effective in situ endoscopic diagnosis and treatment, size measurement and shape characterization of lesions, such as tumors, is important. For this purpose, in the past we have developed a range of 3D endoscopic systems based on active stereo to measure the shape and size of living tissues. In those works, the main shortcoming was that the target area could only be reconstructed at a specific distance from the scope because of off-focus blurring effects and aberrations in the periphery of the field of view. These issues were compounded by the degree of reconstruction instability due to the strong subsurface scattering common in internal tissue. In this paper, we tackle these shortcomings by developing a new micro pattern laser projector to be inserted in the scope tool channel. The new projector uses a Diffractive Optical Element (DOE) instead of a single lens, which solves the off-focus blur. We also propose a new line-based grid pattern with gap coding to counter the subsurface scattering effect. In our experiments on ex vivo human tumor samples, we show that the tissue shapes were successfully reconstructed regardless of depth variance and strong subsurface scattering effects.