Laser Imaging Technology Research Articles

Continuous-wave degenerate cavity laser for optical imaging in scattering media.

Lasers play a significant role in optical communication, medical, and scientific research, owing to their high brightness and high coherence. However, the high spatial coherence will lead to specific challenges, such as speckle noise in imaging and wavefront distortion during propagation through scattering media. Here, a continuous-wave (cw) degenerate cavity laser (DCL) with low spatial coherence is demonstrated with efficient suppression of the thermal lensing effect from the gain crystal. Experimentally, a cw degenerate laser output with about 2000 transverse modes corresponding to a speckle contrast of about 0.0224 is achieved. This laser can be used for speckle reduction and is robust against atmospheric turbulence, which may find applications in the field of laser imaging technology and illumination.

Mask-guided deep learning fishing net detection and recognition based on underwater range gated laser imaging

In this paper, a mask-guided deep learning fishing net detection and recognition method based on underwater range gated laser imaging is proposed. Range gated laser imaging technology is used to obtain high quality underwater fishing net images with less water backscattering effect and background noise. A dual-phase training strategy including mask-guided feature extraction phase and classification finetune phase is proposed to avoid overfitting of training the neural network. The mask-guided feature extraction phase takes advantages of image segmentation training from synthetic dataset to get a better feature extraction performance. The highest overall accuracy of the proposed method reaches 95.49% in fishing net classification task under finetuned weight configuration. The proposed method can effectively help unmanned underwater vehicles and robots from entangling by fishing nets as well as retrieving derelict fishing nets for marine environment protection.

Impact of blur on 3D laser imaging: Monte-Carlo modelling for underwater applications.

3D laser imaging technology could allow visualizing objects hidden in turbid water. Such a technology mainly works at short distances (<50 m) because of the high attenuation of light in water. Therefore, a significant part of the scattering events from the water column is located out of the optical depth of field (DoF), which could induce optical blur on images. In this study, a model is proposed to represent such an optical blur, based on geometric optics. The model is then implemented in a Monte-Carlo scheme. Blur significantly affects the scattered signal from water before the DoF in monostatic conditions, but has less impact in bi-static conditions. Furthermore, it is shown that blur enables a very large variance reduction of 2D images of objects situated within the DoF. Such an effect increases with the extinction coefficient.

Evaluation of Bridge Approach Slab and Dynamic Load Allowance Using Sub-mm 3D Laser Imaging Technology

Evaluation of Bridge Approach Slab and Dynamic Load Allowance Using Sub-mm 3D Laser Imaging Technology

Issue Information

New PhytologistVolume 239, Issue 1 p. 1-4 Cover and Issue InformationFree Access Issue Information First published: 01 June 2023 https://doi.org/10.1111/nph.18241AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Graphical Abstract Cover Legend Seeing plants in a new light: novel laser imaging technology enables rapid data acquisition in full color. Image shows the woody stem of Gnetum woodsonianum created using Laser Ablation Tomography (LATscan). Image courtesy of Benjamin Hall (Cunha Neto et al., pp. 429–444). Volume239, Issue1July 2023Pages 1-4 RelatedInformation

Macrotexture deterioration for micromilled tunnel concrete pavement using 3D laser data

To ensure driving safety and cost effectively preserve pavements, unlike the traditional grooving, cutting joints, highway tunnels used micromilling resurfacing method to improve the skid resistance of concrete pavement. The sensor measured texture depth (SMTD) has been established for quantitatively evaluating micromilled surface quality. This paper explores the possibility of using three-dimensional line laser imaging technology to obtain the ‘full lane’ elevation data of the pavement, then through the calculation of the index SMTD, construct a road surface spatial and temporal deterioration model, and provide quality control covering the whole lane, and identify the problem areas. The results show that the road wear condition gradually worsens with the increase in opening time, after 24 months, the proportion of the good level (>0.55 mm) of the three cells is 70.5%, 75.1%, and 70.2%. Analysis of the test data for three cells revealed that the tunnel pavement shows canalization in wear. The most severely abraded section is offset by 200–300 mm toward the roadway median compared to the theoretical vehicle wheel track zone. Subsequent studies can expand the experimental conditions and consider more influencing factors to study further the texture deterioration of the micromilled pavement.

Deep-learning based non-contact method for assessing pavement skid resistance using 3D laser imaging technology

ABSTRACT Traditional contact and water-based testing devices exhibit some limitations in evaluating pavement skid resistance. This study demonstrates the viability of deep learning (DL) based non-contact pavement skid resistance evaluation using 3D laser imaging technology. Pavement 3D images and friction numbers were collected from 28 field sites in 10 states in the U.S. to cover pavement sections with various texture and friction characteristics. A total number of 28,000 pairs of 3D images and friction numbers were prepared as the database to train and validate the friction prediction model, named as FrictionNet-V, using the convolutional neural network. The input of FrictionNet-V is the 3D pavement image from the left wheel path, and the output is the corresponding friction number ranging from 0.2 to 0.9. Based on the experimental results on 5,600 testing images, FrictionNet-V achieved better performance than other DL models in terms of speed and accuracy. The result demonstrates the potential of highway speed non-contact pavement skid resistance evaluation using high resolution 3D texture images and DL methods at the network level in the future.

Nondestructive Bridge Deck Evaluation Using Sub-mm 3D Laser Imaging Technology at Highway Speeds

Nondestructive Bridge Deck Evaluation Using Sub-mm 3D Laser Imaging Technology at Highway Speeds

Preliminary Study of Novel 0.1 Mm 3d Laser Imaging Technology for Pavement Safety Evaluation

Preliminary Study of Novel 0.1 Mm 3d Laser Imaging Technology for Pavement Safety Evaluation

An unsupervised automatic measurement of wheat spike dimensions in dense 3D point clouds for field application

An accurate measurement of field-grown wheat traits, including spike number, dimension and volume are essential for crop phenotyping and yield analysis. A high-throughput method to image field-grown wheat in three dimensions is presented with an accompanying unsupervised measuring method to obtain individual wheat spike data. Images are captured using four structured light scanners on a field mobile platform, creating dimensionally accurate sub-millimetre resolution 3D point clouds for a 4.5 m 3 volume in less than 10 s. The unsupervised method analyses each trial plot's 3D point cloud, containing hundreds of wheat spikes, calculating the average size of the wheat spike and total spike volume per plot. The analysis utilises an adaptive k -means algorithm with dynamic perspectives, to fit each spike's shape and measures the dimensions with a random sample consensus algorithm. The method generates small cuboids to fit all the wheat spikes and estimate the total spikes volume. Experimental results show that the proposed algorithm is a reliable tool for identifying spikes from wheat crops and identifying individual spikes. Compared with the manual measurement, according to the results of five scenes, the average error rate in the number of spikes, spikes' height and spikes' width in tests were 16.27%, 5.24% and 12.38% respectively. • Laser imaging technology for automatic field phenotyping application. • High-throughput field capture platform was constructed. • Unsupervised algorithm allows for wheat dimensions measurement in 3D point clouds. • Automatic measurement can estimate wheat spike size, volume and number of spikes. • Framework was evaluated by comparing the experiment with manual measurement.

An Alchemy of DNA: Exploring the Chemistry of Biology through Bioart

Abstract This statement is a reflection by artist Anna Dumitriu on her residency with biochemist Robert K. Neely at the University of Birmingham, which led to the creation of The Chemistry of Biology: An Alchemy of DNA, a sculptural and bio-digital installation that premiered at Birmingham Open Media in October 2017. Their project explored the chemical nature of DNA, the enigmatic “instruction book of life” through new super-resolution laser imaging technologies using fluorescent molecules, enabling them to physically observe a region of DNA containing a scarless CRISPR edit to a bacterial genome, building on an earlier project, Make Do and Mend.

Aggregate Characteristics-Based Preventive Maintenance Treatments for Optimized Skid Resistance of Pavements

Skid resistance of pavements plays a significant role in roadway safety. Preventive maintenance (PM) treatments have been used to restore pavement condition and retard future deterioration. As aggregate is the main component of such treatments, this study assessed the skid resistance of pavements in Oklahoma following PM treatment application to evaluate whether skid resistance is maintained or improved and economics are optimized, and presents a methodology to assist pavement engineers manage skid resistance. The 13 commonly used sources of aggregates in Oklahoma were acquired for aggregate morphological characterization in the laboratory in relation to shape, angularity, and surface texture-related index properties, using the Aggregate Imaging System before and after Micro-Deval abrasion. Accordingly, a systematic experimental design was developed to include 45 field testing sites constructed with typical Oklahoma PM treatments and the common aggregate sources. Multiple rounds of field data collection were performed during a 3-year period using the most recent three-dimensional (3D) laser imaging technology for pavement surface characteristics and a Grip Tester for skid resistance. The impacts of aggregate properties and pavement surface characteristics on the skid resistance were investigated and used to develop statistical deterioration models. Subsequently, life cycle cost analysis and performance-based sensitivity analysis were conducted using the developed deterioration model. This study presents a detailed analysis of aggregate characteristics and its relationship to skid resistance of pavements. An understanding of these relationships and application of the presented methodology can result in improvements in pavement safety with enhanced stewardship of financial resources.

Live Detection Technology of SF6 Equipment Based on Computer Aided Laser Imaging Technology

To overcome the limitations of traditional methods for detecting gas leakage for SF6 equipment, such as staff safety being endangered and poor reliability of power supply, this paper introduces the laser imaging technology for gas live detection of SF6 equipment. Through discussing an example of SF6 gas leakage detection, it is shown that the SF6 gas leakage detection method based on computer aided laser imaging technology can be long-distance live detection, and can determine the SF6 gas leakage point safely, quickly and efficiently[1]. It guarantees the safety of personnel, improves the efficiency of maintenance, reduces the time of power failure, and improves the reliability of power supply.

Feature characterization of scarring and non‐scarring types of alopecia by multiphoton microscopy

Non-invasive visualization of hair follicles is important for proper diagnosis and management of alopecia; however, histological assessment remains the gold standard. Laser imaging technologies have made possible noninvasive in vivo evaluation of skin and hair follicle. The aim of this study was to evaluate the ability of multiphoton microscopy (MPM) to non-invasively identify morphological features that can distinguish scarring from non-scarring alopecia. MPM images were obtained from areas on the scalp affected by alopecia. Investigators blinded to the diagnosis analyzed hair follicle and shaft sizes. Patients were recruited and imaged at the UC Irvine Health Medical Center and the University of California, Irvine Beckman Laser Institute. Patients with androgenetic alopecia (AGA) and alopecia areata (AA), and scarring alopecia, in particular frontal fibrosing alopecia (FFA) were recruited and imaged from July 2016 to July 2017. We imaged 5 normal scalp subjects and 12 patients affected by non-scarring (7 subjects) and scarring (5 subjects) alopecia. In normal and non-scarring alopecia patients, MPM identified presence of sebaceous glands associated with hair follicles. MPM images of scarring alopecia were characterized by the presence of inflammatory cells surrounding hair follicles. Measurements of hair follicle diameter sizes were found to be significantly smaller in scarring alopecia patients compared to normal (P < 0.001) and compared to non-scarring alopecia patients (P = 0.046); non-scarring hair follicles were also significantly smaller than normal hair follicles (P = 0.043). This study shows that MPM imaging can non-invasively identify morphological features that distinguish scarring from non-scarring alopecia. Further studies are needed to validate this technique and evaluate its potential to be used as an aid for guiding treatment. Lasers Surg. Med. 51:95-103, 2019. © 2018 Wiley Periodicals, Inc.

A robust tissue laser platform for analysis of formalin-fixed paraffin-embedded biopsies.

Laser emission-based detection and imaging technology has attracted significant interest in biomedical research due to its high sensitivity, narrow linewidth, and superior spectral and spatial resolution. Recent advances have further revealed the potential to use laser emission to investigate chromatin dynamics, as well as to diagnose cancer tissues based on nuclear biomarkers. To move the laser emission based detection technology a step further towards practical use, in this work, we developed a highly robust tissue laser platform by microfabricating an SU8 spacer with a fixed height on the top mirror of the Fabry-Pérot (FP) cavity, which allows generation of reproducible and stable lasing results regardless of tissue thickness. Then we applied this platform to achieve lasing emission from formalin-fixed, paraffin-embedded (FFPE) lung tissues, which account for an overwhelming fraction of tissues collected for research and clinical use worldwide. We further showed that the cancer and normal FFPE lung tissues can be distinguished by their respective lasing thresholds. Two different tissue thicknesses (10 μm and 5 μm) commonly used in pathological labs were explored. Finally, we tested three additional types of tissues (colon, stomach, and breast) that were prepared independently by lab technicians in a pathology lab in China and shipped to the US in order to validate the general applicability and practicality of the laser emission-based technology as well as the corresponding sample preparation protocol and the tissue laser platform. Our work will not only vastly broaden the applications of laser emission-based detection/imaging technology but also help translate it from the laboratory to an automated system for clinical practice that may eventually benefit biomedicine and biological research.

基于盖革APD阵列的微扫描激光成像技术

基于盖革APD阵列的微扫描激光成像技术

Measurement of wavenumber of wall-thinned plate using spatial local wavenumber filtering

The surface of a shell-type structure can generate cracks or wall-thinning due to corrosion, etc. Those can eventually lead to the fracture of the structure, which can trigger enormous fatality and property loss. Thereby, a laser imaging technology on such structures as thin plate structureor piping whose thickness is relatively thin in comparison to the area, has been steadily studied for the past 10 years. The most typical among the laser imaging technology is the pulse laser imaging. By using the same, a new technology for inspecting and imaging a desired area within a relatively short period of time was developed, so as to scan various structures including the thin-plate structure and piping. However, this method builds image by measuring waves reflected from defects, and has a time delay of a few milliseconds at each scanning point. Moreover, complexityof the systems is so high due to additional components such as laser focusing parts. This paper proposes laser imaging method with increased scanning speed based on excitation and measurement of standing waves in structures. It is shown that defects in a structure can be visualized bygenerating standing waves with single frequency and scanning the waves at each point by the laser scanning system suggested in this work. To quantitatively evaluate thickness of a plate, wavenumber is calculated by acoustic wavenumber spectroscopy, and relationship between wavenumber and thickness of the plate is established by Rayleigh-Lamb frequency equation. The proposed technique is validated by wall-thinned plates that have constant wall loss and a linear thickness variation wall loss.

Field Monitoring of the Long Term Pavement Performance (LTPP) Warm-Mix Asphalt (WMA) Site in Oklahoma

As Warm-Mix Asphalt (WMA) moves into mainstream use, the lower WMA production temperature and injection of water in some WMA technologies have raised concerns on how it may affect short- and long-term field performance over the design life. Under the Long Term Pavement Performance (LTPP) Specific Pavement Study 10 (SPS-10) experiment initiative, the Oklahoma Department of Transportation (ODOT) constructed six testing sections with five different WMA methodologies and one HMA control section. This paper presents the application of several art-of-the-state high speed instruments to collect comprehensive array of pavement performance data for long term performance monitoring of this site. The newly developed 3D laser imaging technology is used to collect 1mm 3D surface data for the evaluation of pavement surface distress and transverse profiling for rutting. Longitudinal profiling for roughness and macro-texture for safety are acquired via a high speed inertial profiler, while pavement friction is continuously collected using a Grip Tester. Four data collection events have been performed since the construction of the site. Data collected on the WMA sections and the control HMA section are compared and evaluated for surface performance deterioration. It is demonstrated that the WMA sites using various technologies exhibit better or comparable performance relative to the conventional HMA, in terms of pavement cracking, rutting, and roughness. Aggregate properties and mixture design significantly impact the pavement macro-texture and skid resistance properties.

Effectiveness and performance of high friction surface treatments at a national scale

Although high friction surface treatment (HFST) has been widely installed in recent years, validation efforts considering various materials, installation ages, environmental conditions, and traffic levels are missing primarily due to lacking of high-speed data collection instruments. Utilizing laser imaging technology and fixed-slip friction tester, this study collects comprehensive pavement surface data at 21 HFST sites in 11 states at highway speeds. Measurements on HFST and untreated pavements are compared to determine the effectiveness of HFST. Multivariate analyses are conducted to investigate the impacts of factors on HFST friction. Average temperature and installation age are identified as the significant factors. The HFST sites constructed using calcined bauxite aggregates exhibit better friction performance than those using flints. Subsequently, friction models are developed to aid highway agencies in managing HFST.

Forward model for cranial laser tomography system

Biomedical laser imaging technologies focuse light distribution in tissue media. Light distrubutes as photon energy in a volume voxel. Photon energies are generated as a forward model. In this work, forward model weight matrix functions are provided for a noncontact cranial laser tomography device. Laser tomography systems were designed to image brain injuries which are intracerebral bleeding cases in emergency clinics and ambulances. Continuous wave diffuse optical tomography (CWDOT) relies on diffuse photon migrations, which can be used to detect, localize and characterize optical and dynamic spatial abnormalities, in turbid media. This work focuses on improving a translational 2D to 3D method for CWDOT devices. The 2D Monte Carlo (MC) simulation generates forward model weight matrix functions for brain tissues. Forward model weight matrix functions are generated according to the mapping of photon energies from 2D MC simulation (ANSI C) to 3D image reconstruction environment (MATLAB™). Forward model concepts have potential for better image reconstruction and high blood volume localization performance.