EP0902906A1 - Procede et dispositif pour produire un faisceau lumineux coherent - Google Patents

Procede et dispositif pour produire un faisceau lumineux coherent

Info

Publication number
EP0902906A1
EP0902906A1 EP98905279A EP98905279A EP0902906A1 EP 0902906 A1 EP0902906 A1 EP 0902906A1 EP 98905279 A EP98905279 A EP 98905279A EP 98905279 A EP98905279 A EP 98905279A EP 0902906 A1 EP0902906 A1 EP 0902906A1
Authority
EP
European Patent Office
Prior art keywords
amplifiers
optical system
light
amplifier
coherent
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP98905279A
Other languages
German (de)
English (en)
Inventor
Richard Wallenstein
Bernard Beier
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
LDT Laser Display Technology GmbH
Original Assignee
LDT GmbH and Co Laser Display Technologie KG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by LDT GmbH and Co Laser Display Technologie KG filed Critical LDT GmbH and Co Laser Display Technologie KG
Publication of EP0902906A1 publication Critical patent/EP0902906A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/32—Holograms used as optical elements
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/23—Arrangements of two or more lasers not provided for in groups H01S3/02 - H01S3/22, e.g. tandem arrangements of separate active media
    • H01S3/2383—Parallel arrangements
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/40—Arrangement of two or more semiconductor lasers, not provided for in groups H01S5/02 - H01S5/30
    • H01S5/4012—Beam combining, e.g. by the use of fibres, gratings, polarisers, prisms
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/40—Arrangement of two or more semiconductor lasers, not provided for in groups H01S5/02 - H01S5/30
    • H01S5/4025—Array arrangements, e.g. constituted by discrete laser diodes or laser bar

Definitions

  • the invention relates to a method for generating a coherent light bundle, in which n> 1 primary coherent light bundles with a mutually fixed phase relationship are each directed into one of n optical amplifiers, after which n secondary light bundles are led out of these amplifiers.
  • the invention relates to a device for generating a coherent light bundle, the n> 1 optical amplifiers, each with an input, to which one of n primary light bundles with a fixed phase relationship is supplied, and with one output, from each of which one of n secondary light bundles can be removed.
  • the maximum output power of diode lasers is limited by the maximum permissible intensity of the laser-internal light field at the exit surfaces of the laser crystal.
  • the diode laser material absorbs the internal light field within a layer less than 1 ⁇ m thick on the exit surface. A too high light flux can lead to thermal destruction of the light exit surface or the light exit facet there.
  • the maximum power density for an exit surface is, for example, 50 mW / ⁇ m 2 for gallium arsenide.
  • diode lasers with a transverse emitter width of typically 60 to 500 ⁇ m and an emitter height of approximately 1 ⁇ m. These diode lasers are called broad-band diode lasers.
  • a rectangular current contact area and thus a rectangular reinforcement area are provided.
  • diode lasers are also called “broad-area diode lasers”.
  • conical shapes for the active zone are also used and the lasers are commonly referred to as “tapered amplifiers”.
  • An alternative design, in the case of the so-called “diode laser arrays”, is provided by the parallel arrangement of narrow contact strips at a distance of approximately 10 ⁇ m in order to achieve an enlarged exit area.
  • the high-power diode laser is emitted in a large number of longitudinal modes and, due to the large lateral width of the amplifying zone, in a large number of predominantly transverse resonator modes.
  • This mode structure determines the spectral and spatial beam characteristics of the laser light generated.
  • the maximum output power of the high-power diode laser mentioned is in the range from 1 to 20 W in continuous wave mode.
  • a further increase in performance by widening the active zone is limited by the excitation of transverse modes in the laser. If a higher output power is to be achieved, one usually proceeds to a parallel arrangement of the same diode lasers. In this case one speaks of diode laser bars. The distance between the individual diode lasers is so large that no overlap of the light fields, that is to say no light field coupling, is possible.
  • the emitted radiation is composed spectrally and spatially from the radiation of the individual diode lasers. The emission is spectrally broadband and not limited by diffraction.
  • Oscillator-amplifier systems are particularly suitable for generating narrow-band diffraction-limited radiation. These systems consist of a single-strip diode laser and one or more semiconductor amplifiers. Both trapezoidal diode lasers, broad-band diode lasers and diode laser arrays are suitable as amplifiers. So that the transverse modes of the amplifier are suppressed, the reflectivity of the facets, that is to say the exit surfaces, is greatly reduced, in particular below 10 "5. Without coupling in a primary light bundle, the amplifier only emits amplified light from spontaneous emissions. In contrast, if a primary light bundle of a suitable wavelength is coupled in , the emitted power increases due to the emission stimulated by the incident light beam, while the spectral and spatial properties of the laser light from the primary light beam are retained.
  • the object of the invention is to provide a method and a device with which the power in the diffraction-limited beam can be significantly increased in the case of a plurality of secondary light beams which fail from a multiplicity of amplifiers.
  • the object is achieved in that the n secondary light bundles are combined with a first optical system by superposition in phase to the coherent light bundle to be generated.
  • the M parameter recently also called the diffraction index, is introduced here.
  • the M 2 parameter specifies the ratio of the divergence angles in the far field of the beam to be characterized to a Gaussian beam which is equivalent in terms of beam waist, wavelength and others.
  • the M parameter of interest is further defined in the publication by M. Inguscio and R. Wallenstein, "Solid State Lasers", Plenum Publishing Corporation, New York, 1993, pp. 13-28.
  • a phase-correct superposition can be achieved with optical systems by compensating for the phase differences given by the temperature distribution in the superposition of the n secondary light bundles by means of, in particular, diffractive optics.
  • Such diffractive optics transmit practically 100% of the light beams striking them, so that no thermal effects are expected in the diffractive optics themselves, which could lead to additional phase shifts.
  • the first optical system according to the invention can then be designed in such a way that the M 2 parameter of the combined secondary beams according to phase superposition is equal to that of the n primary beams.
  • the M parameters should therefore advantageously also be the same for all light beams incident on the amplifiers. This is achieved, for example, according to an advantageous further development of the method, in that a partial beam is branched off from some of the n secondary light bundles and is supplied to another amplifier as the primary light bundle, so that an optical series connection is produced.
  • This series connection ensures that the beam parameter of an incident primary light bundle is as similar as possible to the light bundle emerging from the upstream amplifier.
  • a partial beam of the secondary light beam of the first amplifier is primary in this series connection Beams of light fed back into the first amplifier of this series connection. This means that the beam parameters for all amplifiers in the series circuit are set essentially the same.
  • the entire amplifier structure can even be operated as an oscillator, depending on the size of the primary light beam fed back. An almost optimal beam product can be achieved for all light beams that then run through the amplifiers of this series connection.
  • the beam product can be further improved by providing a spatial / spectral filter in a light path of one of these partial beams and using this filter to set single-frequency, multi-frequency or broadband output radiation for the coherent light bundle to be generated.
  • a spatial / spectral filter in a light path of one of these partial beams and using this filter to set single-frequency, multi-frequency or broadband output radiation for the coherent light bundle to be generated.
  • an optimal M 2 parameter of the coherent light bundle to be generated can be achieved above all by spatially limiting this light bundle, for example by means of diaphragms.
  • an input light bundle is broken down into partial light bundles via a second, in particular diffractive, optics, which are fed as primary light bundles to at least some amplifiers.
  • a device for generating a coherent light bundle starting from the prior art mentioned at the outset, is characterized in that a first optical system is provided at the output of the n amplifiers, which unites the n secondary real bundles by superimposed phase in the coherent light bundle to be generated.
  • the device thus contains the first, in particular diffractive, optical system at the output of the n amplifiers for the phase-appropriate superposition, with which the n secondary light beams are combined according to the method to form the coherent light beam to be generated.
  • the first diffractive optical system has one or more holograms.
  • Holograms are particularly suitable as diffractive optical systems because they transmit almost completely and can also be produced in a simple manner as a diffraction image that is suitable for phase-correct superposition.
  • This allows easy adaptation to different amplifier systems. For example, in a given amplifier system for generating this hologram, the secondary light beams emanating from the amplifier can be directed onto a photo plate of suitable resolution, and at the same time a second light beam with the desired beam parameters of the beam to be generated can be directed onto this photo plate.
  • the interference image that arises on the photo plate, the hologram that arises after development, then has exactly the property that the n secondary light bundles unite to form the desired light bundle.
  • This method is particularly suitable for quickly adapting a first optical system to any amplifier arrangement and thus for developing prototypes, since it can be produced very easily and with little effort for the respective apparatus conditions.
  • the first diffractive system has one or more binary optics.
  • this process also offers a great degree of freedom in the design of such diffractive first optical systems within certain limits, which are given, for example, by the preservation of the beam product, since, given the familiarity of the input parameters, practically any beam profile for the coherent laser beam generated can be modeled.
  • the first diffractive optical system has one or more beam splitter plates.
  • Beam splitter plates are known from optics. They can be used to combine n partial beams into a single beam in phase or, conversely, to split a single beam into n in-phase systems. Beam splitter plates of this type are also particularly inexpensive to manufacture.
  • the phase difference should expediently be compensated for on the basis of the temperature gradients within the amplifier bars.
  • the beam splitter plate can then be combined, for example, with a binary optic or a hologram.
  • a beam splitter is provided behind at least one of the amplifiers, with which a partial beam of the secondary partial light beam can be coupled out at the output of this amplifier and this partial beam is fed to another amplifier as the primary light beam;
  • At least m amplifiers with 1 ⁇ m ⁇ n or all amplifiers are connected in series via the beam splitters and the decoupled partial beam from the last amplifier of this series connection is fed back to the first of this series connection;
  • a spatial / spectral filter is provided, in particular in the form of an aperture, a resonator, a single-mode
  • Fiber a grating, a prism or an active optical filter to control the device, in particular for single-frequency, multifrequency or broadband radiation of the coherent Uchtb Bundle to be generated.
  • the device has a second optical system for the coherent and diffraction-limited decomposition of an input light bundle into partial light bundles, which is used as at least some amplifiers primary light beams are fed.
  • the second optical system for disassembling and the first diffractive optical system for merging are constructed from similar components. From the principle of reversibility of light rays one can see that if the first diffractive optical system and the second optical system are similar components, or are even designed as identical components, the M 2 product or the beam product of the coherent light bundle generated should be substantially equal to the input light bundle. This further development also ensures that a very high power, which is practically given by the sum of the individual amplifier powers, is made possible in the far field of the laser beam generated.
  • the second optical system has one or more holograms
  • the second optical system has one or more binary optics
  • That the second optical system has one or more beam splitter plates.
  • the beam splitter plate is particularly advantageous for the second optical system. Without changing the beam product, it splits an incident partial beam into n equal beams with a fixed phase relationship.
  • the outlay for example for the aforementioned parallel connection of amplifiers, is accordingly correspondingly low.
  • the far field of the coherent light beam to be generated can be optimized by providing an adjusting device for adjusting the temperature of each of the n optical amplifiers and by virtue of this adjusting device the coherent light beam generated being adjusted to a predetermined beam shape and / or beam power of the Ucht bundle brought together by the first diffractive optical system is set.
  • the aforementioned phase shift due to the temperature can be used to optimize the combined coherent light beam in the far field.
  • This provides an additional degree of freedom that would not have been possible for all amplifiers by means of an overall temperature setting and would, for example, have made additional optical components necessary for the phase shift. With this setting, a good beam profile or high beam power can still be achieved even after the amplifiers have aged without modification in the optical systems.
  • the effort is kept correspondingly low.
  • the above-mentioned parabolic behavior of the temperature gradient can be reproducibly adjusted when the temperature is set above the operating current, so that the laser power in the far field, or the shape of the coherent light beam generated, is likewise almost optimally and with high stability.
  • the reproducibility becomes particularly high when the temperature of the amplifier is not only controlled but even regulated according to a preferred development of the invention via the setting device.
  • the adjusting device can be controlled by ready-to-use signals, a sensor at least for temporarily detecting the beam profile of the generated coherent light beam for generating the input-side signals for controlling the setting device, and a circuit for evaluating the detected one Beam profile are provided, the circuit containing a network with which the beam profile is regulated via the setting device to the predetermined beam shape and / or beam power of the coherent light beam.
  • the temperature is not regulated indirectly, but the beam shape and / or the beam power of the coherent light beam is regulated directly.
  • the beam profile is thus controlled directly, instead of indirectly via temperature detection as in a conventional temperature control, so that optimum beam profiles and / or beam powers can also be set according to this development.
  • the number of outputs of the network is expediently equal to the number of amplifiers.
  • the sensor can be, for example, a CCD element that records the beam profile, the pixel signals representing the beam profile.
  • the required network becomes arbitrarily complex because of the high number of pixels. For this reason, it is useful, for example, to use a neural network for the network that can learn the optimal conditions for the output beam. If this network is optimized for certain types of the device, however, a network can be used, in particular for series production, which is modeled on this neural network in the optimized state. O 98/30929 ⁇ 1 ° - PCT / EP98 / 00101
  • Figure 1 is a schematic representation for explaining the method and the device for generating a coherent light beam.
  • Figure 2 is a schematic representation of an embodiment with an optical parallel connection of amplifiers.
  • Fig. 3 shows a laser arrangement with a series connection of
  • Fig. 4 is a schematic representation of an embodiment with both parallel and series connection of amplifiers
  • FIG. 5 shows a schematic illustration for explaining a production method for binary optics
  • Fig. 6 is a beam splitter plate, as in the embodiments of
  • Fig. 7 is a schematic representation of a circuit arrangement for controlling currents of the amplifier in the previous embodiments.
  • n 4 amplifiers 12 are used to amplify n primary light beams 14.
  • the number is four only exemplary.
  • the amplifiers 12 are optical semiconductor amplifiers, as are also known from the prior art mentioned at the beginning. These reinforce primary light beams 14, so that more powerful secondary light beams 16 fail from them.
  • the amplifiers 12 are supplied with a current for this power increase. One possibility for regulating these currents is subsequently explained in more detail in connection with FIG. 7.
  • the secondary light bundles 16 are added coherently, i.e. the individual secondary light beams are superposed evenly with regard to their phase.
  • a first optical system 20 is used for this purpose, which is described in more detail below.
  • the optical system 20 is essentially based on the phase-correct assembly of secondary light beams 16.
  • the phase of each secondary light beam 16 can accordingly be adjusted with the aid of diffraction to the phase-correct superposition. This also makes it possible to compensate for the phase differences occurring due to the different transit times in the amplifier 12 due to different temperatures in the center and at the edge, so that the entire beam is coherently combined in the light bundle 10 to be generated.
  • optical system 20 can be implemented, for example, using an appropriately designed phase plate, it is nevertheless shown in FIG. 1 and in the following figures as two separate optical elements 22 and 24, so that its mode of operation can be better explained.
  • the optical element 24 is used here for the phase-appropriate superposition of the individual light bundles and for deflecting in the direction of the coherent light bundle 10.
  • a hologram can be generated, for example, for producing the optical element 24 by operating an amplifier system according to FIG. 1 with the desired working parameters, however, the optical element 24 is replaced by a photo plate onto which a laser beam is simultaneously directed in the opposite direction to the beam 10 to be produced with the desired properties. Then an interference pattern is created on the photo plate.
  • an optical element 24 is then obtained which, due to diffraction alone, is capable of producing the desired coherent light bundle 10.
  • a Fresnel zone plate designed as a diffraction pattern can also be used instead of the lens mentioned as an example for the optical element 22.
  • the optical element 24 can also be realized by a beam splitter plate, which will be explained in more detail later in connection with FIG. 6. Then, however, it is recommended to use diffractive optics for the optical element 22, for example also a hologram, with which different phase delays in the amplifiers 12 are compensated for due to temperature differences.
  • the foregoing discussion shows that a variety of ways to form the first optical system 20 are possible. It is important that at least one optical element 22 or 24 is provided, with which the coherent light bundles 16 can be superposed in phase again, so that a high parallelism of the coherent light bundle 10 to be generated is also possible in the far field. There is a visual limitation for this due to the beam product and the M 2 parameter, which describes the beam properties in the far field. Appropriate phase-appropriate superposition results in any case in a beam product and an M 2 parameter, which are essentially determined only by the corresponding sizes of the primary beam 14. A system can thus be created with which laser radiation in the multi-watt range can be generated. The coherent light bundle 10 is almost diffraction limited and the spectral properties of the system are essentially determined only by the properties of the primary light bundles 14.
  • Such a system is practically scalable, i.e. by adding more amplifiers 12 with primary Uchtbündels 14 theoretically any power in the coherent Uchtbündels 10 can be generated.
  • the upper limit is only that an excessive laser power could destroy the optical system 20.
  • the system of FIG. 1 is also characterized by a compact structure and high mechanical stability.
  • the use of semiconductor lasers enables efficient conversion from electrical to optical power.
  • amplifiers 12 which are made with the aid of semiconductor technology, both great uniformity and high density can be achieved.
  • all components are suitable for mass production, especially if instead of binary optics, as will be explained in more detail in connection with FIG. 5, is used as an example hologram.
  • the primary light bundles 14 should have a fixed phase relationship to one another. Furthermore, the beam parameters of the coherent light bundle 10 to be generated can also be improved if the primary light bundles 14 likewise have the same beam parameters as possible. How this can be achieved is illustrated below using various examples according to FIGS. 2 to 4.
  • a second optical system 30 is provided for the coherent and diffraction-limited series of a coherent input light bundle 32 into the primary light bundles 14.
  • This second optical system 30 can simply be a beam splitter plate.
  • the second diffractive optical system 30 is also formed with two optical elements 34 and 36.
  • the optical element 34 is thus identical in construction to the optical element 24 of the first optical system 20, just as the optical element 36 is identical in construction to the optical element 22 of the first optical system 20. This ensures, based on the principle of reversibility of light paths, that the coherent light bundle 10 to be generated has practically the same beam properties as the incident input light bundle 32.
  • the beam properties of the coherent light bundle 10 to be generated essentially depend only on the quality of the input light bundle 32.
  • an exemplary embodiment is shown in FIG. 3 in which the amplifiers 12 themselves are arranged to build up a laser structure.
  • the secondary light bundle 16 emerging from an amplifier 12 is in each case divided by a partially transparent mirror 40, one of the partial beams being fed via a second mirror 42 to a subsequent amplifier 12 as the primary light bundle 14.
  • the last partial beam of a secondary light beam 16 is transferred from the last mirror 40 an optical isolator 44 and a mirror 45 and a spatial / spectral filter 46 and a mirror 47 are reintroduced into the first of the amplifiers 12.
  • the amplifier arrangement thus forms a ring laser.
  • the amplifiers 12 are all connected in series, which means that in each amplifier 12 with the same quality of the mirrors 40, all the primary light beams 14 have the same beam quality, so that the first optical system 20 can optimally coherently superpose the secondary light beams 16.
  • the spatial / spectral filter 46 determines the spatial and spectral properties of the coherent light bundle 10. With a diaphragm, the beam diameter of the circulating partial beams can essentially be determined. Furthermore, when the filter 46 is constructed by means of a resonator, a single-mode fiber, a grating, a prism or an active optical filter, the spectral properties of the device shown in FIG. 3 can be set practically as desired within the physical limits given by the structure .
  • FIG. 4 also shows an example that combines the positive properties of the exemplary embodiments of FIGS. 2 and 3.
  • Two amplifiers 12 with mirrors 40 and 42 are connected in series. However, the amplifiers are only excited by the two primary light bundles 14, which were obtained by a second optical system 30 from an input light bundle 32 by decomposition.
  • FIGS. 2 and 4 it should also be stated that these systems can also be designed in such a way that the amplifiers 12 themselves are used for reading.
  • the amplifiers 12 themselves are used for reading.
  • FIGS. 1 to 4 essentially holograms for the coherent addition or decomposition of the first optical system or the second optical system and in particular for the optical elements 22 and 24, or 34 and 36 were addressed, which allow an optical system 20 or 30 to be created for any device, with which the light bundle 10 to be generated has optimal beam parameters, but the use of binary optics is much more advantageous for mass production.
  • These can be manufactured using the technology known for the manufacture of VSLI circuits. This technology enables mass production for the optical systems 20 and 30 with a manufacturing price of only a few marks or even just pennies. The manufacturing process is briefly explained here with reference to FIG. 5. Any diffraction structure can be calculated by a computer, which then generates the corresponding lithography masks for the method shown.
  • FIG. 5 shows an example of a diffraction structure 50 which is approximated by this manufacturing method by means of a binary optic 52.
  • On the left side, 54 shows a first photomask, with which a structure made of photoresist 56 is coated on a substrate 58.
  • the subsequent photo step then leads to a structure 60 which, after etching, gives structure 62 and, after removal of photoresist 56, leads to binary structure 64.
  • binary optics stems from the fact that with each step two levels are created for different phase shifts for the light striking the optics.
  • the hologram mentioned by way of example can be used as the output for the structure 50, which is then simulated as binary optics.
  • the interference pattern formed in the hologram can also be calculated in a computer simulation via superposition of waves of the input and output beams, after which the masks can be generated immediately by means of computer control.
  • FIG. 6 shows, by way of example, the joining together of three secondary light beams 16 into one coherent light beam 10 to be generated.
  • a light bundle 32 can also be broken down into primary light bundles 14.
  • the relevant reference numerals are given in brackets in FIG. 6. To explain the mode of operation, only the decomposition of an input beam 32 into the primary light bundles 14 is shown here.
  • An input light beam 32 is incident on a first surface 72 of the beam splitter plate 70, is refracted by it in an incident segment 74 and is thrown onto a second surface 76 opposite the first surface 72, where it is either reflected or transmitted as one of the primary light beams 14 to be split becomes.
  • the light reflected in the beam splitter plate 70 is incident on a segment 78 of the first surface 72, where it reflects back to the surface 76 and further primary light bundles 14 emerge depending on the number of reflections.
  • the second surface 76 is also divided into segments 80, 82 and 84 for each emerging primary light bundle 14.
  • the reflection coefficient of the first segment designated 80 is 66.6% and that of the second segment having the reference number 82 is 50%.
  • Segment 84 is only provided with an anti-reflective coating, so that the last primary light beam 14 can completely drop out of the beam splitter plate.
  • the segments 80, 82, 84, 78 explained in more detail above are embodied as dielectric layers in the exemplary embodiment. However, other training courses can also be provided for this, such as partially transparent mirrors or the like.
  • phase difference between the individual beams 16 normally results from the plate spacing of the first plate 72 and the second plate 76.
  • Amplifier material expressed in different phase shifts.
  • the coefficient for a phase shift is about 15 mA / 2 ⁇ .
  • This phase shift can also be compensated for with the diffractive optics in the optical systems 20 or 30.
  • the overall phase difference of an amplifier 12 can also be changed by additional external phase shifters.
  • each amplifier 12 In order for the system to operate stably, it is expedient to control each amplifier 12 separately by means of a current and, if possible, to regulate it so that the temperature of the amplifier 12 remains the same, so that the secondary light beams 16 are at all times in the coherent light beam 10 to be generated add optimally coherently.
  • a temperature control circuit is exemplified in FIG. 7.
  • An adjusting device 90 which regulates the respective currents, is used to adjust the individual currents of amplifiers 12, in which only one is shown by way of example in FIG. 7.
  • the simplest type of control is the temperature detection of the amplifier 12 and a separate readjustment by the setting device 90 for each amplifier 12.
  • FIG. 7 The simplest type of control is the temperature detection of the amplifier 12 and a separate readjustment by the setting device 90 for each amplifier 12.
  • FIG. 7 is suitable for generating optimal beam parameters independently of the operating time and the outside temperature. Required for standard applications, for example mass production for a laser television to be expected in the future However, one does not cultivate such a well-bred optimal beam parameters, so that one will get by with simpler control circuits such as temperature control of the individual amplifiers 12.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Optics & Photonics (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • General Physics & Mathematics (AREA)
  • Lasers (AREA)
  • Semiconductor Lasers (AREA)

Abstract

L'invention concerne un procédé et un dispositif pour produire un faisceau lumineux (10) cohérent. Selon l'invention, n > 1 faisceaux lumineux (14) cohérents primaires sont guidés chacun avec un rapport de phase mutuel fixe dans un de n amplificateurs (12) optiques d'où (12) sont ensuite ressortis n faisceaux lumineux (16) secondaires. Ces n faisceaux lumineux (16) secondaires sont réunis avec un premier système optique (20) par superposition conforme à la phase, pour former le faisceau lumineux cohérent à produire.
EP98905279A 1997-01-11 1998-01-09 Procede et dispositif pour produire un faisceau lumineux coherent Withdrawn EP0902906A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE19700720 1997-01-11
DE19700720A DE19700720A1 (de) 1997-01-11 1997-01-11 Verfahren und Vorrichtung zum Erzeugen eines kohärenten Lichtbündels
PCT/EP1998/000101 WO1998030929A1 (fr) 1997-01-11 1998-01-09 Procede et dispositif pour produire un faisceau lumineux coherent

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EP0902906A1 true EP0902906A1 (fr) 1999-03-24

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JP (1) JP2000507368A (fr)
DE (1) DE19700720A1 (fr)
IL (1) IL126053A0 (fr)
WO (1) WO1998030929A1 (fr)

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NL1017779C2 (nl) * 2001-04-05 2002-10-11 Stichting Tech Wetenschapp Werkwijze en inrichting voor het genereren van een coherente laserstraal alsmede werkwijze voor het vervaardigen van een daarbij toe te passen hologram.
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WO1998030929A1 (fr) 1998-07-16
JP2000507368A (ja) 2000-06-13
IL126053A0 (en) 1999-05-09
DE19700720A1 (de) 1998-07-16

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