Plane Of Laser Light Research Articles

A Practical Calibration Method for Stripe Laser Imaging System

This article presents a new practical calibration method of a stripe laser imaging system for the 3-D shape measurement of an object. The proposed calibration method has an integrated mathematical approach for the camera imaging parameters and the stripe laser light plane. A simple calibration block with a checkerboard pattern attached is used that has different inclination angle at each face. Because the same scene with the laser light ON and OFF is used for the integrated calibration of the camera and the laser light plane, the calibration process is fast and efficient and the resultant calibration parameters are consistent. The experimental results demonstrated the performance of the proposed calibration method.

Welding Seam Detection and Tracking Based on Laser Vision for Robotic Arc Welding

The welding robots are widely employed in the manufacturing field. In order to measure up to the developing need of automation and intelligent production, real-time welding process sensing and controlling are necessary, in which the welding seam detection and tracking is representative task. Among the kinds of sensors applied in the robotic welding process, vision sensors is one of the most widely used for automatic welding seam tracking and quality control in robotic arc welding. This paper is to present a new framework and the data process algorithm of the sensor. A novel two-step calibration approach is proposed in this paper based on the “Calibration toolbox in Matlab”, the proposed approach acquires the laser light plane by project the linear stripe on the calibration pattern plate during camera calibration process. Experiment result indicates that the fitting error of the detected 3D point data of the weld groove is less than 0.1mm. The tracking error in robotic welding process is no more than 0.2mm. Which is acceptable for robotic welding system.

ПРОЕКЦІЙНО-РАСТРОВІ МЕТОДИ РЕЄСТРАЦІЇ ПЕРЕТИНІВ ПОВЕРХНІ ЛОКАЛЬНИХ ОБ'ЄКТІВ

In work is solved the problem of visualizing terrain contour lines on the surface of the volume bodies. Modern methods andmeans of digital photogrammetry represent a real opportunity to return to the previously known analog methods of visualization,real-time monitoring, analysis and evaluation of the surface shape of the local volume bodies. the Essence of these methodsconsists in designing a linear raster digital projector or laser light plane on the object and the real-time monitoring and, ifnecessary, photographing localized on the family member contour and processing using modern software and hardware anddigital technology. This technique was used quite successfully in the study of local objects of small size in many applicationareas of applied photogrammetry: architecture and construction, studying of monuments of historical and cultural heritage, ship,air, auto, construction, medicine, etc. the paper presents circuits and analysis of their application with the shooting design oflinear raster parallel beam by moving the light plane, the Central design of the raster, the mathematical apparatus of calculationof parameters of acquisition and the results of the survey of the surface of the cone, the blades, and sculptures. The generalizedformulas allow you to select the shooting options of objects to perform calculations and get the dimensions and a graphicalmodel of the contour surfaces.This article is intended for students and teachers in the field of knowledge Architecture and engineering and professionalsworking in the field of application of modern methods of applied photogrammetry.

Underwater Laser Triangulation Sensor Model With Flat Refractive Interfaces

Underwater 3-D measurement has many applications, for example, in the oil and gas industry, archeology, and biology. Systems with laser triangulation sensors (LTSs) are being currently used underwater, even though they face some strong environment influences. Among these challenging influences are poor image quality and refraction, due to optical window interfaces between water and air inside the camera chamber. The refraction effect can be modeled knowing the distance from the camera pinhole center to the surface of refraction, the axis of refraction, the refractive index of the mediums, and the thickness of the optical window. This paper analyses a method for underwater LTS measurement using real experiments. The proposed method is based on the pinhole camera model, a refraction modeling, and a fitted mathematical plane for the projected laser light plane. After the in-air calibration, a step standard is measured underwater and the window distance from the camera is optimized. The method is evaluated according to guidelines for optical systems evaluation (VDI/VDE 2634).

Bending sucks for lampreys

![Figure][1] A lamprey swimming in a plane of laser light. Photo credit: Sean Colin. Wriggling is a dependable swimming mode for a select band of aquatic species. From fish larvae and tadpoles to the gyrating motions of eels and lampreys, these sinuous swimmers appear to scythe through

Experimental Proof of Mass in Photon

The present work deals with the mass of photon which creates a force at the contact point of reflection resulting in slight deviation of photon from its path after reflection. Only the mass of photon can cause deviation due to inertial force. If photon has no mass, it cannot deviate. It is also found that this deviation of photon depends on the angle of polarization plane of laser light with respect to reflecting mirror. Such variation in the angle of deviation by the plane of polarization proves that the mass of photon is neither in the centre of photon nor distributed uniformly but located off-centre (away from the centre of photon). This work proves that photon has mass and the most important part of this work is to discover that the mass of the photon is located off-centre (away from the centre of photon). This discovery explains Wave Particle Duality of electromagnetic radiations.

Dynamic deflectometry: A novel approach for the on-line reconstruction of specular freeform surfaces

The dynamic inspection and reverse engineering of specular freeform surfaces is a challenge so far largely unsolved. Products produced in high quantities in industrial environments are still inspected manually which is labour intensive, expensive, monotonous and subjective. We propose a novel deflectometric hardware setup and methodology to overcome this shortfall. The reflection of a line laser from a moving specular surface is captured on a translucent screen. The resulting complex line provides detailed data about the surface gradients at the intersection of the laser light plane and the surface but cannot create correspondence between points of reflections and surface points. The latter is inherent in a traditional active light scanning setup whose data alone will, for specular surfaces, be subject to high levels of noise. We propose a novel method that by simulation of the reflection fuses the two data sets to allow digitalising moving specular surfaces with the high slope sensitivity of deflectometric methods.

3D Slit Scanning with Planar Constraints★

Abstract We present a planarity constraint and a novel three‐dimensional (3D) point reconstruction algorithm for a multiview laser range slit scanner. The constraint is based on the fact that all observed points on a projected laser line lie on the same plane of laser light in 3D. The parameters of the plane of laser light linearly parametrize a homography between a pair of images of the laser points. This homography can be recovered from point correspondences derived from epipolar geometry. The use of the planar constraint reduces outliers in the reconstruction and allows for the reconstruction of points seen in only one view. We derive an optimal reconstruction of points subject to the planar constraint and compare the accuracy to the suboptimal approach in prior work. We also construct a catadioptric stereo rig with high quality optical components to remove error due to camera synchronization and non‐uniform laser projection. The reconstruction results are compared to prior work that uses inexpensive optics and two cameras.

Laser assisted ultrasound guided aspiration improves procedure time and reduces number of withdrawals

This study evaluated the performance of in-vitro freehand aspiration of a simulated cyst with ultrasound aspiration guided by a newly designed laser assisted (LA) device. The LA device was equipped with an adjustable light source generating a sector light plane. This laser light plane was parallel to and overlapped the ultrasound acoustical plane, to help with needle positioning. Five operators randomly performed 30 freehand or LA ultrasound guided aspirations of a simulated cyst. The frequency was set at 8 MHz and depth at 4 cm. Procedure time and number of syringe withdrawals were statistically compared before and after using the LA device. Both experienced and inexperienced operators required significantly less time to perform the aspiration and had fewer syringe withdrawals when using the LA device. The LA device provides a reference plane in space, allowing the operator to more accurately position and adjust needle direction. Additional in-vivo testing is required to test the clinical practicability.

DORSAL FIN STABILISES TROUT

Keeping on the straight and narrow is significantly more complicated for fish than insects; coordinating as many as seven fins is a much more complex task than the two wings most insects have to bother about. How fish propel themselves through water has puzzled people for a long time. Only recently have scientists begun unravelling the complex fluid dynamics generated by each fin as fish scythe through the currents. More recently George Lauder at Harvard University, working with his colleague Elliot Drucker, have turned their attention to a fin whose role might be less obvious. They wondered how the dorsal fin contributes to a fish's comings and goings. Having studied the sunfish's dorsal fin several years before, they suspected that the trout's dorsal fin was also essential for high speed swimming. But the team were surprised when they found that trout use their dorsal fins less and less as they speed up, and when they looked closer, realised that instead of helping to propel the fish forward, the dorsal fin seemed to stabilise the fish in the water (p. 4479).Lauder's technique of choice to investigate fish fluid dynamics is DPIV. Focusing a thin plane of laser light into a flow tank filled with microscopic reflective beads, the team encouraged the fish to swim at a constant speed so that their body or fins intersected the plane of light, while filming the swirls and vortices generated by their fins visible in the laser light. But this is where DPIV becomes less of a science and more of an art. Lauder admits that the main quality you need for success with this technique is limitless patience. He and Drucker remember spending hours cajoling the timid trout to perform in front of the cameras, but eventually the team had enough data to begin analysing the fish's dorsal fin.Swimming the fish at a range of slow and high speeds, the team quickly realised that the fish used their dorsal fin most when swimming at slow speeds, with the fin hardly moving at all once the fish were cruising at a high speed of 2 total body lengths per second. And when they calculated the forces generated by the fin at different speeds, they realised that it didn't contribute to the fish's forward thrust at all. The fin seemed to be producing a large sideways force at low speeds that diminished as the fish cruised at higher speeds. Lauder and Drucker realised that the dorsal fin was stabilising the fish rather than helping to propel it forwards, which is in complete contrast to what they found when they looked at the sunfish's spiny dorsal fin; that seemed to contribute significantly to the fish's forward momentum. Lauder suspects that the support offered to the sunfish's dorsal fin by its spines help propel the fish forward.Most surprisingly, Lauder and Drucker have identified a new `gait' which they call M-BCF and is distinct from median paired fin gait (MPF) and body caudal fin (BCF) gait. In this new gait, the fish combine dorsal fin oscillations with movements of the body and tail fin at low speeds. The team also suggest that this new gait may be part of a natural progression between the two previously identified and distinct gaits. But Lauder admits that future work on other fish species will be needed to test this idea.

A Rapid Calibration Method for the Laser Scanning 3D Measurement System

A rapid calibration method for the parameters of a laser light plane scanning 3D measurement system is proposed. The mathematic model and the calibrated parameters of the measurement system are presented. A novel orthogonal calibration jig composed of two orthogonal planes is designed. The CCD camera parameters and the light plane parameters of the measurement system can be rapidly calibrated with the orthogonal calibration jig. The laser scanning 3D measurement system is calibrated with the calibration jig. A standard plane is measured at different positions. The accuracy is better than 0.1mm.

Three-dimensional ocean chlorophyll distributions from underwater serial-sectioned fluorescence images

An underwater optical serial-sectioning technique is developed to measure in situ three-dimensional distributions of biological particles. The technique involves scanning of a thin plane of laser light through a range of distances parallel to the imaging plane of a digital CCD camera. Images of induced fluorescence in the sequentially illuminated planes are recorded. An inverse method is then used to reconstruct three-dimensional chlorophyll a distributions from the plane images. Computer simulations of the image formation and reconstruction process indicate that the underwater optical serialsectioning technique is practical for in situ determination and analysis of chlorophyll a microstructures for concentrations as low as 0.1 mg of chlorophyll a per cubic meter in 1--m(3) water volumes.

Measurements of large streamwise vortices in an open‐channel flow

The moving‐bed flume, where the cross‐sectional mean velocity is zero, has proven to be useful for visualization of coherent structures in the flow, especially streamwise vortices with a size scale equal to the depth. The temporal mean of these streamwise vortices is turbulence driven secondary motion. Hydrogen bubbles illuminated by a plane of laser light are used to visualize and measure these vortices. Flow visualization at the zero mean velocity point provides a unique view of the streamwise vortices without the interference of the mean flow velocity.