The spatial characteristics of the focused beam of a fiber 2 kW laser have been measured. The problems of matching this
beam structure, greatly differing from the Gaussian form, with technological operations have been considered.
A brief overview of currently available methods applied in laser synthesis of 3D parts is presented, which range from stereolithography making use of liquid photopolymers to selective laser sintering of metal powders aimed at production of the parts of complex topology.
The technical characteristics of the new three models of diffusion-cooled multichannel waveguide industrial CO2 lasers
excited with acoustic-frequency ac discharge are presented. The industrial lasers of this type have been developed for
years at ILIT RAS.
Generation of low (to 400 W) average power proved to be technically realizable through air cooling of the oscillator,
which makes the laser performance even more attractive. The above lasers can be used to advantage in the laser
processing systems intended for precision cutting of metallic (thickness to 10 mm) and non-metallic (thickness to
40 mm) materials; welding; surfacing and fabrication of parts from composite and metallic powder materials.
The paper also provides the description and the technical characteristics of intellectual medical cardio-surgery laser
systems of "Perfocor" family, developed at ILIT RAS for the transmyocardial laser revascularization (TMLR) which
presents a promising method to cure the ischemic disease of heart. The clinical results (more than 800 operations) are
presented. Owing to application of the TMLR technique the death rate at the A.N. Bakoulev Center is the lowest in the
The project of a new CO2 laser surgery plant "Khirurg" is discussed that would deliver up to 200 W power and is based
on the model TL-300 with a system of biotissue diagnostics.
The paper presents the analysis of the requirements to the laser systems used to cure the ischemic disease of the heart by the method of transmyocardial laser revascularization (TMLR). Among the medical laser systems under discussion (solid-state Nd:YAG, Er:YAG, Ho:YAG, excimer lasers, etc.) the high-power CO2 laser with pulse energy to 40 J is most suited to produce channels in the heart muscle. The paper provides the description and the technical characteristics of medical laser systems of “Perfocor” series, based on high-power waveguide CO2 lasers with pulse energy to 60 J, developed at ILIT RAS. The methods to determine the time of laser radiation penetration through the myocardium/blood boundary have been briefly discussed. The application of the “Perfocor” system in other laser operations on blood-filled organs has also been discussed.
The mechanism of channel punching in the heart muscle (myocardium) by a pulse of high-power CO2 laser was studied. Water, PMMA and biotissue of animals were used as the models. Diagnostics of the punching process was performed by the methods of registration of sound vibrations in the air and back scattering of laser radiation. It has been revealed that at channel punching in various media, sound vibrations are excited in the spectrum region from 1 to 3.5 kHz, which are due to turbulent pulsation of vapor-drop flow ejected from the channel. The spectrum of acoustic vibrations depends on positions of the channel bottom and is sensitive to the boundary between the myocardial tissue and blood. The measurement of sound vibrations spectra can serve as the basis for diagnostics of the process of channel punching in myocardium.
The paper presents the results of technology development for laser modification (hardening, alloying) of stamping tool surfaces in production of automobile parts. The techniques of laser treatment have been selected and developed, which make use of high-power industrial CO2 lasers MTL-2.5 and TL-5 with 2.0 to 5.0 kW power and the special-purpose five- coordinate manipulator of VISP-125A type. Metallographic studies of stamp samples have been conducted following laser hardening and alloying. The testing of the processed samples on test panel of the Metal Forming Institute gave positive results. The data obtained served as the basis for development of specific technologies for laser hardening and allowing of stamping tool for purposes of automobile industry.
The mechanism of channel punching in the heart muscle (myocardium) by a pulse of high-power CO2 laser was studied. Water, PMMA and biotissue of animals were used as the models. Diagnostics of the punching process was performed by the methods of registration of sound vibrations in the air and back scattering of laser radiation. It has been revealed that at channel punching in various media, sound vibrations are excited in the spectrum region from 1 to 3.5 kHz, which are due to turbulent pulsation of vapor- drop flow ejected from the channel. The spectrum of acoustic vibrations depends on positions of the channel bottom and is sensitive to the boundary between the myocardial tissue and blood. The measurement of sound vibrations spectra can serve as the basis for diagnostics of the process of channel punching in myocardium.
For many years the Institute on Laser and Information Technologies RAN has been developing a concept of high-power industrial CO2 lasers with diffusion cooling of the working medium. The paper gives a description of the laser medical system Iguana for transmyocardial laser revascularization (TMLR) as an example of various applications of high-power waveguide CO2 lasers. The clinical results of the TMLR method application in surgical treatment are presented. The methods of determination of the time, when the laser beam passes through the demarcation line between myocardium tissue and blood, are discussed.
Strict requirements of modern industry and medicine to laser beam quality, stimulated to fulfil a lot of special researches have been undertaken concerning: a) gas discharge stability and uniformity; b) enhancement of active medium optical nonuniformities in the presence of laser generation; c) new concepts of optical resonators; beam power modulation with a controllable coupling mirror. As the result of these investigations, several series of fast-flow and of diffusion-cooled waveguide industrial CO2 lasers in 0.5 to 10.0 kW beam power range have been designed in the IPLIT RAN.
Experimental, engineering and modeling aspects of development of high- power industrial waveguide single-beam CO2 lasers are considered. Parameters of an experimental model of this type laser with 0.5 kW beam power are presented and relevant critical problems are discussed. Beam output characteristics depending on different parameters are offered.
The paper presents the results on investigations and development of multichannel waveguide CO2 laser with diffusion cooling of active medium excited by discharge of audio-frequency alternating current. The description of high-power single-mode CO2 laser with average beam power up to 1 kW is presented. The result of measurement of the laser basic parameters are offered, as well as the outcomes of performances of the laser head with long active zone, operating in waveguide mode. As an example of application of these laser, various capabilities a description of the developed medical system 'Genom' used in the transmyocardial laser revascularization (TMLR) procedure and clinical results of the possibilities of the TMLR in the surgical treatment are presented.
The paper presents the description of a high-power waveguide single-mode CO2 laser generating 800 W average beam power and up to 1 kW peak power at pulse duration from 2 to 100 ms. The diffusion-cooled active medium is excited by a capacitive AC discharge of sound frequency. The advantages of the laser are: high (>10%) technical efficiency, upgraded stability of beam parameters at the cost of the use of waveguide generation mode, extremely low (<1 nl/h) consumption of lasing mixture and possibility of operation in quasi-sealed-off regime; design simplicity, compactness and low cost. As an example of application of various capabilities of these lasers, a description of the developed medical system `Genom-4' used in the transmyocardial revascularization (TMR) procedure is presented. The system is equipped with devices which are necessary both to conducting biophysical experiments and to performing operations under clinical conditions; among them are computer control system, cardiograph for synchronization of laser pulse with ECG of the heart under operation, remote articulated mirror manipulator with optical hand-piece for performing operations. The results of biophysical experiments on drilling channels in organic materials and biological tissues in vitro, as well as the results of operations on patients, are presented. Verification of a possible negative influence of shock waves, which can be generated in biotissues during the TMR procedure, has been studied. It has been shown that the pressure excess due to laser action is lower than one bar. Thus, no destruction of biotissues surrounding the channel should be caused. The autodyne Doppler spectroscopy diagnostics of specifying the moment of keyhole punching in myocardium has been discussed. Other possible applications of the system for drilling deep channels in liver, lungs, etc. are mentioned.
The paper considers the experimental, engineering and model-physical aspects of development of high-power waveguide single-beam carbon-dioxide lasers for industrial applications. As an illustration, the parameters of the developed experimental model of this type of laser with 0.5 kW average beam power are presented and relevant critical problems are discussed. The results of inquiry into beam output characteristics are offered depending on different parameters. Main technical and economic data have been obtained.