Stroboscopic illumination scheme for seamless 3D endoscopy

Intraoperative 3D imaging during minimally invasive surgery (MIS) is possible using structured lighting and has applications in the quantification of tissue morphology. However, projection schemes containing various patterns and colours can be disruptive to the surgeon's field of view. In this paper, a stroboscopic system is proposed in which structured lighting and white light images are interleaved during a high-speed camera acquisition so that the patterned light is not perceived and white light can be used solely for navigation and visual assessment. A beam chopper synchronised with the camera switches rapidly between the two lighting modes while still providing video rate display. A spectrally-encoded structured lighting system is provided by an optical fibre-based probe developed in our lab and is suitable for use in endoscopic biopsy channels. In this dual acquisition mode it is possible to display an augmented view so that the centroids of the structured lighting features are visible on the white light image. Sequential acquisition of varying exposure time images with the high speed camera also allowed the generation of high dynamic range images of the wavelength-encoded structured lighting pattern. Possible applications of this work include classification of polyp morphology as an indicator of pathology.