LASER SOURCE, LASER DEVICE AND METHOD OF CUTTING A TISSUE

Abstract

A laser source (101) comprises: (i) a first beam generating configuration (111, 112, 113) adapted to generate a pulsed primary ablating laser beam (162) with pulses having a first emission spectrum and a first temporal pulse width to ablate one type of tissue, (ii) a second beam generating configuration (121, 122, 123) adapted to generate a pulsed secondary ablating laser beam (163) with pulses having a second emission spectrum different from the first emission spectrum and a second temporal pulse width to ablate another type of tissue different than the one type of tissue ablated by the primary laser beam (162), (iii) a third beam generating configuration (121, 122, 123, 126) adapted to generate a pulsed analysis laser beam (161) with at least one pulse having a third emission spectrum and a third temporal pulse width shorter than the first temporal pulse width and shorter than the second temporal pulse width, and (iv) a beam directing optics (125) with beam aligning elements adapted to align the primary ablating laser beam, the secondary ablating laser beam (163) and the analysis laser beam (161) such that the laser source (101) propagates the laser beams (160) along a same propagation path.

Claims

1.-28. (canceled)

29. A laser source comprising: a first beam generating configuration adapted to generate a pulsed primary ablating laser beam with pulses having a first emission spectrum and a first temporal pulse width; a second beam generating configuration adapted to generate a pulsed secondary ablating laser beam with pulses having a second emission spectrum different from the first emission spectrum and a second temporal pulse width; a third beam generating configuration adapted to generate a pulsed analysis laser beam with at least one pulse having a third emission spectrum and a third temporal pulse width shorter than each of the first temporal pulse width and the second temporal pulse width; and a beam directing optics with beam aligning elements adapted to align the primary ablating laser beam, the secondary ablating laser beam and the analysis laser beam such that the laser source propagates the laser beams along a same propagation path.

30. The laser source of claim 29, wherein the first beam generating configuration has a first gain medium to generate the primary ablating laser beam, and the second beam generating configuration has a second gain medium different from the first gain medium to generate the secondary ablating laser beam, and wherein the third beam generating configuration comprises the second gain medium.

31. The laser source of claim 29, wherein the third beam generating configuration comprises a giant pulse former.

32. The laser source of claim 31, wherein the giant pulse former has an optoelectronic element, such as a Q-switching device, or wherein the third beam generating configuration comprises two resonator mirrors and the giant pulse former has a rotator to which one of the two resonator mirrors of the third beam generating configuration is mounted.

33. The laser source of claim 29, wherein the first emission spectrum has a maximum in a range of about 2,900 nm to about 3,000 nm, in a range of about 2,950 nm to about 2,980 nm or in a range of about 2,960 nm to about 2,970 nm, or of about 2,964 nm.

34. The laser source of claim 29, wherein the second emission spectrum has a maximum in a range of about 1'000 nm to about 1'100 nm, in a range of about 1'050 nm to about 1'080 nm or in a range of about 1'060 nm to about 1'070 nm, or of about 1'064 nm.

35. The laser source of claim 29, wherein the third emission spectrum has a maximum in a range of about 500 nm to about 560 nm, or in a range of about 520 nm to about 540 nm, or of about 532 nm.

36. The laser source of claim 29, wherein the beam directing optics comprises a beam combining element arranged to combine the primary ablating laser beam, the secondary ablating laser beam and the analysis laser beam.

37. The laser source of claim 29, wherein the first temporal pulse width and the second temporal pulse width are in a range of about 1 μs to about 1 ms or in a range of about 150 μs to about 300 μs.

38. The laser source of claim 29, wherein the third temporal pulse width is in a range of about 1 ps to about 100 ns or in a range of about 1 ns to about 50 ns.

39. The laser source of claim 29, comprising: at least one flash lamp as a light source of the first beam generating configuration, the second beam generating configuration and/or of the third beam generating configuration, and/or at least one laser diode as a light source of the first beam generating configuration, the second beam generating configuration and/or of the third beam generating configuration.

40. A laser device comprising: the laser source according to claim 29; and a control unit configured to adjust the beam directing optics.

41. The laser device of claim 40, further comprising a plume analysing arrangement adapted to identify a tissue type in a debris of a plume generated by the analysis laser beam hitting a target tissue.

42. The laser device of claim 41, wherein the control unit is configured to automatically activate either the first beam generating configuration of the laser source or the second beam generating configuration of the laser source dependent on the tissue type identified by the plume analysing arrangement, and wherein the plume analysing arrangement is adapted to identify a hydrophilic tissue type and a hydrophobic tissue type.

43. The laser device of claim 42, wherein the control unit is configured to activate the first beam generating configuration of the laser source when the tissue type identified by the plume analysing arrangement is a hydrophilic tissue type and to activate the second beam generating configuration of the laser source when the tissue type identified by the plume analysing arrangement is a hydrophobic tissue type, and wherein the control unit is configured to simultaneously activate the first beam generating configuration and the second beam generating configuration when the tissue type identified by the plume analysing arrangement is a hydrophilic tissue type or a hydrophobic tissue type.

44. The laser device of claim 41, wherein the control unit is configured to activate the third beam generating configuration of the laser source to ablate the target tissue to generate the debris with the plume, and/or to synchronize pulses of the primary ablating laser beam, the secondary ablating laser beam and the analysis laser beam.

45. The laser device of claim 40, further comprising a cooling system configured to cool a target tissue hit by the primary ablating laser beam or by the secondary ablating laser beam.

46. The laser device of claim 40, wherein the third beam generating configuration comprises components of the first beam generating configuration or of the second beam generating configuration.

47. A method of cutting a tissue by means of a laser device according to claim 40, comprising: positioning a tissue in an area of operation of the laser device where the beam directing optics of the laser source direct the laser beams of the laser source; the laser source of the laser device propagating an analysis laser beam generated by the third laser beam generating configuration; identifying a major tissue type in a plume of a debris generated by the analysis laser beam hitting the tissue; selecting either the first beam generating configuration or the second beam generating configuration suiting the identified major tissue type; and ablating the tissue by means of the selected first laser generation configuration or second laser generation configuration of the laser source.

48. The method of claim 47, wherein the steps of identifying the major tissue type and of selecting the first beam generating configuration or the second beam generating configuration are automatically executed by a plume analysis arrangement of the laser device.

49. The method of claim 47, comprising a step of predefining an ablation geometry, wherein the target tissue is ablated by the selected first laser generation configuration or second laser generation configuration of the laser source along the ablation geometry.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Aspects of the laser source according to the invention, the laser device according to the invention and the method according to the invention are described in more detail herein below by way of an exemplary embodiment and with reference to the attached drawings, in which:

[0062] FIG. 1 shows a schematic view of a setup of an embodiment of a laser source according to the invention in an embodiment of a laser device according to the invention suitable for performing an embodiment of a method according to the invention for the ablation of a tissue depending of its water content as well as the identification of the tissue being analysed;

[0063] FIG. 2 shows a schematic detailed view of further components of the laser device of FIG. 1;

[0064] FIG. 2a shows the timing of two ablating laser beams generated by the laser source of FIG. 1 to each other, where At is the time shift or delay between them in an alternating mode;

[0065] FIG. 2b shows the timing of the two ablating laser beams generated by the laser source of FIG. 1, when one ablating laser beam is firing after two laser shots of the other ablating laser beam;

[0066] FIG. 2c shows the timing when only an analysis laser beam generated by the laser source of FIG. 1 is firing;

[0067] FIG. 2d shows the timing of the two ablating laser beams generated by the laser source of FIG. 1, when one ablating laser beam is firing after two laser shots of the other ablating laser beam;

[0068] FIG. 3a shows a schematic view of two possible power supplies used in combination with the laser source of FIG. 1;

[0069] FIG. 3b shows a schematic view of two other possible power supplies used in combination with the laser source of FIG. 1.

DESCRIPTION OF EMBODIMENTS

[0070] In the following description certain terms are used for reasons of convenience and are not intended to limit the invention. The terms “right”, “left”, “up”, “down”, “under” and “above” refer to directions in the figures. The terminology comprises the explicitly mentioned terms as well as their derivations and terms with a similar meaning. Also, spatially relative terms, such as “beneath”, “below”, “lower”, “above”, “upper”, “proximal”, “distal”, and the like, may be used to describe one element's or feature's relationship to another element or feature as illustrated in the figures. These spatially relative terms are intended to encompass different positions and orientations of the devices in use or operation in addition to the position and orientation shown in the figures. For example, if a device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be “above” or “over” the other elements or features. Thus, the exemplary term “below” can encompass both positions and orientations of above and below. The devices may be otherwise oriented (rotated 90 degrees or at other orientations), and the spatially relative descriptors used herein interpreted accordingly. Likewise, descriptions of movement along and around various axes include various special device positions and orientations.

[0071] To avoid repetition in the figures and the descriptions of the various aspects and illustrative embodiments, it should be understood that many features are common to many aspects and embodiments. Omission of an aspect from a description or figure does not imply that the aspect is missing from embodiments that incorporate that aspect. Instead, the aspect may have been omitted for clarity and to avoid prolix description. In this context, the following applies to the rest of this description: If, in order to clarify the drawings, a figure contains reference signs which are not explained in the directly associated part of the description, then it is referred to previous or following description sections. Further, for reason of lucidity, if in a drawing not all features of a part are provided with reference signs it is referred to other drawings showing the same part. Like numbers in two or more figures represent the same or similar elements.

[0072] FIG. 1 shows an embodiment of a laser device 100 according to the invention equipped with an embodiment of a laser source 101 according to the invention and implementing an embodiment of a method according to the invention. The laser device 100 is in the following also referred to as universal tissue laser device 100 or UTL device 100.

[0073] The laser source 101 comprises a first flash lamp (FL) 112 arranged to pump an Er:YAG solid state rod 111 as a first gain medium, and two first resonator mirrors 113 embedding the Er:YAG solid state rod 111. The first flash lamp 112, the Er:YAG solid state rod 111 and the two first resonator mirrors 113 together form a first beam generating configuration 110, which is also referred to as first laser 110. The first beam generating configuration 110 is adapted to generate a pulsed primary ablating laser beam 162 with pulses having a first emission spectrum and a first temporal pulse width as described in more detail below.

[0074] The laser source 101 further comprises a second flash lamp (FL) 122 arranged to pump an Nd:YAG rod 121 as a second gain medium, two second resonator mirrors 123 embedding the Nd:YAG rod 121, and a Q-switching device 126 as optoelectronic element. The second flash lamp 122, the Nd:YAG solid state rod 121 and the two second resonator mirrors 123 together form a second beam generating configuration 120, which is also referred to as second laser 120. Furthermore, the same second flash lamp 122, the Nd:YAG solid state rod 121 and the two second resonator mirrors 123 form together with the Q-switching device 126 a third beam generating configuration 120, which is also referred to as second or third laser 120. The second beam generating configuration 120 is adapted to generate a pulsed secondary ablating laser beam 163 with pulses having a first emission spectrum and a first temporal pulse width as described in more detail below. The third beam generating configuration 120 is adapted to generate a pulsed analysis laser beam 161 with pulses having a third emission spectrum and a third temporal pulse width shorter than the first temporal pulse width and shorter than the second temporal pulse width as described in more detail below.

[0075] The laser source 101 is additionally equipped with a beam directing and shaping optics 125 with plural mirrors as beam aligning elements adapted to align the primary ablating laser beam 162, the secondary ablating laser beam 163 and the analysis laser beam 161 such that the laser source 101 propagates the three laser beams 160 along a same propagation path. The beam directing optics 125 further have a beam shaping optics 171 to correct for the different divergence or the primary ablating laser beam 162 and the analysis laser beam 161, and a first beam combining element 170 to combine the combined secondary ablating and analysis laser beam 161/163 with the primary ablating laser beam 162.

[0076] Besides the laser source 101 the UTL device 100 comprises a central power supply 130, a central cooling system 140 and a bus 200 for communication between the UTL device 100 and further components such as a robot to guide the laser source 101.

[0077] In FIG. 2 additional components of the UTL device 100 are shown. In particular, the UTL device 100 further comprises a control unit 190, an analysis unit 180 as plume analysing arrangement, a beam splitting unit 210, a beam focussing element 211 and an electronics 132 for the Q-switching device 126. The control unit 190 is coupled to the cooling system 140, the power supply 130, the analysis unit 180 and external components such as the robot to guide the laser source 101 via the bus 200. The electronics 132 is embedded in the power supply 130 which energizes the complete UTL device 100.

[0078] The beam splitting unit 210 is positioned in the propagation path. It is arranged to direct the three laser beams 160 towards the beam focussing element 211 where they are focussed and directed towards a target tissue 230. Light reflected or emitted, e.g. fluorescence from some of the fragments of the tissue converted into debris, from the target tissue due to the interaction of the analysis laser beam 161 with the target tissue 230 can be guided back contra-propagating along the optical path and captured by the analysis unit 180. This light is referred to as analytical light 164 which is used for LIBS in the analysis unit 180. The result of the real time analysis of the captured analysis light 164 by the analysis unit 180 can be further used by the control unit 190 and/or other components to further control the ablation process or other devices.

[0079] The beam splitting unit 210 can consist of multiple opto-mechanical elements such as, e.g., mirrors, dichroic mirrors or lenses to properly align different optical pathways to each other, e.g. collinear or parallel. The beam-focusing element 211 can be a lens system, reflective optics or a combination of both. Preferably, a scanner mirror as reflective optics is adapted to focus the cutting laser beam and the imaging laser beam. Thereby, the scanner mirror can be a concave mirror mounted on a movable scanning unit which can simplify alignment and controlling. Such a reflective optics design has further the advantage of smaller losses and no chromatic aberrations when using different wavelengths. In this way, a particular efficient operation of the laser ablating device is possible.

[0080] The analysis laser beam 161 has a maximum wavelength at 1'064 nm and is operated using the Q-Switching device 126 to deliver short pulses, i.e. having a temporal width of about 10 ns, of high energy. Such analysis laser beam 161 produces a high temperature plasma that excites electronically some of the degradation products in the debris which can be analysed conveniently by laser induced fluorescence (LIF) inside the analysis unit 180. For that purpose, light reflected from the analysis laser beam 161 hitting the target tissue 230 is guided to the analysis unit 180 as analytical light 164. Furthermore, the UTL device 100 also applies analysis with laser induced breakdown spectroscopy (LIBS). In particular, the analysis laser beam 161 tightly focused on the target tissue 230 generates a plume in which the debris has some of the following ions when the target tissue is a biological tissue and particularly a bone tissue: Ca.sup.++, Mg.sup.++, Na.sup.+, K.sup.+, H.sup.+, O.sup.2− but also other ions. These ions have long lifetime decaying emission in the visible part of the spectrum that can be easily monitored using LIBS in the analysis unit 180. Other elements that are detectable in the debris of the plume are Fe.sup.+++ and other ions. The ratios of the emission intensities of such excited elements are correlated with the type of tissue. Based on the identified type of tissue the control unit 190 selects which ablation laser beam 162, 163 to use. For LIBS surface analysis, the short laser pulses of the analysis laser beam 161 are particularly efficient to generate an element emission spectrum. However, also other laser beams with other wavelengths can be used for the same purpose provided that such laser can generate a plasma of at least 3'000 Kelvin within typically ns or even shorter pulses, because they may be less destructive for the targeted tissue.

[0081] In principle, LIBS can analyse any matter regardless of its physical state, be it solid, liquid or gaseous because all elements emit light of characteristic frequencies when excited to sufficiently high temperatures. When the components of a material to be analysed are known, LIBS may be used to evaluate the relative abundance of each constituent element, or to monitor the presence of impurities. Because comparably small amount of material is consumed during the LIBS process, the technique is considered essentially non-destructive or minimally-destructive, and with a total average power of less than one watt at the target there is almost no heating surrounding the ablation site. LIBS is also a very rapid technique giving results within seconds, making it particularly useful for the purpose at hand, i.e. real-time. LIBS is an entirely optical technique such that it requires only optical access to the specimen. And being an optical, non-invasive and non-contact techniquemakes LIBS particularly suitable and efficient to be implemented in the UTL device 100.

[0082] Technically, LIBS can be done by double laser pulses by one or different laser wavelengths, where the delay between both laser pulses is in the range of 5 μs or shorter. The first laser pulse is used to produce a clean and dry surface only while the second pulse is used for analysing the pure tissue surface. Using a low intense Er:YAG laser pulse in free-running mode to ablate biofluids and water, whereas the subsequent laser short pulse from activating the Q-switching device 126 of the third laser 120 hit the pure target tissue 230.

[0083] The UTL device 100, with its analysing laser beam 161 allows the tissue surface analysis before subsequent cutting with the ablating laser beams 162, 163. Also, during cutting by means of any of the primary or secondary ablating laser beams 162, 163, the short analytical pulses of the analysis laser beam 161 can be used at any time to generate proper debris to be conveniently analysed by the analysis 180, e.g. applying LIBS. At any time the control unit 190 may select the appropriate ablating laser beam 162, 163 in accordance with the tissue type identified by the analysis unit 180.

[0084] Among lasers that are used to ablate substrates such as human hard tissue and particularly bone tissue, solid state Erbium (Er) lasers emitting at 2'964 nm being a wavelength strongly absorbed in water are emerging as the most suitable for various technical reasons. Particularly, they can provide a high absorption of water at their 2'964 nm wavelength emission line with the possibilities to miniaturize them to be integrated into the medical device 100 and, comparably low servicing requirements. Therefore, this type of laser is embodied in the first beam generating configuration 110.

[0085] Other lasers having similar benefits used to ablate substrates such as human hard tissue and particularly bone tissue are solid state Holmium (Ho) lasers emitting light at a similar wavelength whereas these later lasers appear most suitable for internal medicine because it is easier to find waveguides to be used to bring the laser light into the body by means of, e.g., endoscopes. Er lasers are better suitable than Ho lasers for light propagation in the free-space such as air for open surgeries whereas Ho lasers for e.g. minimally invasive surgical interventions because light can be launched into optical fibres of any type.

[0086] Er:YAG and Nd:YAG crystals, where YAG stands for Yttrium Aluminium garnet (YAG=Y3Al5O12), as employed in the first gain medium 111 and the second gain medium 121, respectively, are pumped with the first and second flash lamps 112, 122 but could alternatively also be pumped with laser diodes (LDs). They are often used in flash lamp pumped Q-switched lasers to shorten pulse durations. In the context of the present invention the Nd:YAG laser will be used in both, a) the so-called free-running mode to produce relatively long pulses in the microsecond range depending primarily on the time width of the pumping FL, as embodied by the second beam generating configuration, as well as in b) the Q-switched mode to generate short pulses in the nanosecond range, as embodied by the third laser beam generating configuration. The Er:YAG laser, as embodied by the first beam generating configuration, will be used exclusively in the free-running mode delivering pulses of more than 100 microseconds.

[0087] LD pumped LD-Er:YAG and Nd:YAG lasers can be more efficient in transferring energy to create population inversion than when pumped by FLs (i.e. FL-Er:YAG) and they are easier to miniaturize with regard to their optics as well as to their electronics. Also, LD pumped Er and Nd lasers can be operated at higher repetition rates such as up to kHz repetition rates than FL pumped lasers which are usually operated at 10 to 20 Hz. Both lasers can be operated in free-running or Q-switched mode. In the context of the present invention FL pumped lasers are used.

[0088] The FL 112, 122 are used for high pulsed energies. They are rather inefficient because they produce a broad spectrum of light causing most of the energy to be wasted as heat in the gain medium whereas DL have a sharp wavelength emission and thus less energy is lost in the form of heat.

[0089] In summary, advantages of FL-Er:YAG lasers are: comparably high pump power (particularly peak power) can be generated; the price per watt of generated pump power is comparably low; and the lamps are fairly robust, e.g. immune to voltage or current spikes. Their disadvantages are: the lifetime is comparably limited (usually some hundred or up to a few thousand operating hours or, in terms of flashes about five million shots); the electrical energy to light conversion efficiency of the laser is comparably low (typically at most a few percent); and the electric power supplies usually involve high voltages which raise additional safety issues when it comes to a medical device. Consequences of the low conversion efficiency are not only higher electricity consumption but also a higher heat load, which can make necessary a more powerful cooling system.

[0090] Disadvantages of LD-Er:YAG as compared to FL-Er:YAG particularly in the context of human or animal tissue ablation purposes are the poorer quality of the laser beam (i.e. higher M2) which makes focusing comparably difficult and the comparably low peak power in long pulses degrading the ratio of electromagnetic energy that is transformed into debris as compared with that is converted reaching heat in the remaining tissue walls of, e.g., a bone being cut.

[0091] Advantages of free-running FL-Er:YAG as compared to LD-Er:YAG particularly within certain limits, can be that the former lasers can be controlled with a long time window among relatively shorter pulses such as less than 400 μs which allows to enhance the ratio of electromagnetic energy that is transformed into debris with respect to h eat flowing into the walls as compared to the LD-Er:YAG having e.g. the same total energy (e.g. 10 W in pulses having time widths of e.g. 1 ms or even longer) in low peak powers due to the much longer pulse widths and a big fraction of its energy flows as compared to heat in the remaining tissue walls of, e.g., when a bone tissue being cut.

[0092] The cooling of the lasers is embodied by the single cooling system 140 considering that in most cases only one of the first and second lasers 110, 120 is active at the same time. The tubing of the cooling is thus connected in line, i.e. the cooling liquid pass through one laser 110, 120 first and then through the other laser 110, 120.

[0093] As mentioned, the UTL device 100 can be mounted on a robotic device or any other actuating device for positioning as part of a medical device or any device that communicates to the UTL device 100 via the bus 200. Thereby, the UTL device 100 can be configured as the “slave” and the medical device as “master”.

[0094] FIG. 2a to FIG. 2d show schematic illustrations of various modes of operation with possible firing sequences. In FIG. 2a there is a pulse of the analysing laser beam 161 to generate plume with a small amount of debris to determine what kind of tissue is encountered using the analysis unit 180 embodying LIBS. Depending on this information single pulses of either one of the primary and secondary ablating laser beams 162, 163 are fired. The time space between the pulses, Δτ, of the analysis laser beam 161 and those of either pulses of the ablating laser beams 162, 163 are of identical repetition rate, i.e. frequency Δτ(1).

[0095] However, and considering that the amount of tissue to be encountered does not change over many ablation laser beam 162, 163 pulses, a user could choose to fire analysis laser beam 161 at much lower repetition rate spaced by a longer time Δτ(2) as shown in FIG. 2b. In such case the repetition rate of analysis laser beam 161, Δτ(2) could be conveniently chosen, but not necessarily, to be an even fraction of that of ablating laser beams 162, 163, Δτ(1).

[0096] FIG. 2c shows a case similar to the one shown in FIG. 2b displaying the transition from ablating with the primary ablating laser beam 162 to the secondary ablating laser beam 163.

[0097] FIG. 2d correspond to a firing arrangement where the repetition rates of any of the analysis and ablating laser beams 161, 162, 163 are not constant. Such situation could be encountered when the analysis unit 180 requires more time to determine the composition of the debris in the plume and thus what type of tissue is being ablated therefore each pulse will have a different time spacing Δτ.

[0098] FIG. 3a depicts a simplified schematically overview of the power supply 130 consisting of two separate power circuits. One circuit 130.6 is for the primary or first laser 110 and another circuit 130.7 for the secondary or second laser 120. An additional third circuit 132 is used to control the Q-Switching device 126. All three circuits are controlled by a power supply controller 130.5 which can also control the cooling system 140 and is connected to the control unit 190 which defines the pulse setting and flashing modes.

[0099] Each power circuit 130.6, 130.7 is arranged to fire either the first laser 110 or the second laser 120. In the power circuits 130.6, 130.7 there is a charging circuit 130.1 responsible to transform the AC, i.e. alternate current supply, input to a defined DC, i.e. direct current, voltage. A capacitor unit 130.2 stores the required energy and is charged by the charging circuit 130.1 to the defined voltage level. The combination of the capacitor and charging circuit is designed such that sufficient energy is present for all applicable pulse shapes and repetition rates required in the FLs. In parallel to the FL 112, 122 there is an ignition circuit 130.3 which ignites the lamp by means of a high voltage in the range of kilo-volts applied to the FL 112, 122. To keep the respective FL 112, 122 ignited after the ignition, a simmer circuit within the pulse circuit 130.4 applies a DC-voltage to the lamp. The controller 130.5 closes the circuit over the FL 112, 122 by means of a switch integrated within the pulse circuit 130.4 for the defined time of the pulse width. This leads to flashing of the FL 112, 122 for a desired pulse width. Such a switch can be realized with any high power switch.

[0100] The power supply circuit 132 for the Q-Switching device 126 depends upon the used Q-Switching device 126. If, e.g., an electro-optic device is used the power supply 132 has to provide high voltages in the range up to kilovolts. If, e.g., an acousto-optic device is used the Q-Switching power supply 132 can embody a high RF-circuit supplying frequencies in the range of hundreds of megahertz.

[0101] FIG. 3b shows, compared to FIG. 3a, a special combination of the two power circuits 130.6 for the first laser 110 and the power circuit 130.7 of the second laser 120. In this embodiment there exists only one charging 130.1 and one capacitor circuit 130.2 for both power circuits. This simplifies the design, however, restricts flexibility of pulsing the first and second lasers 110, 120 at any time independently.

[0102] This description and the accompanying drawings that illustrate aspects and embodiments of the present invention should not be taken as limiting-the claims defining the protected invention. In other words, while the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive. Various mechanical, compositional, structural, electrical, and operational changes may be made without departing from the spirit and scope of this description and the claims. In some instances, well-known circuits, structures and techniques have not been shown in detail in order not to obscure the invention. Thus, it will be understood that changes and modifications may be made by those of ordinary skill within the scope and spirit of the following claims. In particular, the present invention covers further embodiments with any combination of features from different embodiments described above and below. For example, whereas most examples and explanation above are in the field of surgery, the principle underlying the present invention also be used in other technical fields. In particular, the invention can be useful for cutting any heterogeneous substrate which advantageously is cut with different wavelengths and/or pulse widths. Or, it is possible to operate the invention in an embodiment having more than three beam generating configurations for providing additional ablating and/or analysis laser beams.

[0103] The disclosure also covers all further features shown in the Figs. individually although they may not have been described in the afore or following description. Also, single alternatives of the embodiments described in the figures and the description and single alternatives of features thereof can be disclaimed from the subject matter of the invention or from disclosed subject matter. The disclosure comprises subject matter consisting of the features defined in the claims or the exemplary embodiments as well as subject matter comprising said features.

[0104] Furthermore, in the claims the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. A single unit or step may fulfil the functions of several features recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. The terms “essentially”, “about”, “approximately” and the like in connection with an attribute or a value particularly also define exactly the attribute or exactly the value, respectively. The term “about” in the context of a given numerate value or range refers to a value or range that is, e.g., within 20%, within 10%, within 5%, or within 2% of the given value or range. Components described as coupled or connected may be electrically or mechanically directly coupled, or they may be indirectly coupled via one or more intermediate components. Any reference signs in the claims should not be construed as limiting the scope.