Laser Scanning Mechanism Research Articles

3D Data Processing and Entropy Reduction for Reconstruction from Low-Resolution Spatial Coordinate Clouds in a Technical Vision System.

This paper proposes an advancement in the application of a Technical Vision System (TVS), which integrates a laser scanning mechanism with a single light sensor to measure 3D spatial coordinates. In this application, the system is used to scan and digitalize objects using a rotating table to explore the potential of the system for 3D scanning at reduced resolutions. The experiments undertaken searched for optimal scanning windows and used statistical data filtering techniques and regression models to find a method to generate a 3D scan that was still recognizable with the least amount of 3D points, balancing the number of points scanned and time, while at the same time reducing effects caused by the particularities of the TVS, such as noise and entropy in the form of natural distortion in the resulting scans. The evaluation of the experimentation results uses 3D point registration methods, joining multiple faces from the original volume scanned by the TVS and aligning it to the ground truth model point clouds, which are based on a commercial 3D camera to verify that the reconstructed 3D model retains substantial detail from the original object. This research finds it is possible to reconstruct sufficiently detailed 3D models obtained from the TVS, which contain coarsely scanned data or scans that initially lack high definition or are too noisy.

Multi-MHz laser-scanning single-cell fluorescence microscopy by spatiotemporally encoded virtual source array.

Apart from the spatial resolution enhancement, scaling of temporal resolution, equivalently the imaging throughput, of fluorescence microscopy is of equal importance in advancing cell biology and clinical diagnostics. Yet, this attribute has mostly been overlooked because of the inherent speed limitation of existing imaging strategies. To address the challenge, we employ an all-optical laser-scanning mechanism, enabled by an array of reconfigurable spatiotemporally-encoded virtual sources, to demonstrate ultrafast fluorescence microscopy at line-scan rate as high as 8 MHz. We show that this technique enables high-throughput single-cell microfluidic fluorescence imaging at 75,000 cells/second and high-speed cellular 2D dynamical imaging at 3,000 frames per second, outperforming the state-of-the-art high-speed cameras and the gold-standard laser scanning strategies. Together with its wide compatibility to the existing imaging modalities, this technology could empower new forms of high-throughput and high-speed biological fluorescence microscopy that was once challenged.

Research and Development of High-speed Laser Scanning Galvanometer System

This study developed and controlled laser scanning mechanism and circuit design, in order to reduce the vibratory magnitude resulted from high-speed operation. The principle of mechanism design is that the output end mirror can swing within ± 3° when the laser scanning mechanism is in operation, the accuracy value is ± 0.2°. The static simulation and dynamic measurement were carried out for mutual validation. The vibration generated in the operation of machine causes dynamic unbalance, influencing the stability of machine. In order to overcome and improve the dynamic unbalance generated when the mechanism is in motion, different solutions were proposed, such as changing the output end mass, to add elastic material in or to change constant speed control of input end motor to variable speed control.

Empirical study of variation in lidar point density over different land covers

Point density in airborne lidar surveys is one of the key parameters that influence not only the accuracy of generated DSM/DEM but also processing and costs. Point density variations occur (independently of keeping constant flight parameters) throughout the survey depending on the topography, the land cover, and the laser scanning mechanism. In this article, variations in point density across different land covers are analysed with an airborne oscillating mirror laser scanner. A wide group of samples from the different land covers is taken from single flight strips over level ground in order to minimize the effect of topography. The influence of the oscillating mirror laser scanner system is also minimized considering points along the central swath area. Mean values for each land cover are established regarding ground point density and first pulse returns. Significant differences in both raw points as well as on-the-ground points are registered, mainly due to the presence of features over the ground and the degree of opacity thereof. Regarding ground points, the relative differences between the two software packages used are 5% approximately. Significant point density differences can be found among the six analysed land covers. Furthermore, extrapolated pulse rate increments are presented to fulfil lidar specifications that neglect land cover as an input parameter to satisfy ground point density values, namely in non-overlapping areas.

Aerial Laser Inspection of Buildings Facades Using Quadrotor

Monitoring is the backbone of any project management task. In construction, where the service or product to be delivered is directly related to human beings, quality assurance reigns supreme in terms of priority and importance.Construction project goes beyond handing over of the building. The upkeep of the building requires continuous monitoring to maintain the safety aspects as well as aesthetic elements of the building including facades and marble constructions. Laser scanning and photogrammetry can be used for inspection and detection of defects, which can be very valuable for preventive maintenance.We offer to expand the role of the terrestrial laser scanning mechanism, to an aerial inspection and 3D building model generation using quadrotors based on simulations. This will automate the scanning process, increase range of the inspecting device and minimize the time of shifting and setting up the laser or the cameras, especially when operating in difficult site conditions, hence the aim of this paper.

Research and Development of High-speed Laser Scanning Galvanometer System

This study developed and controlled laser scanning mechanism and circuit design, in order to reduce the vibratory magnitude resulted from high-speed operation. The principle of mechanism design is that the output end mirror can swing within ± 3° when the laser scanning mechanism is in operation, the accuracy value is ± 0.2°. The static simulation and dynamic measurement were carried out for mutual validation. The vibration generated in the operation of machine causes dynamic unbalance, influencing the stability of machine. In order to overcome and improve the dynamic unbalance generated when the mechanism is in motion, different solutions were proposed, such as changing the output end mass, to add elastic material in or to change constant speed control of input end motor to variable speed control.

Highly reproducible laser beam scanning device for an internal source laser desorption microprobe Fourier transform mass spectrometer

Traditionally, mass spectrometry has relied on manipulating the sample target to provide scanning capabilities for laser desorption microprobes. This has been problematic for an internal source laser desorption Fourier transform mass spectrometer (LD-FTMS) because of the high magnetic field (7 Tesla) and geometric constraints of the superconducting magnet bore. To overcome these limitations, we have implemented a unique external laser scanning mechanism for an internal source LD-FTMS. This mechanism provides adjustable resolution enhancement so that the spatial resolution at the target is not limited to that of the stepper motors at the light source (∼5 μm/step). The spatial resolution is now limited by the practical optical diffraction limit of the final focusing lens. The scanning mechanism employs a virtual source that is wavelength independent up to the final focusing lens, which can be controlled remotely to account for focal length dependence on wavelength. A binary index provides an automatic alignment feature. The virtual source is located ∼9 ft from the sample; therefore, it is completely outside of the vacuum system and beyond the 50 G line of the fringing magnetic field. To eliminate reproducibility problems associated with vacuum pump vibrations, we have taken advantage of the magnetic field inherent to the FTMS to utilize Lenz’s law for vibrational dampening. The LD-FTMS microprobe has exceptional reproducibility, which enables successive mapping sequences for depth-profiling studies.

Laser scanning gradient index optics microscope: submicrometre scale spectroscopy and imaging at cryogenic temperatures.

A laser scanning far-field optical microscope for low-temperature imaging and spectroscopy based on gradient index optics is presented. A rod-shaped gradient index microlens is used as a zero-working-distance solid immersion objective lens. The obtained lateral resolution is 310 nm of the FWHM at a wavelength of 545 nm. A laser scanning mechanism located outside an optical cryostat enables one to achieve large scanning ranges independent of temperature. The use of the microscope for submicrometre-scale spectroscopy and low-temperature photochemistry performed on molecular J aggregates in thin polymer films is presented.

Laser scanning microscope for low temperature single molecule and microscale spectroscopy based on gradient index optics

A scanning optical microscope for low temperature imaging and spectroscopy with a gradient index rod-shaped microlens as an objective lens is presented. The solid immersion effect enhances the resolution to 310 nm of the full-width at half-maximum at the wavelength of 545 nm. Laser scanning mechanism located outside an optical cryostat enables to achieve large scanning ranges independent of temperature. The performance is demonstrated at 1.6 K on single molecules of terrylene in a dodecane crystal and on molecular J aggregates in thin polymer films.

Two-year clinical experience with a computed radiography system.

Computed radiography (CR) is a radiographic imaging technology, announced in 1 981 [1], that generates a conventional radiographic image in digital form. The system has been gradually introduced into various clinical environments during the past 3 years [2, 3]. Currently, more than 80 systems are in operation, most of them in Japan. A CR system consists of two major components: (1) a reusable laser-stimulated luminescent phosphor imaging plate and (2) a scanning and recording mechanism. The imaging plate is housed inside a cassette similar to the one used in a film/screen system. Exposure to radiation causes a latent image to form on the plate. The plate is processed through a laser scanning mechanism for extracting the radiographic image, a process that is analogous to the development of a film. The extracted image can either be recorded on a lasersensitive film as an 8 x 10 in. (20.3 x 25.4 cm) or a 7 x 8.5 in. (1 7.5 x 21 .5 cm) hard copy or stored as a digital image. The latter can be archived to a digital storage device and displayed on a video monitor. Because the imaging plate has a much larger dynamic range than a film/screen receptor, CR has the potential of minimizing technical errors caused by overor underexposure as wall as lowering the radiation dose delivered to the patient. We installed the system (1) to investigate various clinical applications of this new technology, (2) to attempt to lower the radiation dose to the patient without sacrificing image quality, and (3) to use it as an image-acquisition device for our picture archiving and communication systems (PACS) [4, 5]. This report describes our experience with the system during its first 2 years in clinical practice. The Computed Radiography System and Its Accessories