Proposed Scanning System Research Articles

An ultrasonic scanning system for the inspection of composite stiffened panels from elastic constant identification via inversion of guided waves

This paper describes an ultrasonic scanning system for the inspection of stiffened composite panels used in modern aircraft construction based on elastic constant identification. Conventional ultrasonic scanning systems track individual features of the propagating waves (e.g. amplitude, arrival time, etc.) to detect damage by tracking the associated wave scattering. An ability to map the elastic constants of the composite part can greatly enhance the sensitivity of the scan to structural damage that can be detected and quantified by a corresponding reduction in the stiffness components. Elastic constants can be also correlated to residual strength. The proposed scanning system utilizes a “single-input-dual-output“ (SIDO) scheme whereby ultrasonic guided waves are excited by an impact and detected by two air-coupled ultrasonic sensors. The phase velocity dispersion curves of the waves are experimentally measured under a single excitation at each scanning line using a phase-spectrum technique. These curves are then inverted using a Semi-Analytical Finite Element (SAFE) method as the wave propagation forward model and Simulated Annealing as the optimization routine. This approach yields estimates of several elastic effective constants of the composite panel at each scanning line. These constants are then related to impact damage in stiffened stringer-skin composite panels.

Enhancement of a Single-Axis Femtosecond Laser Scanning System by Using Two Galvanometers to Improve the Telecentricity and the Effective Scanning Length on Laser Process

The galvanometer scanning system plays a crucial role in modern laser material processing. With the development of this industry, the requirements for galvanometer scanners are getting higher and higher, especially to overcome the inherent disadvantages that still exist, such as image distortion, marking speed and accuracy in state-of-the-art scanning systems. In this paper, a single-axis optical scanner using two galvanometers in combination with one f-theta telecentric lens and a 343 nm femtosecond pulse laser source is proposed as a new approach for enhancing the precision of laser micromachining technology. The additional second galvanometer is used to manipulate the output laser beam of the first galvanometer to the path with less lens aberration to enhance the telecentricity correction and the effective scanning area. This is based on the international standard regulation ISO (the International Organization for Standardization) 11145:2018 requirements in optics and photonics, in which an important criterion is for the roundness of the focused beam spot to be greater than 87% to determine the effective working length of the proposed scanning system compared to the conventional scanning system. It is demonstrated by optical simulations and real optical experiments that the effective working length can be increased by 3.6 mm, corresponding to 8.1% of the effective scanning field, to achieve a laser material processing system with ISO standard. The damped least squares (DLS) algorithm in optical design software ZEMAX is used to optimize the deflected angle of the two galvanometers to obtain the optimal incident position of the f-theta lens.

Low cost 3D foot scan with Kinect

Accurate 3D digital foot model is extremely useful in shoe or orthotics design and other medical situations such as podiatric therapy. In view of the fact that most of the 3D data-acquisition devices on the market are either expensive though high accuracy (e.g., high-end laser scanner), or with poor maneuverability and efficiency (e.g., image-based stereography), or deficient portability (e.g., large-size scanning machine or types requiring support frame), we propose a new method for human foot scanning in this paper. Microsoft Kinect sensor was adopted as the key device in this approach and proved a smart and efficient scanner in 3D foot data acquisition according to a detailed comparison with other scanners in terms of scan time, cost, operability and portability. Accuracy check of the sphere and foot scanning results also demonstrates decent precision of the proposed scanning system.

Low cost 3D foot scan with Kinect

Accurate 3D digital foot model is extremely useful in shoe or orthotics design and other medical situations such as podiatric therapy. In view of the fact that most of the 3D data-acquisition devices on the market are either expensive though high accuracy (e.g., high-end laser scanner), or with poor maneuverability and efficiency (e.g., image-based stereography), or deficient portability (e.g., large-size scanning machine or types requiring support frame), we propose a new method for human foot scanning in this paper. Microsoft Kinect sensor was adopted as the key device in this approach and proved a smart and efficient scanner in 3D foot data acquisition according to a detailed comparison with other scanners in terms of scan time, cost, operability and portability. Accuracy check of the sphere and foot scanning results also demonstrates decent precision of the proposed scanning system.

3D Model Reconstruction System Development Based on Laser-Vision Technology

We propose a three-dimensional (3D) scanning system based on laser-vision technique and rotary mechanism combination for automatic 3D model reconstruction. The proposed scanning system consists of a laser projector, camera, and turntable. For laser-camera calibration, a new and simple method is applied. The 3D point cloud data of the surface of the scanned object are fully collected by integrating the extracted laser profiles from the laser stripe images corresponding to the rotary angles of the rotary mechanism. The obscured laser profile problem is solved by an additional camera at another viewpoint. From the collected 3D point cloud data, the 3D model of the scanned object is reconstructed based on the facet-representation method. The reconstructed 3D models showed the effectiveness and applicability of the proposed 3D scanning system in many 3D model-based applications.

레이저 비전 기술을 이용한 물체의 3D 모델 재구성 방법에 관한 연구

In this study, we proposed a three-dimensional (3D) scanning system based on laser-vision technique and rotary mechanism for automatic 3D model reconstruction. The proposed scanning system consists of a laser projector, a camera, and a turntable. For laser-camera calibration a new and simple method was proposed. 3D point cloud data of the surface of scanned object was fully collected by integrating extracted laser profiles, which were extracted from laser stripe images, corresponding to rotary angles of the rotary mechanism. The obscured laser profile problem was also solved by adding an addition camera at another viewpoint. From collected 3D point cloud data, the 3D model of the scanned object was reconstructed based on facetrepresentation. The reconstructed 3D models showed effectiveness and the applicability of the proposed 3D scanning system to 3D model-based applications.

A Low-cost Multi Camera 3D Scanning System for Quality Measurement of Non-static Subjects

In medical field, a growing interest is now focused on non-invasive diagnostic 3D image-based methods. The aim of this work is to develop a powerful, easy and low cost scan-system, based on close-range photogrammetry, capable to perform a complete acquisition of a non-static subject over 360°. The proposed scanning system has some advantages compared to the scanning systems traditionally used in medical field for human application, it is a non-invasive systems alternative respect to laser and structured light scanners, and demonstrate to be accurate and reliable for medical diagnostic application on human body. Video abstract [Display omitted]

Micro-mirror laser scanner combined with a varifocal mirror

A laser beam scanning system consisting of a scanning micro-mirror and a varifocal micro-mirror is fabricated for laser beam sensing with variable beam diameter. The scanning micro-mirror is operated under the resonant oscillation condition with an electrostatic comb-drive actuator. The varifocal micro-mirror is driven by a bending moment generated at the circumference of mirror with a parallel-palate electrostatic actuator. The scanning micro-mirror and the varifocal mirror are fabricated on a silicon on insulator wafer. The rotational angle of 9° at 766 Hz is obtained at the voltage of 300 V. The spot size of the laser beam is adjusted from 0.5 to 3.5 cm at the distance of 43 m by changing varifocal voltage. The proposed scanning system can be useful for several sensing techniques.