Determination of the Influence of Laser Welding Parameters on the Weld Quality Assurance of Heat-Resistant Alloys

In this study, the method of determining the influence of laser welding parameters on the quality provisions of welded joints made with multicomponent heat-resistant alloys was developed. The regularities of the formation of the welded joint structure of multicomponent heat-resistant alloys obtained by laser welding have been studied. The causes and methodological approaches to eliminate defects in the form of hot cracks were identified. Keywords: laser welding, multicomponent alloys, heat-resistant alloys, welded joints, quality

LASER IN PERIODONTOLOGY- A REVIEW

Lasers are used in implant and periodontal field practices. Laser has various periodontal applications including calculus removal, decontamination of root and implant surfaces and bio stimulation, incision and ablation, osseous surgery, excision of the soft tissue, and bacterial reduction. There is a strong evidence that laser is used for surgical and nonsurgical periodontal therapies including root bio modification, bacterial decline and decontamination of infected implant surface, and removal of the pocket epithelium.Waterlase® and Periowave™ systems are recent devices that have further revolutionized the laser technology for its favorable clinical applications; however, the procedural cost with the laser device constitutes an obstacle for its routine application. Keywords: laser, biomodulation, fluorencence, LANAP

Structure and mechanical properties of surface layers of structural and tool steels formed by laser alloying with carbide-forming elements and boron

The research results of the process of laser alloying of structural and tool steels with different chemical elements are presented. Keywords: laser alloying, microstructure, hardness, diffusion, carbides, convective mixing, solid solutions. [email protected]

ELECTRON DENSITY SPECTROSCOPIC MEASUREMENT IN AL LASER INDUCED PLASMA

Plasma generated by a 1064 nm pulsed Nd: YAG laser with pulse duration of 10 ns concentrated onto an Al solid target under vacuum pressure was examined spectroscopically. The temperature and electron density specifying the plasma were measured by time-resolved spectroscopy of neutral atom and ion line emissions in the time period range of 300–2000 ns. An echelle spectrograph is utilized to appear the plasma emission lines. The temperature was obtained using the spectral line comparison method and the electron density was calculated using the Stark Broadening (SB) method. The electron density was characterized as a function of laser pulse energy. The time range where the plasma is optically thin and is also in local thermodynamic equilibrium (LTE), significant for the laser-produced plasma (LPP) which was evaluated from the temporal profile of the intensity ratio of two Al I lines (λ1=380.581nm, 398.014nm, and 393.1996nm), (λ2= 586.781nm). It is found to be 700–1000 ns. Keywords: Laser Induced Plasma, Spectrometer, Electron Density, Plasma Physics, And Plasma Plume.

Application of laser"shock"wave treatment to increase crack resistance of materials

A finite element model is developed for predicting the appearance of new and the propagation of existing cracks during laser-shock-wave treatment (LSWT) of materials with linear and V-shaped cracks. The optimal modes of LSWT were determined for the maximum reduction in the rate of crack propagation. Keywords laser-shock-wave treatment, finite element method, residual stresses, stress intensity factor, crack growth rate, crack resistance. [email protected]

POLARIZATION MICROSCOPIC TOMOGRAPHY OF THE POLYCRYSTALLINE STRUCTURE OF VITREOUS BODY PREPARATIONS IN DIAGNOSTICS TIME OF THE SINCE DEATH

Purpose of the study. Develop a complex of new forensic objective criteria to enhance the functionality of accurate definition time of the since death (TSD) estimation according to polarization microscopic tomography of the polycrystalline structure of human vitreous body (VB). Materials and methods. The object of study is polycrystalline VB layers taken from 56 people who died from cardiovascular disease with known time of death ranged from 3 to 36 h. Measuring parameter distributions of birefringence of the polycrystalline component of VB preparations were carried out with a standard Stokes-polarimeter. Results. The time dynamics of the magnitude of the set of statistical moments of the 1–4th order, which characterize the distributions of the birefringence of the polycrystalline component of the VB layers at different TSD values were investigated. The sensitivity range of the method of polarization tomography of the distributions of the birefringence of the polycrystalline component of the VB layers was determined (24 h), with the accuracy of TSD estimation – 20 min. The efficiency of wavelet analysis of the distribution of the magnitude of the birefringence layers of human VB layers at different TSD values is demonstrated. Scale-selective analysis has been shown to increase the sensitivity range up to 36 h while increasing the accuracy of TSD determination to 15 min. Conclusion. The efficiency of the method of polarization microscopic tomography of the polycrystalline structure of human VB preparations in the determination of TSD is demonstrated. Sensitivity ranges method up to 36 h was determined with an accuracy of up to 15 min. Keywords: laser polarimetry, time since death, vitreous body.

MAPPING OF AZIMUTHS OF POLARIZATION OF LASER MICROSCOPIC IMAGES OF HISTOLOGICAL SECTIONS OF HUMAN RGANS IN THE DIFFERENTIATION OF POISONING BY ETHANOL AND CARBON MONOXIDE

Purpose of the study. This work is aimed at research and substantiation of information possibilities of objective method of polarization mapping of microscopic images of histological sections of human biological tissues for the establishment and differentiation of С2Н5ОН and CO poisoning. Materisls and methods. Native histological sections of the brain, myocardium and adrenal glands from ethanol poisoning (n = 30) and CO (n = 20) were investigated using a laser polarimeter of standard scheme. Subsequently, statistical processing of the obtained results was conducted. Results. Statistical moments of 1–4th order were determined by the method of polarization mapping of microscopic images of histological sections of human biological tissues. The values of the statistical moments of the 1–4th order for brain tissue for С2Н5ОН and CO poisoning reach differences by 2–2,5 times, for myocardial tissue – 2,2–2,9 times, the adrenal glands – 1,4–1,8 times. Accordingly, the statistical moments of the 3rd and 4th order are more sensitive to the detection and differentiation of poisons, whereby the accuracy of the method of differential diagnosis of poisoning С2Н5ОН and CO reaches an adequate level (~ 90%) in the study of histological sections of the myocardium and brain. Conclusion. The obtained results show that the method of polarization mapping of microscopic images of human biological tissues gives an objective possibility of reliable establishment and differentiation of С2Н5ОН and СО poisoning. Keywords: laser polarimetry, poisoning, ethanol, carbon monoxide, forensic medicine.

ЛАЗЕРНЫЙ ДЕФОРМОГРАФ С ФОРМИРОВАНИЕМ КВАДРАТУРНЫХ СИГНАЛОВ

В данной работе приведены некоторые результаты разработки, создания и использования регистрирующих систем для длиннобазовых лазерных деформографов и других измерительных приборов, созданных на его основе. В качестве источника излучения используется частотностабилизированный лазер с длиной волны 633 нм. Приведено описание регистрирующей системы лазерного деформографа с использованием квадратурных сигналов, позволяющей достигать высокой чувствительности (L/L 1010), способной регистрировать колебания высокой частоты (до 4 кГц), имеющей высокую надежность. Представлены результаты испытаний данной системы и ее работы в составе измерительного комплекса. Ключевые слова: лазер, интерферометр, лазерный деформограф.This article gives a brief overview of results achieved in process of design, developing and using of data acquisition systems for LSM (longbase strainmeters) and other devices based on laser interferometers. А frequencystabilized 633 nm laser is used as a light source. The data acquisition system of homodyne quadrature LSM was described, and main characteristics of the instrument are: high sensivity (L/L 1010), high sample rate (up to 4 kHz), high reliability. Trial records and experimental data obtained in measuring complex were processed and some results are presented. Keywords: laser, interferometer, laser strainmeter.

Purwarupa Alat Kalibrasi Kerataan Bidang Kerja menggunakan Laser Sensor

ABSTRAKSalah satu elemen teknologi pendukung dari industri manufaktur elektronika adalah mesin Die Attach. Mesin ini digunakan pada proses assembly komponen dengan metode pick and place komponen pada material. Sebagai proses yang penting dalam industri manufaktur, mesin ini memerlukan kalibrasi secara reguler dan tepat yang akan menjadi kunci sukses dari kualitas suatu produksi. Penelitian ini bertujuan membuat suatu purwarupa alat yang digunakan sebagai pengontrol kalibrasi dengan menggunakan laser sensor. Proses kalibrasi dilakukan dengan cara mengukur kerataan titip sisi work holder menggunakan laser sensor. Kerataan didapatkan dengan membandingkan jarak yang terukur oleh laser sensor pada tiap titik uji. Jarak yang sama pada tiap titik uji menunjukkan kerataan dari work holder. Pergerakan laser sensor dikontrol oleh dua buah motor yang bergerak ke arah sumbu X dan Y. Alat ini telah diuji dengan mengkalibrasi pada empat sisi work holder. Hasil pengujian kemudian dibandingkan dengan pengukuran manual dan didapatkan error rata-rata pengukuran sekitar 4%.Kata kunci: Laser sensor, kerataan, kalibrasi, die attach machine ABSTRACTOne of the element technology supporting an industrial manufacturing is Die Attach machine. This machine is used at component assembly using component pick and place. As an important process, this machine requires regular and precise calibration to support quality of the product. This research aims to build a prototype system using laser sensor which can be used as calibration instrument. The callibration proses was done by measuring the flatness of each side of work holder using laser sensor. The flatness was obtained by comparing the distance of each testing point. The same distance on each testing point represented the flatness of the wrok holder. The movement of laser sensor was controlled by two motors which moved to X and Y axis. The system has been tested to calibrate each side of work holder. The experimental results were then compare with manual measurement and showed the measurement error about 4%.Keywords: Laser sensor, flatness, callibration, die attach machine.

PENGGUNAAN LASER ARGON SEBAGAI FOTOKOAGULASI LASER DALAM TERAPI PENYAKIT PERDARAHAN RETINA DI BEBERAPA TEMPAT PELAYANAN KESEHATAN MATA

Laser has been used for treating retinal hemorrhage. Argon is still used for photocoagulation. This study aimed to determine the use of Argon laser photocoagulation in retinal hemorrhage. This was a retrospective descriptive study carried out by using secondary data from the medical record of patients. The results showed that laser photocoagulation was mostly applied to female patients with age range between 40-60 years old. The amount of laser was <500 shots, particularly for retinal hemorrhage caused by Proliferatif Diabetic Retinopathy (PDR).Keywords: Laser photocoagulation, Argon laser, retinal hemorrhageAbstrak : Sinar laser digunakan sebagai terapi pada pasien dengan penyakit perdarahan retina. Untuk fotokoagulasi masih sering digunakan laser Argon. Penelitian ini bertujuan untuk mengetahui penggunaan laser Argon sebagai fotokoagulasi pada perdarahan retina. Penelitian ini bersifat deskriptif retrospektif dengan menggunakan data rekam medik pasien sebagai data sekunder. Hasil penelitian memperlihatkan bahwa fotokoagulasi laser paling banyak dilakukan pada pasien wanita. Dari segi usia terbanyak didapati pada kisaran usia 40-60 tahun. Tembakan laser yang sering diberikan yaitu dengan dosis < 500 tembakan, dan lebih khusus diterapkan pada perdarahan retina dengan penyebab Proliferatif Diabetic Retinopathy (PDR) atau retinopati diabetik proliferatif.Kata Kunci: Fotokoagulasi laser, laser argon, perdarahan retina