Excimer laser
 Method and device for producing laser beam / 2244990Proposed method used for producing beam from pulse-periodic laser pumped with self-maintained spatial discharge with XeXl, KrF, CO2, and HF base active means includes formation of at least one electrode of a number of plasma generations near effective surface with self-maintained spatial discharge producing repetitive plasma structure and generation of laser beam. Plasma generations are formed in any plane perpendicular to optical axis of laser near effective surface of at least one of electrodes, its size being smaller than maximal size of plasma generation at one repetition period of plasma structure and smaller than or equal to size of laser radiation beam produced in same plane near effective surface of mentioned electrode. Device implementing this method has at least two opposing electrodes connected to common buses of pumping source and optical cavity; at least one of electrodes is made of repetitive parts each having its respective effective surface. Repetitive electrode parts are installed either in planes parallel to optical axis of laser or in those disposed at acute angle to this axis, or in cylindrical surfaces with generating lines perpendicular to optical axis of laser and guides of these surfaces in the form of curves or broken lines. Such design ensures desired energy distribution for various processes. |
 High-frequency excited co2 waveguide laser / 2244367Proposed laser has two channels of which first one functions as discharge channel, as well as high-reflection and light-splitting mirrors installed at ends of discharge channel. Each channel is bound on opposite ends with extreme and central electrodes and on two other ends, with insulating wafers. One of extreme electrodes has rectangular longitudinal slot of depth L ≥ 1.5h and width H ≥ h + 1 to form insulating space together with closest second channel holding additional working gas supply, where h is discharge channel width. |
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High-frequency excited co2 waveguide laser / 2244367 Proposed laser has two channels of which first one functions as discharge channel, as well as high-reflection and light-splitting mirrors installed at ends of discharge channel. Each channel is bound on opposite ends with extreme and central electrodes and on two other ends, with insulating wafers. One of extreme electrodes has rectangular longitudinal slot of depth L ≥ 1.5h and width H ≥ h + 1 to form insulating space together with closest second channel holding additional working gas supply, where h is discharge channel width. |
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Method and device for producing laser beam / 2244990 Proposed method used for producing beam from pulse-periodic laser pumped with self-maintained spatial discharge with XeXl, KrF, CO2, and HF base active means includes formation of at least one electrode of a number of plasma generations near effective surface with self-maintained spatial discharge producing repetitive plasma structure and generation of laser beam. Plasma generations are formed in any plane perpendicular to optical axis of laser near effective surface of at least one of electrodes, its size being smaller than maximal size of plasma generation at one repetition period of plasma structure and smaller than or equal to size of laser radiation beam produced in same plane near effective surface of mentioned electrode. Device implementing this method has at least two opposing electrodes connected to common buses of pumping source and optical cavity; at least one of electrodes is made of repetitive parts each having its respective effective surface. Repetitive electrode parts are installed either in planes parallel to optical axis of laser or in those disposed at acute angle to this axis, or in cylindrical surfaces with generating lines perpendicular to optical axis of laser and guides of these surfaces in the form of curves or broken lines. Such design ensures desired energy distribution for various processes. |
 Excimer laser / 2249282Proposed excimer laser that can be used for intracavitary therapy in medicine, for microelectronics, laser chemistry, and processes using heavy-power ultraviolet rays has electrode system, pulse power circuit with storage capacitor, and switch in the form of thyratron. Electrode system has insulating plate that carries electrodes; thyratron is connected in series with storage capacitor and electrode system. Electrode system is designed to ensure pumping of excimer gas medium with discharge creeping over insulating plate surface. |
 High-frequency discharge excited gas laser / 2411619Transverse pumped gas laser has a housing, an optical resonator, an electrode connected to a resonance-tuned high-frequency power supply, a cooling heat exchanger and a centrifugal compressor. The housing is formed by an outer cylindrical metal casing and an inner cylindrical dielectric casing placed eccentrically inside the said outer casing, hermetically joined to front flanges and forming a gas-dynamic channel for circulating the active medium. The centrifugal compressor creates a stream of gaseous medium which envelopes the inner cylindrical dielectric casing. The section of the gas-dynamic channel with the narrowest cross section forms a plasma chamber and has a symmetrical or asymmetrical profile which varies on the height and has an arc-like or flat shape with angular opening in the direction of flow of the active medium along the width of the zone of the optical resonator. The electrode adjoins the outer surface of the inner cylindrical dielectric casing with its surface. The inner surface of the outer cylindrical casing on the said section of the gas-dynamic channel is insulated from the gas stream and the plasma by a dielectric layer, and the outer cylindrical metal casing is earthed. |
 Pulse-periodic te-laser / 2419933Laser includes gas-filled chamber with the main discharge electrodes installed in it, charging circuit and discharging circuit. Charging circuit includes pulse voltage source and peaking capacitors. Discharging circuit includes peaking capacitors and the main discharge electrodes, at least one corona pre-ioniser in the form of dielectric tube with inner and outer electrodes. Outer electrode of pre-ioniser covers part of surface of dielectric tube and is connected to the main discharge electrode. At that, outer electrode of corona pre-ioniser is current lead of charging circuit. |
 Method to stabilise volume charge in hf/df pulse-periodic chemical laser / 2465697Method includes supply of pulse voltage to barrier electrodes joined with metal electrodes. Pulse voltage is supplied at current density of volume phase of discharge of at least 1 kA/cm2 to barrier electrodes, having semiconductor properties, combining active and capacitance resistances. Active resistance is determined by volume resistance of barrier electrode material equal to 48 - 52 Ohm·cm, and capacitance resistance is determined by the value of relative dielectric permeability of barrier electrode material equal to 1800 - 2200. |
 Two-dimensional intracavity radiation scanning gas laser / 2477913Gas laser has a system for high-frequency excitation of the active medium with a scanning device, having two metal disc electrodes, one of which on the side of the interelectrode space is coated by a dielectric layer which current-conducting wedge-like metal tracks are deposited. The laser optical cavity is formed by two circular annular mirrors. On one half of the perimeter of the mirror, the coating provides partial reflection, and the other half of the surface of the circular annular mirror (3) is in form of an orthogonal array composed of n×m controlled mirrors (5), having a coating with a controlled reflection coefficient (6) such that the form of the common surface of the array repeats the form of half of the surface of the annular mirror which partially transmits radiation. There are additional actuating elements (19) in amount of n×m per controlled mirror of the array and an electronic switch (20) for elevation-angle deviation of output radiation which carries the deviation signal to the ij-th actuating element (19) for changing the reflection coefficient of the ij-th controlled mirror (1≤i≤m, 1≤j≤n) to a value closer to one. |
 Apparatus for generating volumetric self-sustained discharge / 2517796Apparatus for generating volumetric self-sustained discharge has a discharge chamber in which are mounted three electrode pairs which are connected to a pumping source, each pair consisting of plate-like profiled electrodes. Each cathode plate is situated in the plane of the corresponding anode plate and electrode pairs are mounted either parallel to the longitudinal axis of the chamber or at an acute angle to said axis. The working edge of the central cathode plates has at the centre a straight portion to which portions with a Stepperch profile adjoin at both sides. The working edge of the central anode plates has an arched shape and faces the discharge gap with its convex surface. Portions of the working edges of the outermost anode and cathode plates, facing the centre electrodes, repeat the profile of the working edge of corresponding anode and cathode central plates. Outer portions of working edges of the outermost anode and cathode plates have an arched shape and a longer length than portions of working edges of the outermost anode and cathode plates facing the centre electrodes, wherein all portions of the working edges have smooth mating. |
 Apparatus for exciting spatial charge in dense gases / 2519657Invention relates to quantum electronics and can be used to excite active media of gas lasers. The apparatus for exciting spatial charge in dense gases includes a high-voltage source connected to elongated, blade-shaped corona and current-collecting electrodes mounted along a dielectric cylinder which is capable of rotating. An electroconductive screen and a dielectric film are placed on the outer surface of the cylinder, wherein the corona electrode is placed along the radius of the cylinder with spacing from the cylinder. The screen is in form of two or more sections extending along the cylinder and electrically insulated from each other, wherein the section passing through the zone of the blade-shaped corona electrode is connected by a sliding contact to the grounded terminal of the source, and the section pass through the zone of the blade-shaped current-conducting electrode is connected by a sliding contact to the potential terminal of the source. Potential applied to a section of the screen can be controlled, for example, by a potentiometer. |
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Excimer laser / 2249282 Proposed excimer laser that can be used for intracavitary therapy in medicine, for microelectronics, laser chemistry, and processes using heavy-power ultraviolet rays has electrode system, pulse power circuit with storage capacitor, and switch in the form of thyratron. Electrode system has insulating plate that carries electrodes; thyratron is connected in series with storage capacitor and electrode system. Electrode system is designed to ensure pumping of excimer gas medium with discharge creeping over insulating plate surface. |
 Space-saving pulsed gas laser and magnetic pulse compressing device for its excitation / 2254650Proposed laser has coaxial sectionalized discharge cell forming low-inductance power transmission line with pulse shaping circuit connected to central electrode, and thyratron placed in conducting shell which is part of common low-inductance power transmission line. Pulse shaping circuit made in the form of magnetic pulse compressing device has saturating reactors inductively and capacitively coupled with discharge tube mounted in magnetic pulse compressing device. Laser has coaxial sectionalized discharge cell with gas gap between plates. Gas gap thickness to discharge tube wall thickness ratio is higher than dielectric constant of discharge tube material. Sheet-steel ballast capacitors are disposed coaxially to discharge cell and symmetrically to magnetic pulse compressing device. The latter uses parallel circuit arrangement for connecting magnetic compression power lines. Each line incorporates additional saturating reactor in first section. Parallel-connected to ground are limiting saturating reactor and peaking capacitor. |
 Chemical element vapor pulse-periodic laser / 2254651Proposed laser has gas-discharge tube, high-voltage rectifier, resonant charging choke, charging diode, storage capacitor, thyratron, generator, feed-through capacitor, negative bias source, and power supply. Gas-discharge tube is placed in cavity. High-voltage rectifier is coupled through one of its outputs witch input of resonant charging choke. Generator output is electrically connected via feed-through capacitor to gate electrode that functions as thyratron grid. Negative bias source is connected to gate electrode. High-voltage rectifier is coupled through its other output with storage capacitor. Second lead of the latter is connected through charging diode to output of resonant charging choke. Common generator output is connected to thyratron cathode. Thyratron anode is electrically connected to storage capacitor and to charging diode. Thyratron cathode is coupled with gas-discharge tube anode and has decoupling filter and two storage capacitors. Decoupling filter is made in the form of two inductance coils. |
 Method of generating plasma of gaseous medium and apparatus for realising said method / 2454749High-voltage pulse is transmitted from a pumping oscillator, said pulse having amplitude higher than breakdown voltage Ubr of the active gaseous medium and duration of not more than 100 ns with voltage rising edge of not more than 30 ns, an exciting inductor 6 with overall inductivity which satisfies the relationship 50 nH≤L/n≤500 nH, where L is inductance of one solenoid, n is the number of solenoids 5 connected in parallel and lying from each other at a distance h<H. The exciting inductor ensures efficient transmission of energy from the pumping oscillator to the gaseous medium in form of an alternating magnetic field. As a result of movement of changes, circular electric currents are induced, which form inductive vortex discharge in the gas within the width of the solenoids 5. In that case, the plasma of the inductive discharge takes the shape of a cylinder near the inner surface of the discharge tube, and then begins to interact with plasma of neighbouring solenoids, thereby increasing the total discharge length to n×H+(n-1)×h. If h>H, vortex discharge takes place only inside the solenoids of the exciting inductor and not in spaces between the solenoids. |
FIELD: laser engineering.
SUBSTANCE: proposed excimer laser that can be used for intracavitary therapy in medicine, for microelectronics, laser chemistry, and processes using heavy-power ultraviolet rays has electrode system, pulse power circuit with storage capacitor, and switch in the form of thyratron. Electrode system has insulating plate that carries electrodes; thyratron is connected in series with storage capacitor and electrode system. Electrode system is designed to ensure pumping of excimer gas medium with discharge creeping over insulating plate surface.
EFFECT: enhanced pulse repetition rate, reduced gas medium consumption.
1 cl, 2 dwg
The present invention relates to lasers and can be used mainly for the treatment of intraoral infections, including abscesses, such as cavernous tuberculosis. The invention can also be used in microelectronics, laser chemistry, and in other processes that require the action of a powerful UV radiation.
In the patent of Russia №2064801, published on August 10, 1996, describes a device for the treatment of destructive forms of pulmonary tuberculosis. On the inner surface of the cavity defocused effect of pulsed ultraviolet radiation. As specified source of radiation using a nitrogen laser with a wavelength of 337 nm pumped by sliding over the surface of the dielectric discharge. Electrode system nitrogen laser includes a dielectric plate placed on the electrodes. On the surface of the plate is formed a layer of moving plasma discharge, which serves as a pumping source laser. Due to the fact that the moving plasma discharge is a plasma sheet thickness of 1 mm, rapid cooling of the gas in the discharge zone, in the intervals between pulses, which allows to increase the frequency of pulse generation of the nitrogen laser to 350 Hz without gas flow instead of a 10 Hz laser pumped by the classical scheme the Popper the aqueous discharge volume.
In the treatment of destructive forms of tuberculosis according to the technique according to patent No. 2064801 positive results, in particular the treatment time is reduced at least by half.
However, as shown by further research, radiation with a wavelength of 337 nm is not optimal, since the peak of the death of mycobacteria is located in the wavelength range of 220-290 nm with the maximum near 250 nm. The discrepancy between the wavelength of the radiation with the spectral peak of bactericides is a significant drawback of the nitrogen laser.
A suitable source of pulsed ultraviolet radiation in this range is a solid-state laser-Nd : YAG with frequency conversion of the radiation into the fourth harmonic 266 nm and excimer KrF laser with a wavelength of 248 nm.
In the patent of the Russian Federation 2141859, issued in 1998, describes the use of ultraviolet radiation generated by the solid-state laser-Nd : YAG-converting radiation at a wavelength of 1.06 µm in the fourth harmonic. The use of solid state laser diode pumped allowed to obtain the generation of the necessary radiation with an average power of 5 mW with a pulse frequency generation up to 5000 Hz in comparison to the maximum achievable pulse repetition rate of generation of 100 Hz in the case of lamp pumping. This allowed the use of a quartz fiber with a diameter of 0.6 is m for conveying laser radiation with a wavelength of 266 nm from the laser to the affected cavity, as a pulsed output not exceeding 100 W at a pulse generation 10 NS.
To date, the solid-state laser medical facilities for treatment of destructive forms of pulmonary tuberculosis has not received proper distribution due to the high cost of laser diodes and crystals for frequency conversion generating the fourth harmonic. In addition, the conversion of the fundamental frequency of the laser in the fourth harmonic requires a very fine adjustment of the optical system of the laser, which complicates the mechanical design of the laser system.
A relatively simple and reliable source of radiation in the desired frequency range is an excimer KrF laser with a wavelength of 248 nm. Required for medical purposes, the average radiation power of several tens of mW can be obtained in a simple and relatively small systems with sufficient for application in medicine resource. Medical laser installation on excimer laser KrF has also found extensive application in ophthalmology, laser vision correction.
But the classic pump excimer laser with transverse discharge does not allow the generation frequency of the pulse generation above 100-300 Hz without pumping the gas mixture through the volume of the resonator of the laser. This results in required radnich the radiation power and the duration of the laser pulse ~ 10 NS to peak radiation power up to 10 kW, that at the wavelength of 248 nm leads to a rapid destruction of the light guide fiber used for the transportation of radiation.
Known excimer laser described in Tutsumi Goto at all (Rev.Sci. Instrum, 66 (11), November 1995), containing 2-electrode system with pre-ionization of the gas in the working volume between the electrodes and the pulse circuit with a switch, such as a thyratron connected in parallel to the electrode system. To the electrodes of the thyratron is connected chain: cumulative capacity of the resistor. The frequency of this generation excimer laser with transverse discharge for volumetric pump laser gas medium increase by implementing quick pumping gas active medium through the bit period of the laser. In particular, reported receiving a powerful generation in l excimer laser with a repetition rate of pulse generation up to 5 kHz. While leveling speed was 137 m/S.
Obviously, for use in excimer lasers intended for medical purposes, this method of increasing the frequency of pulse generation of little use, as it increases the size of the machine and a large flow rate of the gas mixture.
The present invention is the task of creating an excimer laser, providing the generation of ultraviolet radiation in mA is the first volume with a pulse repetition rate of 2000 Hz without pumping the gas active medium through the volume of the laser.
The problem is solved in that in the excimer laser containing an electrode system, a pulse circuit with a storage capacity and a switch in the form of a thyratron, according to the invention, the electrode system includes a dielectric plate on which is placed the electrodes, while the thyratron connected in series to the storage capacitor and the electrode system.
In the excimer laser according to the invention, the electrode system for the organization of the volumetric pump laser gas medium with transverse bulk electric discharge is replaced by an electrode system that provides pumping sliding over the surface of the dielectric discharge. This allows a small volume to get generation with pulse frequency generation 2000 Hz.
Further, the invention is illustrated specific embodiments thereof and the accompanying drawings, on which:
figure 1 depicts the electrode system of the moving discharge;
figure 2 - schematic wiring diagram of an excimer laser.
Electrode system excimer laser contains extended electrodes 1, 2 (figure 1), placed on the dielectric plate 3 to form between them a working volume of the laser gas medium. One of the electrodes, for example electrode 1 is high voltage and the other electrode 2 is grounded. Di is elektricheska plate 3 is made of synthetic sapphire.
The pump laser includes an electrode system with series connected switch in the form of a thyratron 4 (2) and storage capacity Withn.
When voltage is applied to the storage containernis it charging until the voltage of the power source. Upon actuation of the switch thyratron 4 voltage is applied to the electrodes 1, 2 and on the surface of the dielectric plate 3 is formed a layer of moving plasma discharge with a thickness of 1-1 .5 mm, which is the active medium of the laser. Obsterilnaya capacity Withaboutcan be structurally formed by the moving electrodes of the discharge, located on both sides of the dielectric, or by location in a low-inductance capacitor in a discharge chamber directly to the discharge gap, which provides the minimum inductance of the discharge circuit. The use of thyratron 4 as switch allows you to increase the frequency of pulse generation and go in kHz wet range.
In the absence of the charging resistance is the shortening of the leading edge of the voltage on the electrodes of the moving bits, which is a sufficient condition of lasing on excimer mixture. The duration of the pulse voltage is ~ 25-30 NS.
The difference in pumping requirements excimer laser is s from the requirements for pumping nitrogen is to ensure the conditions of formation of inverted population in the excimer laser requires a higher level of invested in discharge capacity, i.e. reducing the time of the contribution of the energy in the discharge. This is carried out by the organization in a low-inductance discharge circuit, i.e. the use of low-inductance energy storage, interconnection of circuit elements tires, the maximum possible approximation of the elements of the discharge circuit to discharge the interval.
High frequency pulse generation is achieved by forming a thin layer of plasma (the thickness of 1-1,5 mm) sliding discharge, which serves as a pumping source laser. The moving plasma discharge is ignited on the surface of the sapphire plate, which rests on a solid metal electrode 2, which usually is grounded. This creates optimal conditions for the dissipation of heat from the layer of plasma and allows to increase the pulse repetition rate pumping and generation.
The use of sliding along the surface of the dielectric discharge to pump the excimer laser was first allowed to get generation in KrF laser at a wavelength of 248 nm with a pulse repetition rate of generation 2000 Hz without pumping the gas mixture. At this frequency and average radiation power of 20 mW peak power pulse generation glutelin the capacity of 10 NS is not more than 1.0 kW, that allows you to transport energy hard ultraviolet radiation from laser irradiated cavity in quartz svetovolokna diameter of 0.6 mm without its destruction.
The excimer laser containing an electrode system, a pulse circuit with a storage capacity and a switch in the form of a thyratron, characterized in that the electrode system includes a dielectric plate on which is placed the electrodes, while the thyratron connected in series to the storage capacitor and the electrode system, the electrode system is arranged to provide pump excimer gas medium sliding surface of the dielectric plate discharge.