DE2502899A1 - LIQUID LASER - Google Patents

Description

Patent attorneys L / ipi.-Ing. R. B E E T Z sen. Dipl.-Ing. K. LAMPRECHT Dr.-Ing. R. B E E TZ Jr. Munich 22, steinsdorfstr.

Tel. (089) 227201/227244/295910

Telegr. Allpatent Munich Telex 522O48

052-23.7O4P (23.7O5H)

1st 1975

Jersey Nuclear-Avco Isotopes, Inc ♦

Address: Exxon Nuclear Company,

Bellevue ("Washington) V. St. A.

Liquid laser

The invention relates to a laser and, more particularly, to a liquid laser for generating laser radiation along its optical lines Axis, with a laser liquid flowing transversely to and through the optical axis.

Solids, gases and liquids are used as active materials used in lasers. Laser radiation is created by raising energy levels of the atoms in the active material from the normally occupied levels to a higher energy level or an excited state

052- (436 573-AERL-147) -Me-r (8)

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triggered. This excitation method is generally used in a Liquid laser achieved by a (light) strong light source.

When the atoms of an active liquid material, liquid for short called, are in the excited state, they can through interaction be stimulated with an incident photon to emit a photon. Hence the incident photon or the incident one Wave amplified by the one emitted by the excited atom. The triggered wave oscillates in phase with the wave, that triggered the trip. This results in a reinforcing effect.

The active fluid is excited while in a laser cell is included. In order to keep the laser running, it forms the laser cell is part of a resonator with two separate reflective surfaces, one of which is partially permeable. The one caused by the emission of the photon from the atom in the excited material Wave must travel a path that is substantially parallel to the longitudinal axis of the resonator so that it repeats can be reflected by the active material. As the wave passes through the material, it stimulates more atoms to emit of photons that further amplify the wave. Every time the wave is reflected on the partially transparent reflection surface, occurs a small part by the area. This small part forms the laser output beam or laser beam.

Two desirable properties of the laser output beam are Coherence and collimation. Optical distortion or distortion

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The output of the laser beam occurs when any of these are impaired Properties on. The optical characteristic of an active liquid that mainly determines the quality of the laser output beam, is the uniformity of the refractive index of the liquid, which in turn depends on the uniformity of temperature and density the liquid. When an optically pumped liquid laser is excited, large amounts of heat can be released from the liquid unevenly are absorbed, whereby it has warmer and colder layers, which results in a non-uniform refractive index. A suggestion from the Under these unequal conditions can cause optical distortion of the laser output beam. Can continue if flow separation, eddies, vortices or the like occur in the active area or resonator, non-uniform densities and temperatures arise, which further optical distortions in the laser output beam cause.

Optical distortion of the output beam can be partial by ensuring isothermal conditions in active or laser beams releasing area can be prevented, both before and during the excitation. The flowing liquid laser, in which the active liquid constantly flowing through the active area, a liquid laser was designed for frequent, successive To create suggestions. The time between successive stimuli, i.e. H. the pulse repetition rate depends on the speed with which the liquid flows through the active area.

Minimal optical distortion of the laser output beam is only achieved to the extent that the density and temperature gradients

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Cause gradients of the refractive index, a minimum in the active area are. Furthermore, the maximum pulse frequency and / or output power is only achieved to the extent that the above is achieved necessary uniform flow conditions an excited liquid is replaced by non-excited liquid and the Cross-section of the active area can be optimized for optical pumping and mode control

It is an object of the invention to provide a new cross-flow liquid laser to develop an optimization of the cross-section of the active area for optical pumping and mode control allowed, wherein a flow separation of the laser material in or near the active area can be avoided.

The object is achieved according to the invention in that the excitation of the laser with flowing liquid along the longitudinal axis of the active area takes place at its narrowest point. Since the liquid flows in the transverse direction, every excitation creates an excited one. Volume of the laser material that extends along the entire longitudinal axis of the cell and extends only a relatively small distance on both sides of this axis in the transverse direction. This excited Liquid volume has temperature gradients, which is why it is advisable not to pass the entire volume of the excited liquid through excited isothermal active liquid before the next laser excitation to replace. Since the liquid flows across the excitation and only the smallest transverse section of the liquid is excited, it must entire volume of the excited liquid flow only a small transverse distance before a new isothermal liquid volume

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becomes available for suggestion. This way it becomes a relatively high In the pulse repetition frequency achieved with a relatively low linear flow velocity. Since the light sources are arranged at the point of smallest or smallest cross-section, which depends on the Properties of the light sources can be changed both in the transverse and in the longitudinal direction, an optimization of the active Area for optical pumping and mode control can be easily obtained. With a liquid laser designed in this way material homogeneity can be achieved in the active area.

A flash lamp pumped laser according to the invention which uses a liquid such as a dye solution to produce a laser beam used, contains an active area with a longitudinal and a Transverse axis, a continuously convexly narrowing inlet chamber and a continuously convexly widening outlet chamber, the are connected to the active area along the transverse axis at a distance from one another. Together with the end walls are the active ones Area, the inlet and the outlet chamber next to the active area formed by two opposing convexly curved Walls made of a suitable translucent material such as quartz. An elongated inlet pipe or manifold is preferably provided for uniformly introducing the active liquid into the inlet chamber in the longitudinal direction or along the longitudinal axis of the active area. Around the outlet of the active Area an elongated guide member is provided with a substantially cylindrical cross-section and to obtain a negative Pressure gradients in the dye flow through the entire laser beam generating area formed and arranged. The negative one

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Pressure gradient is used to reduce the flow separation, eddies, eddies or the like in or near the active area, due to the non-uniform Densities and temperatures in the laser beam emitting fluid could occur. According to an advantageous further development, a elongated outlet tube can be provided for both the execution of the liquid laser material, called laser liquid for short, as well as for Achieving the key effects. A liquid-cooled flash (light) lamp is releasably attached behind each curved wall at the point of smallest cross-section of the active area. One touch of the Flash lamp coolant with the parts of the curved walls turned away from the active area is prevented by suitable devices. Devices are connected to the flash lamps in order to generate the pump light of the flashlights to direct the active area, these devices and the curved walls coolant flow channels form in which the flash lamps are arranged.

In accordance with the invention, uniform density and temperature are achieved by providing an elongated active area that is substantially has the cross-section of an hourglass, whereby the active liquid to the inlet of the active area at a given uniform temperature, with detachable, opposing, liquid-cooled light sources near the narrowest section of the active area, whereby a non-uniform supply of heat into the active area at or near the inlet of the active area is prevented and thereby uniform flow conditions are achieved in the active area.

The invention thus provides a new laser at

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the optimal use of the stimulating light source is achieved and the energy and coolant required to operate the laser successfully is reduced.

A cross-flow liquid laser is also provided, with two liquid-cooled, opposite and easily detachable ones exciting light sources, together with an active area, which has essentially the cross-section of an hourglass, which passes through opposing curved side walls is formed, and with optimal optical quality of the liquid in the active area.

The active area is preferably represented by opposing, curved, translucent side walls formed through which light from the liquid-cooled stimulating light sources is radiated into the active area, whereby no loss of coolant or active liquid can occur.

The invention thus provides a flash lamp pumped laser which uses a liquid such as a dye solution to generate a laser beam used, and which contains an elongated "hollow cell, with an active or laser beam emitting area including a constriction or constriction between a continuously narrowing inlet chamber and a continuously widening one Outlet chamber. The active area and the inlet and outlet chambers adjacent to the active area are formed by two opposing, inwardly curved walls made of translucent Material like quartz. An elongated inlet branch guides the liquid emitting laser beams uniformly into the inlet

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chamber in the transverse direction to the laser output beam along the longitudinal extent of the active area. An elongated outlet branch is on the outlet chamber as and for the same purpose as the inlet pipe intended. A baffle is provided in the flared portion of the outlet chamber just downstream of the active area and designed to reduce flow separation, eddies, eddies, and the like, caused by non-uniform densities and temperatures in the liquid emitting laser beams within the active area or when leaving it. The leading link can be integral with the outlet branch or separate from it. Likewise, the outlet manifold can act as the guide member. A liquid-cooled Flash lamp is releasably provided behind each curved wall at the narrowest portion of the active area, and facilities are provided to prevent the flashlamp coolant from contacting the portions of the curved wall facing away from the active area impede. Devices are connected to the flash lamp to direct the light of the flash lamps onto the active area and around with the curved walls to form coolant channels for the flash lamps.

The invention is based on the exemplary embodiments shown in the drawing explained in more detail. Show it:

1 shows a plan view of a section through a liquid laser according to the invention ,

FIG. 2 shows a section 2-2 according to FIG. 1,

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3 shows, partly schematically, partly as a block diagram, a tunable optical resonator with a working area according to the invention,

Fig. 4 schematically in side view a part of another embodiment Example of the laser according to the invention with indication of the directions of flow. ·

In FIGS. 1 and 2, a dye (liquid s -) laser is in accordance with of the invention, which includes a main frame 11 of rectangular cross-section, opposing side walls 12 and 13, themselves opposing optical pumping assemblies 14, 15 extending from the side walls 12, 13 and include detachable flash lamp parts 16, 17, a liquid inlet junction 18 and a liquid outlet junction 19 provided within the frame 11. Laser windows 25 and 26 that are used for working or laser beams emitting area 27 between the flash lamp parts 16, 17 occurring stimulated emissions are permeable, are tight in End walls 28, 29 of the frame 11 supported.

The flat inner surfaces of the frame 11 and the side walls 12, 13 without the opposing optical arrangements form a oblong cuboid volume .. The optical arrangements are of the Central portions of the side walls 12, 13 are supported and extend essentially along their longitudinal extent and separate through their inwardly protruding convex training the inside of the frame 11 effective into an inlet chamber 31, an outlet chamber 32 and a working area 27 between the inlet and outlet chambers 31, 32.

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The frame 11 is expediently made of a flat floor 33, a flat ceiling 34 and flat end walls 28, 29 to form a one-piece and rigid member constructed to support the other components and to be attached to a base (not shown). The sides of the frame 11 are provided with grooves or depressions 35, 36 for receiving O-rings which form the side walls 12, 13 touch tightly. In order to facilitate maintenance and repair, the side walls 12, 13 are expediently detachable from the frame 11 connected, e.g. by means of screws or bolts 41. The frame 11 and the side walls 12, 13 are made of a suitable rigid electrical insulating material such as PVC.

The provision of a frame to which side walls are releasably tightly attached, as shown, in which the frame is rigid with is connected to a base, allows substantially complete disassembly and reassembly of the laser without the Alignment of the components that contain the optical resonator influence.

Openings 42, 43 are provided in the central portion of each side wall 12, 12 and extend substantially along the length thereof for detachable mounting of the flash lamp sections or Parts 16, 17 of the optical pump assemblies 14, 15. On the inner surface of the side walls 12, 13 are the openings 42, 43 of depressions or grooves 44, 45, each containing a silicone seal 46 for receiving the edge of transparent or translucent semi-cylindrical wall members 47, 48, which are expediently made from one half of a quartz tube closed at both ends

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forms are. The semi-cylindrical translucent wall members 47, 48 can be tightly connected to the side walls 12, 13 via the silicone seals 46 by end tensioning or clamping straps 51, 52. Quartz is preferred for the wall members 47, 48 because of its resistance to discoloration or color fastness. the translucent wall members 47, 48 are inwardly against each other curved to form a nozzle or constriction or constriction 53, the optical axis 54 preferably at the location of the the smallest distance is arranged. Even if a cylindrical configuration of the wall members 47, 48 is shown, this is not critical. Therefore, the side sections facing away from the optical axis can have a different curvature or inclination as shown.

uniform patterns, if this results in a possible / flow through and from the working or area 27 emitting laser beams is provided.

On opposite sides of the optical axis 54, flash (light) lamps 55, 56 are provided, each of which is supported by support members 57, 58 are held in the side wall openings 42, 43 tight are durable. The support members 57, 58, which can be made of aluminum, are each provided with a channel or a recess 61, 62 provided to form narrow leg sections each with an end surface which is at least close to the inner surface of the translucent Wall members 47, 48 are arranged. In the recesses 61, 62 are elongated U-reflectors 63, 64 added, in which the flash lamps 55, 56 are arranged. The reflectors 63, 64 are expediently made of quartz, the outer surfaces of which are designed to be reflective so that the reflective coating is protected from the coolant flowing around and along the ^ flashlights 55, 56, like that on

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is explained below. The reflectors 63, 64 can be attached to the support members 57, 58 be glued, by means of z. B. a suitable adhesive such as ETV, so that they can be held in place and so that they can Restrict coolant to the area surrounding flash lamps 55, 56.

t.

As best seen in Figure 1, the flashlamp portions or portions 16, 17 extend substantially inwardly the longitudinal extent of the frame 11. The metal support members 57, 58 are arranged within the side walls 12, 13 and for safety reasons covered with electrically insulating cover plates 59, 60. A coolant inlet passage 66 is at one end of each support member 57, 58 and a coolant outlet passage 67 is provided at the opposite end. The flash lamps 55, 56 are secured by metal clips 68, 69 held. The brackets 68 are (electrically) conductively connected to the support members 57, 58 and act via the support members 57, 58 as Ground connection of the high-voltage circuit of the flash lamps 55, 56. In the coolant inlet passage 66 and from the support members 57, 58 electrically isolated, e.g. B. by high-voltage insulating sleeves 70 is a metal tube 73 is arranged, at the end of which the clamp 69 is arranged. The coolant is introduced through the pipe 73, the also acts as a high-voltage lead for the flash lamps 55, 56.

The sections of the volume enclosed by the transparent wall members 47 which do not contain the flash lamp parts 16, 17, are filled with an insulating material or insulator 65 to protect against heat transfer from the flashlamp coolant into the active liquid in inlet and outlet chambers. Such an isolator 65

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essentially restricts coolant flow only to the die Flash lamps 55, 56 immediately surrounding area. Therefore, the flow of the flashlamp coolant on them becomes the immediate Flash lamps 55, 56 surrounding area are limited, whereby the occurrence of thermal discontinuities or inhomogeneities in the active Liquid is avoided when it enters and flows through the laser beam emitting area, which otherwise would occur when a hot dormant coolant fills these areas would. This property of maintaining the beam quality is achieved by using simple and inexpensive components.

The active liquid is in the inlet chamber 31 via a

Junction 18 with a plurality of outlet openings or slots 70

introduced

in the longitudinal extension of the working area 27 / Γ the inlet branch 18 acts to introduce the active liquid uniformly into the inlet chamber 31 and see a uniform flow in it Longitudinal expansion of the active region 27 before, even if the active liquid enters the branch 18 only at one end.

A second branch 19 is arranged in the outlet chamber 32, with a plurality of inlet openings or slots 71 for receiving it of the active liquid on its side or on its sections which are arranged at least essentially facing away from the working area 27 are. In this way, as best seen in FIG. 4, the active liquid flows from the inlet manifold 18 substantially along the flow paths 21, 22 to and through the active Area 27 past the guide member 23 and into the outlet chamber 32. From the outlet chamber 32, the active liquid either flows directly

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or via an outlet branch into a suitable one (not shown) Pump, a tank and / or a heat exchanger, and then back to the inlet branch 18.

The provision of liquid-cooled flash lamps 55, 56 together with convex, translucent wall members 47, 48 is in particular beneficial in preventing, if not completely eliminating, leaks or losses. The provision, the structure and the assignment of the frame 11 and the wall members 47, 48 according to the invention not only practically eliminates the possibility of coolant leakage in the active liquid, but also a leak both in reverse direction and out of the laser. Preventing the Leakage of the active liquid, such as fluorescent organic solutions such as Rhodamine 6G, has been an extremely troublesome problem so far, and in some cases it was impossible because of reliable prevention given up work or research on some dye lasers. Lasers constructed in accordance with the invention exhibit such defects not on.

Neither the direction of flow of the active material nor the provision of inlet and outlet branches 18, 19 as shown and described is critical. If necessary, e.g. the inlet and outlet branches are omitted as such and the active one Material through a wall member or part, e.g. B. the bottom 33 introduced and carried out through the other wall part. Then, however, it is necessary to provide at least one elongate guide member 23 that has the special shape and is spaced from the optical axis 54 and the outlet chamber sections of the light-permeable

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casual wall members 47, -48, such as the z. B. shown in Figs in order to avoid a flow separation in the working area 27, which is caused by the increasing pressure gradient, which begins approximately at the optical axis 54 and extends downstream.

This results in the flow of liquid from the inlet to the outlet by

P + —-— = constant = total pressure,

with P = fluid pressure,

£ = mass density of the liquid,
ν = velocity of the liquid.

As can be seen from this, the pressure decreases when the flow is accelerated upon entering the working area 27. Without a suitably shaped guide member 23 or an outlet branch 19 in the downstream area, which not only has the same effect as the molded guide member 23, but also a simple and effective device provides for suction or discharge of the active liquid, increases the pressure, however, increases when the speed of the flow decreases after leaving the working area 27, thereby in the working area 27 Flow separation, eddies, eddies and the like occur or can occur, as a result of which non-uniform densities and temperatures can arise. Density and temperature gradients in the working rich 27 cause gradients in the refractive index of the material emitting laser beams, which distort the laser output beam.

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According to a feature of the invention, the guide member 23 and / or the outlet branch 19 is shaped and sufficiently close to the optical axis 54 arranged at the constriction 53 in order to provide a favorable pressure gradient over the flow in the active area. Since the flow is subsonic (fluid), this limb affects the flow pressure upstream of its foremost End and generates a favorable pressure gradient even if it does not extend into the constriction 53. That will be in the substantially achieved when the total cross-sectional area between the outlet branch 19 or the guide member 23 and the translucent Wall members 47, 48 is comparable to the cross-sectional area of the constriction 53.

In other words, this is also achieved when the distance between the guide member 23 and the transparent wall members 47, 48 is comparable to the width of the narrowing or constriction. If necessary, the small stagnation area that can occur in the upstream portion of the guide member 23 can be eliminated by Drainage of the liquid through small holes provided at this point. Where these are provided, the area of the discharge holes should be be small compared to the main exhaust ports 72 so that the desired pressure profile is not adversely affected.

A guide member 23 as such and together with an outlet branch 19 for the stated purpose can be in the widening area of the outlet chamber 32 just downstream of the active area 27 be provided, as can be seen from the example shown in FIG. The cross-sectional shape of the guide member 23 depends on the

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Shape of the wall members 47, 48 from. For cylindrically shaped wall sections. 47, 48, as shown in Fig. 4, the guide member 23 is advantageously with a nose-shaped or pointed ("cusp-shaped") Cross-section executed. The guide member 23 is preferably made of an inert heat insulating material such as a suitable one Plastic like PVC to prevent thermal gradients from forming in the laser liquid, and shouldn't be noticeable in the active ones Area 27 protrude where it could cause parasitic laser modes. The provision of a guide member 23 allows flexibility in the use, size and / or design of the outlet branch 19, including its omission, and serves for the better Maintaining, if not for maintaining one in itself negative pressure gradient in the flow of the active liquid through the entire laser beam emitting area.

A particularly useful property of lasers, the fluorescent Using organic solutions like Rhodamine 6G as a reinforcing material is the wide range over which the reinforcement is achieved occurs. As a result, the output wavelength of such a laser can be changed by several devices. Of these the usual use of a diffraction grating or a prism are most suitable, as tuning by simple mechanical Setting is achievable. The main advantage of prism tuning is that prisms can be determined so that the; Light enters close to the Brewster angle, as a result of which reflection losses occur which are considerably smaller than the diffraction grating losses. This feature is beneficial for flashlamp-pumped lasers as the Wavelength range is expanded beyond the sufficient gain

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for laser beam generation is obtainable, and since the power output is increased. Another advantage of prism tuning over commercial replica or copy diffraction gratings is that significantly higher limit value of glass for destruction by laser radiation.

FIG. 3 shows the working area 27 and the flash lamps 55, 56 together with a tuning device 81, which is a chain 82 contains five prisms to provide variable output wavelengths. Next to and outside of the side wall 12 is a stationary, partially transparent, conventional output mirror 83 arranged. The output mirror 83 can be approximately 85% transparent and is aligned with the optical axis 54. Beside and outside The chain 82 of five prisms is arranged on the opposite side wall 13 for receiving the output radiation from the working area 27 along the optical axis 54 and for viewing an adjacent, completely or totally reflective tuning mirror 84.

The output mirror 83 and the tuning mirror 84 form, as is conventional, an optical resonator. The prism chain 82 is in Arranged light path 85 and adjusted the tuning mirror 84 about its axis to allow a prism deflection or displacement. Further, the inner surface of the exit mirror 83 is preferably so designed so that the alignment of the optics is facilitated, and the outer surface is designed to correct those caused by the inner surface Scattering.

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As with any tuning device, considerable care is required in aligning the mirrors 83, 84. The laser beam must remain perpendicular to the stationary or exit mirror 83, so that the beam angle remains stationary on the prism surface next to the laser, when the tuning mirror 84 is rotated. However, the angles between the laser beam and the other surfaces change during the Vote by an amount that increases when the tuning mirror 84 is approached so that the beam of the desired wavelength on the tuning mirror 84 always strikes perpendicularly and through the prism arrangement is reflected back.

The setting of the tuning mirror 84 determines the wavelength that is reflected in the working area 27, and therefore the Wavelength that is amplified and passed through the output mirror 83 as the laser output beam is transmitted.

As can be seen from this, the tuning device 81 can be a Contain set of prisms that are arranged to shed the light from the laser beam emitting material of a given wavelength passes through each prism and mirror on a flat tuning 84 is reflected in itself by the laser beam emitting material and to the exit mirror 83. The angles of the prisms, and that Glass from which they are made are chosen so that light is underneath one Angle entering and exiting each prism, the least reflection loss results, d. H. at the Brewster angle of the arrangement. A suitable angle for the prisms is 60. This angle is expedient because the manufacturing costs are relatively low.

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A light beam of the frequency to which the optical system is tuned and which is parallel to the optical axis 54 is im Laser material amplified, enters through an exit window to the first Prism where a part is reflected and lost. The remainder is deflected or broken when passing through the prism. The deflection is such that the beam hits the nearest prism where it is deflected or refracted again to strike the nearest prism. This continues until the beam hits the tuning mirror 84 occurs and is reflected in itself. A ray of longer or shorter wavelength traveling the same way through the The prism system begins, is broken less or more, and therefore also hits the tuning mirror 84 at a certain angle to the perpendicular and is therefore reflected off the axis and is lost. As mentioned, the desired wavelength is through Rotating the tuning mirror 84 selected.

The prism tuning is explained in detail e.g. See, for example, F.C. Strome, Jr., J.P. Webb, "Flash Tube-Pumped Dye Laser with Multiple-Prism Tuning, "Applied Optics, Volume 10, No. 6, June 1971.

During operation, an active liquid such as B. Rhodamine 6G dissolved in methanol is pumped through the working area 27, in which it is irradiated by the flash lamps 55, 56. The active material emits stimulated emission at a characteristic wavelength that depends on the active material and the geometry of the optical Space depends. The direction of flow through the active area 27 is perpendicular to that of the radiation from flash lamps 55, 56, and both are perpendicular to optical axis 54.

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■ Rhodamine 6G emits laser beams in a bandwidth of approx 5800 A - 6000 A (yellow-orange). Different wavelength bands over which the laser can be tuned can be set using different active materials and / or, solvents achieved will.

By using various known compositions of e.g. B. dyes and solvents, the laser can be tuned over a range of about 4500 A - 6500 A , ie approximately over the entire visible spectrum.

The flash lamps 55, 56 can be conventional xenon-quartz flash lamps which are operated with a pulse frequency of 1-50 Hz. The flash lamps 55, 56 are cooled and at a suitable operating temperature held by the flow of a suitable volume of coolant such as tap water along their length . The active material is typically circulated from a container to and through the laser and back into the container. Of the Container can contain cooling devices for the active material, so that it is always at a certain constant temperature in the laser is introduced. Cooling devices separate from the container can also be provided.

If inlet and outlet branches 18, 19 according to the preferred Embodiment are used, they can be provided with a series of flow openings or slots 70, 71, 72. The inlet slots 70, 71 suitably have a size and a Arrangement through which most or all of the pressure drop

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occurs when the active material flows through it to become a uniform Flow over the total longitudinal extent of the inlet branch to create.

Preferably the inlet manifold 18 is below the outlet manifold 19, with the active material flowing out at the bottom of the inlet junction 18, through the work area 27 flows up and out of the laser through the outlet junction 19 flows out. A separate baffle 23 may be provided or, as in the preferred embodiment, an outlet junction 19 may be provided, which serves as a guide member 23 to prevent flow separation, eddies, vortices occurring in the working area 27 and the like by the distortion of the laser output beam may occur.

Usual xenon flash lamps are used as spectral lamps bd one given current density operated. At a slightly higher current density, xenon flash lamps emit than a black body with a continuous Spectrum that extends across the entire visible spectrum and well into the ultraviolet range.

As some dyes that are in the blue spectral range laser radiation must be pumped with ultraviolet radiation, the flash lamps must be operated at sufficiently high current densities

2
the, such. B. over 10,000 A / cm.

Of all the energy generated in the flash lamps, only about 10% converted into laser light and only about 10 - 20%

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the electrical energy supplied to the flash lamps turns into light implemented. The flash length can be between about 0.1 to 1 µs, depending on the repetition frequency used. The shorter ones Pulses are used at higher "repetition rates. The laser pulse is essentially the same length as the Flashlamp pulse. The lifetime of the inverted cast is short, generally about 5 ns, which is why the laser radiation stops as soon as the flash lamps switch off. When the flashlamp pulse is increased sufficiently, a point is reached at which the active material is heated unevenly and the laser beam quality decreases.

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Claims (16)

Claims (1 J ^ liquid laser for generating laser radiation along its optical axis, with a laser liquid flowing transversely to and through the optical axis, marked by a) an elongated hollow body with an active area (27), which between an inlet chamber (31) with an inlet opening to Inflow of the laser liquid and an outlet chamber (32) coupled with an outlet opening for outflow of the laser liquid and which has a transverse axis and a longitudinal axis defining the optical axis (54) with the laser fluid from the inlet chimney he (31) through the active area (27) "and into the outlet chamber (32) flows in the longitudinal extension of the longitudinal axis and parallel to the transverse axis, b) a pair of opposing curved translucent wall members (47, 48) extending substantially longitudinally of the hollow body between the inlet chamber (31) and the outlet chamber (32) extend and are supported therein and the respective are inwardly curved and have an inner central window portion between first and second side panels, wherein opposing sides of the active area (27) are formed by the central window section, the first side parts being part of the Inlet chamber (31) next to the inflow end of the active area (27) and the second side parts form part of the outlet chamber (32) 509832/0703 form next to the outflow end of the active area (27), c) a feed device for feeding the laser liquid into the inlet chamber (31), d) a discharge device for discharging the laser liquid from the outlet chamber (32), e) a guide device provided in the outlet chamber (32), which at least essentially prevents an increase in pressure in the laser liquid as it flows out of the active area (27), f) a strong light source to excite the laser liquid in the active area (27), g) a detachable coolant supply to the. Conducting a flow of coolant about the light source including a pair of elongated, substantially U-reflectors (63, 64), the light source in the U-reflectors (63, 64) are arranged to substantially the entire Directing light from the light source into the active area (27), h) an insulator (65) which is essentially a heat transfer prevented into the laser liquid through the first side parts of the inlet chamber (31), and i) a coupling element for coupling the laser beam out of the hollow body along the optical axis (54). 2. Laser according to claim 1, characterized in that the guide 509832/0703 device prevents the outflow of the laser liquid from the active area (27) along the transverse axis, the guide device a flow path (21, 22) along every other side panel forms. 3. Laser according to claim 1 or 2, characterized in that the guide device contains a guide member (23) which extends in the longitudinal extent of the active area (27). 4. Laser according to claim 3, characterized in that the guide member (23) contains a substantially cylindrical hollow ring, having a longitudinal axis parallel to the optical axis (54) and spaced from the optical axis (54) at a distance of the order of magnitude the diameter of the hollow ring. 5. Laser according to claim 4, characterized in that the Hollow ring has a plurality of openings (72) which connect the interior of the outlet chamber (32) with the interior of the hollow ring, the Interior of the hollow ring is connected to the outlet opening of the outlet chamber (32). 6. Laser according to claim 5, characterized in that the openings (72) in the hollow ring facing away from the second side parts for guiding the laser liquid flow at least substantially behind the second side panels. 7. Laser according to claim 2 to 6, characterized in that the 809832/0703 Hollow body contains: a hollow rigid central frame (ll), and opposite side walls that are tightly connected to the frame (II) (12, 13), the translucent wall members (47, 48) sealingly with the inner surfaces of the side walls (12, 13) in the middle of the Frame (ll) are connected and the detachable feeds are tightly held by the side walls (12, 13) and through them into the wall members (47, 48) protrude. 8. Liquid laser for generating laser radiation along its optical axis, with a laser liquid, marked by a) an elongated active area (27) having a first and a second curved translucent side wall facing each other and convexly curved inwardly, said active area (27) has a transverse axis and a longitudinal axis and the longitudinal axis forms the optical axis (54), and with an inlet and a Outlet section which extends in the longitudinal direction at opposite one another Sides of the optical axis (54) extend, b) one with the inlet portion of the active area (27) connected Inlet chamber (31) for directing the laser liquid into the active area (27), the inlet chamber (31) having a third and a fourth elongated, converging side wall facing each other at the inlet portion of the active area (27), 509832/0703 c) means connected to the outlet portion of the active region (27) outlet chamber (32) for receiving the laser liquid from the _r active region (27), wherein the outlet chamber (32), a fifth and a sixth elongate diverging side wall extending opposite, at the outlet portion of the active area (27), d) a supply device for receiving the laser liquid under pressure from a source of the laser liquid and for introducing it the laser liquid into the inlet chamber (31), e) a discharge device for discharging the laser liquid from the outlet chamber (32), f) a guide device arranged in the outlet chamber (32) which at least substantially increases the pressure in the laser liquid prevents them from flowing out of the active area (27), g) a strong light source to excite the laser liquid in the active area, h) a detachable coolant supply for guiding a coolant flow via the light source with an elongated U-reflector (63, 64), the outer ends of which are attached to the exterior of the first and second side walls initiate, with the. Light source arranged in the U-reflector (63, 64) is to direct substantially all of the light from the light source into the active area (27), i) an insulator (65) which provides substantial heat transfer into the laser fluid through the side walls of the inlet chamber (31) prevented, and 509832/0703 j) a coupling element for coupling the laser beam out of the active area (27) along the optical axis (54). 9. Laser according to claim 8, characterized in that the guide device includes an obstruction to laser liquid flow into the outlet chamber (32) along the transverse axis; and laser liquid flow forcing out of the active area (27), which is substantially uniform along the fifth and sixth side walls flows. 10. Laser according to claim 8 or 9, characterized in that the guide device includes a first hollow ring which extends along the active region (27), has a longitudinal axis parallel to and spaced from the optical axis (54), substantially between and spaced from the fifth and sixth side walls of the outlet chamber (32), and a plurality of the interior of the outlet chamber (32) with the interior of the first hollow ring connecting openings (72), the interior of the first hollow ring with the Discharge device is connected. . 11. Laser according to one of claims 8-10, characterized in that that the feed device contains a second hollow ring which extends along the active region (27) and has a longitudinal axis parallel to and spaced from the optical axis (54), in is arranged substantially between and spaced apart from the third and fourth side walls of the inlet chamber (31) and several that The interior of the inlet chamber (31) is connected to the interior of the hollow ring 509832/0703 binding openings (70, 71), the interior of the hollow ring is connected to the feeder. 12. Laser according to one of claims 1 to 11 with a cell, characterized in that the cell contains: a) the inlet chamber (31) for receiving the laser liquid, b) the lap chamber (32) for dispensing the laser liquid, c) the active area (27) connected to the inlet and outlet chambers (31, 32) and arranged between them and which is formed by the A pair of opposing curved wall members (47, 48) are formed which are arranged in the cell and substantially extend in the longitudinal extension of the optical axis (54), wherein the wall members (47, 48) are curved inward and each have an inner central translucent window section, the opposite Form sides of the active area (27), and d) the guide device in the outlet chamber (32) next to the active area (27), which at least substantially increases the pressure in the laser liquid flowing out of the active area (27). 13. Laser according to claim 12, characterized in that the guide device is an obstacle to the laser liquid flow that enters the outlet chamber (32), along the optical axis (54), which contains the laser liquid emerging from the active area (27) flows out, forces, essentially uniformly along the curved 509832/0703 th wall members (47, 48) to flow, and the one non-uniform Prevents flow condition in the laser liquid leaving the active area. 14. Laser according to claim 12 or 13, characterized in that the guide device contains a guide member (23) with opposite side surfaces which converge substantially to the optical axis (54) and spaced from the curved wall members (47, 48) to form flow paths (21, 22), the curvature of the side surfaces is essentially the same as that of the respective opposing curved wall members (47, 48). 15. Laser according to claim 14, characterized in that the guide device is an elongated hollow laser liquid outlet ~ branch (19), which is arranged in the outlet chamber (32) for Receiving the laser liquid from the guide element (23) and for discharging the laser liquid from the outlet chamber (32). 16. Laser according to claim 12 or 13, characterized in that the guide device is an elongated, substantially cylindrical hollow Contains laser liquid outlet junction (19) with a longitudinal axis parallel to the optical axis (54), at a distance from the optical Axis (54) in the order of magnitude of the diameter of the outlet branch (19). 509832/0703 Blank page