Lyubomir Lazov

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• Doctor of Engineering
• Researcher at Rezekne Academy of Technologies

Laser Surface Hardening (LSH) is an advanced technique applicable to a wide range of metals and alloys in modern industrial manufacturing, including the automotive sector. Among the various laser types used for hardening, CO₂, solid-state Nd: YAG, and fibre lasers have traditionally been the most common. However, with the development of high-power...

Determination of preliminary operating intervals of power density is the first step in optimizing laser technological processes for AISI 316 stainless steel. The study focuses on the laser technological processes of laser marking, laser cutting, and laser welding. Based on the heat conduction equation and the heat balance equation, calculations wer...

This publication examines two principal techniques of fibre laser marking on copper and brass substrates, focusing on the achievement of both dark and white (light) markings. It investigates the effects of marking speed, power density, frequency, and raster pitch on marking contrast. The study identifies the power density threshold that distinguish...

This study investigates the laser marking of graphene-modified KM2-440 ballistic Kevlar fabric, exploring how different laser parameters affect its properties. A 1x4 matrix was marked on the fabric using the SUNTOP ST-CC9060 laser system, with each square measuring 30 mm in length and 40 mm in width. Our adjustments to the laser marking parameters...

Theoretical numerical calculations and numerical experiments with the Temperaturfeld3D software were carried out for laser marking with a fiber laser of AISI 304 stainless steel samples. The theoretical numerical experiments are based on the interrelation of the quantities affecting the technological process, obtained from the heat conduction equat...

The surface treatment for product marking indicates a significant impact on the recognition of a product by an electronic reader for both the manufacturer and the end customer. This is achieved by receiving a unique code, which must be robust and durable over time. This paper investigates the influence of technological parameters speed, raster step...

Abstract — In this subsequent investigation, we expand upon our initial research by delving into the laser engraving and marking of Grade 2 Titanium (Ti Gr 2) using frequencies of 300 kHz and 700 kHz. Building upon our preliminary experiments involving 100 kHz and 500 kHz, we utilized the Rofin PowerLine F 20 Varia fiber laser to mark Grade 2 titan...

Laser color marking on stainless steel is an advanced technique for producing durable, high-contrast colors on metal surfaces. This article explores recent advancements in laser technology, focusing on optimizing laser parameters and refining oxidation techniques to enhance color formation and stability. By using diverse laser sources such as nanos...

The aim of this research is to achieve a high-quality and long-lasting laser marking of ammunition, which is of interest to the defense industry. The study is about the effects of speed, raster pitch and power on the roughness and microhardness of the marked areas of copper samples. The experiments were carried out with a fiber laser and a copper b...

In modern production, each finished product entering the market is identified by a special marking. Each mark must meet requirements such as good coding, easy to see, easy to read by certain readers, stable over time, etc. In the present casting, laser marking of the C75 steel was carried out with a fiber laser with an average power of P = 30 W and...

Laser marking with a nanosecond fiber laser is one of the most common ways to permanently mark various engineering materials. The roughness of the machined surface and its observation is essential to evaluate the impact on the contrast of the marking as well. Experimental studies of the roughness obtained as a result of the laser marking, were insp...

The application of lasers in many fields of technology and medicine is constantly increasing. This causes the development of new physical methods and principles for correct measurement of power, energy, and other parameters of laser sources. In most cases, the correct measurement of the laser power is important because the quality of the processes...

In this scientific study, the ability to modify the surface using nanosecond 1064 nm fiber laser by controlling the speed and scanning line step in the marking process was demonstrated. An experimental matrix for laser marking was developed, consisting of 8 columns for marking line step and 5 rows for marking speed. The laser marked surfaces were m...

This study examines the effect of pre-heat treatment on laser engraving of aspen thermowood. We used an infrared CO2 laser with a wavelength of 10640 nm to engrave aspen thermowood samples with different pre-treatment temperatures, including one non-treated sample (base). The samples had a similar moisture content of about 6 - 8%, but exhibited dif...

Marking of metal products is essential in many industrial processes. It is mandatory for the finished products according to regulations of the European and world legislation. Traditional marking usually creates contrasting symbols that can easily be erased and forged.In recent years, a new method for product identification has appeared - color mark...

The quality of the marked surfaces changes the optical characteristics. The aim of the study is to optimize the contrast in laser marking of Steel 75. The influence of the step in the raster marking and the influence of the repetition frequency of the pulses on the reflection coefficient were analysed. The experimental investigations of the reflect...

In this work, a numerical model of laser texturing is considered. A finite element model of a representative sample of pure aluminum was created. The impact of a laser pulse was simulated, assuming a Gaussian volume distribution of the heat flux. Material properties are assumed to be constant and latent heat is accounted for. Results are obtained f...

Titanium Gr 2 is widely used in engineering and medicine due to its excellent mechanical and corrosion-resistant properties. Laser marking is a crucial process for many applications that require high-contrast, durable markings. In this study, we used a Rofin PowerLine F 20 Varia fiber laser to mark titanium Gr 2 with a 6x6 matrix of 5x5 mm squares....

The requirements for marking in terms of contrast and durability are constantly increasing. In order to meet all these challenges, it is necessary to carry out research leading to the optimisation and increase in efficiency of the technological process of laser marking. In the case of aluminium, the contrast and durability of the marking depend on...

The role of basic quantities influencing the process of laser raster marking of AISI 304 stainless steel products using a fiber laser was investigated. Some dependencies were found when changing the contrast of the marking when changing the parameters in wide intervals. As the raster step increases, a non-linear decrease in contrast occurs as the r...

The development of marking technologies for telecommunications connectors requires increasingly detailed information about their applications. One solution is to use QR codes that contain sufficient information about the connectors' applications. Accurate marking of connectors requires a precise marking system, such as a laser marking system. In th...

The aim of the work is to explain the danger of phenol and phenolic compounds to human health and the environment. In addition, it explains where and why pollution by phenol and its compounds occurs, especially in industrial wastewater. The authors investigate the possibility of using laser technologies for the decomposition of phenol, as well as f...

Fine-tuning laser parameters is necessary to achieve the desired quality of the process of laser surface texturing. This requires a set of experiments to assess the influence of the main process parameters on the quality of the surface of a treated alloy. By varying the laser parameters, different laser-material interactions, such as heating, melti...

Stainless steel is a widely used material in industry, architecture, and medical instruments. However, after various thermal processing of stainless steels, chromium carbides can be formed, which locally depletes the chromium available to form a passive film and reduces the corrosion performance. Laser surface treatment can change the surface chemi...

Composite materials, consisting of fibers and binders of natural and artificial origin, are increasingly used in various fields of industry. Processing of the obtained materials into finished forms is often difficult and expensive. Treatment of composite materials, such as milling, cutting, or grinding, is currently dominant. At present, lasers are...

Surface texturing is one of the most effective approaches to modifying the surface to improve many properties: tribological, corrosion resistance, microhardness and others characteristics of a number of engineering materials. Among the surface texturing techniques developed in recent years, the most widely used method is the laser surface texturing...

Surface texturing is one of the most effective approaches to modifying the surface to improve many properties: tribological, corrosion resistance, microhardness and others characteristics of a number of engineering materials. Among the surface texturing techniques developed in recent years, the most widely used method is the laser surface texturing...

Studies have been made on the development of military science and it has been established that for the modernization of the army and the defense industry it is necessary to develop and search for new innovative technological solutions in the field of laser technology and photonics. According to the trends in the use of laser technologies for milita...

This study displays the effect of laser surface hardening parameters on the Ck 45 steel. The method is mostly based on experimental tests, with micro-hardness data being used to obtain the hardness profile Ck 45.The beauty of the surface laser hardening technique is that, it hardens a specific area without changing the surface qualities of the surr...

The purpose of this review article is to explain the hazards of phenol and phenol compounds to human health and the environment. To describe where and how phenol and its compounds occur, especially in industrial effluents. To study the possibility of using laser technologies for phenol cleavage, as well as for the treatment of industrial wastewater...

The study of the process of laser welding of various aluminum-steel joints is necessary to promote the possibility of realization of new products and designs in instrumentation and mechanical engineering. Laser welding, due to its many advantages, is considered a very promising process of joining different materials, although its application in ind...

This research examines an approach for finding the optimal modes of laser treatment with CO2 laser on advertisement boards made of aluminium composite panels. To achieve the optimal area of the processing mode, an experimental methodology has been developed and an experiment has been planned for finding the limits at the given parameters of the s...

This research examines various methods of producing nanoparticles. The comparison and preferences of various laser parameters based on their classification and characteristics are discussed. The main objective of this study is to reveal the dominant laser parameters for the laser ablation process to generate nanoparticles in aqueous media. The meth...

This research examines an approach for finding the optimal modes of laser treatment with CO2 laser on advertisement boards made of aluminium composite panels. To achieve the optimal area of the processing mode, an experimental methodology has been developed and an experiment has been planned for finding the limits at the given parameters of the spe...

The aim of this study was to investigate the microstructure and micromechanical properties of pulsed laser irradiated stainless steel. Laser marking was performed for AISI 304 stainless steel samples using a Nd:YAG fiber laser (1064 nm). AISI 304 steel finds applications in a variety of industries due to its excellent properties: Automotive and aer...

Nowadays, traceability, combined with stable and constant identification of industrial parts, is becoming a crucial element of production processes. Laser marking of metal parts is a technology that shows many advantages compared to labeling, inkjet, or dot marking. The advantages include no consumables, faster cycle time, reliability and repeatabi...

Copper is well known for its extraordinary features to increase human immunity in warm weather places. To investigate those properties via nanoparticles, experiments were carried out on copper samples. The process of pulsed laser ablation in a liquid is used to obtain these nanoparticles, so it is extremely important to understand and study the phy...

Silver has been an influential segment of pharmaceutical utilization for remedies & hygiene in the latest era. The first topic reviews the study on air sanitization ventilation & air sanitizer systems using laser ablated silver nanoparticles (inspired by 2020 Pandemic) directing to contamination of deadly biological particles. Intention of this inv...

Today we are witnessing the rapid development of the laser industry. Laser sources with new wavelengths, higher powers and energies, different modes of operation (generation of laser pulses), as well as various applications in industry, medicine, environmental protection etc. are emerging. This requires the development of new physical methods and p...

Laser engraving is one of the most commonly used laser procedures for interacting with laser material. The speed, ease of use and high precision make it an attractive process for use by manufacturers and for removing insulation from various cables. Cable stripping is a particularly common operation in aeronautics. The aircraft is equipped with seve...

Today, methods for marking parts and components in industrial production are constantly improving, and they must meet several basic criteria for active traceability by consumers. The parameter that is of paramount importance for the quality of the marking is related to the contrast of the marked sign or QR code. To achieve optimal contrast, a numbe...

This research includes a Comsol Mutiphysics model describing the temperature distribution on aluminum during the laser conductivity welding process. The influence of laser power and speed on the welding process is discussed and compared with experiments. Numerical simulations of laser welding process have been performed to determine the temperature...

A number of policies and standards regarding food safety issues and quality management have been established for the food industry. One of these requirements is related to the marking of food products describing the expiration date, content and quality. The report examines the possibility of using laser technology to mark chicken eggs. The contrast...

A comparison is made between the laser and sandblasting methods for removing paint from industrial facilities. The advantages of laser ablation are discussed. The possibilities of laser paint removal systems - stationary and moving - are shown. The main factors influencing the laser ablation process and the indicators that determine the quality of...

Silver has been part of active medical use for treatment and disinfection from ages, even in the present times. Particularly relevant today is the question of the effect of silver nanoparticles on bacteria and viruses, including against COVID-19. The study reviews distinct methods for producing silver nanoparticles. The comparison and preferences o...

The laser marking process by melting samples of C110W carbon tool steel was studied. The experiments were performed with a fiber laser and a CuBr laser. A field of squares is marked in a raster method for different values of the overlap coefficient and power density. The contrast of the marking is determined on each marked square. From the obtained...

Laser beam welding of aluminium offers a huge potential for a wide variety of welding of different thickness parts with the method of thermal conductivity due to the relatively high difference between melting temperature and evaporation. However, due to the high melting temperature and good thermal conductivity of this light metal, the temperature...

Every year, the use of lasers for military purposes continues to grow. Many armies from different countries use different types of laser systems for their specific combat tasks and actions. Traditional troops of land forces, artillery, air defence, and aviation forces today recognize the laser as a major operational element in increasing the accura...

The study is about the process of laser marking by melting products made of carbon structural steel 15Cr2 with wide application in industry. A fibre laser operating in the near-infrared region was used to perform the experiments. A raster marking method was used by varying the power density of the laser radiation and the frequency of pulses repetit...

Laser technologies are a major priority in the development of our economy and society in the 21st century. One of the main applications of lasers is laser marking / engraving. The laser engraving method is widely used in many industries, including the glass industry. There are many ways to engrave glass, for example sandblasting, but it is time con...

The report considers the possibility of using laser technology for neoprene engraving and cutting. This modern material is a type of synthetic rubber with great strain resistance, general durability and excellent temperature insulation properties. This study uses a CO2 laser system SUNTOP ST-CC 9060 with a wavelength of 10640 nm with a goal to achi...

The report considers the possibility of reducing the roughness after laser polishing of Aluminum plates. A CHANXAN CX-20G fiber laser with a wavelength of 1064 nm is used for the research. As a result of the experiment, 4 matrices were marked with a fiber laser on 3 samples for each series of the experiment. Then, using a multifunctional microscope...

Depending on the processing of a particular material, the laser marking process must meet certain requirements. A certain laser peak intensity or fluency must be reached on the treatment surface above which the laser ablation process starts. Some experimental studies have shown that this particular marking threshold is related to many other paramet...

This work makes use of the finite element model, whose results are validated by experiments. The effect is discussed of the speed on the laser marking process. Numerical experiments are performed to determine the temperature fields produced by laser pulses on samples of aluminum, a material with wide industrial uses. The numerical calculations are...

Laser marking and engraving has developed in many ways into an attractive process for identifications of consumer goods made of plastic. It is a quick and inexpensive process that offers a variety of flexible options for designing identification products (barcodes, security information, codes). This report examines the possibility of marking PVC pr...

Marking and engraving of aluminum was carried out by a CuBr (copper bromide) laser operating at the wavelength of 511 nm with a pulse duration of 30 ns. The reflection was investigated of the laser-ablated aluminum surface depending on the laser beam scanning speed and the distance between the laser lines. The changes of the aluminum surface were o...

Over the last decade, laser surface treatment of stones has gained increasing scientific interest. New technologies and processes based on different types of laser sources and processing modes are being studied. This report examines the process of laser ablation of a marble surface using a fiber laser. Three factors influencing the process of laser...

The article reviews the research on disinfecting the air through air filters and ventilation systems using silver nanoparticles (encouraged from the present situation of COVID-19) focusing on to stop the spreading of deadly viruses. The primary goal of the research is to demonstrate possible anti-viral silver nanoparticles formulations to be delive...

This report identifies some of the problems of higher education in the Republic of Bulgaria related to the demographic crisis in the transition process and measures to overcome them. Emphasis is placed on the legislative framework, the rating system, the financing of higher education institutions and the science in them, the quality of training, th...

The purpose of this report is to provide useful and adequate information needed to minimise dangers associated with laser radiation in military and training activities of the Army. The assessment made in the report is based on the ability of laser beam to cause biological damage to the eye during laser system's malfunction or inability to protect t...

The paper investigates and describes laser hardening of steels, types of lasers, important parameters of laser hardening, as well as steels that are suitable for laser hardening process. The laser hardening process of steel C45 samples is described, the analysis of the results is described and the result is summarized. The results of the experiment...

The construction of a laser weapon began shortly after the first laser was shown in 1960 by Theodor Meyer. Today lasers are widely used a variety of tasks in the army, not just as destructive but also for prevention and protection. Turn on laser technology in existing weapons has improved the ability for effective detection, tracking and identifyin...

For a number of new laser technology processes, it is essential to plan an experimental plan for primary experimental engineering activities in terms of quality. The assessment of the critical power density to reach the melting or evaporation temperature of the surface with a suitable theoretical model is an important stage in the development of a...

Studying the impact of speed on a number of laser processes such as marking, engraving, cutting, welding and others is crucial for the optimization of these technological processes. The processing speed, along with the frequency of laser pulses and their duration, also determines the time of action in the processing area and hence the absorbed quan...

A new methodology for determining and optimizing the contrast of the technological laser marking process has been developed. It can evaluate the quality of the markings regardless of the type of material and the type of laser system. To perform the test analysis, a specialized test field is programmed, which including the change of two of the main...

Progress in direct laser marking when processing plastics with unmatched quality of markings, contrast and speed. This article presents the latest generation of laser materials and laser equipment systems. When properly applied, laser marking can provide quality for production and add value to the appearance and function of the product.Describe the...

The ability to laser machine materials with high resolution and high throughput is critical in advanced manufacturing for a vast array of applications, from photovoltaic cells to bio-compatible micro-components. Copper bromide (CuBr) lasers with their excellent beam quality promised noticeable advantages and improvements in high precision and mater...

Brass Alloy 260 is widely used in mechanical engineering (odometer contacts, radiator cores), electrical engineering (electrical connectors, screw shells), plumbing (bathroom fixtures), consumers (watch parts, buttons, lamps) etc. The paper presents an analysis of the laser marking and engraving process. The ability Rofin powerline f20 laser system...

In the last decades, a large application has been found by lasers in marking and cutting on textiles, plexiglass, wood, metals and other materials. These items apply to both the military and the economy of the countries of the world. A group of Bulgarian students from the National Military University Vasil Levski, led by Dr. Nikolay Dolchinkov, con...

Describe the parameters influencing the depth of the laser marking of textile products. Experimental results are presented to determine the quality of cuts on felt surfaces of different colors at specific parameters - power and speed. Approximately 100 extras were made on two materials with a change in laser power and speed. As a result, the optima...

The purpose of this report is to provide useful and adequate information needed to minimise dangers associated with laser radiation in military and training activities of the Army. The assessment made in the report is based on the ability of laser beam to cause biological damage to the eye during laser system’s malfunction or inability to protect t...

On the global agenda, environmental issues are becoming ever more pressing every moment. At present, it is not enough for individual countries to tackle global climate issues on their own. The time has come for a joint effort to mitigate climate change. The Paris Agreement is an agreement within the United Nations Framework Convention on Climate Ch...

The laser marking has been established in recent years as one of the modern innovative methods for marking many industrial products. The report examines a new laboratory exercise for the subject Laser Technology, studied in some technical universities. A new approach is proposed to determine the contrast of the laser marking process. Described is t...

Abstrct: Currently, the development of electric vehicles has high global priority on the political agenda. The strict environmental protection targets for exhaust gasses and the new technological approaches force the market progress. The report examines innovative production technologies based on the latest laser resources which offer a fast and fl...

Every year, the use of lasers for military purposes continues to grow. Many armies from different countries use different types of laser systems for their specific combat tasks and actions. Traditional troops of land forces, artillery, air defence, and aviation forces today recognize the laser as a major operational element in increasing the accura...

Evaluation of the optimal laser cutting parameters is very important for the high cut quality. This is highly nonlinear process with different parameters which is the main challenge in the optimization process. Data mining methodology is one of most versatile method which can be used laser cutting process optimization. Support vector regression (SV...