Application of Three-dimensional Laser Scanning Technology in the Teaching Practice of Surveying and Mapping of Ancient Buildings

Based on the study of the application of three-dimensional laser scanning technology in ancient building surveying and mapping,this paper briefly describes the working principle and flow of three-dimensional laser scanning technology.Based on the practical application,this paper puts forward the discussion of related problems and matters needing attention.This has a certain reference significance for the study of new technology in surveying and mapping of ancient buildings.

Research on 3D Laser Scanning Reconstruction of Ancient Buildings Combined with BIM Technology

After more than 30 years of scientific and social development, surveying and mapping technology by leaps and bounds, engineering surveying technology has undergone tremendous changes. In the process of protecting ancient buildings, it is necessary to obtain the precise dimensions of architectural details. In this study, the path of 3D laser scanning combined with BIM technology is explored. Taking the observation and protection of the ancestral hall of the Liu family as an example, this study aims to draw drawings that reflect the relevant information about the ancient buildings, the accurate three-dimensional model of ancient buildings is established with BIM technology, which provides new methods and ideas for the research and protection of ancient buildings. .

Three-dimensional printing technology for patient-matched instrument in treatment of cubitus varus deformity:A case report

BACKGROUND Recently,medical three-dimensional printing technology(3DPT)has demonstrated potential benefits for the treatment of cubitus varus deformity(CVD)by improving accuracy of the osteotomy through the use of an osteotomy guide,with or without a patient-mated plate.Here,we present an interesting CVD case,involving a patient who was treated with corrective biplanar chevron osteotomy using an innovative customized osteotomy guide and a newly designed patient-matched monoblock crosslink plate created with 3DPT.CASE SUMMARY A 32-year-old female presented with a significant CVD from childhood injury.A computer simulation was processed using images from computerized tomography scans of both upper extremities.The biplanar chevron osteotomy was designed to create identical anatomy between the mirror image of the contralateral distal humerus and the osteotomized distal humerus.Next,the customized osteotomy guide and patient-matched monoblock crosslink plate were designed and printed.A simulation osteotomy was created for the real-sized bone model,and the operation was performed using the posterior paratricipital approach with k-wire positioning from the customized osteotomy guide as a predrilled hole for screw fixation to achieve immediate control of the reduction after osteotomy.Our method allowed for successful treatment of the CVD case,significantly improving the patient’s radiographic and clinical outcomes,with satisfactory result.CONCLUSION 3DPT-created patient-matched osteotomy guide and instrumentation provides accurate control during CVD correction.

Application and Analysis of Computer Virtual Simulation Technology in Three-dimensional Animation Production

With the continuous promotion of computer technology, the application system of virtual simulation technology has been further optimized and improved, and has been widely used in various fields of social development, such as urban construction, interior design, industrial simulation and tourism teaching. China's three-dimensional animation production started relatively late, but has achieved good results with the support of related advanced technology in the process of development. Computer virtual simulation technology is an important technical support in the production of three-dimensional animation. In this paper, firstly, the related content of computer virtual simulation technology was introduced. Then, the specific application of this technology in the production of three-dimensional animation was further elaborated, so as to provide some reference for the improvement of the production effect of three-dimensional animation in the future.

Application Status and Prospect of Three-Dimensional Printing Technology in the Field of Medical Devices

Three-dimensional(3D)printing technology belongs to a new manufacturing science and has been widely used in various fields of industry.This article will apply 3D printing technology as its main research topic,with emphasis on its application in the field of medical devices and prospects for contribution.

Digital measurement of bone tumor volume by CT three-dimensional reconstruction technology

Objective To discuss the measurement of bone tumor volume on the basis of three dimensional images segmentation technology. Methods Twenty patients with lacunar bone tumor from Tianjin Hospital and Tongji Hospital were included in the

Slope excavation quality assessment and excavated volume calculation in hydraulic projects based on laser scanning technology

Slope excavation is one of the most crucial steps in the construction of a hydraulic project. Excavation project quality assessment and excavated volume calculation are critical in construction management. The positioning of excavation projects using traditional instruments is inefficient and may cause error. To improve the efficiency and precision of calculation and assessment, three-dimensional laser scanning technology was used for slope excavation quality assessment. An efficient data acquisition, processing, and management workflow was presented in this study. Based on the quality control indices, including the average gradient, slope toe elevation, and overbreak and underbreak,cross-sectional quality assessment and holistic quality assessment methods were proposed to assess the slope excavation quality with laserscanned data. An algorithm was also presented to calculate the excavated volume with laser-scanned data. A field application and a laboratory experiment were carried out to verify the feasibility of these methods for excavation quality assessment and excavated volume calculation. The results show that the quality assessment indices can be obtained rapidly and accurately with design parameters and scanned data, and the results of holistic quality assessment are consistent with those of cross-sectional quality assessment. In addition, the time consumption in excavation quality assessment with the laser scanning technology can be reduced by 70%e90%, as compared with the traditional method. The excavated volume calculated with the scanned data only slightly differs from measured data, demonstrating the applicability of the excavated volume calculation method presented in this study.

Development of an In-Situ Laser Machining System Using a Three-Dimensional Galvanometer Scanner

In this study, a three-dimensional (3D) in-situ laser machining system integrating laser measurement and machining was built using a 3D galvanometer scanner equipped with a side-axis industrial camera. A line structured light measurement model based on a galvanometer scanner was proposed to obtain the 3D information of the workpiece. A height calibration method was proposed to further ensure measurement accuracy, so as to achieve accurate laser focusing. In-situ machining software was developed to realize time-saving and labor-saving 3D laser processing. The feasibility and practicability of this in-situ laser machining system were verified using specific cases. In comparison with the conventional line structured light measurement method, the proposed methods do not require light plane calibration, and do not need additional motion axes for 3D reconstruction;thus they provide technical and cost advantages. The insitu laser machining system realizes a simple operation process by integrating measurement and machining,which greatly reduces labor and time costs.

A 15 Gbps-NRZ, 30 Gbps-PAM4, 120 mA laser diode driver implemented in 0.15-μm GaAs E-mode pHEMT technology

This paper presents the design and testing of a 15 Gbps non-return-to-zero(NRZ),30 Gbps 4-level pulse amplitude modulation(PAM4)configurable laser diode driver(LDD)implemented in 0.15-μm GaAs E-mode pHEMT technology.The driver bandwidth is enhanced by utilizing cross-coupled neutralization capacitors across the output stage.The output transmission-line back-termination,which absorbs signal reflections from the imperfectly matched load,is performed passively with on-chip 50-Ωresistors.The proposed 30 Gbps PAM4 LDD is implemented by combining two 15 Gbps-NRZ LDDs,as the high and low amplification paths,to generate PAM4 output current signal with levels of 0,40,80,and 120 mA when driving 25-Ωlasers.The high and low amplification paths can be used separately or simultaneously as a 15 Gbps-NRZ LDD.The measurement results show clear output eye diagrams at speeds of up to 15 and 30 Gbps for the NRZ and PAM4 drivers,respectively.At a maximum output current of 120 mA,the driver consumes 1.228 W from a single supply voltage of-5.2 V.The proposed driver shows a high current driving capability with a better output power to power dissipation ratio,which makes it suitable for driving high current distributed feedback(DFB)lasers.The chip occupies a total area of 0.7×1.3 mm^(2).

New Progress on All Solid State Laser Technology in China

1 Significance of All Solid State Laser (DPL) Technology in Field of LaserBecause of the advantages of high conversion efficiency, good beam quality, small size and light weight, DPL becomes the hotspot and priority of development of laser technology. It may be the main body of laser in the future and replace gas laser and liquid laser. It is a great revolution of laser technology.The developed countries vie in developing DPL. China has achieved great success in this field, but there is a wide gap between the developed countries and us. We should attach great importance to it.

Recent Research and Development Status of Relaxed Optics and Laser Technology: A Review

It is shown that for laser technologies it was necessary to create a new branch of physics: Relaxed Optics (synthesis of methods of the physical optics, quantum electronics, physical chemistry, physics of irreversible phenomena in unitary system). It is allowed to explain complex chain processes of interaction light and matter. Possible applications of Relaxed Optical methods for the modeling of the laser-induced processes phenomena, including laser implantation (surface and subsurface processes), laser-induced optical breakdown (volume processes) and laser annealing of radiation and other defects in solid, are discussed. Perspectives of using these methods for the creation of new laser technologies, including creation new types of optoelectronic devices (heterostructures, diffraction lattices, etc.), resolution the problems of metallurgy, material science, painting, architecture and a building, are analyzed.

Preface to the special issue on laser processing and micro-nano technology

In 2022, coinciding with the 20th anniversary of the School of Physics and Electronics at Central South University, we plan to publish the special issue “Laser processing and micro-nano technology” in the Journal of Central South University, which aims to commemorate the 20th anniversary of the school and comprehensively present the latest achievement in the fields of laser processing and micro-nano technology to domestic and foreign universities.

Three-dimensional Deposition of Silicon Structure from Silicate Glass with Dispersed Metallie Muminum by Femtosecond Laser Irradiation

We fabricated a silicon structure in silicate glass prepared with metallic aluminum in the starting material, using femtosecond laser irradiation. Small Si-rich structures such as Si clusters were transformed into larger, but still nano-sized, Si particles by laser irradiation. These structures grew to microsize particles due to the thermite reaction promoted by heat treatment. We determined the effect of focused laser pulses on the Si deposition process using the time-resolved transient lens method. Localized high-temperature, high-pressure, and the generation of shock waves appear to be very important in forming the Si-rich structures that ultimately grow into Si particles.

Blood–brain barrier and laser technology for drug brain delivery

Here,we discuss an important problem in medicine as development of efctive strategies for brain drug delivery.This problem is related to the blood-brain barrier(BBB),which is a“customs”controlling the entrance of different molecules from blood into the brain protecting the normal function of central nervous system(CNS).We show three interfaces of anatomical side of BBB and two functional types of BBB一physical and transporter barriers.Although this protective mechanism is essential for health of CNS,it also creates a hindrance to the entry of drugs into the brain.The BBB was discovered over 100 years ago but till now,there is no efective methods for brain drug delivery.There ane more than 70 approaches for overcoming BBB incuding physical,chenical and biological techniques but all of these tools have limitation to be widely used in clinical practice due to invasi venes,challenge in performing,very costly or lim-itation of drug concentration.Photodynamic therapy(PDT)is usual clinical method of surgical navigation for the resection of brain tumor and anti-cancer therapy.Nowadays,the application of PDT is considered as a potential promising tool for brain drug delivery via opening of BBB.Here,we show the first sucoessful experimental results in this field discussing the adventures and disadv antages of PDT-related BBB disruption as well as altematives to overcome these limitations and possi ble mechanisms with new pathways for brain clearance via gly mphatic and lymphatic systems.

A fast and precise three-dimensional measurement system based on multiple parallel line lasers

This paper conducts a trade-off between efficiency and accuracy of three-dimensional(3 D)shape measurement based on the triangulation principle,and introduces a flying and precise 3 D shape measurement method based on multiple parallel line lasers.Firstly,we establish the measurement model of the multiple parallel line lasers system,and introduce the concept that multiple base planes can help to deduce the unified formula of the measurement system and are used in simplifying the process of the calibration.Then,the constraint of the line spatial frequency,which maximizes the measurement efficiency while ensuring accuracy,is determined according to the height distribution of the object.Secondly,the simulation analyzing the variation of the systemic resolution quantitatively under the circumstance of a set of specific parameters is performed,which provides a fundamental thesis for option of the four system parameters.Thirdly,for the application of the precision measurement in the industrial field,additional profiles are acquired to improve the lateral resolution by applying a motor to scan the 3 D surface.Finally,compared with the line laser,the experimental study shows that the present method of obtaining 41220 points per frame improves the measurement efficiency.Furthermore,the accuracy and the process of the calibration are advanced in comparison with the existing multiple-line laser and the structured light makes an accuracy better than 0.22 mm at a distance of 956.02 mm.

Research on wind erosion processes and controlling factors based on wind tunnel test and 3D laser scanning technology

The study of wind erosion processes is of great importance to the prevention and control of soil wind erosion.In this study,three structurally intact soil samples were collected from the steppe of Inner Mongolia Autonomous Region,China and placed in a wind tunnel where they were subjected to six different wind speeds(10,15,17,20,25,and 30 m/s)to simulate wind erosion in the wind tunnel.After each test,the soil surfaces were scanned by a 3D laser scanner to create a high-resolution Digital Elevation Model(DEM),and the changes in wind erosion mass and microtopography were quantified.Based on this,we performed further analysis of wind erosion-controlling factors.The study results showed that the average measurement error between the 3D laser scanning method and weighing method was 6.23%for the three undisturbed soil samples.With increasing wind speed,the microtopography on the undisturbed soil surface first became smooth,and then fine stripes and pits gradually developed.In the initial stage of wind erosion processes,the ability of the soil to resist wind erosion was mainly affected by the soil hardness.In the late stage of wind erosion processes,the degree of soil erosion was mainly affected by soil organic matter and CaCO_(3)content.The results of this study are expected to provide a theoretical basis for soil wind erosion control and promote the application of 3D laser scanners in wind erosion monitoring.

Innovations in Retinal Laser Technology

Retinal laser photocoagulation is a proven, effective treatment for various retinal disorders, including diabetic retinopathy, retinal vein occlusions, and sickle cell retinopathy. To minimize iatrogenic retinal damage while maintaining therapeutic effects, retinal laser technology has evolved significantly since its introduction in ophthalmology more than half a century ago. These innovations have included both optimizations of laser parameters in addition to the development of novel laser delivery systems. This review summarizes recent innovations in retinal laser technology, including subthreshold micropulse laser, selective retinal therapy and nanosecond laser, innovative modes of laser delivery including pattern scanning laser, endpoint management, navigated laser, and newly described photo-mediated ultrasound therapy.

Controlling Three-Dimensional Electron-Electron Correlation via Elliptically Polarized Intense Laser Field

The three-dimensional electron-electron correlation in an elliptically polarized laser field is investigated based on a semiclassical model. Asymmetry parameter α of the correlated electron momentum distribution is used to quantitatively describe the electron-electron correlation. The dependence of α on elliptieity e is totally different in three directions. For the z direction （maJor polarization direction）, α first increases and reaches a maximum at ε = 0.275, then it decreases quickly. For the y direction in which the laser field is always absent, the ellipticity has a minor effect, and the asymmetry parameter fluctuates around α = -0.15. However, for the x direction （minor polarization direction）, α increases monotonously with ellipticity though starts from the same value as in the y direction when ε = 0. The behavior of α in the x direction actually indicates a transformation from the Coulomb interaction dominated correlation to the laser field dominated correlation. Therefore, our work provides an efficient way to control the three-dimensional electron electron correlation via an elliptically polarized intense laser field.

A Single Mode Hybrid Ⅲ-Ⅴ/Silicon On-Chip Laser Based on Flip-Chip Bonding Technology for Optical Interconnection

A single mode hybrid Ⅲ-Ⅴ/silicon on-chip laser based on the flip-chip bonding technology for on-chip optical interconnection is demonstrated. A single mode Fabry-Perot laser structure with micro-structures on an InP ridge waveguide is designed and fabricated on an InP/AIGaInAs multiple quantum well epitaxial layer structure wafer by using i-line lithography. Then, a silicon waveguide platform including a laser mounting stage is designed and fabricated on a silicon-on-insulator substrate. The single mode laser is flip-chip bonded on the laser mounting stage. The lasing light is butt-coupling to the silicon waveguide. The laser power output from a silicon waveguide is 1.3roW, and the threshold is 37mA at room temperature and continuous wave operation.

Fabrication of 32 Gb/s Electroabsorption Modulated Distributed Feedback Lasers by Selective Area Growth Technology

A 32 Gb/s monolithically integrated electroabsorption modulated laser is fabricated by selective area growth technology. The threshold current of the device is below 13mA. The output power exceeds 10mW at 0V bias when the injection current of the distributed feedback laser is 100mA at 25℃. The side mode suppression ratio is over 50 dB. A 32Gb/s eye diagram is measured with a 3.SVpp nonreturn-to-zero pseudorandom modulation signal at -2.3 V bias. A clearly opening eyediagram with a dynamic extinction ratio of 8.01 dB is obtained.