Search

Increase the weld strength is main directions of development of laser welding technology. Laser solders are used to increase tensile strength of welds and reduce of tissue temperature necrosis. Soldering components interaction effect the solder tensile strength characteristics of laser welds. Tensile strengths for welds obtained using of solder various concentration BSA and SWCNT was measured. Dimensions laser solder aggregates were measured. The dependence between the dimensions of the aggregates of laser solder and the tensile strength of the weld has been revealed.

Unlike those of other ordinary laser scanning microscopies in the past, nonlinear optical laser scanning microscopy (SHG, THG microscopy) applied ultrafast laser technology which has high peak powers with relatively inexpensive, low-average-power. It short pulse nature reduces the ionization damage in organic molecules. And it enables us to take bright label-free images. In this study, we measured cell division of zebrafish egg with ultrafast video images using multimodal nonlinear optical microscope. The result shows in-vivo cell division label-free imaging with sub-cellular resolution.

Most laser scanners applications require a linear scanning function, i.e., a constant scanning speed. One of the possible and simplest methods to achieve this – for both scanners with rotational (i.e., polygonal) or oscillatory (i.e., galvanometer) mirrors – is to increase the distance between the mirror and the scanned plane. In order to achieve this, we propose and study a simple and low-cost optical configuration with two plane mirrors set at a certain adjustable angle. The multiple reflections of a laser beam on the two mirrors are considered, the number of images produced is deduced, and the total optical path is obtained. The device is considered for a dimensional measurement application, usually called an optical micrometer - in a set-up which includes the two angular mirrors between a laser scanner with oscillatory or rotational mirrors and its objective lens. This simple device increases the path of the laser beam between the scanning mirror and the lens in a compact construct. The linearity of the scanning function is thus increased, while the total size of the system is reduced – with regard to other possible set-ups. A multi-parameter analysis is proposed and briefly pointed out with regard to the characteristics of the system.

A laser processing is widely applied to cutting, drilling, welding, bending and surface treatment in industry. Lasers with a wavelength of 1 μm are mainly used and the processing is realized by melting materials. This thermal process has a high productivity but the processed surface is hard to use for precision machining. This report is focusing on two materials which are classified in wide band gap. Ablation rate was measured with a laser microscope and an optical one. Excimer laser is expected to be a useful tool for these materials

We report a new type of all-optical ultrafast laser-scanning microscopy( (at a line-scan rate of 20 MHz) based on a phenomenon called free-space angular-chirp-enhanced delay (FACED). It results in the generation of a reconfigurable array of spatiotemporally encoded virtual pulsed sources, which acts as a scanning laser beam. We demonstrate its application in high-throughput multivariate image-based single-cell analysis (10,000 cells/sec).

This paper presents preliminary results of using commercial time of flight depth camera for 3D scanning of underwater objects. Generating accurate and detailed 3D models of objects in underwater environment is a challenging task. This work presents experimental results of using Microsoft Kinect v2 depth camera for dense depth data acquisition underwater that gives reasonable 3D scanned data but with smaller scanning range. Motivations for this research are the user friendliness and low-cost of the device as compared to multi view stereo cameras or marine-hardened laser scanning solutions and equipment. Preliminary results of underwater point cloud generation and volumetric reconstruction are also presented. The novelty of this work is the utilization of the Kinect depth camera for real-time 3D mesh reconstruction and the main objective is to develop an economical and compact solution for underwater 3D scanning.

This paper presents a new object classification technique for 3D point cloud data acquired with a laser scanner. In general, it is not straightforward to distinguish objects that have similar 3D structures but belong to different categories based only on the range data. To tackle this issue, we focus on laser reflectance obtained as a side product of range measurement by a laser scanner. Since laser reflectance contains appearance information, the proposed method classifies objects based on not only geometrical features in range data but also appearance features in reflectance data, both of which are acquired by a single laser scanner. Furthermore, we extend the conventional Histogram of Oriented Gradients (HOG) so that it couples geometrical and appearance information more tightly. Experiments show the proposed technique combining geometrical and appearance information outperforms conventional techniques.

We discuss the development and application of a laser-scanning, nonlinear optical microscope capable of generating vibrationally resonant images based on sum-frequency generation (SFG), coherent anti-Stokes Raman scattering (CARS) or third-order sum-frequency generation (TSFG). The combination of these three modalities allows vibrationally sensitive imaging of both χ (2) and χ (3) -active structures in biological tissues, addressing both Raman-active as well as IR-allowed vibrational modes. We show the practical utility of these vibrationally sensitive modalities by imaging collagen I rich tissues.

In the last decades, fabrication of microlens array in materials with high-damage threshold has attracted increasing interest, especially in the application of high-power laser. In this paper, we propose an advanced strategy to efficiently fabricate microlens array on the surface of glass using a single-pulsed femtosecond laser wet etch process, which is a combination of high-speed laser scanning and the subsequent chemical etch with HF solution. Based on this method, double-sided microlens array, non-regular arrays consisting of close-packed concave microlens array on one side and regular concave MLA on the other side, were fabricated on the 1cm*1cm glass. Especially over one million microlenses could be acquired within an hour, exhibiting great superiority in practical application. Moreover, the optical properties of the asymmetric double-sided MLA were experimentally characterized, and the experimental results reveal the good light homogenization performance.

Nowadays, 3D measurement and re-construction technologies are widely used not only in industry area, but also in the appreciation and research of ancient architecture and historical relics. Many methods are used for the architecture measurement in large scale, but as for the details of architecture or precision historical relics, these methods meet difficulties. Thus, historical relic objects with specular surface or complex sculptural surface could not be measured by traditional method. Focusing on these problems, this paper proposed 3D measurement technique which contains two levels of measurement. Firstly, when measuring ancient architecture in large scale, laser scanning and photometry methods are used. Then, when measuring details of architecture, a fast and adaptive 3D measurement system is used. Multi-view registration is also used for the measurement of hollowed-out structure of sculptural relics. The experiments indicate that the system can achieve 3D measurement and re-construction of different types of ancient architecture and historical relics.

We discuss implementation of the combined node scanning SRS lidar system for high-speed and high spatial resolution (about 3 cm) scanning in wide and narrow angle at a distance of 50-100 m. Narrowband scanning is performed by the deflector moving along a spiral path. Rotating angle wedges of the deflector deviate a beam by an angle of ± 50. This design constitutes an "optical reduction" wedge between the steering angle and the deflection angle of the optical axis and allows 15 ' positioning accuracy. overview of the entire study area for no more than 1 ms at a frequency of rotation of each of the wedges of 50-200 Hz. Unambiguous definition of the geographical coordinates of the probed object is achieved by using high-precision GPS-module and the Vincenty's algorithms. It allows to build a 3D spatial distribution of concentrations of air pollutants.

We report on a technique that records and displays fluorescence lifetime images at a rate of 10 images per second. Data acquisition is based on multi-dimensional TCSPC in combination with confocal or two-photon laser scanning. The image are calculated from the TCSPC FLIM data via the first moment of the decay data in the pixels of the images. The first-moment technique combines near-ideal photon efficiency with calculation times shorter than the frame times of the commonly used galvanometer scanners. The image rate is thus not slowed down by the lifetime calculation process. Potential applications are clinical FLIM, where suspicious areas can be identified for subsequent high-accuracy imaging, and standard FLIM microscopy, where the technique it helps the user select interesting cells in a large field of view for detailed analysis.

Microscopy imaging with a single technology is usually restricted to a single contrast mechanism. Multimodal imaging is a promising technique to improve the structural information that could be obtained about a device under test (DUT). Due to the different contrast mechanisms of laser scanning microscopy (LSM), confocal laser scanning microscopy (CLSM) and optical beam induced current microscopy (OBICM), a combination could improve the detection of structures in integrated circuits (ICs) and helps to reveal their layout. While OBIC imaging is sensitive to the changes between differently doped areas and to semiconductor-metal transitions, CLSM imaging is mostly sensitive to changes in absorption and reflection. In this work we present the implementation of OBIC imaging into a CLSM. We show first results using industry standard Atmel microcontrollers (MCUs) with a feature size of about 250nm as DUTs. Analyzing these types of microcontrollers helps to improve in the field of side-channel attacks to find hardware Trojans, possible spots for laser fault attacks and for reverse engineering. For the experimental results the DUT is placed on a custom circuit board that allows us to measure the current while imaging it in our in-house built stage scanning microscope using a near infrared (NIR) laser diode as light source. The DUT is thinned and polished, allowing backside imaging through the Si-substrate. We demonstrate the possibilities using this optical setup by evaluating OBIC, LSM and CLSM images above and below the threshold of the laser source.

Holographic line-shaped femtosecond processing was developed for large-area machining. It can be performed with high throughput in laser cutting, peeling, grooving, and cleaning of materials. We demonstrated the single-shot fabrication of a line structure in a glass surface using a line-shaped pulse generated by a holographic cylindrical lens displayed on a liquid-crystal spatial light modulator, a line-shaped beam deformed three-dimensionally for showing the potential of holographic line-shaped beam processing, laser peeling of an indium tin oxide film, in-process laser cleaning of debris on the surface of a fabricating sample, and laser grooving of stainless steel.

Taking advantage of the inherent characteristics of femtosecond laser used for machining, we developed an interferometric system able to evaluate and correct the focal position with an accuracy of a few microns, implementing a technique based on low coherence interferometry. This approach measures at the exact spot that the laser is machining, in real time, and is sensitive to any sample that acts as a scatterer to the wavelength in use. The experimental evaluation was divided in two steps: in the first a system based on a superluminescent LED was mounted to check the viability and develop the controlling software; in the second part a setup was mounted employing a femtosecond laser, and several kinds of samples using the active focus control, among which the results obtained with glass sample and a bovine tooth are meticulously described in this paper. The system was able to improve the performance in both samples, keeping them in the confocal region for an extended positioning range, resulting in better engraving by the laser.

We demonstrate ultrafast time-stretch microscopy in, to the best of our knowledge, the shortest wavelength regimes, i.e. 532 nm. This is enabled by a new all-optical ultrahigh-speed laser-scanning technique called free-space angular-chirpenhanced delay (FACED) that achieves a line-scan rate as high as 20 MHz. In contrast to the predominant fiber-based implementation, time-stretch imaging based on FACED allows wavelength-independent and low-loss operations, and more intriguingly reconfigurable all-optical laser-scanning rate. Using this technique, we present high-resolution single-cell images captured in an ultrafast microfluidic flow (1.5m/s). This could unleash numerous cell and tissue imaging applications, e.g. high-throughput image flow cytometry and whole-slide imaging.

Today one of the main areas of application of two-photon microscopy is biology. This is due to the fact that this technique allows to obtain 3D images of tissues due to laser focus change, that is possible due to substantially greater penetration depth on the main wavelength into biological tissues. Self-developed microscopy system provides possibility to service it and modify the structure of microscope depending on highly specialized experimental design and scientific goals. This article may be regarded as a quick reference to laboratory staff who are wishing to develop their own microscopy system for self-service and modernization of the system and in order to save the lab budget.

Rail wear measurement is a necessary task in railway infrastructure inspection. To acquire the wear amounts accurately with more continuous scanning data, a rail wear measurement method based on structured light scanning is proposed in this paper. The CAD model of the rail is converted into a point set, and the data registration is implemented by aligning the scanning data to the point cloud generated by the CAD model. On a cross section plane of the rail, the vertical and lateral wear amounts are calculated by the nearby points projected onto the plane. To verify the accuracy of wear measurement based on structured light scanning, the wear amounts calculated by laser scanning data are compared. For the comparison, an experiment is designed to ensure that the same plane is sliced in two different kinds of measurement. On the cross section plane, the wear amounts are calculated by the distances from these points to the 2D profile of the rail CAD model, and then the results are compared with those from laser scanning data for the accuracy evaluation. It indicates that the accuracy of the structured light scanning is sufficient for railway track wear measurement.

Previous studies have established that carious lesions can be imaged with high contrast using near-IR wavelengths coincident with high water absorption, namely 1450-nm, without the interference of stains. It has been demonstrated that computer-controlled laser scanning systems utilizing IR lasers operating at high pulse repetition rates can be used for serial imaging and selective removal of caries lesions. In this study, a point-to-point scanning system was developed integrating a 1450-nm diode laser with the CO2 ablation laser. This approach is advantageous since it does not require an expensive near-IR camera. In this pilot study, we demonstrate the feasibility of a combined NIR and IR laser system for the selective removal of carious lesions.

There is a 500 billion USD world market for packaging expected to grow to a trillion in 2030. Austria plays an important role world wide for high speed laser engraving applications — especially when it comes to high end solutions. Such high end solutions are fundamental for the production of print forms for the packaging and decorating industry (e. g. cans). They are additionally used for security applications (e. g. for printing banknotes), for the textile printing industry and for creating embossing forms (e. g. for the production of dashboards in the automotive industry). High speed, high precision laser engraving needs laser resonators with very stable laser beams (400 – 800W) especially in combination with AOMs. Based upon a unique carbon fiber structure – stable within the sub-micrometer range – a new resonator has been developed, accompanied by most recent thermo-mechanical FEM calculations. The resulting beam is evaluated on an automated optical bench using hexapods, allowing to optimize the complete beam path with collimators and AOM. The major steps related to laser engraving of dry offset printing plates during the full workflow from the artists design to the printed result on an aluminum can is presented in this paper as well as laser characteristics, AOM integration and correlative CLSM and SEM investigation of the results.

Multiphoton laser scanning microscopes exhibit highly localized nonlinear optical excitation and are powerful instruments for in-vivo deep tissue imaging. Customized multiphoton microscopy has a significantly superior performance for in-vivo imaging because of precise control over the scanning and detection system. To date, there have been several flexible software platforms catered to custom built microscopy systems i.e. ScanImage, HelioScan, MicroManager, that perform at imaging speeds of 30-100fps. In this paper, we describe a flexible software framework for high speed imaging systems capable of operating from 5 fps to 1600 fps. The software is based on the MATLAB image processing toolbox. It has the capability to communicate directly with a high performing imaging card (Matrox Solios eA/XA), thus retaining high speed acquisition. The program is also designed to communicate with LabVIEW and Fiji for instrument control and image processing. Pscan 1.0 can handle high imaging rates and contains sufficient flexibility for users to adapt to their high speed imaging systems.

Intravital multiphoton microscopy has emerged as a powerful technique to visualize cellular processes in-vivo. Real time processes revealed through live imaging provided many opportunities to capture cellular activities in living animals. The typical parameters that determine the performance of multiphoton microscopy are speed, field of view, 3D imaging and imaging depth; many of these are important to achieving data from in-vivo. Here, we provide a full exposition of the flexible polygon mirror based high speed laser scanning multiphoton imaging system, PCI-6110 card (National Instruments) and high speed analog frame grabber card (Matrox Solios eA/XA), which allows for rapid adjustments between frame rates i.e. 5 Hz to 50 Hz with 512 × 512 pixels. Furthermore, a motion correction algorithm is also used to mitigate motion artifacts. A customized control software called Pscan 1.0 is developed for the system. This is then followed by calibration of the imaging performance of the system and a series of quantitative in-vitro and in-vivo imaging in neuronal tissues and mice.

Non-contact measurement techniques using 3D laser scanning have the power to deliver tremendous benefits to most notably manufacturing, and have the advantage of high speed and high detail output. However, procedures for evaluation and verification of non-contact laser line scanner have not been well-established because of many influencing factors like scan depth, incident angle, probe head orientation and surface properties. A truncated pyramid artifact representation of five- planar with different included angles was designed and used to straightforwardly identify the influence of in-plane and out-of-plane angle, as well as scan depth on dimensional measurement accuracy of the laser scanner. Then, a series of easy, fast and representative experiments, based on this simple artifact, were performed on a commercial laser line scanner, and found that the output of this scanner can be improved for metrology applications after calibration.

Single line scanning is the main method in traditional 3D hand-held laser scanning, however its reconstruction speed is very slow and cumulative error is very large. Therefore, we propose a method to reconstruct the 3D profile by parallel multi-line 3D hand-held laser scanning. Firstly, we process the two images that contain multi-line laser stripes shot by the binocular cameras, and then the laser stripe centers will be extracted accurately. Then we use the approach of stereo vision principle, polar constraint and laser plane constraint to match the laser stripes of the left image and the right image correctly and reconstruct them quickly. Our experimental results prove the feasibility of this method, which improves the scanning speed and increases the scanning area greatly.

Rail track geometric parameters measurement requires knowledge of left and right rail head location in each section. First of all displacement in transverse plane of rail head point located at a distance of 14 mm below the running surface, must be controlled [1]. It is carried out by detecting of each rail profile using triangulation laser scanners. Optical image recognition is carried out successfully in the laboratory, approaches used for this purpose are widely known. However, laser scanners operation has several features on railways leading to necessity of traditional approaches adaptation for solving these particular problems. The most significant problem is images noisiness due to the solar flashes and the effect of "Moon path" on the smooth rail surface. Using of optical filters gives inadequate result, because scanner laser diodes radiation frequency varies with temperature changes that forbid the use of narrow-band filters. Consideration of these features requires additional constructive and algorithmic solutions, including involvement of information from other sensors of the system. The specific usage of optical scanners for rail profiles control is the subject of the paper.

A small exit-pupil restricts the application of the Retinal Scanning Display (RSD) in the intelligent head-mount display (HMD). In this paper, we use the microlens array to solve this problem. A new thermal reflow process was designed and a circular-type microlens array with 70% fill factor in the form of a hexagonal close-packed arrangement by melting photoresist was prepared. The aperture size of every lens is 14μm and the period is 16μm. The gap is filled by a metal film to reflect off the beam which will not be modulated by the microlens. This achieves a more uniform exit-pupil expansion. We study the effect of different defects of the microlens array on the pupil expansion. The result shows that the NA and expansion angle of the microlens array are 0.38 and 45°, respectively.

Laser speckle on the screen of laser display system is due to the strong coherence characteristic of laser. In order to eliminate the influence of the speckle on image quality, the method of laser speckle reduction based on MEMS two-dimensional scanning mirror is proposed in this paper. The experimental results show that the speckle contrast can be reduced to 3.7%, which meets the requirement of laser display. And this system could be used in laser display field and improve the display performance.

The appearance of 3D laser scanning technology has provided a new method for the acquisition of spatial 3D information. It has been widely used in the field of Surveying and Mapping Engineering with the characteristics of automatic and high precision. 3D laser scanning data processing process mainly includes the external laser data acquisition, the internal industry laser data splicing, the late 3D modeling and data integration system. For the point cloud modeling, domestic and foreign researchers have done a lot of research. Surface reconstruction technology mainly include the point shape, the triangle model, the triangle Bezier surface model, the rectangular surface model and so on, and the neural network and the Alfa shape are also used in the curved surface reconstruction. But in these methods, it is often focused on single surface fitting, automatic or manual block fitting, which ignores the model's integrity. It leads to a serious problems in the model after stitching, that is, the surfaces fitting separately is often not satisfied with the well-known geometric constraints, such as parallel, vertical, a fixed angle, or a fixed distance. However, the research on the special modeling theory such as the dimension constraint and the position constraint is not used widely. One of the traditional modeling methods adding geometric constraints is a method combing the penalty function method and the Levenberg-Marquardt algorithm (L-M algorithm), whose stability is pretty good. But in the research process, it is found that the method is greatly influenced by the initial value. In this paper, we propose an improved method of point cloud model taking into account the geometric constraint. We first apply robust least-squares to enhance the initial value’s accuracy, and then use penalty function method to transform constrained optimization problems into unconstrained optimization problems, and finally solve the problems using the L-M algorithm. The experimental results show that the internal accuracy is improved, and it is shown that the improved method for point clouds modeling proposed by this paper outperforms the traditional point clouds modeling methods.

A low-cost confocal endoscope was developed consisting of a 3D printed laser scanner, a lens, and a housing. The developed tool, mainly made out of low cost polymer offers a disposable use. The scanner unit is overall 10x10mm and electromagnetically actuated in 2-dimensions using a magnet that is attached to the 3D printed scanner and an external miniaturized coil. Using 3D printer’s fabrication advantages the first two vibration modes of the scanner were tailored as out-of-plane displacement and torsion. The scanner employs lissajous scan, with 190 Hz and 340 Hz scan frequencies in the orthogonal directions and we were able to achieve ± 5° scan angles, respectively, with ~ 100 mA drive current. The lens which has 6-mm diameter and 10-mm focal length is 3D printed with Veroclear material and then polished in order to reach optical quality surface. Profilometer (Dektak) measurements indicate only x2 increase in rms roughness, with respect to a commercial glass lens having identical size and focal length.

PMP (Phase measuring Profilometry) is an excellent 3D online measurement method for its high precision. However, the measuring range is limited. While the rail is so long that far exceeds the measuring limit, the image stitching should be used to extent it. In this paper, based on the improved Stoilov algorithm, the rail shape is three-dimensionally reconstructed and the abrasion is detected combines image stitching. Two types of schemes are researched: (1)image stitching is firstly used on the deformed fringe patterns and then a larger range rail is constructed with Stoilov algorithm; (2)the three-dimensional construction of two fringe pattern is firstly performed, and then the constructed images are stitched into longer rail. In this paper, the improved Stoilov algorithm based on statistical approach and stitching algorithm are analyzed. 3D Peaks function is simulated to verify the two methods, and then three-dimensional rail shape is recovered based on these two methods and the rail abrasion is measured with the relative precision of higher than 0.1%, which is much higher than traditional methods, such as linear laser scanning.

Non-contact measurement techniques using laser scanning have the power to deliver tremendous benefits to most notably manufacturing, and have the advantage of high speed and high detail output. However, a major obstacle to their widespread adoption in more complex on-line producing environments is their geometric constraints and low accuracy compared to the contact-based counterparts. The work presented in this paper introduces a performance evaluation test of laser line scanning for in-process inspection of 3D geometries. Some straightforward test methods that use a designed artifact are proposed. First, one work aims to experimentally investigate the location accuracy of knee point or corner point of edge features using a commercial laser stripe scanner, which is common in mechanical parts. Another work experimentally investigates the formation of outliers that may be usually promoted by reflective surfaces around surrounding area of corner point, and these outliers are characterized with large measurement errors, which significantly deteriorate the quality of the scanned point cloud data. Scanning path planning and outlier filter design are respectively discussed.

In this work we apply a new laser scanning apparatus in multiple ways to measure various aspects of in-process and final silicon-on-insulator (SOI) wafers in high volume manufacturing (HVM). The laser scanner enables high-spatialresolution whole-wafer metrology of topographic features, film thickness variation, and two scattering channels, while bridging between 200 mm and 300 mm diameters on a single platform.

Laser shock micro-forming is a non-thermal laser forming method that use laser-induced shockwave to modify surface properties and to adjust shapes and geometry of work pieces. In this paper, we present an adaptive optical technique to engineer spatial profiles of the laser beam to exert precision control on the laser shock forming process for free-standing MEMS structures. Using a spatial light modulator, on-target laser energy profiles are engineered to control shape, size, and deformation magnitude, which has led to significant improvement of the laser shock processing outcome at micrometer scales. The results presented in this paper show that the adaptive-optics laser beam forming is an effective method to improve both quality and throughput of the laser forming process at micrometer scales.

In China, X-ray timing and polarization (XTP) observatory will have a collection area of 9,000 cm 2 at 2~6 keV. The observatory consists of five identical hard X-ray telescopes and ten identical soft X-ray telescopes. The angular resolution is about 1 arcminute of HPD (half-power diameter). Each telescope consists of a large number of mirror segments precisely assembled together. Our development of the mirror glass substrate is presented in this manuscript. These substrates are produced by slumping commercially available thin glass sheets. Here, we report on our work of manufacturing these substrates. The optimization of the slumping procedure is described and optimal procedure parameters are reported. The figure error of slumped glass substrates was measured by a laser scanner and an interferometer with CGH. The measurement demonstrated that the figure error is lower enough for the construction of XTP telescopes.

Laser line is a beam of laser, spanned in one direction using a beam shaper to form a fan of light. This illumination tool is important in laser aided machine vision, 3D scanners, and remote sensing. For some applications the laser line should have a specific angular power distribution. If the distribution is nonsymmetrical, the beam shaper is required to be nonsymmetrical freeform, and its design process using optical design software is time consuming due to the long optimization process which usually converges to some local minimum. In this paper we introduce a new design method of a single element refractive beam shaper of any predefined general 1D angular power distribution. The method makes use of a notion of "prism space", a geometrical representation of all double refraction prisms, and any 1D beam shaper can be described by a continuous curve in this space. It is shown that infinitely many different designs are possible for any given power distribution, and it is explained how an optimal design is selected among them, based on criteria such as high transmission, low surface slopes, robustness to manufacturing errors etc. The method is non-parametric and hence does not require initial guess of a functional form, and the resultant optical surfaces are described by a sequence of points, rather than by an analytic function.

High-Throughput Phenotyping (HTP) is a discipline for rapidly identifying plant architectural and physiological responses to environmental factors such as heat and water stress. Experiments conducted since 2010 at Maricopa, Arizona with a three-fold sensor group, including thermal infrared radiometers, active visible/near infrared reflectance sensors, and acoustic plant height sensors, have shown the validity of HTP with a tractor-based system. However, results from these experiments also show that accuracy of plant phenotyping is limited by the system’s inability to discriminate plant components and their local environmental conditions. This limitation may be overcome with plant imaging and laser scanning which can help map details in plant architecture and sunlit/shaded leaves. To test the capability for mapping cotton plants with a laser system, a track-mounted platform was deployed in 2015 over a full canopy and defoliated cotton crop consisting of a scanning LIDAR driven by Arduinocontrolled stepper motors. Using custom Python and Tkinter code, the platform moved autonomously along a pipe-track at 0.1 m/s while collecting LIDAR scans at 25 Hz (0.1667 deg. beam). These tests showed that an autonomous LIDAR platform can reduce HTP logistical problems and provide the capability to accurately map cotton plants and cotton bolls. A prototype track-mounted platform was developed to test the use of LIDAR scanning for High- Throughput Phenotyping (HTP). The platform was deployed in 2015 at Maricopa, Arizona over a senescent cotton crop. Using custom Python and Tkinter code, the platform moved autonomously along a pipe-track at

Precise topographical information has a very important role in geology, hydrology, natural resources survey and deformation monitoring. The extracting DEM technology based on synthetic aperture radar interferometry (InSAR) obtains the three-dimensional elevation of the target area through the phase information of the radar image data. The technology has large-scale, high-precision, all-weather features. By changing track in the location of the ground radar system up and down, it can form spatial baseline. Then we can achieve the DEM of the target area by acquiring image data from different angles. Three-dimensional laser scanning technology can quickly, efficiently and accurately obtain DEM of target area, which can verify the accuracy of DEM extracted by GBInSAR. But research on GBInSAR in extracting DEM of the target area is a little. For lack of theory and lower accuracy problems in extracting DEM based on GBInSAR now, this article conducted research and analysis on its principle deeply. The article extracted the DEM of the target area, combined with GBInSAR data. Then it compared the DEM obtained by GBInSAR with the DEM obtained by three-dimensional laser scan data and made statistical analysis and normal distribution test. The results showed the DEM obtained by GBInSAR was broadly consistent with the DEM obtained by three-dimensional laser scanning. And its accuracy is high. The difference of both DEM approximately obeys normal distribution. It indicated that extracting the DEM of target area based on GBInSAR is feasible and provided the foundation for the promotion and application of GBInSAR.

Neptec Technologies Corp. has developed a family of obscurant-penetrating 3D laser scanners (OPAL 2.0) that are being adapted for airborne platforms for operations in Degraded Visual Environments (DVE). The OPAL uses a scanning mechanism based on the Risley prism pair. Data acquisition rates can go as high as 200kHz for ranges within 240m and 25kHz for ranges exceeding 240m. The scan patterns are created by rotating two prisms under independent motor control producing a conical Field-Of-View (FOV). An OPAL laser scanner with 90° FOV was installed on a Navajo aircraft, looking down through an aperture in the aircraft floor. The rotation speeds of the Risley prisms were selected to optimize a uniformity of the data samples distribution on the ground. Flight patterns simulating a landing approach over snow and ice in an unprepared Arctic environment were also performed to evaluate the capability of the OPAL LiDAR to map snow and ice elevation distribution in real-time and highlight potential obstacles. Data was also collected to evaluate the detection of wires when flying over water, snow and ice. Main results and conclusions obtained from the flight data analysis are presented.

LIDAR has become the inevitable technology to provide accurate 3D data fast and reliably even in adverse measurement situations and harsh environments. It provides highly accurate point clouds with a significant number of additional valuable attributes per point. LIDAR systems based on Geiger-mode avalanche photo diode arrays, also called single photon avalanche photo diode arrays, earlier employed for military applications, now seek to enter the commercial market of 3D data acquisition, advertising higher point acquisition speeds from longer ranges compared to conventional techniques. Publications pointing out the advantages of these new systems refer to the other category of LIDAR as "linear LIDAR", as the prime receiver element for detecting the laser echo pulses - avalanche photo diodes - are used in a linear mode of operation. We analyze the differences between the two LIDAR technologies and the fundamental differences in the data they provide. The limitations imposed by physics on both approaches to LIDAR are also addressed and advantages of linear LIDAR over the photon counting approach are discussed.

The purpose of this study is to present and evaluate the benefit and capabilities of high resolution 3D data from unmanned aircraft, especially in conditions where existing methods (passive imaging, 3D photogrammetry) have limited capability. Examples of applications are detection of obscured objects under vegetation, change detection, detection in dark or shadowed environments, and an immediate geometric documentation of an area of interest. Applications are exemplified with experimental data from our small UAV test platform 3DUAV with an integrated rotating laser scanner, and with ground truth data collected with a terrestrial laser scanner. We process lidar data combined with inertial navigation system (INS) data for generation of a highly accurate point cloud. The combination of INS and lidar data is achieved in a dynamic calibration process that compensates for the navigation errors from the lowcost and light-weight MEMS based (microelectromechanical systems) INS. This system allows for studies of the whole data collection-processing-application chain and also serves as a platform for further development. We evaluate the applications in relation to system aspects such as survey time, resolution and target detection capabilities. Our results indicate that several target detection/classification scenarios are feasible within reasonable survey times from a few minutes (cars, persons and larger objects) to about 30 minutes for detection and possibly recognition of smaller targets.

A 3-D Monte Carlo ray-tracing simulation of LiDAR propagation models the reflection, transmission and ab- sorption interactions of laser energy with materials in a simulated scene. In this presentation, a model scene consisting of a single Victorian Boxwood ( Pittosporum undulatum ) tree is generated by the high-fidelity tree voxel model VoxLAD using high-spatial resolution point cloud data from a Riegl VZ-400 terrestrial laser scanner. The VoxLAD model uses terrestrial LiDAR scanner data to determine Leaf Area Density (LAD) measurements for small volume voxels (20 cm sides) of a single tree canopy. VoxLAD is also used in a non-traditional fashion in this case to generate a voxel model of wood density. Information from the VoxLAD model is used within the LiDAR simulation to determine the probability of LiDAR energy interacting with materials at a given voxel location. The LiDAR simulation is defined to replicate the scanning arrangement of the Riegl VZ-400; the resulting simulated full-waveform LiDAR signals compare favorably to those obtained with the Riegl VZ-400 terrestrial laser scanner.

The single aperture implementation of laser radars in combination with beam scanning solutions enables low cost, compact and efficient laser systems for 3D acquisition. The design benefits include the lack of dead zones, improved stability and compact footprint for the system implementation. In our presentation we focus on the scanning solution development for 3D laser radars that is based on all solid state magneto-optic design. The novel solid-state scanner implementation results are presented. Keywords Laser radar, eye safe, 3D, range finder 1. INTRODUCTION The use of 3D capable laser radars for drone vision and driverless cars is quickly changing the ranged sensors field. The use of 2D beam scanning solutions in combination with the high repetition ranging for laser radars delivers 3D acquisition capability [1] (see Figure 1). Mechanical means of beam steering for the laser radars have a number of limitations that include slow scanning speed, mechanical inertia and limited lifetime

In recent years, three-dimensional (3D) terrestrial laser scanning technologies with higher precision and higher capability are developing rapidly. The growing maturity of laser scanning has gradually approached the required precision as those have been provided by traditional structural monitoring technologies. Together with widely available fast computation for massive point cloud data processing, 3D laser scanning can serve as an efficient structural monitoring alternative for civil engineering communities. Currently most research efforts have focused on integrating/calculating the measured multi-station point cloud data, as well as modeling/establishing the 3D meshes of the scanned objects. Very little attention has been spent on extracting the information related to health conditions and mechanical states of structures. In this study, an automated numerical approach that integrates various existing algorithms for geometric identification and damage detection of structural elements were established. Specifically, adaptive meshes were employed for classifying the point cloud data of the structural elements, and detecting the associated damages from the calculated eigenvalues in each area of the structural element. Furthermore, kd-tree was used to enhance the searching efficiency of plane fitting which were later used for identifying the boundaries of structural elements. The results of geometric identification were compared with M3C2 algorithm provided by CloudCompare, as well as validated by LVDT measurements of full-scale reinforced concrete beams tested in laboratory. It shows that 3D laser scanning, through the established processing approaches of the point cloud data, can offer a rapid, nondestructive, remote, and accurate solution for geometric identification and damage detection of structural elements.

A 3D printer is a device which can directly produce objects whose shape is the same as the original 3D digital data. Hydrogels have unique properties such as high water content, low frictional properties, biocompatibility, material permeability and high transparency, which are rare in hard and dry materials. These superior characteristics of gels promise useful medical applications. We have been working on the development of a 3D gel printer, SWIM-ER (Soft and Wet Industrial – Easy Realizer), which can make models of organs and artificial blood vessels with gel material. However, 3D printing has a problem: the mechanical properties of the printed object vary depending on printing conditions, and this matter was investigated with SWIM-ER. In the past, we found that mechanical properties of 3D gel objects depend on the deposition orientation in SWIM-ER. In this study, gels were printed with different laser scanning speeds. The mechanical properties of these gels were investigated by compression tests, water content measurements and SMILS (Scanning Microscopic Light Scattering).

This paper presents a damage visualization technique using a fully noncontact laser ultrasonic measurement system and a synchronized scanning strategy. The noncontact laser ultrasonic measurement system is composed of a Q-switched Nd:YAG laser for ultrasonic wave generation and a laser Doppler vibrometer (LDV) for ultrasonic wave detection. The laser beams for ultrasonic wave generation and detection are shot on the target structure with a constant and tiny distance, and these two laser beams are synchronously moved over the scanning area. Compared with conventional laser scanning strategies, the ultrasonic responses detected through the synchronized scanning strategy owns a much higher and more stable signal to noise ratio and the scanning time can be significantly reduced with less time averaging. By spatial comparison in the scanning area, damage can be detected and visualized without relying on baseline data obtained from the pristine condition of the target structure. In this paper, the developed technique is validated by visualization hidden corrosion in a steel straight pipe and a steel elbow pipe.

Laser engraving is used for decades as a well-established process e. g. for the production of print and embossing forms for many goods in daily life, e. g. decorated cans and printed bank notes. Up to now it is more or less a so-called fire-and-forget process. From the original artist’s plan to the digitization, then from the laser source itself (with electronic signals, RF and plasma discharge regarding CO 2 lasers) to the behavior of the optical beam delivery — especially if an AOM is used — to the interaction of the laser beam with the material itself is a long process chain. The most recent results using CO 2 lasers with AOMs and the research done with scanning electron microscope (SEM) and confocal laser scanning microscope (CLSM) — as a set for correlative microscopy to evaluate the high speed engraving characteristics — are presented in this paper.

One- and two-dimensional MEMS scanning mirrors for resonant or quasi-stationary beam deflection are primarily known as tiny micromirror devices with aperture sizes up to a few Millimeters and usually address low power applications in high volume markets, e.g. laser beam scanning pico-projectors or gesture recognition systems. In contrast, recently reported vacuum packaged MEMS scanners feature mirror diameters up to 20 mm and integrated high-reflectivity dielectric coatings. These mirrors enable MEMS based scanning for applications that require large apertures due to optical constraints like 3D sensing or microscopy as well as for high power laser applications like laser phosphor displays, automotive lighting and displays, 3D printing and general laser material processing. This work presents modelling, control design and experimental characterization of gimbal-less MEMS mirrors with large aperture size. As an example a resonant biaxial Quadpod scanner with 7 mm mirror diameter and four integrated PZT (lead zirconate titanate) actuators is analyzed. The finite element method (FEM) model developed and computed in COMSOL Multiphysics is used for calculating the eigenmodes of the mirror as well as for extracting a high order (n < 10000) state space representation of the mirror dynamics with actuation voltages as system inputs and scanner displacement as system output. By applying model order reduction techniques using MATLABR a compact state space system approximation of order n = 6 is computed. Based on this reduced order model feedforward control inputs for different, properly chosen scanner displacement trajectories are derived and tested using the original FEM model as well as the micromirror.

We report a novel method to manipulate the direction of a laser beam by controlling the thickness of a dielectric elastomer. The system is controlled by applying different voltages to multi-layers of dielectric elastomers without mechanical movement. We employed laser beams with different wavelengths to test the proposed system, and the experimental results showed that it has an excellent transmittance profile in the ultraviolet and visible wavelength bands, and that we achieved high-precision control in the micrometer range. The results show the feasibility of this technique for laser applications that require high positional accuracy, such as laser cutting, drilling machines, and 3D printing.

Depth super-resolution is becoming popular in computer vision, and most of test data is based on indoor data sets with ground-truth measurements such as Middlebury. However, indoor data sets mainly are acquired from structured light techniques under ideal conditions, which cannot represent the objective world with nature light. Unlike indoor scenes, the uncontrolled outdoor environment is much more complicated and is rich both in visual and depth texture. For that reason, we develop a more challenging and meaningful outdoor benchmark for depth super-resolution using the state-of-the-art active laser scanning system.

Mobile laser scanning (MLS) t echnologies have been actively studied and im plemented over the past decade, as their application fields are rapidly expanding and extending be yond conventional topographic mapping. Trimble’s MX-8, as one of the MLS systems in the current ma rket, generates rich survey-grade laser and image data for urban surveying. The objective of this study is to evalua te whether Trimble MX-8 MLS data satis fies the accuracy requirements of urban surveying. According to the formula of geo-referencing, accuracies of navigati on solution and laser scanner determines the accuracy of the collected LiDAR point clouds. Two test sites were selected to test the performance of Trimble MX-8. Those extensive tests confirm that Trimble MX-8 offers a very promising tool to survey complex urban areas Index Terms —Mobile laser scanning, Trimble MX-8, Positional accuracy, point accuracy