RADIATION AMPLIFYING SYSTEM

A radiation amplifying system comprising a laser active medium for amplifying a radiation field and an optical assembly which defines an optical path for a pumping radiation field with which the laser active medium is optically pumped. The optical path comprises a plurality of branches and the optical assembly comprises at least two focusing units and a deflection arrangement. The laser active medium is spatially arranged between the at least two focusing units, and the focusing units define several pumping branches of the optical path for focusing the pumping radiation field which propagates along the optical path onto a pumping area in the laser active medium. Several deflection units of the deflection arrangement define respective deflection branches of the optical path for connecting the several pumping branches. The optical path comprises at least one correction branch for correcting at least one mismatch in the optical assembly to a focusing condition.

CROSS-REFERENCE TO RELATED PATENT APPLICATION

This patent application relates to the subject matter disclosed in and claims the benefit of European application No. 23161592.3 filed Mar. 13, 2023, the teachings and disclosure of which are hereby incorporated in their entirety by reference thereto for all purposes.

BACKGROUND OF THE INVENTION

The invention relates to a radiation amplifying system comprising a laser active medium for amplifying a to be amplified radiation field and an optical assembly which defines an optical path for a pumping radiation field for optically pumping the laser active medium.

SUMMARY OF THE INVENTION

The object underlying the invention is to improve such radiation amplifying systems.

This object is achieved by embodiments of the invention by a radiation amplifying system comprising a laser active medium for amplifying a to be amplified radiation field and an optical assembly which defines an optical path for a pumping radiation field with which the laser active medium is optically pumped, wherein the optical path comprises a plurality of branches and wherein the optical assembly comprises at least two focusing units and a deflection arrangement wherein the laser active medium is spatially arranged between the at least two focusing units and the focusing units define several pumping branches of the optical path for focusing the pumping radiation field which propagates along the optical path onto a pumping area in the laser active medium und wherein several deflection units of the deflection arrangement define respective deflection branches of the optical path for connecting the several pumping branches and wherein the optical path comprises at least one correction branch for correcting at least one mismatch in the optical assembly to a focusing condition.

For example, an advantage of the invention is that with the at least two focusing units and the deflection arrangement the pumping radiation field can be guided many times through the laser active medium for efficiently pumping the same while with the at least correction branch mismatches in the assembly, which are for example due to aberrations in the optical elements of the assembly and/or due to spatial constrains in the set-up of the elements of the optical assembly, are corrected for and advantageously a blurring and a widening of the pumping radiation field is at least reduced and therefore the pumping efficiency during the many times of propagation of the pumping radiation field through the laser active medium is enhanced.

In particular, the deflection arrangement can be optimized for connecting a large number of pumping branches, for example at least ten pumping branches, preferably at least thirty pumping branches, in order to increase the passages of the pumping radiation field through the laser active medium and potentially therewith associated mismatches can be corrected by the at least one correction branch.

Advantageously, the fine tuning for achieving a good quality of the pumping radiation field along the optical path is achieved by the at least one correction branch.

In particular, one focusing condition is that the pumping area within the laser active medium is distanced to the at least two focusing units with the respective focal length.

An advantage thereof is, that the pumping radiation field is focused in the pumping area.

This can be explained by recalling the thin lens formula 1/G+1/B=1/F for an optical imaging of an object which is a distance G away from the principal plane of an optical lens onto an image which is at a distance B away from the principal plane of the optical lens and wherein F is the focal length of the optical lens.

Accordingly, a collimated beam of the pumping radiation field which represents an object at the distance G=infinity and which hits one of the at least two focusing units has its focused image the focal length F away from the respective focusing unit (i.e., B=F) and is therefore focused in the pumping area if the pumping area is distanced with the focal length F from the respective focusing unit. Vice versa, the pumping area distanced the focal length F away from one of the two focusing units (i.e., G=F) is imaged by this focusing unit at B=infinity. That is the pumping radiation field coming from such distanced pumping area is transformed by this focusing unit to a collimated beam.

In particular, the pumping radiation coming from the pumping area which is distanced the focal length F away from one of the at least two focusing units is transformed by this focusing unit to a collimated beam and this collimated beam is deflected by the deflection arrangement to one of the at least two focusing units, for example to the one focusing unit from which this collimated beam is coming, such that the radiation field of this collimated beam is focused again onto the pumping area.

Advantageously, therewith the pumping area is imaged onto itself by the optical assembly. In particular, the focusing area is imaged onto itself in a one to one imaging. In particular, the pumping area is imaged onto itself in a focused manner.

As a side note, if one had an optical system with one lens which has a focal length F′ for a one to one imaging of this object the object would have to be distanced twice the focal length F′, i.e. 2F′, from the principal plane of the optical lens and its image would be distanced twice the focal length from the principal plane, wherein in the one to one imaging the object and its image have the same size.

That is, for the present optical assembly with a telescope like optics typically at least one focusing condition, in particular at least the focusing condition for an one to one imaging, is different than in an optical system with only one lens.

Nonetheless, a focusing condition for the present optical assembly with a telescope like optics can be derived from a focusing condition for the special case of an one to one imaging by one lens with a focal length F′ as follows. Consider conceptually the one lens as two halves each of which having a focal length of 2F′, that is half of the focusing power of the one lens, and separating the two halves. In between the two halves there will be a collimated beam. Each of the halves has a focal length of F=2F′ and the object has a distance G=F from the one half and the image of the object has a distance B=F from the other half.

In particular, one focusing condition is, that the deflection units have to be in a proper distance to the respective focusing unit in order to produce a sharp image and to avoid a widening of the pumping radiation field.

Preferably, the optical assembly is designed, such that at least along the deflection branches the pumping radiation field propagates in an at least approximately collimated manner.

For example, for an idealistic optical system a reflective surface of a deflection unit should be distanced to the focusing unit by the focal length of the focusing unit.

In embodiments of the invention one has a telescope like imaging system in which in particular a so called 4F-condition as focusing condition has to be fulfilled as exemplarily described hereafter.

In particular, according to the 4F-condition in a telescope like optics with two focusing optics A and B, here in particular with the at least two focusing units, an object O is positioned the focal length F away from the focusing optics A and the image I is produced the focal length F away from the second focusing optics B and the focusing optics A and B are distanced to each other by two times the focal length F such that in total the image I is distanced to the object O by four times the focal length F.

At least if the pumping radiation field multiple times passes through the optical system mismatches to this 4F-condition worsen the quality of the pumping radiation field. For example, these mismatches result in a widening of the radiation field.

In the telescope like optics, a radiation field propagates from the object to a first focusing optics and from the first focusing optics to a second focusing optics and after passing the second focusing optics the object is imaged.

In embodiments of the invention the imaging of the pumping area onto itself by the pumping radiation field propagating from the pumping area to one of the at least two focusing units and further to the associated deflection unit and back from that deflection unit to said one of the at least two focusing units and further again to the pumping area is of that kind of a telescope like optics.

Advantageously, for having the pumping radiation field being focused in the pumping area, the pumping area has to be distanced with a focal length F from the respective focusing unit. This is in particular due to the conditions for the optics as described above.

In particular, between the at least two focusing optics in a telescope like optics, and in embodiments of the invention along the branches from one of the at least two focusing units to the associated deflection unit and back to the one of the at least two focusing units, the radiation field is preferably essentially collimated.

In particular, the object, here for example the pumping area, has a spatial extension and is not only located in the focal point of the focusing optics, here for example in the focusing point of one of the focusing units. Therefore, the different rays of the essentially collimated radiation field between the at least two focusing optics are not exactly parallel to each other because they steem from different spatial locations of the object.

In particular, in a geometrical plane which is parallel to the principal plane of the focusing optics and distanced to the principal plane by the focal length F of the focusing optics the different rays of the essentially collimated radiation field all cross each other.

In particular, in the geometrical plane distanced by the focal length F from the principal plane of the focusing optics the respective spatial information in each of the different rays are at least essentially entirely transferred to the Fourier space. Therefore, this plane is also called the Fourier plane. In this plane the essentially collimated radiation field contains the information of the Fourier transformation of the object.

A diameter of the at least approximately collimated beam coming from one of the focusing units is the smallest at the Fourier plane. The diameter becomes the larger the further the beam propagates further away from the Fourier plane.

In particular, at the distance of two times the focal length F the beam has the same diameter like at the focusing unit.

Advantageously, in order to maintain a diameter of the pumping radiation field, the at least two focusing optics in a telescope like optics, that is in embodiments of the invention the at least two focusing units, have to be distanced to each other by twice the focal length F.

This is in particular preferable in embodiments of the invention because the pumping radiation field should be concentrated on the pumping area and the diameter of the pumping radiation field should not widen.

In particular, because for these telescope like optics the object and its image are distanced by four times the focal length F, this focusing condition is also called the 4F-condition.

The discussion herein, in particular of the 4F-condition, mainly considers examples in which at least mostly, in particular except for the focusing units, flat optical elements are used.

In particular, in the deflection arrangement at least mostly only flat optical elements are used.

For example, flat optical elements comprise flat mirrors, prisms with planar surfaces, plates with parallel and planar surfaces and the like.

In embodiments with exactly one or several non-planar optical elements. typically the effect of the curvature of the at least one non-planar optical element may have to be taken into account.

For example, non-planar optical elements comprise spherical optical elements, aspherical optical elements, freeform optical elements and the like, for example cat's eye designed reflectors and also prisms with curved surfaces.

In such embodiments with non-planar optical elements, the at least one focusing condition, in particular the 4F-condition, has to be fulfilled, too, but the discussed distances, for example the distance between the object and its image of four times the focal length F, may have to be corrected for the effect of the curvature of the at least one non-planar optical element.

In some advantageous embodiments, at least one non-planar optical element is arranged in at least one correction branch, for example in a correction unit. In particular, at least one non-planar optical element preferably in at least one correction branch is used to at least partly correct at least one mismatch and for example to deflect the radiation filed. For example, therewith the number of required optical elements can be reduced.

If a radiation field propagates only once through a telescope like optics, a mismatch to the focusing condition of the telescope like optics, in particular to the 4F-condition, is not too adverse because typically the negative impact of the mismatch is not too large. However, if a radiation field passes multiple times through a telescope like optics like in preferred embodiments of the invention a mismatch to the focusing condition of the telescope like optics, in particular to the 4F-condition, sums up and has a major negative impact on the (pumping) radiation field, for example on its beam quality.

In particular, if the diameter of the radiation field widened during the multiple passages through the optics, larger optical elements would be needed and/or losses in the radiation field would occur at optical elements which are too small for the widened radiation field.

Similarly, with respect to the deflection arrangement at least one focusing condition has to be fulfilled.

In particular, the optics of the imaging from the one set of deflection units associated with the one of the at least two focusing units through the one of the at least two focusing units and through the other of the at least two focusing units onto the other set of deflection units associated with the other focusing unit is a telescope like optics and therefore the respective focusing condition for a telescope like optics has to be fulfilled. In particular, the respective 4F-condition for this optics has to be fulfilled.

In particular, due to this optical arrangement the deflection units associated to one of the at least two focusing units have to be distanced to the respective focusing unit by the focal length F of the respective focusing unit.

In particular, due to this optics, the at least two focusing units have to be distanced by the sum of their focal length F.

In particular, with respect to this telescope like optics from one set of deflection units through the at least two focusing units to the other set of deflection units, a focusing condition is that the pumping area has to be positioned in the middle between the at least two focusing units and at a distance of the focal length F away from each focusing unit.

However, in real optical systems typically one or more focusing conditions cannot be fully met and aberrations cannot be avoided. In embodiments of the invention the therewith associated mismatches are corrected for by the at least one correction branch.

Preferably, the at least two focusing units and the laser active medium are arranged to fulfill the one condition, that the focal point of the at least two focusing units is positioned within the pumping area.

However, the pumping radiation field has a finite width and in real optical systems not all rays of the pumping radiation field run through the focal point, which is anyway an idealized point without spatial extension.

In particular, the deflection branches are however too short to fulfill a focusing condition, in particular a focusing condition in the telescope like optics, for example the 4F-condition. This is for example in order to achieve a compact design of the radiation amplifying system and/or due to spatial constrains in positioning the deflection units. Advantageously, an additional optical path length provided by at least one correction branch and/or at least one correction unit corrects for this mismatch.

In advantageous embodiments, at least one correction branch corrects for a mismatch in a focusing condition of the telescope like optical system of the at least two focusing units and the deflection arrangement.

Preferably, at least one correction branch corrects for a mismatch in the 4F-condition for the optical system of the at least two focusing units and the deflection arrangement.

In particular, at least one correction branch corrects for that at least along one deflection branch the optical path length is too short. In particular the optical path length comprises a part from one of the at least two focusing units to the deflection arrangement and for example a part through the deflection arrangement and a part from the deflection arrangement to one of the at least two focusing units.

In particular, said optical path length is too short, because the respective deflection unit in said deflection branch has a distance to said focusing unit which is smaller than required. In particular, therewith a mismatch in the 4F-condition occurs which is preferably corrected for by at least one correction branch.

In particular, in embodiments of the invention the finding is used, that the mismatch to a focusing condition in a single or in several branches can be effectively and efficiently corrected for in a branch, namely in at least one correction branch, which is different to the branch in which the mismatch occurs.

Advantageously, a mismatch which occurs in at least one branch of the optical path is corrected for in at least one correction branch of the optical path, with the correction branch being arranged before or after the branch in which the mismatch occurs and for example at least one other branch is between these two branches.

In particular, herewith the finding is used that for correcting a mismatch, in particular a mismatch related to the 4F-condition, can be corrected for in another branch.

Preferably, several pumping branches and deflection branches are subsequently directly connected to each other and along these branches mismatches to the focusing condition sum up and a thereafter arranged correction branch corrects at least partly the mismatches.

In some preferred embodiments, at least one sixth, preferably at least one fifth, for example at least one quarter, of the pumping branches and the deflection branches are subsequently directly connected to each other and then one correction branch is arranged.

In some advantageous embodiments, one correction branch, for example the only correction branch in the optical path, is arranged at least approximately in the middle of the passage of the pumping radiation field through the system of the at least two focusing units and the deflection arrangement.

For example, at least approximately the same number of pumping branches is arranged in the propagation direction of the pumping radiation field before the correction branch and after the correction branch.

No further details about the set-up of the at least one correction branch have been given so far.

In some preferred embodiments a mismatch is at least partly, for example at least approximately fully, corrected for by the optical path length of at least one correction branch.

In some advantageous embodiments a mismatch is at least partly, for example at least approximately fully, corrected for by a correction unit. In particular, the correction unit is an optical unit of at least one optical element, for example of several optical elements which are arranged for achieving the desired correction.

Preferably, at least one correction unit is a misadjusted correction unit. In particular a misadjustment in at least one correction unit affects the quality of the pumping radiation field. For example, a misadjustment in at least one correction unit affects at least one property of the pumping radiation field. The at least one affected property is for example the diameter of the radiation field. For example, the correction unit comprises a telescope like optics wherein in particular the telescope like optics is misadjusted.

Advantageously, the misadjustment in the correction unit at least partly compensates the mismatch which is to be corrected for.

In preferred embodiments the optical assembly comprises at least one correction component which defines at least one correction branch.

For example, at least one correction component defines the optical path length of its correction branch.

For example, at least one correction component comprises a correction unit.

Preferably, at least one correction component comprises at least one deflection element, in particular for deflecting an incoming part of its correction branch, for example directly or indirectly via at least one other deflection element, into an outgoing part of its correction branch.

In advantageous embodiments at least one correction component comprises at least one adjustable deflection element.

Preferably, with at least one adjustable deflection element an optical path length of the correction branch and/or its influence on the shape of the pumping radiation field is adjustable.

For example, with at least one adjustable deflection element a misadjustment in at least one correction unit can be tuned.

An advantage thereof is in particular that the optical system of the at least two focusing units and the deflection arrangement can be mounted in a suitable manner but in a simplified manner, because the set-up of the system has not to be fine-tuned to meet the at least one focusing condition because the fine-tuning can be achieved with the adjustable deflection element of the correction component.

For example, the adjustable deflection element of the correction component is a mirror.

In particular, the position of the adjustable deflection element in the correction component can be adjusted in the direction of propagation of the pumping radiation field. For example, therewith the length of the correction branch and/or a misadjustment in a correction unit is adjustable.

In some preferred embodiments, at least one correction branch, in particular at least one adjustable deflection element of at least one correction component, is adjusted with respect to the shape of the pumping radiation field, for example to reduce a widening of the pumping radiation field.

In the alternative or in addition in advantageous embodiments, at least one correction branch, in particular the adjustable deflection element of the correction component, is adjusted with respect to an efficiency of the radiation amplifying system, in particular with respect to an amplification of the to be amplified radiation field, for example with respect to a power of the to be amplified radiation field after passing through the laser active medium and/or with respect to a pumping energy introduced by the pumping radiation field into the laser active medium.

In preferred embodiments, the optical assembly is calibrated during its installation. In particular, at least one correction branch is adjusted during the installation to correct for at least one mismatch.

In some advantageous embodiments, the radiation amplifying system comprises at least one sensor for detecting, in particular directly or indirectly, at least one property of the radiation amplifying system, preferably at least one property of the to be amplified radiation field and/or of the pumping radiation field and/or of the optical assembly, and the detected values of the sensor are used to adjust at least one correction branch, in particular the adjustable deflection element of the correction component.

For example, the at least one property detected by the sensor is one or several of a shape of the pumping radiation field and/or an amplification of the to be amplified radiation field and/or a power of the to be amplified radiation field and/or an energy introduced by the pumping radiation field into the laser active medium.

Preferably, the radiation amplifying system comprises a controller which performs the adjustment of in particular at least one correction branch and/or the adjustable deflection element, preferably performs the adjustment based on the detected values of the sensor. Advantageously, the controller evaluates the values detected by the sensor.

In particular, the adjustment is achieved on demand by a user.

With respect to the correction no further details have been given so far.

In particular, with the correction by the at least one correction branch a mismatch, to which the pumping radiation field is exposed to, is at least reduced.

In some preferred embodiments, at least one correction branch, in particular its optical path length and/or at least one correction unit in the correction branch, is defined to at least reduce a mismatch which the pumping radiation field is exposed to when propagating along the optical path in the part of the optical assembly which is with respect to the propagation direction of pumping radiation field before this at least one correction branch.

In particular, an optical path length of the at least one correction branch is at least as long as the differences between the optical path length of at least several pumping branches and/or deflection branches, for example the optical path length of each pumping branch and deflection branch, before the correction branch in the optical assembly and the respective ideal optical path length of these branches. The ideal optical path length is defined such that no mismatch would occur.

In some preferred embodiments, at least one correction branch, in particular its optical path length and/or at least one correction unit in the correction branch, is defined to at least reduce a mismatch which the pumping radiation field is exposed to when propagating along the optical path in the part of the optical assembly which is with respect to the propagation direction of pumping radiation field after this at least one correction branch.

In particular, an optical path length of the at least one correction branch is at least as long as the differences between the optical path length of at least several pumping branches and/or deflection branches, for example the optical path length of each pumping branch and deflection branch, after the correction branch in the optical assembly and the respective ideal optical path length of these branches. The ideal optical path length is defined such that no mismatch would occur.

In some preferred embodiments, at least one correction branch, in particular its optical path length and/or at least one correction unit in the correction branch, is designed to at least approximately equalize the exposed to mismatch.

For example, the optical path length of at least one correction branch is at least approximately equal to the sum of the differences between the optical path length of the pumping and deflection branches relative to their ideal optical path length.

In other advantageous embodiments at least one correction branch, in particular its optical path length and/or at least one correction unit in the correction branch, is designed to over-compensate the exposed to mismatch.

For example, the optical path length of at least one correction branch is longer than the sum of the differences between the optical path length of the pumping and deflection branches relative to their ideal optical path length.

For example, an advantage thereof is that after the correction branch the overcompensation will correct for a mismatch to which the pumping radiation field will be exposed to and the pumping radiation field will propagate in a more balanced manner along the optical path.

No further details about the design and/or arrangement of at least one correction branch have been given so far.

In particular, at least one correction branch comprises at least one incoming part, which in particular extends from one of the at least two focusing units to a deflection element of the correction component, and an outgoing part, which in particular extends from one deflection element of the correction component to one of the at least two focusing units.

Preferably, the incoming part and the outgoing part of the correction branch extend between the same deflection element and the same focusing unit.

Advantageously, the ingoing part and/or the outgoing part of the correction branch run at least essentially parallel to the optical axis.

In particular the ingoing part and the outgoing part of the correction branch run at least essentially parallel to each other.

In some preferred embodiments, the ingoing part and the outgoing part of the correction branch are distanced to each other.

In some advantageous embodiments, the ingoing part and the outgoing part of the correction branch fall upon each other.

In preferred embodiments, at least a part of at least one correction branch, for example a correction part, is in the radial direction further away from the optical axis than the plurality of deflection branches and/or pumping branches.

In particular, at least a part of at least one correction branch, for example a correction part, runs in an angle to the optical axis, in particular at least approximately perpendicular to the optical axis.

In particular, a correction part is defined in at least one correction branch preferably, with respect to the propagation direction of the pumping radiation field, between the ingoing part and the outgoing part of this correction branch.

For example, the correction part of the correction branch is defined between a deflection element and the adjustable correction element of the correction component.

In particular, in the correction part of the correction branch a correction for the mismatch is imposed to the pumping radiation field, for example by manipulating the shape of the pumping radiation field and/or by adjusting the length of the correction part.

In advantageous embodiments, the direction of propagation of the pumping radiation field is reversed in at least one correction branch.

In particular, therewith the pumping radiation field propagates along the same pumping branches and deflection branches before entering this one correction branch and after exiting this one correction branch by propagating along these same branches in reverse propagation direction and therefore the pumping of the laser active medium is increased.

In some advantageous embodiments, at least one correction branch is spatially arranged on a side with respect to one of the at least two focusing units, which is opposite to the side at which the laser active medium is arranged.

This is particularly preferable for a focusing unit which is at least for the pumping radiation field transparent.

An advantage hereof is for example that on the side opposite to the side with the laser active medium usually more space for arranging the correction branch is available and for example therefore the set-up of the optical assembly can be simplified.

In advantageous embodiments, at least one correction branch is spatially arranged in the space, in particular in the axial space with respect to the optical axis, between the at least two focusing units.

For example, therewith a more compact set-up of the optical assembly can be achieved.

In particular, a correction branch which is arranged in the space between the at least two focusing units is suitable for a focusing unit which is at least for the pumping radiation field reflective.

In some preferred embodiments, the pumping radiation field is introduced in the optical system of the at least two focusing units and the deflection arrangement in an at least essentially collimated manner.

In the alternative or in addition the object of the invention is solved in embodiments of the invention by a radiation amplifying system which comprises a laser active medium for amplifying a to be amplified radiation field and an optical assembly which defines an optical path for a pumping radiation field with which the laser active medium is optically pumped, wherein the optical path comprises a plurality of branches and wherein the optical assembly comprises at least two focusing units and a deflection arrangement and wherein the laser active medium is spatially arranged between the at least two focusing units and the focusing units define several pumping branches of the optical path for focusing the pumping radiation field which propagates along the optical path onto a pumping area in the laser active medium and wherein several deflection units of the deflection arrangement define deflection branches of the optical path for connecting the several pumping branches and wherein the pumping radiation field is introduced to the optical system of the at least two focusing units and the deflection arrangement with a deviation from a manner set by a focusing condition, wherein the deviation corresponds at least partly to a mismatch in the optical system of the at least two focusing units and the deflection arrangement to a focusing condition.

In particular, an advantage hereof is that upon propagation of the pumping radiation field along the optical path through the system of the at least two focusing units and the deflection arrangement, due to the mismatch in the optical system the deviation in the pumping radiation field from the manner set by the focusing condition becomes smaller and preferably along at least a part of the optical path through the optical system of the at least two focusing units and the deflection arrangement the pumping radiation field fulfills at least essentially the focusing condition.

In particular, the deviation in the introduced pumping radiation field from the at least one focusing condition is contrary to a deviation set to the pumping radiation field by the mismatch in the optical assembly.

For example, the deviation is such that the pumping radiation field at least approximately at half way along the optical path through the optical system of the at least two focusing units and the deflection arrangement fulfills at least essentially the focusing condition.

In some preferred embodiments, the deviation is such that the pumping radiation field at least approximately at half way along the optical path from the introduction to the optical system of the at least two focusing units and the deflection arrangement to the first or only correction branch among the plurality of deflection and pumping branches fulfills at least essentially the focusing condition.

In particular, there is a correction branch in the optical path before entering the optical system of the at least two focusing units and the deflection arrangement at which the proper deviation is set to the pumping radiation field.

In particular, the deviation is a deviation from a collimated manner.

For example, the radiation amplifying system, in particular the optical assembly, comprises a collimating unit at which a pumping radiation field from a source is collimated in a desired manner.

Depending on the embodiment the collimated pumping radiation field from the collimating unit is directly introduced to the optical system or the deviation is applied to the collimated pumping radiation field along the one correction branch before entry of the optical system.

No further details concerning the at least two focusing units have been given so far.

In particular, the optical axis is defined by the at least two focusing units and their arrangement relative to each other.

In some advantageous embodiments at least one focusing unit, that is in particular one or both of the at least two focusing units, is built by a respective single focusing element.

In some preferred embodiments at least one focusing unit, that is in particular one or both of the at least two focusing units, is built by a plurality of focusing elements.

In some preferred embodiments at least one focusing unit, that is in particular one or both of the at least two focusing units, is transparent at least for the pumping radiation field.

In particular, the single focusing element or at least one focusing element, preferably at least several, for example all, focusing elements of the plurality of focusing elements of the transparent focusing unit is/are at least for the pumping radiation field transparent.

In particular, the transparent focusing unit comprises at least one lens as a focusing element.

For example, an advantage of a transparent focusing unit is that the pumping radiation field passes through the transparent focusing unit and that the pumping branch at the one side of the transparent focusing unit can be transferred to a deflection branch at the other side and accordingly a space at the side with respect to the transparent focusing unit which is opposite to the side at which the laser active medium is arranged can be used to arrange deflection units and advantageously in this space the deflection units can be arranged with less spatial constrains than between the at least two focusing units.

In particular, the transparent focusing unit has a finite thickness which introduces aberrations to the pumping radiation field which are advantageously corrected for by at least one correction branch.

In some advantageous embodiments, at least one focusing unit, that is in particular one or both of the at least two focusing units, is reflective for at least the pumping radiation field.

In particular, the single focusing element or at least one focusing element, preferably several, for example all, focusing elements of the plurality of focusing units of the reflective focusing unit is/are reflective at least for the pumping radiation field.

In particular, the reflective focusing unit comprises at least one, for example curved, reflective surface.

Preferably, the reflective focusing unit comprises at least one mirror, for example parabolic mirror, as a focusing elements.

For example, one advantage thereof is that reflective focusing units are suitable and resistant for pumping radiation fields with high power, for example for pumping radiation fields with powers of 1 kW or more, in particular 10 kW or more and for example up to powers of 100 kW.

In particular, the pumping radiation field hits the reflective focusing unit off the optical axis and at a region with finite extent at which for example the reflective surface is differently curved such that aberrations are introduced to the pumping radiation field which advantageously are corrected for by at least one correction branch.

Preferably, the at least two focusing units have at least approximately the same focal length.

In some advantageous embodiments, the at least two focusing units are differently designed, for example one is reflective and the other transparent.

In some preferred embodiments, the at least two focusing units are at least mostly designed the same.

With respect to the deflection arrangement no further details have been given so far.

In some preferred embodiments, at least several deflection units, in particular at least most of the deflection units, for example all deflection units, of the deflection arrangement are arranged spatially between the focusing units.

In particular, therewith a compact design of the set-up of the optical system can be achieved. In particular, the arrangement of at least several deflection units spatially between the focusing units is advantageous if at least one focusing unit is reflective.

For example, for the arrangement of at least several deflection units between the at least two focusing units there are spatial constrains due to which a positioning of the deflection units in accordance to at least one focusing condition cannot be realized and an accompanying mismatch to the focusing condition is corrected for by at least one correction branch.

In some advantageous embodiments at least several deflection units of the deflection arrangement are arranged spatially on a side which is with respect to one focusing unit opposite to a side on which the laser active medium is arranged.

In particular, at least one focusing unit is spatially arranged between at least several deflection units and the laser active medium.

In particular such an arrangement of at least several deflection units is preferable for a transparent focusing unit.

For example, an advantage of the arrangement of several deflection units on a side which is with respect to one focusing unit opposite to the side at which the laser component is arranged is that there typically more space is available for positioning the deflection units.

In particular, there is one set of deflection units which are with respect to one of the at least two focusing units on a side opposite to the side at which the laser active medium is arranged and another set of deflection units which are with respect to the other of the at least two focusing units arranged on a side which is opposite to the side at which the laser active medium is arranged.

In some advantageous embodiments each deflection unit of at least several deflection units, for example of at least most of the deflection units, for example of all deflection units, of the deflection arrangement is built by a respective single deflection element.

In particular, an advantage thereof is that for each of these deflection units only a single deflection element is needed and therefore less deflection elements are needed for the deflection arrangement and therefore a set-up of the deflection units is simplified and/or the deflection arrangement is cheaper to build.

In particular a respective single deflection element of a deflection unit transfers an incoming part of a respective deflection branch to an outgoing part of this deflection branch.

In some preferred embodiments, each deflection unit of at least several deflection units, in particular of at least most deflection units, for example of all deflection units, of the deflection arrangement is built by several deflection elements, in particular by a pair of deflection elements.

For example, the several deflection elements are reflective at least for the pumping radiation field.

In particular, an advantage thereof is that due to the several deflection elements a deflection branch defined by the deflection unit can be designed more flexible.

In particular for reflective deflection elements an advantage is that these can be used for pumping radiation fields with a high power.

In particular, an incoming part of a respective deflection branch is deflected from one deflection element of the deflection unit to another deflection element of the deflection unit and one deflection element of the deflection unit provides an outgoing part of the deflection branch which is defined by this deflection unit.

Preferably, a deflection element of a pair of deflection elements deflects an incoming part of the respective deflection branch to an intermediate part of the deflection branch which extends to the other deflection element of the pair of deflection elements which deflects the intermediate branch to the outgoing part of the deflection branch which is defined by the deflection unit built by this pair of deflection elements.

In some advantageous embodiments, at least one deflection element is part of several deflection units.

For example, the at least one deflection element is part of two different deflection units.

In particular, several deflection elements, in particular most of the deflection elements of the deflection arrangement, for example all deflection elements of the deflection arrangement, are each part of several deflection units, for example part of two different deflection units.

For example, therewith the deflection arrangement can be built with less deflection elements and/or in a more compact manner.

In particular, the deflection arrangement comprises a set of deflection units associated with one of the at least two focusing units and another set of deflection units associated with the other of the at least two focusing units.

In particular, a deflection unit associated to one of the at least two focusing units defines a deflection branch which extends from the one focusing unit the deflection unit is associated to, to this deflection unit and back to this focusing unit.

For example, both sets of deflection units are arranged spatially between the at least two focusing units.

Preferably at least one deflection element is, in particular at least several, for example at least most of the deflection elements are each, part of one deflection unit associated with one of the at least two focusing units as well as part of a deflection unit associated with the other of the at least two focusing units.

In some preferred embodiments the set of deflection units associated with one of the at least two focusing units is arranged at one side which is with respect to this one focusing unit opposite to the side at which the laser active medium is arranged.

Preferably, at least several deflection units, for example at least most of the deflection units, in particular at least the deflection units of one set of the deflection arrangement, are arranged in a radial distance to the optical axis of the radiation amplifying system and arranged subsequently in a circumferential direction around the optical axis.

In particular, the several deflection branches are designed in an at least essentially similar manner.

Preferably, the incoming part, which in particular extends from one of the focusing units to a respective deflection unit, and the outgoing part, which in particular extends from the deflection unit to one of the focusing units, of a same deflection branch run at least essentially parallel to each other but in particular distanced to each other.

In particular, the incoming parts and the outgoing parts of at least most, for example of all, deflection branches run at least essentially parallel to each other but in particular distanced to each other.

Preferably the incoming parts and/or outgoing parts of at least some, in particular of at least most, for example of all, deflection branches run at least essentially parallel to the optical axis of the system.

In particular, at least several deflection branches, in particular deflection branches designed by deflection units associated to one of the at least two focusing units, are at least in so far similar designed that with a rotation around the optical axis of the optical system they can be mapped onto each other.

Preferably, the deflection units of the deflection arrangement are fixedly arranged relative to each other and in particular relative to the focusing units.

Advantageously, therewith the arrangement of the deflection units is fixed and potential mismatches in the arrangement are at least approximately corrected for by the at least one correction branch.

In particular a respective deflection branch connects two pumping branches.

With respect to the pumping area, the pumping branches and the laser active medium no further details have been given so far.

In particular, in the pumping area a single pumping spot or several pumping spots, for example an array of pumping spot, is/are defined and each pumping branch extends through a respective pumping spot.

In particular, the pumping branches run through the laser active medium and extend in particular from one focusing unit to the other focusing unit.

For example, the pumping branches are defined in a similar manner with respect to the optical axis.

In particular, by a rotation around the optical axis each of at least several pumping branches can be mapped onto at least another respective pumping branch, in particular each pumping branch can be mapped onto another respective pumping branch.

In particular, the radiation amplifying system comprises an optical device for defining an optical passage way for the to be amplified radiation field.

In particular, the passage way for the to be amplified radiation field runs through the pumping area and advantageously through the laser active medium. Accordingly the to be amplified radiation field transmits through the laser active medium.

In some preferred embodiments a single part, for example a thin disk, provides the laser active medium.

In some advantageous embodiments, there are several parts, for example thin disks, which provide the laser active medium. Preferably, the several parts are arranged adjacently to each other.

In preferred embodiments the laser active medium is clamped between two bodies, preferably between two heat spreading bodies which are advantageously built by a good thermal conducting material.

Advantageous features of the laser active medium and the laser amplifying component comprising the laser active medium are disclosed in EP 3 309 913 A1 and in EP 3 309 914 A1 to which it is referred to for advantageous details of the laser amplifying component.

Above and below at least features and elements which are described to be provided advantageously and/or preferably and/or for example and/or in particular and/or the like are optional features and optional elements which for example provide inventive improvements and which are not essential for the success of the basic idea of the invention.

Above and below the formulation “at least essentially” in connection with a feature is in particular to be understood that technically reasoned and/or technically irrelevant deviations are also comprised by the at least essentially provided features.

Above and below the formulation “at least approximately” in connection with a provided feature is in particular to be understood that the feature is provided at least essentially and/or for example deviations within 10%, in particular within 5%, preferably within 1%, advantageously within 0.1%, from the provided feature are comprised by an at least approximately provided feature.

Above and below the formulation “at least most of” in connection with a plurality of elements at least most of which have a feature, is in particular to be understood, that at least 50%, in particular at least 80%, for example at least 90% of the elements have this feature and/or that in particular all except for 5, for example all except for one or two, of these elements have this feature.

The solutions in accordance with the present invention comprise, in particular, the combinations of features defined by the following embodiments numbered consecutively.

1. Radiation amplifying system (100) comprising a laser active medium (124) for amplifying a to be amplified radiation field (112) and an optical assembly (142) which defines an optical path (144) for a pumping radiation field (114) with which the laser active medium (124) is optically pumped, wherein the optical path (144) comprises a plurality of branches (164,176,252) and wherein the optical assembly (142) comprises at least two focusing units (152,154) and a deflection arrangement (172) wherein the laser active medium (124) is spatially arranged between the at least two focusing units (152,154) and the focusing units (152,154) define several pumping branches (164) of the optical path (144) for focusing the pumping radiation field (114) which propagates along the optical path (144) onto a pumping area (156) in the laser active medium (124) and wherein several deflection units (174) of the deflection arrangement (172) define respective deflection branches (176) of the optical path for connecting the several pumping branches (164) and wherein the optical path (144) comprises at least one correction branch (252) for correcting at least one mismatch in the optical assembly (142) to a focusing condition.

2. Radiation amplifying system (100) according to embodiment 1, wherein the optical assembly (142) is designed, such that at least along the deflection branches (176) the pumping radiation field (114) propagates in an at least approximately collimated manner.

3. Radiation amplifying system (100) according to one of the preceding embodiments, wherein at least one correction branch (252) corrects for a mismatch in a focusing condition of the telescope like optical system of the at least two focusing units (152,154) and the deflection arrangement (172).

4. Radiation amplifying system (100) according to one of the preceding embodiments, wherein at least one correction branch (252) corrects for a mismatch in the 4F-condition for the optical system of at least two focusing units (152,154) and the deflection arrangement (172).

5. Radiation amplifying system (100) according to one of the preceding embodiments, wherein at least one correction branch (252) corrects for that at least along one deflection branch (176) the optical path length is too short.

6. Radiation amplifying system (100) according to one of the preceding embodiments, wherein the optical assembly (142) comprises at least one correction component (254) which defines at least one correction branch (252).

7. Radiation amplifying system (100) according to one of the preceding embodiments, wherein in at least one correction branch (252) a mismatch is at least partly corrected for by the optical path length of the at least one correction branch and/or by a correction unit, wherein in particular the at least one correction unit comprises at least one optical element which is arranged for achieving the desired correction.

8. Radiation amplifying system (100) according to any of the two previous embodiments, wherein the correction component (252) comprises at least one in particular adjustable deflection element (256,260).

9. Radiation amplifying system (100) according to the previous embodiment, wherein with the at least one adjustable deflection element (260) an optical path length of the correction branch (252) is adjustable.

10. Radiation amplifying system (100) according to one of the preceding embodiments, wherein at least one correction branch (252) is adjusted with respect to the shape of the pumping radiation field (114) and/or with respect to an efficiency of the radiation amplifying system (100).

11. Radiation amplifying system (100) according to one of the preceding embodiments, wherein the radiation amplifying system (100) comprises at least one sensor for detecting at least one property of the to be amplified radiation field (112) and/or of the pumping radiation field (114) and/or of the optical assembly (142) and the detected values of the sensor are used to adjust at least one correction branch (252), in particular to adjust at least one adjustable deflection element (260) of the correction component (254).

12. Radiation amplifying system (100) according to one of the preceding embodiments, wherein the radiation amplifying system (100) comprises a controller which performs the adjustment, in particular performs the adjustment based on the detected values of the sensor.

13. Radiation amplifying system (100) according to one of the preceding embodiments, wherein at least one correction branch (252) is designed to at least reduce, in particular to at least approximately equalize, a mismatch to which the pumping radiation field (114) is exposed to when propagating along the optical path (144).

14. Radiation amplifying system (100) according to one of the preceding embodiments, wherein at least one correction branch (252) is designed to at least reduce, in particular to at least approximately equalize, a mismatch to which the pumping radiation field (114) is exposed to when propagating along the optical path (144) in the part of the optical assembly (142) which is with respect to a propagation direction of the pumping radiation field (114) before this at least one correction branch (252).

15. Radiation amplifying system (100) according to one of the preceding embodiments, wherein at least one correction branch (252) is designed to at least reduce, in particular to at least approximately equalize, a mismatch to which the pumping radiation field (114) is exposed to when propagating along the optical path (144) in the part of the optical assembly (142) which is with respect to a propagation direction of the pumping radiation field (114) after this at least one correction branch (252).

16. Radiation amplifying system (100) according to one of the preceding embodiments, wherein at least one correction branch (252) is spatially arranged on a side with respect to one of the at least two focusing units (152,154) which is opposite to a side at which the laser active medium (124) is arranged.

17. Radiation amplifying system (100) according to one of the preceding embodiments, wherein at least one correction branch (252) is spatially arranged in the space between the two focusing units (152,154).

18. Radiation amplifying system (100), in particular according to one of the preceding embodiments, comprising a laser active medium (124) for amplifying a to be amplified radiation field (112) and an optical assembly (142) which defines an optical path (144) for a pumping radiation field (114) with which the laser active medium (124) is optically pumped, wherein the optical path (144) comprises a plurality of branches (164,176,252) and wherein the optical assembly (142) comprises at least two focusing units (152,154) and a deflection arrangement (172) wherein the laser active medium (124) is spatially arranged between the at least two focusing units (152,154) and the focusing units (152,154) define several pumping branches (164) of the optical path (144) for focusing the pumping radiation field (114) which propagates along the optical path (144) onto a pumping area (156) in the laser active medium (124) and wherein several deflection units (174) of the deflection arrangement (172) define respective deflection branches (176) of the optical path for connecting the several pumping branches (164) and wherein the pumping radiation field (114) is introduced to the optical system of the at least two focusing units (152,154) and the deflection arrangement (156) with a deviation from a manner set by a focusing condition, in particular with a deviation from a collimated manner, wherein the deviation corresponds at least partly to a mismatch in the optical system of the at least two focusing units (152,154) and the deflection arrangement (142) to a focusing condition.

19. Radiation amplifying system (100) according to one of the preceding embodiments, wherein at least one focusing unit (152,154) is transparent at least for a pumping radiation field (114).

20. Radiation amplifying system (100) according to one of the preceding embodiments, wherein at least one focusing unit (152,154) is reflective for at least the pumping radiation field (114).

21. Radiation amplifying system (100) according to one of the preceding embodiments, wherein at least several deflection units (174) of the deflection arrangement (156) are arranged spatially between the at least two focusing units (152,154).

22. Radiation amplifying system (100) according to one of the preceding embodiments, wherein at least several deflection units (174) of the deflection arrangement (156) are arranged spatially on a side which is with respect to one focusing unit (152,154) opposite to a side at which the laser active medium (124) is arranged.

23. Radiation amplifying system (100) according to one of the preceding embodiments, wherein each deflection unit (174) of at least several deflection units (174) of the deflection arrangement (156) is built by a respective single deflection element (222) which in particular transfers an incoming part of a deflection branch (176) to an outgoing part of the deflection branch (176).

24. Radiation amplifying system (100) according to one of the preceding embodiments, wherein each deflection unit (174) of at least several deflection units (174) of the deflection arrangement (156) is built by several deflection elements (222) wherein in particular an incoming part of a deflection branch (176) is deflected from one deflection element (222) to another deflection element of the same deflection unit (174) and one deflection element (222) of the deflection unit (174) provides an outgoing part of the deflection branch (176).

25. Radiation amplifying system (100) according to one of the preceding embodiments, wherein at least one deflection element (222) is part of several different deflection units (174).

Preferred features and for example advantages of the invention are provided by the following detailed description and in the drawings of several embodiments.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of a radiation amplifying system which is designated in its entirety with100comprise an optical unit110for guiding and amplifying a to be amplified radiation field112and for guiding a pumping radiation field114and in which an optical axis116is defined, as exemplarily schematically shown inFIG.1.

In particular, the radiation amplifying system100comprises a source for the to be amplified radiation field112and a source for the pumping radiation field114.

In particular, the optical unit110comprises a laser amplifying component122with a laser active medium124for amplifying the to be amplified radiation field112and which is optically pumped by the pumping radiation field114.

In some variants a single part provides the laser active medium124and in other variants several parts provide the laser active medium124.

Preferably, a part providing the laser active medium124is a thin laser disk.

Advantageously, the laser active medium124is clamped between two bodies126I and126II, in particular to heat spreaders, which are aligned on a respective side of two opposing sides of the laser active medium124as exemplarily shown inFIG.2.

In particular, the heat spreaders126are built from a good thermal conductive material, for example the material at least comprises or is a diamond.

Preferably, the sides of the laser active medium124at which a respective body126is arranged and/or a respective side of the body126which is aligned at a side of the laser active medium124are, in particular slightly, convex shaped.

The bodies126are for example in direct contact with the laser active medium124or an anti-reflection layer is provided either on the respective body or the respective side of the laser active medium124and the other element is contacting this layer.

In particular, there is a clamping apparatus128which presses the bodies126at the respective side onto the laser active medium124, in particular with an adaptable and settable force.

In particular, the laser active medium124defines a geometrical amplification plane129which in particular is arranged at least essentially perpendicular to the optical axis116of the optical unit110.

For example, in case of a thin laser disk as the laser active medium124, the thin laser disk extends essentially in the geometrical amplification plane129and the thickness of the laser disk which is measured perpendicular to the geometrical amplification plane129is much smaller, for example at least ten times smaller, than the extension of the laser disk within the geometrical amplification plane129.

In particular, the sides of the laser active medium124at which the bodies126are arranged are opposing each other with respect to the geometrical amplification plane129.

Advantageously the laser active component122with the laser active medium124which is preferably clamped between the bodies126I,126II for example by the clamping apparatus128has one or several features as described in EP 3 209 913 A1 and/or EP 3 209 914 A1. According to these references, advantageous embodiments comprise a there called amplifying unit onto which at least one there called optical device is pressed in particular with a there called mounting system and preferably at least one of the optical devices is part of a heat dissipation system. Regarding advantageous features it is fully referred to these references.

In particular, the optical unit110comprises an optical device132which defines an optical passage way for the to be amplified radiation field and in operation the to be amplified radiation field propagates along this optical passage way.

The optical passage way passes, preferably at least approximately perpendicular to the geometrical amplification plane129, through the laser active medium124and in particular through the bodies126between which the laser active medium124is clamped and thus the laser active medium124is used with regard to the to be amplified radiation field in transmission.

In particular, at least in the region around the laser amplifying component122the optical passage way is aligned along the optical axis116of the optical unit110and thus in operation the to be amplified radiation field112propagates at least in this region on the optical axis116.

The optical unit110comprises an optical assembly142of optical elements which defines an optical path144for the pumping radiation field114and in operation the pumping radiation field114propagates along the optical path144.

The optical assembly142comprises two focusing units152,154for focusing the pumping radiation field114which propagates along the optical path144on a pumping area156in the laser active medium124and the optical passage way of the to be amplified radiation field112passes through the pumping area156.

The laser amplifying component122is spatially arranged between the two focusing units152,154.

In particular, the two focusing units152,154are arranged opposite to each other with respect to the geometrical amplification plane129.

In particular, the optical axis116is defined by the two focusing units152,154and for example by their arrangement with respect to each other.

The laser active medium124and the focusing units152,154are arranged, in particular on the optical axis116, in a distance to each other such that the respective focal points of the two focusing units152,154, which lie at least essentially upon each other, are within the pumping area156and accordingly each focusing unit152,154is arranged in a distance to the laser active medium124, in particular in a distance to the geometrical amplification plane129, which is at least essentially its focal length F.

Preferably, the two focusing units152,154have at least essentially the same focal length F.

Between the two focusing units152,154a plurality of pumping branches164are defined which extend from one of the two focusing units152,154to the other of the two focusing units154,152and pass through the pumping area156in the laser active medium124and in particular through the focal points of the focusing units152,154.

In some variants there is a single pumping spot in the pumping area156and each pumping branch164runs through the single pumping spot.

In other variants, there are several pumping spots, for example an array of pumping spots, in the pumping area156and each pumping branch164runs through a respective pumping spot.

Furthermore, the optical assembly142comprises a deflection arrangement172of several deflection units174which define a plurality of deflection branches176of the optical path144.

In particular, the deflection units174are designed to transfer an incoming part184of a respective deflection branch176into an outgoing part188. In particular, the pumping radiation field114propagates along the outgoing part188at least essentially in an opposite direction than along the incoming part184and the incoming part184and the outgoing part188are offset to each other in a direction which is at least essentially perpendicular to the propagation direction of the pumping radiation field114.

Each of at least most of the deflection branches176, for example every deflection branch176, connects two pumping branches164.

In particular, a respective pumping branch164coming to one of the focusing units152,154is transferred by the focusing unit152,154at a respective transfer region into a deflection branch176, in particular to the incoming part184of the deflection branch176and an outgoing part188of a deflection branch176coming from the deflection unit174extends to one of the focusing units152,154, in particular to the focusing unit152,154from which the ingoing part184is coming, and at a respective transfer region of the focusing unit152,154the deflection branch176is transferred to another pumping branch164.

Preferably, transfer regions at which a pumping branch164is transferred to a deflection branch176or a deflection branch176is transferred to a pumping branch164at the focusing units152,154are arranged in a radial distance to the optical axis116and in particular are arranged at a respective focusing unit152,154subsequently in a circumferential direction around the optical axis116.

In some embodiments there is one set192I of deflection units174which are associated with one of the two focusing units, here for example with the focusing unit152, and another set192II of deflection units174which are associated with the other focusing unit, here for example with the focusing unit154, as exemplarily shown inFIG.1.

In other embodiments there are at least most of the deflection units174associated with both focusing units152,154, and for example the separately shown deflection units174inFIG.1of the two sets192I and192II are in such embodiments the same deflection units174.

A deflection unit174which is associated with one of the two focusing units152,154defines a deflection branch176which connects at the associated focusing unit152,154two pumping branches.

In particular, the focusing units152,154have an in particular material-free corridor198at which the optical passage way for the to be amplified radiation field112passes through such that the propagation of the to be amplified radiation field112is not disturbed by the focusing units152,154.

In particular, the optical axis116runs through the corridor198.

In some embodiments, as exemplarily shown inFIG.3in a variant, at least one focusing unit152,154, in particular both focusing units152,154is/are a reflective unit.

At a respective transfer region of the reflective focusing unit152,154, the pumping radiation field114which propagates along the optical path144is reflected and thereby a pumping branch164is transferred to a deflection branch176and/or a deflection branch176is transferred to a pumping branch164.

In some variants, the reflective focusing unit152,154is built by a single focusing element208.

In particular, the single focusing element208provides the several transfer regions.

For example, the single focusing element208has a breakthrough which provides the corridor198for the optical passage way.

In some variants, the reflective focusing unit152,154is built by a plurality of focusing elements.

In particular, each focusing element of the plurality of focusing elements provides at least one transfer region.

For example, at least several focusing elements of the plurality of focusing elements are arranged in a circumferential direction around the optical axis116and/or around the corridor198for the optical passage way.

In particular, the single focusing element or each of at least several focusing elements of the plurality of focusing elements of the reflective focusing unit152,154has a reflective surface212, preferably a curved reflective surface.

The reflective surface212is shaped such that the in particular along a deflection branch incident pumping radiation field114is reflected by the reflective surface212into a pumping branch164and focused on the pumping area156and that the pumping radiation field114which comes from the pumping area156along a pumping branch164and is incident on the reflective surface212is reflected by the reflective surface212and transferred to a respective deflection branch176.

Preferably, the reflective focusing unit152,154comprises at least one mirror, in particular a parabolic shaped mirror, as a focusing element.

Preferably the deflection arrangement172is arranged in such embodiments spatially between the two focusing units152,154, in particular spatially in the middle between the two focusing units152,154such that the deflection units174of the deflection arrangement172have from both focusing units152,154at least essentially the same distance with the distance being in particular measured along the axial direction of the optical axis116.

In particular, the deflection arrangement172is arranged at an axial position along the optical axis116at which at least approximately also the laser amplifying component122with the laser active medium124is positioned.

In some preferred variants of the embodiment the deflection arrangement172comprises several deflection elements222which build the deflection units174and are in particular associated with both focusing units152,154, as exemplarily shown inFIGS.3and4.

Preferably, respective pairs of deflection elements222build each a deflection unit174.

In these variants, an incoming part184of a respective deflection branch176which comes from one of the two focusing units152,154reaches one deflection element222of a deflection unit174from which the pumping radiation field114propagating along this branch176is deflected to an intermediate part226of the deflection branch176towards another deflection element222of the deflection unit174and at another deflection element222of the deflection unit174the pumping radiation field114is deflected to an outgoing part188of the deflection branch176which extends to the one of the two focusing units152,154.

Preferably, the incoming part226and the outgoing part228run at least essentially parallel to each other and in particular at least essentially parallel to the optical axis116.

For example, the intermediate part226extends between the two deflection elements222of a pair of deflection elements222.

In particular, each deflection element222has at least one reflective surface232at which the pumping radiation field114is reflected and the respective part184,226of the deflection branch176is transferred to a respective part226,188.

Preferably, each deflection element222is part of two different deflection units174′,174″ for two different deflection branches176′,176″ where in particular one of the two different deflection units174′,174″ is associated to one of the focusing units152,154and the other of the two different deflection units174′,174″ is associated with the other of the two focusing units152,154.

Preferably, each deflection element222has two reflective surfaces232′ and232″ which in particular are arranged on opposing sides of the deflection element222and each reflective surface232′,232″ belongs to a different of two deflection units174′,174″ and in particular one of the two deflection units174′,174″ is associated with one of the two focusing units152,154and the other of the two deflection units174′,174″ associated to the other of the two focusing units154,152.

Preferably, each of the two reflective surfaces232′,232″ is facing towards the one of the two focusing units152,154to which the deflection unit174to which the respective reflective surface232′,232″ belongs to is associated to.

In particular, a deflection element222I faces with its one reflective surface232′ of two reflective surfaces232to a reflective surface232′ of another deflection element222II which together build a deflection unit174′ for one deflection branch176′ and with the other reflective surface232″ of the two reflective surfaces232this deflection element222I faces towards a reflective surface232″ of yet another deflection element222III together with which it forms another deflection unit174″ for a deflection branch176″.

In particular, the deflection elements222are arranged at a same radial distance to the optical axis116and subsequently in a circumferential direction around the optical axis116.

Advantageously, each of at least most of the deflection elements222build with each of the two deflection elements222which are arranged with respect to the circumferential direction of the optical axis116adjacent to it on opposite sides a respective deflection unit174.

Preferably, the reflective surfaces232are flat surfaces and are arranged in an angle to the optical axis116.

In particular, the reflective surfaces232are arranged under an angle of at least approximately 45° to the optical axis such that an incoming part184which runs at least approximately parallel to the optical axis116is transferred to an intermediate part226which runs at least approximately in a perpendicular direction with respect to the axial direction of the optical axis116and/or an intermediate part226which runs at least approximately in a perpendicular direction with respect to the axial direction of the optical axis116is transferred to an outgoing part188which runs at least approximately parallel to the axial direction of the optical axis116.

Furthermore, the optical assembly142defines an introducing branch242of the optical path144along which the pumping radiation field114propagating along the optical path144is introduced into the optical system246comprising the deflection arrangement172and the focusing units152and154.

In particular, the introducing branch242extends to one of the focusing units152,154and is transferred there preferably into a pumping branch164and from there on the pumping radiation field114propagates along the plurality of pumping branches164and deflection branches176of the optical path144as described above.

A variant of an introducing branch242comprising a deflection element248is shown exemplarily inFIGS.3and4, in which the introducing branch242extends to the deflection element248and from there to one of the focusing units152,154.

For efficient pumping of the pumping area, the width of the pumping radiation field114along the optical path144should not widen too much, preferably the width should remain at least along corresponding branches, at least approximately the same.

Preferably, along the several deflection branches176the width of the pumping branches should be at least approximately the same and/or the pumping radiation field114should be at least essentially collimated.

In particular, along the several pumping branches164the pumping radiation field114should pass through the pumping area156with the at least approximately same width and/or the pumping radiation field114should be focused on the pumping area156.

The width of the pumping radiation field114is taken at least essentially perpendicular to the propagation direction of the pumping radiation field114.

One focusing condition or several focusing conditions should be fulfilled by the optical system246of the two focusing units152,154and the deflection arrangement172.

In particular, one focusing condition is that the respective focal point of each of the focusing units152,154is located within the pumping area156. Advantageously, therewith the pumping radiation field is focused onto the single pumping spot or the several pumping spots.

Accordingly, due to this focusing condition, which typically is fulfilled, thus the requirement that each of the focusing units152,154is distanced to the pumping area156by the respective focal length F.

Advantageously, therewith the pumping radiation field is focused to the pumping area156and an efficient pumping is realized.

In particular, the optical system of the two focusing units152,154and the deflection arrangement172is built like a telescope like optics.

A telescope like optics is sketched exemplarily inFIG.6.

In a telescope like optics an object O is imaged through a first focusing optics A and a second focusing optics B onto an image I.

In particular, the object O and the focusing optics A, B and the image I are arranged along the optical axis116of this optics.

The object O is positioned in the focal plane of the first focusing optics A and is therefore distanced from the first focusing optics A by the focal length F of this first focusing optics A. The image I is produced in the focal plane of the second focusing optics B and is therefore distanced to the second focusing optics B by the focal length F of the second focusing optics B.

For a very small object O which is positioned at least essentially at the focal point of the first focusing optics A, the radiation field which images the object O onto its image I is approximately collimated between the two focusing optics A and B.

However, due to the finite spatial extension of the object O not all rays of the radiation field steeming from the object O come exactly from the focal point of the focusing optics A since the focal point is only an idealized mathematical point without spatial extension. Therefore, the different rays of the radiation field are not perfectly parallel to each other between the two focusing optics A and B.

In particular, in a plane P the different light cones coming from different spatial positions of the object O are crossing each other.

In particular, corresponding rays from different spatial positions of the object O cross each other in a plane P. For example, corresponding rays are the outermost rays of different light cones from different spatial positions of the object O.

In particular, the plane P runs perpendicular to the optical axis116and is distanced to the focusing optics A and B by the respective focal length F.

In particular, the information in the radiation field at the plane P corresponds to the Fourier transformation of the object O. Therefore the plane P is also called the Fourier plane.

Because the different light cones cross each other at the plane P, there the diameter of the radiation beam is the smallest. Upon further propagation of the radiation beam away from the plane P the diameter of the radiation beam widens. At the distance corresponding to the focal length F behind the Fourier plane P the diameter of the radiation beam equals the size of the diameter at the focusing optics A, B from which this beam is coming. Therefore, in order to avoid a widening of the radiation beam the other focusing optics B, A is advantageously positioned two times the focal length F away from the focusing optics A, B, from which the radiation beam is coming.

To summarize, preferably the object O is positioned the focal length F away from the focusing optics A and the image I is produced the focal length F away from the second focusing optics B and the focusing optics A and B are distanced to each other by two times the focal length F such that in total the image I is distanced to the object O by four times the focal length F. Therefore, this focusing condition is also called the 4F-condition.

In particular, in the embodiment a telescope like optics is realized by the mapping of the pumping area156onto itself by the pumping radiation field114which propagates from the pumping area156to one of the two focusing units152,154and further to the deflection units174associated with this one focusing unit152,154and from there back to the one focusing unit152,154to be focused back onto the pumping area156such that the image of the pumping area156is produced again at the pumping area156.

Accordingly, to fulfill the 4F-condition the deflection units174have to be arranged such that the optical path length between the two focusing units152,154is two times their focal length F.

In particular, the optics for mapping the one set192of deflection units174associated with one of the two focusing units152,154onto the other set192of deflection units174associated with the other of the two focusing units154,152by the two focusing units152,154can be seen as a telescope like optics for which the 4F-condition has to be fulfilled, too.

However, due to mismatches in real systems focusing conditions can not entirely fulfilled and mismatches occur.

For example, there are spatial constrains for the positioning of the deflection units174such that at least one focusing condition, in particular the 4F-condition, cannot be fulfilled.

In particular, the deflection unit174and in particular their deflection elements222have a finite extension and are arranged between the two focusing units152,154. But the two focusing units152,154have to be distanced to each other by the sum of their respective focal length F and therefore in between the two focusing units152,154, there is not the space that the deflection units174can be positioned in a distance to each of the two focusing units152,154by the respective focal length F and accordingly in particular the 4F-condition cannot be fulfilled.

For example, a finite and optically effective thickness of optical elements in the focusing units152,154shortens the optical path length. This may occur in curved, for example strongly curved, parabolic reflectors. In particular, a shortening of the optical path length occurs in cases in which the radiation field hits the parabolic reflector offset, for example strongly offset, the optical axis of the parabolic reflector. In particular, a shortening of the optical path length occurs if the axis of the radiation field and the axis of the parabolic reflector are offset, for example strongly offset.

In particular, within a real optical system246with real focusing units152,154and real deflection elements174deviations from the idealistic behavior occur and corresponding mismatches to the focusing conditions occur.

In particular, there are mismatches to the focusing conditions due to the finite width of the pumping radiation field114such that the focusing condition cannot be fulfilled along the entire cross section of the pumping radiation field114which is taken perpendicular to the propagation direction because, for example, the focal point is an idealistic point without extension and/or due to the finite width of the pumping radiation field114a transfer region at the focusing unit has a finite width and therefore the focusing condition cannot for all rays of the pumping radiation field114be fully fulfilled.

For example, a mismatch occurs due to a finite penetration length at a reflection along the optical path in the optical system246.

In particular due to mismatches in real systems, for example as described above, the length of the part of the deflection branch176which extends from one focusing unit152,154to the deflection unit174should be indeed larger than the focal length F but in fact this distance is smaller than the focal length F, because the deflection unit174should be positioned at least essentially in the middle between the two focusing units152,154but not the entire separation between the two focusing units152,154is available for the propagation of the pumping radiation field114because of the finite extension of the deflection unit174and in particular the finite extension of their deflection elements222.

Therefore, a correction branch252of the optical path144is defined by the optical assembly142which corrects for mismatches to the at least one focusing condition which occur in the deflection branches176and/or pumping branches164for and/or after the correction branch252with respect to the propagating direction of the pumping radiation field114along the optical path144.

In particular, a mismatch to the at least one focusing condition in the pumping radiation field114is at least reduced while the pumping radiation field114propagates along the correction branch252.

In some advantageous variants of the embodiments the mismatch to the focusing condition in the pumping radiation field114is at least essentially compensated when the pumping radiation field114has propagated through the correction branch252.

In other variants of the embodiment the mismatch to the focusing condition in the pumping radiation field114is overcompensated while the pumping radiation field114propagates along the correction branch252.

In particular, the pumping radiation field114is modified during the propagation through the correction branch252such that the focusing condition is at least essentially met but then the pumping radiation field114is further modified in the same manner and therefore leaves the correction branch252with a mismatch to the focusing condition but in a converse manner compared with the mismatch it had when entering the correction branch252. Therefore, if the pumping radiation field114propagates further along the optical path144this mismatch in the converted manner is compensated by the mismatch in the subsequent pumping branches164and/or deflection branches176such that later on along the optical path144the pumping radiation field114at least essentially fulfills the focusing condition.

In preferred variants in the introducing branch242a correction for a mismatch in the optical path lengths of the subsequent branches164,176is implemented and therefore preferably the introducing branch242is a correction branch252, too.

Preferably, the optical assembly142comprises a correction component254in which one correction branch252is defined.

For example, the correction component254comprises a deflection element256for deflecting an incoming part of the correction branch252into an extension part, which provides for an extension of the optical path length to correct the mismatch in the optical system246to the focusing condition.

In particular, the deflection element256of the correction component254has a reflective surface for reflecting the incoming pumping radiation field114towards the extension part of the correction branch252.

Preferably, the deflection element256of the correction component254is arranged at least approximately at the same axial position with respect to the optical axis116like the deflection units174of the deflection arrangement172and is positioned in the circumferential arrangement around the optical axis116together with the deflection units174.

In particular, the correction component254comprises a reverse element258, for example a mirror, for reversing the direction of propagation of the pumping radiation field in the correction component254, such that the pumping radiation field propagates along the correction branch252at first in one direction and after being reversed by the reverse element258in the opposite direction

For example, the reverse element258is provided subsequent to the deflection element256, such that the pumping radiation field propagates in the correction branch252first, in particular along the incoming part, to the deflection element256and then, in particular along the extension part, further to the reverse element258and from there back to the deflection element256and then further along the incoming part which is therefore also an outgoing part of the correction branch252.

In some preferred embodiments, a correction for a mismatch is achieved in at least one correction branch at least partly by a correction unit in addition to and/or in the alternative to the correction provided by the additional optical path length provided by the correction branch. In particular, the correction unit is an optical unit of several optical elements and these elements are arranged for the desired correction.

For example, the correction unit comprises a telescope like optics. In particular, this telescope like optics is arranged to have a misadjustment wherein the misadjustment is designed to correct for the mismatch.

In preferred variants a mismatch to at least one focusing condition in the pumping radiation field114is at least reduced and/or at least essentially compensated and/or overcompensated by the correction unit. This is at least similar to the variant in which the correction is achieved by the additional optical path length of the correction branch252. In particular, a correction branch with a correction unit is at least partly similarly built like a correction branch252in which a mismatch is corrected for by the defined optical path length of the correction branch252. Therefore, for further details it is fully referred to the description above and hereafter in order to avoid repetitions.

A correction for a mismatch is at least partly provided by correction unit also in some preferred variants of further embodiments described below.

Advantageously, the correction component254comprises an adjustable correction element260with which the correction behavior of the correction component254is adjustable in particular by a controller and/or by a user of the radiation amplifying system100adjustable.

For example, in some variants the correction element260influences the shape of the pumping radiation field, in particular focuses and/or collimates the pumping radiation field, preferably in an adjustable manner.

For example, the correction element260comprises a curved surface, preferably with an adjustable curvature.

For example, in some variants the correction element comprises one lens or several lenses, preferably with an adjustable focusing behavior, for example a distance between the lenses is adjustable.

In some preferred variants of the embodiment with an in particular adjustable correction element260the optical path length of the correction branch252is adjustable.

For example, the correction element260comprises a mirror, the position of which is adjustable within the correction component254in the direction of propagation of the pumping radiation field114.

In particular, the distance from the correction element260to the deflection element256of the correction component254is adjustable.

For example, the reverse element258is the adjustable correction element260such that the length of the extension part is adjustable.

In preferred variants, the optical assembly142is for example during its installation calibrated and in particular the at least one correction branch252is adjusted in its length such that the mismatch in at least one focusing condition is corrected for. Then the elements of the calibrated optical assembly142, in particular with the adjusted at least one correction branch252, are fixed. Therefore, during operation of the radiation amplifying system100advantageously no, for example elaborated adjustment is necessary.

In some advantageous variants, the radiation amplifying system100comprises an adjustment unit in particular with a sensor and a controller for adjusting the adjustable correction element260.

In particular, with a sensor the value of at least one property of the to be amplified radiation field112and/or of the pumping radiation field114is measured and the controller evaluates the at least one detected value und initiates an adjustment of the adjustable correction element260based on the detected value.

Preferably, the adjustment of the adjustable correction element260is based on at least one property, in particular on the output power of the to be amplified radiation field112and/or on the energy introduced by the pumping radiation field114to the pumping area156and/or on a shape of the pumping radiation field114, in particular its width and/or a spreading of the rays of the pumping radiation field114, and the sensor detects at least one parameter associated directly or indirectly with the corresponding property.

In some variants of the embodiment in addition or in the alternative, a deflecting correction element is provided in at least one of the deflection branches176in order to extend the optical path length of the deflection branch176in order to correct for a mismatch to a focusing condition. For example, the deflecting correction element comprises one prism or several prism and/or one mirror or several mirrors.

In particularly advantageous variants of the embodiment the deflection arrangement172comprises a shifting unit for the pumping radiation field114in which an incoming branch of the optical path144is transferred in an outgoing branch along which the pumping radiation field114propagates in the opposite direction as the direction along the incoming branch and the outgoing branch is slightly shifted with respect to the incoming branch in a direction at least essentially perpendicular to the propagation direction. Therewith, the pumping radiation field114can propagate through the deflection arrangement172twice, namely along corresponding branches which are slightly shifted perpendicular to the propagation direction.

In particular, preferred designs and preferred features and for example advantages of embodiments of the invention are briefly as follows:

The radiation amplifying system100comprises a laser amplifying component122for amplifying the to be amplified radiation field112.

The radiation amplifying system100comprises an optical assembly142defining an optical path144for the pumping radiation field114with the optical path144comprising a plurality of pumping branches164which pass through a pumping area156in the laser active medium124of the laser amplifying component122such that advantageously the pumping radiation field114efficiently pumps the laser active medium124.

The optical assembly142comprises two focusing units152,154for focusing the pumping radiation field114onto the pumping area156as the pumping radiation field114propagates along a respective pumping branch164.

Furthermore, the optical assembly142comprises the deflection arrangement172with deflection units174by which along a respective deflection branch of several deflection branches176two respective pumping branches164are connected and the pumping radiation field114is guided from one pumping branch164along the deflection branch176to another pumping branch164.

Within the optical system246of the deflection arrangement172and the focusing unit152,154at least one focusing condition has to be fulfilled, for example that the focusing units152,154are distanced to each other with the sum of their respective focal lengths F and/or that the deflection units174are in the proper distance to the respective focusing unit152,154for proper imaging of the pumping radiation field114.

In particular, if the focusing condition is fulfilled, a widening of the pumping radiation field114when propagating along the optical path144is at least essentially suppressed.

Because due to spatial constraints and/or due to optical aberrations and/or due to further discrepancies in the real optical system246from an idealistic system there are mismatches to the focusing condition in particular mismatches in the optical path length.

In order to correct one or several mismatches in the at least one focusing condition the optical assembly142comprises at least one correction component254which defines a correction branch252.

In particular, the optical path length of the correction branch252and/or a correction unit in the correction branche252is designed to at least reduce the mismatch in the focusing condition and/or essentially eliminates the mismatch and/or overcompensates the mismatch.

Preferably, the correction component254comprises the in particular adjustable correction element256with which in particular the optical path length of the correction branch252and/or a setting of the correction unit is adjustable for correcting for the mismatch and/or with which for example a shape of the pumping radiation field can be influenced for correcting for a mismatch.

For example, the radiation amplifying system100comprises a controller which initiates and/or controls the adjustment of the correction element260and preferably the system100comprises a sensor for detecting the value of at least one parameter and the adjustment of the correction element260is based on the detected parameter value.

In particular, the deflection units174of the deflection arrangement172are spatially fixed arranged to each other and for example spatially fixed with respect to the laser amplifying component122and in particular spatially fixed with respect to the focusing unit152and154.

Preferably, the adjustable correction element260, which in its position is adjustable, is spatially adjustable with respect to the deflection units174of the deflection arrangement172and in particular spatially adjustable in its position relative to the focusing unit152and154and for example spatially adjustable in its position with respect to the laser component124.

Accordingly, advantageously the mounting of the optical assembly142and for example a set-up thereof can be simplified because it is sufficient to arrange the several deflection units174in a proper arrangement for defining deflection branches176which connect pumping branches164and in particular the deflection units174can be fixed in this arrangement and potentially occurring mismatches to the focusing condition are corrected for by the at least one correction branch252defined by the correction component254. In particular, therewith an extensive fine-tuning of the arrangement of the several deflection units174can be avoided.

For example, therewith the optical assembly142and for example the deflection arrangement172can be designed in a more compact manner.

Advantageously, with the adjustable correction element260the adjustment of the correction branch and therefore the correction of a mismatch are even more simplified.

In particular, with the adjustable correction element260even during the operation of the radiation amplifying system100an adjustment in particular on demand of a user can be performed.

Preferably, with the at least one sensor a property of the radiation amplifying system100, in particular of the pumping radiation field114and/or of the to be amplified radiation field112and/or for example of the optical assembly142, for example of the correction component254, is measured and advantageously the adjustment is based on the detected parameter value.

Preferably, the adjustment of the correction component254, in particular of the adjustable correction element260, is performed by a controller in particular based on the at least one detected parameter value of the sensor.

In particular, even large numbers of pumping branches164are efficiently possible in the optical assembly142because potential and in particular unavoidable mismatches to the focusing condition which would sum up during the propagation of the pumping radiation field along the large number of pumping branches and would reduce the pumping efficiency can be corrected for by the at least one correction branch252.

In connection with the description of other embodiments those features and/or elements and/or parts which are designed at least essentially the same and/or at least fulfill the at least basically same function as in another embodiment the same reference sign is used and in so far as no further details regarding these are provided in connection with one of these embodiments it is fully referred regarding further details and/or advantageous features to the description of the other embodiments, in particular to the ahead described embodiment and/or to one of the below described embodiments.

In particular, is with respect to a feature and/or element and/or part a specific design to be emphasized a respective letter designating the respective embodiment is appended to the reference sign as a suffix.

In an embodiment of a radiation field amplifying system100athe optical assembly142for the pumping radiation field114comprises a deflection arrangement172awith deflection units174awhich are built by one deflection element222aas exemplarily shown inFIG.5.

In particular, the deflection elements222aare designed as prisms.

In particular, an incoming part184of a respective deflection branch176is deflected by the deflection element222ato an outgoing part188.

For example, the prism building the deflection element222ahas a base surface262at which the incoming part184enters into the deflection element222aand the incoming part184is deflected internally in the deflection element222ainto the outgoing part188which exits the deflection element222ain particular at the base surface262.

In particular, the prism is a triangular prism with two side surfaces264I and264II which extend from a respective end of the base surface262to a tip266of the prism at which the two side surfaces264I and264II meet each other in an angled manner. In particular, the pumping radiation field114entering the prism at the base surface262is reflected at the side surfaces264such that it exits the prism at the base surface262again along the outgoing part188.

For example, there is one set192I of deflection elements222aassociated with one of the two focusing units152,154and another set192II of deflection elements222aassociated with the other of the two focusing units152,154.

Preferably, the deflection units174aare arranged at least approximately in the middle between the two focusing units152,154in particular as described above.

Preferably, the deflection elements222aare arranged subsequently in a circumferential direction around the optical axis116and for example the deflection element222aof the two sets192I and192II associated with one respective of the two focusing units152,154are arranged alternating next to each other.

In particular, the respective base surface262of the deflection elements222afaces towards the focusing unit152,154to which the deflection element222ais associated to.

Advantageously, a deflection element222ais arranged with its extension from its base surface262to its tip266in a space between two deflection elements222aassociated with the other focusing unit with this space in particular being bounded by respective angled side surfaces264of these other deflection elements222a.

InFIG.5, there are shown exemplarily for two deflection units174atwo deflection branches176I and176II which are shifted with respect to each other as described above for duplicating the passage of the pumping radiation field114through the optical system246.

The deflection arrangement172aof this embodiment comprises a correction component254adefining a correction branch252for correcting a mismatch in at least one focusing condition in particular at least basically as described above.

In particular, the correction component254acomprises a deflection element256awhich is for example a prism.

In embodiments of a radiation amplifying system100bat least one focusing unit, for example both focusing units152band154b, are transparent for the pumping radiation field114, as exemplarily shown inFIG.7.

In some variants, the transparent focusing unit152b,154bis built by a single focusing element208b.

In particular, the single focusing element208bprovides the several transfer regions.

For example, the single focusing element208bhas a breakthrough which provides the corridor198for the optical passage way.

In some variants, the reflective focusing unit152b,154bis built by a plurality of focusing elements.

In particular, each focusing element of the plurality of focusing elements provides at least one transfer region.

For example, at least several focusing elements of the plurality of focusing elements are arranged in a circumferential direction around the optical axis116and/or around the corridor198for the optical passage way.

For example, the transparent focusing unit152b,154bcomprises at least one lens as a focusing unit.

In particular, a laser amplifying component122with the laser active medium124is positioned with respect to the axial direction of the optical axis116between the two focusing units152band154band preferably at the respective focal point of the two focusing units152b,154b.

Several pumping branches164of the optical path144for the pumping radiation field114extend between the two focusing units152band154band run through a pumping area156in the laser active medium124and in particular through the respective focal point of the two focusing units152band154b.

At the transparent focusing unit152b,154bthe optical path144runs through a respective transfer region of the transparent focusing unit152b,154band the pumping branches164are transferred to a respective deflection branch176and the deflection branches176are transferred to a respective pumping branch164.

In particular, the deflection branches176exit and enter the transparent focusing unit152b,154bat a side which is, in particular with respect to the axial direction of the optical axis116, opposite to the side of the focusing unit152b,154bat which the pumping branches164enter and exit the focusing unit152b,154b.

Furthermore, the optical assembly142bof this radiation field amplifying system100bcomprises a deflection arrangement172bwith a respective set192of deflection units174bassociated to the transparent focusing unit152b,154bbeing arranged on a side with respect to the focusing unit152b,154bwhich is with respect to the axial direction of the optical axis116opposite to the side at which the laser amplifying component122is arranged. Accordingly, the transparent focusing unit152b,154bis spatially arranged between the laser amplifying component122and the set192of deflection units174bwhich are associated to this transparent focusing unit152b,154b.

Preferably, the deflection units174btransfer an incoming part184of the respective deflection branch176which comes from the focusing unit152b,154binto an outgoing part188which runs at least approximately parallel to the incoming part184but with the incoming part184and the outgoing part188being in a direction which is at least essentially perpendicular to the propagation direction of the pumping radiation field114along these parts184,188offset to each other.

For example, the deflection units174bare built from two deflection elements222bwhich are reflective and define an intermediate part226of the deflection branch176between them as exemplarily shown inFIG.7.

In other variants of the embodiment, the deflection units174bare built by one deflection element222, in particular by a prism, as for example explained above in connection with the other embodiment.

Advantageously, in some variants of the embodiment, the optical assembly142bcomprises a correction component254which defines a correction branch252for correcting at least one mismatch in the pumping branches164and/or deflection branches176, of the optical path.

Preferably, the correction component254has in these variants of the embodiment at least one in particular adjustable correction element260for adjusting preferably the length of the correction branch252for correcting for a mismatch and optimizing the optical path for the pumping radiation field and/or for example for adjusting the shape of the pumping radiation field114and therefore advantageously the pumping of the laser active medium124is increased.

In other variants of the embodiment in addition and/or in the alternative the deflection branches176are adjusted to compensate for mismatches in the focusing condition.

In yet other embodiments of a radiation amplifying system100cat least several deflection units174care built by one deflection element222cas exemplarily shown inFIG.8.

In particular, the one deflection element222chas two reflective surfaces232I and232II which are arranged in an angle for example of at least approximately 90°. Preferably the two reflective surfaces232are at least essentially flat.

For example, the one deflection element222cis a folded thin material with reflective surfaces.

In some variants the deflection element222cis a prism.

In particular, the one deflection element222cis arranged with respect to one of the focusing units152,154such that an incoming part184and an outgoing part188of a respective deflection branch176run at least essentially parallel and offset to each other.

In particular, an intermediate part226is defined between the two reflective surfaces232I and232II and connects the incoming part184and the outgoing part188of a deflection branch176.

In particular, the focusing unit152,154to which the deflection units174cbuilt by the one deflection element222care associated to is transparent for the pumping radiation field114and the transparent focusing unit152,154is spatially arranged between the laser amplifying component122and the one deflection element222c, as is exemplarily shown inFIG.8.

In other variants the one deflection element222cis spatially arranged between the laser amplifying component222and the one focusing unit152,154which is in particular in such cases a reflective focusing unit152,154.

These embodiments advantageously comprise a correction component254defining a correction branch252and preferably with an adjustable deflection element256, in particular as described in connection with the other embodiments.

In particular, therewith a simple set-up and mounting of the optical assembly142cis enabled with arranging the one deflection element222cin particular in fixed arrangement with the least one focusing unit152,154and potential and in particular unavoidable mismatches in the optical path144defined by the optical assembly142can be corrected by the correction component154.

Depending on the different variants of the embodiment, deflection units174associated to the other of the two focusing units152,154are built in an at least basically similar manner by one deflection element222cor for example as in one of the previously described embodiments.

For a variant for which at least several of the deflection units174associated with a respective of the two focusing units152,154are each built by one deflection element222c, the optical path144is sketched inFIG.9exemplarily.

An axis272of the one deflection element222cfor the set192I of deflection units174associated to the one focusing unit152and an axis274of the one deflection element222cfor the set192II deflection units174associated to the other focusing unit154are offset to each other and rotated around the optical axis116by an angle which in particular corresponds to (90°+360°/2N) with N being the number of pumping branches164running through the pumping area156of the laser active medium124.

For example, at the respective axis272,274the two reflective surfaces232I and232II meet.

At one focusing unit152respective spots are indicated by capital letters and respective spots at the other focusing unit154are indicated by small letters and at the respective focusing unit152,154the spots are marked with the respective letter subsequently in a circumferential direction around the optical axis116. At these spots, a deflection branch176is transferred to a pumping branch or vice versa.

In particular, the respective sports at a focusing unit152,154are distanced to the respective neighboring spots with at least approximately the same distance.

The introducing branch252hits the one focusing unit152at the spot G where it is transferred to a pumping branch164which extends until a spot c at the other focusing unit154where it is transferred to a deflection branch and is deflected by the associated deflection unit174to the spot g at the focusing unit154. The following spots at the focusing units152and154at which the optical path144runs through and the pumping branch164is transferred to a deflection branch176or a deflection branch176is transferred to a pumping branch164are the spot C at focusing unit152which is connected by a deflection branch176to spot G at focusing unit152which is connected by a pumping branch164to spot H at focusing unit154which is connected by a deflection branch176to spot b at the focusing unit154which is connected to spot F at focusing unit152by a pumping branch and which in turn is connected by a deflection branch to spot A at focusing unit152which in turn is connected by a pumping branch to spot E at focusing unit154.

This spot e is connected to a spot a by a deflection branch176defined by another deflection unit174built in particular by two separated deflection elements222which for example are each a mirror, for shifting in a vertical direction the set-up of the pumping branches164and deflection branches176.

Spot a at focusing unit154is connected by a pumping branch to spot E at focusing unit152which is connected to a spot B by a deflection branch176which in turn is connected by a pumping branch164to a spot f at focusing unit154which is connected to spot d by a deflection branch176from which a pumping branch extends to spot H at focusing unit152.

Preferably, from spot H a branch extends to a reflective deflection element and/or a shifting unit and/or a reverse element, for example a mirror such that the pumping radiation field114propagating along the optical path144propagates twice through the optical assembly142and in the second turn in the opposite direction as described before.

Preferably, the branch from this spot H and back to the spot H is designed as a correction branch252and the deflection element is an in particular adjustable element260of the correction component254. In particular, the correction component254is adjustable at least basically as described before.

For example, in some variants the other deflection unit174with separated deflection elements222is also or in the alternative designed as a correction component254and in particular the deflection elements222are adjustable arranged for example to each other for adjusting the length of the part defined between them for defining a correction branch.

For example, the one deflection element222chas a breakthrough if it is so large that it would cover the passage way of the to be amplified radiation field112such that the to be amplified radiation field112can pass through the breakthrough being disturbed by the one deflection element222c.

As far as elements and/or features of particular variants of embodiments are not or not in detail described in connection with the particular variant itself they are preferably at least partly built as described in connection with another variant and/or another embodiment such that for the specifications of these elements and/or features it is fully referred to the explanations provided in connection with the other variants and/or other embodiments in order to avoid repetitions.

In some advantageous variants of the embodiments features and/or elements of several variants and/or several embodiments as described before are combined.

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