Ultra-miniaturized structured-light projector for tissue profiling in chip-on-tip endoscopy

SignificanceOptical technologies can be used to accelerate the process of cancer diagnostics. For colorectal cancers, for example, one of the crucial parameters in classifying colon polyps is their shape and size, both of which can be optically characterized with structured light illumination.AimWe develop an ultra-miniaturized structured-light projector suitable for chip-on-tip architecture that projects a desired pattern onto an area of 5 cm×5 cm at a working distance of 3 cm facilitating one-shot surface evaluation of the tissue to be examined.ApproachThe pattern projection is based on a diffractive optical element with pixel sizes down to 200 nm enabling high diffraction angles of up to 40 deg. The entire setup consisting of a vertical-cavity surface-emitting laser, a collimation lens and the diffractive optical element is miniaturized to fit into the space constraints of the chip-on-tip architecture.ResultsThe developed projector has a length of 3.9 mm and a diameter of 4.2 mm including a cover glass to protect the optical components. The projector generates a stripe pattern with a stripe spacing of 5 mm and the desired projection size.ConclusionsThe results show the development of a compact projector for structured light illumination that fits into chip-on-tip endoscopes and allows one-shot structured-illumination of colon polyps.