Proceedings of the
9th International Conference of Asian Society for Precision Engineering and Nanotechnology (ASPEN2022)
15 – 18 November 2022, Singapore
doi:10.3850/978-981-18-6021-8_OR-15-0111
High-speed multi-Line structured-light 3-D scanning system for accurate surface profilometry
1Department of Mechanical Engineering, National Taiwan University, No. 1, Section 4, Roosevelt Rd., Taipei City, 10617, Taiwan
ABSTRACT
A method for precision surface profilometry by applying a novel galvanometer-scanned multi-line Optomechatronics design principle is proposed. Based on the structured-light triangulation scanning principle, the proposed system was realized in a single integrated optical module while remaining excellent height measuring resolution and precision with a high-speed imaging sensor. In work, different from the traditional laser line generator, a cylindrical array lens is designed as a condenser, and a green light-emitting diode (LED) is used to generate multiple linear light beams that can be projected and manipulated by a galvanometer as a scanning structured-light projector, and avoid the uncertainty that comes from transitional laser speckle effect. The proposed method can avoid the disadvantages of the traditional laser triangulation scanning methods relying on the movement of measuring objects, which increases uncertainties introduced by positioning uncertainty incurred from conveyor belts or mechanical stages. With a precise galvanometer mirror integrated into the scanning system, the scanning uncertainty can be significantly reduced to achieve high precision 3D measurement speedily. Moreover, the developed system is designed to achieve a micron-level measuring accuracy by applying a novel sub-micron peak detection algorithm. Verified by experimental tests, the developed method is capable of measuring a highly scattered surface of metallic surfaces made by the directed energy deposition (DED) 3-D printing process, and the depth accuracy can reach better than 20 micrometers with a measuring time of less than 2 seconds.
Keywords: Surface profilometry, laser triangulation, structured-light, 3D reconstruction, precision metrology.
1Department of Mechanical Engineering, National Taiwan University, No. 1, Section 4, Roosevelt Rd., Taipei City, 10617, Taiwan
ABSTRACT
A method for precision surface profilometry by applying a novel galvanometer-scanned multi-line Optomechatronics design principle is proposed. Based on the structured-light triangulation scanning principle, the proposed system was realized in a single integrated optical module while remaining excellent height measuring resolution and precision with a high-speed imaging sensor. In work, different from the traditional laser line generator, a cylindrical array lens is designed as a condenser, and a green light-emitting diode (LED) is used to generate multiple linear light beams that can be projected and manipulated by a galvanometer as a scanning structured-light projector, and avoid the uncertainty that comes from transitional laser speckle effect. The proposed method can avoid the disadvantages of the traditional laser triangulation scanning methods relying on the movement of measuring objects, which increases uncertainties introduced by positioning uncertainty incurred from conveyor belts or mechanical stages. With a precise galvanometer mirror integrated into the scanning system, the scanning uncertainty can be significantly reduced to achieve high precision 3D measurement speedily. Moreover, the developed system is designed to achieve a micron-level measuring accuracy by applying a novel sub-micron peak detection algorithm. Verified by experimental tests, the developed method is capable of measuring a highly scattered surface of metallic surfaces made by the directed energy deposition (DED) 3-D printing process, and the depth accuracy can reach better than 20 micrometers with a measuring time of less than 2 seconds.
Keywords: Surface profilometry, laser triangulation, structured-light, 3D reconstruction, precision metrology.
