Laser beam scanning-based 3D structured light scanner combining a bi-resonant MEMS mirror with low-cost imaging sensor

Abstract

This paper presents a technique of structured light 3D scanning based on Laser Beam Scanner (LBS) using a bi-resonant vacuum-packaged MEMS mirror and a low-cost imaging sensor. A single infrared continuous-wave laser source, together with the MEMS scanner, generates dynamic Lissajous patterns delivering a continuous increase of scan precision over time. A collimated laser beam is directly coupled with the MEMS mirror without the need for diffractive optics. Lissajous patterns are captured by a low-cost CMOS imaging sensor having a short integration time while a bandpass filter ensures that only infrared signals are detected from the camera. Due to the non-repeatability of the generated Lissajous patterns, all pixels of the sensed environment are illuminated within few consecutive images. The spatial depth resolution is defined by the sensor resolution, enabling very high-density 3D scans due to the high imaging resolution achievable by CMOS sensors. Advanced image processing algorithms are implemented to accurately calculate pixel-wise depth on taken images.The hardware complexity of the proposed system is significantly reduced compared to other 3D sensing solution, which leads to a lower bill of materials. All components are mass-producible and easy to assemble, making the system advantageous for high volume markets and suitable for integration into consumer products. The proposed 3D scanning system can be integrated in AR and MR headsets for use-cases such as hand gesture scanning and indoor SLAM. Due to its high resolution capability, the presented 3D scanning technique can also be used for facial scanning and avatar generation.