System for wavelength-resolved digital holographic imaging

Abstract

The invention relates to a system (1) for digital holographic imaging, comprising at least the following components: a beam splitter (2) that defines four sides with a beam splitter surface (2a), a retroreflector array (3) that is arranged on the second or the third side (22, 23) and comprises a plurality of retroreflector elements (30), and a reference mirror (4) that is arranged on an adjacent side (23, 22) to the retroreflector array (3), wherein the system (1) is configured to impress wavelength-dependent phase shifts on object light (100) for each retroreflector element (3), said phase shifts being different for a plurality of retroreflector elements (3).

Description

[0001] System for wavelength-resolved digital holographic imaging

[0002] Description

[0003] The invention relates to a system for digital holographic imaging according to the features of claim 1.

[0004] Systems for digital holographic imaging are known from the state of the art.

[0005] From DE 102021114059 A1, an optical imaging device for examining an object is known, comprising a beam splitter with a beam splitter surface that defines four sides of the beam splitter. On one side, corresponding to a first side, object light from the object under investigation is collected and reflected by partial reflection towards a second side, on which a reference mirror is arranged, and directed by partial transmission to a third side, on which a retroreflector array is arranged, wherein the reflected object light forms an interference pattern on a fourth side. This interference pattern is recorded by a camera arranged on the fourth side and evaluated by a computer, thereby enabling the determination of a holographic representation of the object.

[0006] In principle, the beam path with respect to the second and third sides of the beam splitter is interchangeable, i.e., the reference mirror can be located on the third side and the retroreflector array can be located on the second side.

[0007] However, one problem with digital holography is to also evaluate the color information of the object light in such a way that different wavelength ranges of the object light can be resolved independently of each other in the digital representation.

[0008] In current technology, for color resolution, the spectral channels are therefore recorded sequentially, so that each spectral channel has its own interference pattern, which is evaluated separately to prevent a detrimental mixing of all color and spatial information. The underlying problem with broadband recordings is that the spatial information at one wavelength corresponds to a compressed or stretched spatial information at another wavelength in the interference pattern, making it seemingly impossible to resolve these seemingly identical contributions in the interference pattern.

[0009] To solve this problem, the interference pattern would need to reveal information that allows a distinction between wavelength and spatial information. If this is not possible, the spatial information becomes increasingly blurred with a wider spectral range.

[0010] Color cameras on the detection side would provide a solution, but these bring other disadvantages. In particular, it is often desirable to resolve more than the usual three colors, red, green, blue (RGB), but rather to examine, for example, several narrowband spectral ranges or an infrared range.

[0011] However, color cameras suffer from a comparatively high light loss, as only one spectral component is detected per pixel. Furthermore, crosstalk between the color pixels complicates the analysis, and for narrowband spectral ranges, implementing appropriate narrowband pixel filters is difficult.

[0012] No system known in the prior art achieves a narrowband wavelength-dependent resolution of the object light without sequentially recording the different wavelengths.

[0013] Simulations have shown that, depending on the permissible propagation angle (e.g., < 100 mrad) of the object light relative to the optical axis of the system, even a narrowband spectral range, a so-called subband, can be imaged without adverse destructive interference. The theory assumes a single wavelength.

[0014] However, it is desirable to generate the spatial information of all color bands simultaneously and to separate the digital holograms into the corresponding color bands, thus resolving the spectral information as if it had been recorded sequentially. This would improve the signal-to-noise ratio and, moreover, require only a single recording instead of numerous recordings, which can be extremely advantageous when capturing time-critical images, such as when the object being recorded is moving.

[0015] Building upon this foundation, such a color band could consist not only of a single laser wavelength or a narrow wavelength band (e.g., a few nanometers, such as 5 nm), but of a broad spectral band. Especially when daylight or a light source consisting of multiple broadband colored light sources is to be used, it is essential to be able to utilize at least approximately 30 nm per color in order to harness as much light energy as possible. This should also be possible without the usual color filters, which absorb light energy from other colors and also reduce the effectively usable camera pixels per color. With a 30 nm bandwidth per color, this color band could then be "divided" into, for example, 6 individual sub-bands, so that with three colors, a total of 18 sub-bands would need to be separated.

[0016] The object of the invention is therefore to provide a device that eliminates these disadvantages in the prior art.

[0017] The problem according to the invention is solved by a system of the type mentioned at the outset according to claim 1. Advantageous embodiments of the invention are specified in the dependent claims and are described below.

[0018] A digital holographic imaging system is then provided, comprising at least the following components: a beam splitter with a beam splitter surface defining at least the following sides:

[0019] (a) a first side for collecting object light, comprising a multitude of sub-bands,

[0020] (b) a second side to which the collected object light is reflected, in particular by the beam splitter surface, the second side extending adjacent to the first side,

[0021] (c) a third side extending opposite the first side and, in particular, adjacent to the second side, (d) a fourth side extending opposite the second side and, in particular, adjacent to the first and third sides, such that object light reflected from the second and third sides propagates to the fourth side and forms an interference pattern of the object light on the fourth side, a retroreflector array arranged on the second or third side and comprising a plurality of retroreflector elements, a reference mirror arranged on a side adjacent to the retroreflector array, wherein that adjacent side is the second or third side, wherein the reference mirror is configured to reflect object light in the direction of the beam splitter surface, in particular an array detector configured to record the interference pattern for further evaluation,in particular where the array detector is a monochrome array detector.

[0022] According to the invention, the system is configured to impose predefined wavelength-dependent phase shifts on the object light for a plurality of retroreflector elements, in particular for each retroreflector element and in particular for a plurality of subbands, which are different for a plurality of retroreflector elements, in particular for each retroreflector element of the retroreflector array, in particular wherein the phase shifts are dimensioned with respect to the object light reflected from the reference mirror, in particular wherein the predefined wavelength-dependent phase shifts include information in the interference pattern that allows a plurality of subbands of the object light to be evaluated separately, in particular so that each subband can be resolved, i.e. calculated, as a separate digital hologram.

[0023] It is known to those skilled in the art that, in order to generate an interference pattern, the collected object light must exhibit sufficiently high spatial and temporal coherence. The more broadband the object light, the shorter the coherence length. The invention also solves this problem, since, by separately evaluating the subbands resolvable according to the invention, even broadband object light exhibits a sufficiently high coherence length in the subbands.

[0024] In the context of this specification, the term "imprinted" in connection with a phase shift is understood to mean, in particular, that the phase of the object light, especially as referenced by the reference mirror and measured at the detector array, is shifted differently depending on the wavelength and the retroreflector element. This phase shift occurs, for example, relative to a different wavelength or subband.

[0025] In particular, each subband is assigned a wavelength-dependent phase shift for a multitude of retroreflector elements or for each retroreflector element, which allows these subbands to be resolved algorithmically independently of each other.

[0026] Crucial for this form of phase coding is the phase relationship of the object light, which originates from the second and third sides and leads to the interference pattern on the fourth side, which is detected, in particular, by a detector array. The invention provides that at least part of the phase coding is achieved by the retroreflector array in the manner described above. However, the final phase relationship on the fourth side is determined, in particular, relative to the object light originating from the reference mirror.

[0027] This means that a distinction can be made between the following phase shifts:

[0028] A) A retroreflector array phase shift that occurs on the side of the retroreflector array. This phase shift can be measured, for example, relative to a hypothetical retroreflector array that would not cause wavelength-dependent phase shifts that would be different for each retroreflector element.

[0029] B) A reference mirror phase shift occurring on the side of the reference mirror. This phase shift can be measured, for example, relative to a particularly hypothetical reference mirror that would not cause any wavelength-dependent phase shifts. It is noted that, depending on the embodiment of the invention, the reference mirror can generate wavelength-dependent or wavelength-independent phase shifts.

[0030] C) A phase shift on the fourth side. This phase shift is measured from the phase relation of the object light reflected by the retroreflector array (A) and the object light reflected by the reference mirror (B).

[0031] The phase shift on the fourth side is the one that determines the interference pattern. It can also be referred to as the cumulative phase shift to clarify the distinction from the other two phase shifts, if necessary.

[0032] It is not strictly necessary for each retroreflector element to impose a different wavelength-dependent phase relationship on the object light. However, retroreflector elements that impose the same phase relationship on the object light would contribute redundant information, so ideally each retroreflector element should impose a different phase relationship.

[0033] The invention makes it possible to achieve phase coding via the phase shifts of the object light, particularly on the side of the retroreflector array, which allows the interference pattern to be designed in such a way that individual subbands can be resolved in the reconstruction.

[0034] According to the invention, it is necessary to impose several predefined wavelength-dependent phase shifts on the object light for each retroreflector element, which are different for each retroreflector element of the retroreflector array.

[0035] In particular, any phase shift is detected in the form of a wavelength-dependent increase or decrease in the optical path length of the object light in the second or third arm, i.e., in comparison to the phase of the object light that it would have if it had not traveled an increased or decreased optical path length in at least one of the two arms. The phase shift could therefore be specified relative to a system configured such that the optical path length for the object light was the same for each retroreflector element, thus imposing no wavelength-dependent phase shift on the object light that would differ for each retroreflector element.

[0036] An important functional aspect of the invention is as follows: The phases encoded in the interference pattern on the fourth side are formed by phase shifts of the phases of the object light reflected from the second and third sides. Crucially, these phase shifts are wavelength-dependent and different for each retroreflector element.

[0037] This phase relation, or this subband-dependent phase shift, is also referred to as phase coding in the context of the specification.

[0038] The phase of the object light reflected by the reference mirror can, at least in some embodiments, be assumed to remain unchanged over a surface of the reference mirror for a single wavelength or for a subband for an incidence angle of the object light essentially along the optical axis. It is, of course, possible, and also provided for in a possible embodiment, that the reference mirror also imparts wavelength-dependent phases to the object light. It is also possible to increase the incidence angle of the object light to, for example, 100 mrad or more relative to the optical axis, since the corresponding lateral influences with respect to phase are preferably identical in the second and third arms.In combination with the wavelength-dependent phases of the object light reflected by the retroreflector array, which are different for each retroreflector element, the phase coding results, and thus a corresponding interference pattern that reflects the corresponding phase shifts on the fourth page.

[0039] Furthermore, the information that allows a multitude of subbands of the object light to be evaluated separately is contained within the entire interference pattern. Specifically, this information is contained exclusively in the form of an intensity distribution of the interference pattern. Therefore, this information is not contained as separately recorded information for each subband of the object light, e.g., sequentially recorded information within the interference pattern.

[0040] The invention enables spectral resolution of the subbands in the object light without filtering the subbands, for example, via a color filter.

[0041] This is made possible by the fact that the system according to the invention is configured to imprint wavelength-dependent phase information on the object light, depending on the wavelengths / sub-bands encompassed by the object light, which modifies the resulting intensity distribution of the interference pattern. As already described, the phase distribution arises from the phase differences of the object light, among other things due to the different optical path lengths of the object light on the second and third sides, whereby different phases are imprinted on the object light via the retroreflector array for each retroreflector element, depending on the wavelength.

[0042] Subsequent analysis of the interference pattern allows the wavelength-dependent phase shift information contained within it to be used to generate digital holograms of single or, if desired, multiple spectral subbands. Essentially, the wavelength-dependent phase shift must be known in detail, which can be readily achieved through system design and / or appropriate system measurements.

[0043] The basic concept of the invention utilizes the fact that light exhibits a wavelength-dependent propagation speed in different media. The system allows the phase relationship between the object light from the second and the third arm to be adjusted differently for each retroreflector element, depending on the wavelength.

[0044] The phase shifts should be designed so that a digital hologram can be determined from a wavelength range of the object light for a multitude of sub-bands encompassed in the wavelength range, based on the interference pattern for each sub-band.

[0045] This means that the phase shifts allow the incident spectral band, i.e., the object light in one or the entire encompassed wavelength range, to be encoded into a multitude of sub-bands, so that a digital hologram can be determined for each sub-band based on the interference pattern and the knowledge of the phase shifts for each retroreflector element.

[0046] The system can be configured so that the applied phase shifts are chosen to make it possible to resolve a predefined number of sub-bands.

[0047] In the context of this specification, the term "subband" refers specifically to a contiguous wavelength range that can have a width of up to 15 nm relative to the wavelength of light in a vacuum. In particular, a subband has a spectral width of up to 10 nm. This wavelength range of the subband can also have a width of up to 5 nm or even only 3 nm. Typically, a subband is wider than 1 nm or 2 nm. Each subband can be associated with a central wavelength with respect to which the subband can be evaluated.

[0048] In the context of this specification, the wavelength-dependent phase shifts are considered to be different, in particular, if the wavelength-dependent phase shifts of one retroreflector element are linearly independent of the wavelength-dependent phase shifts of the other retroreflector elements. Analogously, this definition can also be applied to the phase relations of the subbands based on their associated central wavelength.

[0049] In particular, the subbands can have different spectral widths.

[0050] This phase coding of the object light subbands, imposed via phase shift, is motivated as follows: Similar to the Fourier transform, which is well known to those skilled in the art, each subband is assigned a phase in the form of a phase shift relative to the other subbands. The corresponding object light waves then add up according to the known laws of optics as a mixture of frequencies (and associated phases) to form an interference pattern.

[0051] On the side of a reconstruction algorithm, since the phase for each subband is known due to the phase shifts and is different for a multitude of retroreflector elements or for each retroreflector element, the interference pattern coming from each retroreflector element can be evaluated with the known phase shift, for example, using a mathematical algorithm, to extract the hologram information for each subband.

[0052] The signal corresponding to each subband is then algorithmically filtered out based on the known phase shift, such that the signal of this subband constructively adds up, while the signals of the other subbands cancel each other out. This process can then be repeated for the other subbands. This reconstruction can be performed individually or by means of a matrix inversion, which is known to those skilled in the art.

[0053] Algorithmically, the phase-coded sum signal detected by each retroreflector element on the fourth side is vectorially added by phase-shifting the desired subband with its known phase coding (per retroreflector element), so that only the signals of the desired subband are added constructively, while the signals of all other subbands are added destructively, thus eliminating each other to zero or close to zero. This process is repeated for all desired subbands. This reconstruction can also be parallelized using matrix inversion to optimize computational speed.

[0054] The information thus obtained about the subbands can be used to overcome the uniformity of the information regarding wavelength and spatial orientation (angle of incidence). By appropriately re-scaling the information / spatial coordinates of the subbands, a comparatively sharp object can be generated that encompasses the information across the entire spectral range or at least for selected subbands, while simultaneously allowing for the resolution of color in the object light.

[0055] In particular, the difference between a largest and a smallest imposed wavelength-dependent phase shift in each phase coding step is between 0 and 2TT.

[0056] In the context of this specification, the term "arm" is sometimes used synonymously with the term "side" in connection with the beam splitter. The term "arm" primarily aims to help a person skilled in the art understand the different beam paths of the beam splitter, while the term "side" emphasizes the geometric arrangement of the components.

[0057] The second arm thus corresponds in particular to the beam path between the beam splitter surface and the second side. The same applies to the further numbering of the arms and sides.

[0058] It is familiar to those skilled in the art how the beam splitter surface of a beam splitter (e.g., a beam splitter cube) is defined as having four sides (first to fourth sides). These four sides correspond, in particular, to the sides of the beam splitter that are perpendicular to the optical axes of the beam splitter.

[0059] According to one embodiment of the invention, each retroreflector element forms a sub-aperture of the system.

[0060] In principle, for the retroreflector array and especially for each retroreflector element, the incident light is reflected back along the same direction, i.e., the angle of incidence of the light is identical to the angle of reflection.

[0061] According to a further embodiment of the invention, the system is configured to impose a wavelength-dependent, assigned predefined phase shift on the object light for each subband, wherein the coding is different for each retroreflector element across the individual subbands.

[0062] According to a further embodiment of the invention, each comprises

[0063] Retroreflector element: a retroreflector mirror.

[0064] According to a further embodiment of the invention, each comprises

[0065] A retroreflector element comprises a lens and an associated retroreflector mirror, in particular wherein the retroreflector mirrors are arranged in a focal region encompassing a focal plane of the associated lens, such that substantially collimated light is focused onto the associated retroreflector mirror. The focal region is in particular a region encompassing a focal plane of the lens, wherein the focal region further extends along the optical axis around the focal plane, such that the arrangement of the lens with respect to the retroreflector mirror can exhibit at least a manufacturing tolerance and also takes into account a displacement of the focal plane due to different wavelengths of the object light or a displacement of a reflection plane of the retroreflector mirror.

[0066] The fundamental aim is to illuminate each retroreflector element with a collimated wavefront of the object light. However, the larger the diameter of the retroreflector array, the more the wavefront of the object light deviates from a straight line / plane due to quadratic components at the edges. Therefore, this embodiment should be understood to mean that a wavefront deviation of the object light at the edges of the retroreflector array of TT / 4 can still be considered collimated.

[0067] According to a further embodiment of the invention, the system comprises one or more dispersion elements, each dispersion element being configured to impose wavelength-dependent phase shifts on the incident object light, which are different for each retroreflector element, in particular wherein a coding over the individual subbands is different for each retroreflector element.

[0068] The use of one or more dispersion elements is / are an advantageous embodiment of the invention, since the dispersion element makes it possible to imprint the phase shifts onto the object light without moving components.

[0069] According to a further embodiment of the invention, at least, in particular exactly one of the one or more dispersion elements is arranged on the retroreflector array and extends over several retroreflector elements, in particular wherein the dispersion element extends over all retroreflector elements, so that wavelength-dependent phase shifts are imposed on the object light incident on the plurality of retroreflector elements, in particular wherein a wavelength-dependent phase shift is imposed per subband, in particular wherein the phase shift is a phase coding, wherein the phase coding is different over the individual subbands for the plurality of retroreflector elements.

[0070] In particular, the dispersion element extends over the second or third side, especially over an entire side aperture of the respective side.

[0071] Such a dispersion element exhibits, in particular, different dispersion relationships in the area of ​​the retroreflector elements, so that the wavelength-dependent phase shifts differ for the multitude of retroreflector elements.

[0072] This embodiment enables the invention to be implemented with only a single dispersion element, which is arranged in front of the retroreflector array, i.e. between the beam splitter surface and the retroreflector elements.

[0073] This embodiment makes it possible, in particular, to use fewer dispersion elements than there are retroreflector elements in the retroreflector array.

[0074] According to a further embodiment of the invention, the one, in particular the exact one, or the several dispersion elements are each designed as a multiple wedge plate with a plurality of wedge elements, in particular as a double wedge plate with two wedge elements, wherein each wedge element has an Abbe number different from the other wedge elements, in particular wherein the multiple wedge plate has a plane-parallel inlet and outlet aperture.

[0075] This embodiment also makes it possible to use fewer dispersion elements than retroreflector elements in the retroreflector array. The wedge-plate structure allows each retroreflector element to be configured to impart a wavelength-dependent phase shift to the incident object light, which differs from that of the other retroreflector elements.

[0076] Furthermore, the different Abbe numbers make it possible to precisely adjust the phase shift for different sub-bands.

[0077] According to a further embodiment of the invention, the system comprises a plurality of dispersion elements, wherein each dispersion element is assigned a, in particular exactly one, retroreflector element, in particular wherein each retroreflector element comprises a dispersion element, wherein each dispersion element is configured to impose wavelength-dependent phase shifts on incident object light, which are different for each dispersion element, in particular wherein the phase shifts are measured with respect to the object light reflected from the reference mirror.

[0078] In particular, each retroreflector element is also assigned a dispersion element.

[0079] This embodiment provides in particular that each retroreflector element is assigned a dispersion element and in particular is encompassed by it.

[0080] This embodiment therefore also includes an integrated retroreflector array in which the dispersion elements are already arranged on each retroreflector element.

[0081] Furthermore, this embodiment allows for the use of individual material compositions per dispersion element.

[0082] According to a further embodiment of the invention, at least some dispersion elements of the plurality of dispersion elements, in particular all dispersion elements except two dispersion elements, each comprise a layer system, wherein each layer system comprises a first layer element with a first Abbe number and a second layer element with a second Abbe number, wherein the first and the second Abbe number are different from each other, in particular wherein one dispersion element of the dispersion elements comprises only the first layer element, wherein another dispersion element of the dispersion elements comprises only the second layer element, in particular wherein each dispersion element has a plane-parallel inlet and outlet aperture, in particular wherein the first and the second layer element each have plane-parallel inlet and outlet apertures.

[0083] This embodiment extends the technical teaching to an advantageous structure and implementation of the dispersion elements. The layered elements allow the wavelength-dependent phase shift to be precisely and predefined for the associated retroreflector elements. Furthermore, this type of dispersion element is relatively easy to implement, and its effect can be precisely predicted.

[0084] The Abbe number is known to those skilled in the art as a dimensionless number used to optically characterize the dispersion of a material. Various definitions of the Abbe number exist. For the purposes of this specification and the selection of materials for the dispersion elements, the following definition of the Abbe number v may be advantageous: where n e the refractive index of the material at the Fraunhofer line e of mercury, i.e. the refractive index at 546 nm, where n F, the refractive index of the material at the Fraunhofer line F' of cadmium, i.e., the refractive index at 480 nm, and where n c , the refractive index of the material at the Fraunhofer line C' of cadmium is, i.e., the refractive index at 644 nm.

[0085] To maintain constant coherence conditions in the first and second arms across the retroreflector array (also known as optical matching conditions), layer elements are advantageous whose refractive index at the green spectral range, i.e., around 546 nm, is (almost) identical in both layer elements, meaning, in particular, that they differ from each other by no more than 20%. For example, layer elements made of N-F2 (Abbe number 36.4) and N-SSK8 (Abbe number 49.8) can be used. The Abbe numbers refer to an older definition of the Abbe number, which is based on the d-line of helium (588 nm), the F-line of hydrogen (486 nm), and the C-line of hydrogen (656 nm).

[0086] According to a further embodiment of the invention, each dispersion element of the plurality of dispersion elements has a total thickness that is the same for all dispersion elements, wherein the first and second layer elements each have a thickness that is different for each dispersion element and which add up to the total thickness of the dispersion element.

[0087] In an extension of the inventive concept to this embodiment, it may be advantageous that at least some dispersion elements comprise a third layer element with a third Abbe number, wherein the first, second and third Abbe numbers are each different from one another.

[0088] Another embodiment, which allows for even more precise adjustment of the desired wavelength-dependent phase shift, provides that at least some dispersion elements comprise N layer elements, each layer element having a respective Abbe number, wherein the Abbe numbers of each layer element are each different from one another, where N>2 and is an integer, for example 4 or 5, in particular where N<10.

[0089] The considerations regarding the embodiment with only two layer elements per dispersion element can be applied accordingly to this embodiment.

[0090] The layer elements are, in particular, solid layer elements, i.e., not gaseous.

[0091] According to a further embodiment of the invention, the retroreflector array extends along a retroreflector array plane which forms an angle of intersection a = 45° + 8 with a beam splitter plane extending along the beam splitter surface, wherein |<5| > 0° , so that different wavelength-dependent phase shifts are imposed on the object light incident on the retroreflector array for a plurality of retroreflector elements.

[0092] This embodiment provides that the wavelength-dependent phase shifts are generated, in particular, exclusively by the different optical path lengths for each retroreflector element caused by the tilting of the retroreflector array.

[0093] The wavelength-dependent phase shifts are caused in particular by the resulting differences in optical path lengths between a plane that forms an angle of exactly 45° with the beam splitter plane and the retroreflector array plane extending at an angle of 8° to it. The system is specifically configured such that the wavelength-dependent phase shifts are caused exclusively by these differing optical path lengths. It should be noted that in this embodiment, some retroreflector elements impart the same or nearly identical phase relations to the object light. However, for the reasons mentioned above, this has no adverse effect as long as a large number of retroreflector elements impart different wavelength-dependent phase relations to the object light.

[0094] Alternatively, embodiments comprising one or more dispersion elements can be readily combined with this embodiment.

[0095] In the aforementioned considerations, the dispersion of air is negligible. Rather, for example, with different optical delta path lengths, a "blue" wavelength undergoes several 2TT oscillations than a "red" wavelength. Since the phase difference is crucial, it is clear that with a larger optical path length difference (between the second and third arms), the phases of the blue and red wavelengths diverge more and more until a phase difference that causes phase coding eventually reaches 2TT. Smaller phase coding angles are also desirable.

[0096] According to a further embodiment of the invention, the system is configured such that an optical path length is different for a plurality or for each retroreflector element, so that wavelength-dependent phase shifts are imposed on the object light, which are different for each retroreflector element.

[0097] According to a further embodiment of the invention, a plurality of retroreflector mirrors, or each retroreflector mirror, is configured such that wavelength-dependent phase shifts are imposed on the incident object light by the respective retroreflector mirror. These phase shifts are different for the plurality of retroreflector elements or for each retroreflector element of the retroreflector array. In particular, the reference mirror is also configured such that light reflected at the reference mirror undergoes a predefined wavelength-dependent phase shift (or dispersion), and these phase shifts are uniform across the reference mirror in the lateral direction. This embodiment offers a further possibility of imposing wavelength-dependent phase shifts on the object light, which are different for the plurality of retroreflector elements, and in particular for each retroreflector element.

[0098] These types of mirrors, which allow wavelength-dependent phase shifts, are known, for example, as Bragg mirrors. In the special case of continuous (nearly quadratic) phase profiles, these dispersive mirrors are known, for example, from the field of chirped mirrors.

[0099] Particularly due to considerations of the coherence length, it can be advantageous to impose a phase shift on the object light also on the side of the reference mirror, which is wavelength-dependent across the surface of the reference mirror, but can be the same across the reference mirror in the lateral direction (i.e. perpendicular to the optical axis).

[0100] Furthermore, in the combination of Bragg or dispersive mirrors, the phase response for the detected interference signal can be designed by terminating the second or third arm in such a way that (dispersive) influences of the optics are compensated and only the phase coding in the fourth arm remains.

[0101] This design also allows for a system that operates without moving components. The retroreflector mirrors can be designed to have the desired individual phase shift characteristics (phase coding).

[0102] According to a further embodiment of the invention, each retroreflector mirror of the plurality of retroreflector elements, in particular each retroreflector element, comprises a layered system mirror or is configured as such, wherein each layered system mirror is configured such that incident object light is reflected in a wavelength-dependent manner, such that object light from different subbands travels a different optical path length in the layered system mirror, in particular wherein the reference mirror comprises a layered system mirror or is configured as such.

[0103] According to a further embodiment of the invention, each retroreflector mirror of the plurality of retroreflector elements, in particular each retroreflector element, comprises a plurality of Bragg mirrors. A Bragg mirror, in particular, has an alternating sequence of layers with higher and lower refractive indices.

[0104] In such a Bragg mirror, a specific subband with a predefined phase is reflected in the retroreflector element, while other subbands are transmitted. For example, a first Bragg mirror reflects a first subband, and a second and subsequent subbands are transmitted. A second Bragg mirror, positioned behind (i.e., optically along the direction of incidence) the first Bragg mirror, reflects the second subband with a different phase. This process can be repeated for a multitude of subbands and Bragg mirrors arranged in series. The Bragg mirrors form a layered mirror system or Bragg composite mirror, whereby these individual Bragg mirrors can be arranged in a precise sequence or partially nested, which saves space.

[0105] To comply with the coherence conditions, the reference mirror can be equipped with a layered system mirror or Bragg composite mirror analogous to the one above, with the difference that individual subband-dependent phases do not change across the lateral extent of the reference mirror.

[0106] The layered mirrors in the second and / or third arm cause wavelength-dependent phase shifts to be imposed on the incident object light. These phase shifts are unique for the multitude of retroreflector elements, and in particular for each retroreflector element of the retroreflector array. The coherence conditions are met, especially when the path differences of the corresponding Bragg mirrors of the retroreflector elements and the reference mirror are less than or equal to one wavelength, in order to achieve phase coding between 0 and 2TT ZU. This can be ensured by a suitable design of the reference mirror.

[0107] It is noted that the coherence length of the object light can certainly span several wavelengths. With typical subband spectral widths of 3 nm to -10 nm, the coherence length is between 5 pm and 15 pm, i.e., on the order of 10 pm. This embodiment specifies a way to design the retroreflector mirrors such that wavelength-dependent phase shifts are imposed on the incident object light by the retroreflector mirror. These phase shifts are different for the multitude of retroreflector elements, in particular for each retroreflector element of the retroreflector array, thus achieving subband phase coding.

[0108] Layered system mirrors can be manufactured very precisely according to predefined design specifications.

[0109] According to a further embodiment of the invention, the layer system mirror of each retroreflector element comprises reflective layers (in particular Bragg mirrors), wherein each reflective layer is configured to reflect light from a predefined subband assigned to the respective reflective layer, wherein the reflective layers in the layer system mirror are arranged such that light from different subbands is reflected with a predefined phase assigned to the respective retroreflector element.

[0110] The reflective layers are therefore designed to reflect light in a wavelength-dependent manner. Specifically, the reflective layers are transparent to at least some other wavelength ranges and subbands, so that object light is reflected by different reflective layers, which are arranged one behind the other in the retroreflector mirror along the optical axis.

[0111] The reflective layers are specifically tuned to the respective subbands. Similarly, the reference mirror can be structured accordingly.

[0112] According to a further embodiment of the invention, the reflective layers in each layer system mirror are arranged and spaced apart along a propagation direction of the light in such a way that light from the sub-bands is given a wavelength-dependent continuous and almost quadratic phase response.

[0113] This type of layered system mirror is known in the prior art as chirped mirrors. In particular, it is provided that the reference mirror is a layered system mirror and that the reflective layers of the reference mirror are arranged and spaced along a direction of light propagation such that light from the subbands is imprinted with a wavelength-dependent quadratic phase response, in particular where the phase response is the same over the entire reference mirror.

[0114] According to a further embodiment of the invention, the reflective layers of the layer system mirrors and / or the entrance and / or exit aperture of the dispersion elements are aligned at a predefined angle or at different angles to the optical axis.

[0115] According to a further embodiment of the invention, the system is configured to adjust a position and / or angle of the retroreflector array and / or the reference mirror relative to the beam splitter plane, so that a relative alignment of the retroreflector array and the reference mirror can be adjusted in which a phase difference between conjugate points in the second and third arm is approximately TT, so that the subtraction of these interference signals (holograms) leads to a reduction of the DC component of the object light (DC light).

[0116] Furthermore, this embodiment allows a reduction of the so-called twin image when the phase difference is TT / 2, which is state of the art.

[0117] According to a further embodiment of the invention, the system comprises one or more actuators, in particular piezo actuators, which are configured to adjust the position and / or angle of the retroreflector array and / or the position and / or angle of the reference mirror relative to the beam splitter plane.

[0118] Additionally or alternatively, the system includes an electrically controllable refractive index layer that changes its refractive index depending on an applied voltage or current. This refractive index layer can produce the same effects as adjusting the aforementioned angle or position.

[0119] This embodiment makes it possible to reduce or suppress the so-called twin image. Furthermore, it allows for the reduction or suppression of so-called DC light (direct current light). DC light is particularly disruptive when reconstructing the center point of an object, i.e., the point of the imaged object that lies in focus on the optical axis of the system.

[0120] The phase shift for reducing the twin image or the DC light can be achieved by one or more actuators and / or the refractive index layer.

[0121] According to a further embodiment of the invention, the system comprises a processor configured to evaluate recording data, which includes information about the light recorded by the array detector, and to generate and output data for a digital hologram, wherein the data includes color information about a plurality of sub-bands of the object light of a recorded object, wherein the color information for at least one sub-band, in particular wherein the color information of one, several or all sub-bands in the data can be retrieved and displayed individually and separately.

[0122] According to a further embodiment of the invention, the processor is configured to evaluate recording data comprising information about the light recorded by the array detector and to output data via a digital hologram, wherein the data are evaluated in such a way that the hologram is corrected for wavelengths from different sub-bands.

[0123] For this purpose, the methods of matrix inversion, familiar to those skilled in the art, can be used. The additional phase encoding of the subbands in the interference pattern is crucial here in order to be able to evaluate the information from the subbands separately.

[0124] Furthermore, the processor can be advantageously configured to scale the object information generated by the processor for each color information using one, several, or all subbands according to their wavelengths, so that regardless of the wavelength of the object's light, the object captured in the hologram always has the same size. This information about the captured and scaled object can then be summed, for example, across all subbands to create an object for each color, in order to a) increase the signal-to-noise ratio and / or b) minimize speckle noise.

[0125] The term "color" or color information refers specifically to a wavelength range that extends around a central wavelength. This wavelength range typically has a spectral width of around 30 nm. The central wavelength lies in the middle of the range and defines the color. For example, blue (B) can be defined as the range between 410 nm and 460 nm, with a central wavelength of 435 nm. Green (G) can be defined as the range between 520 nm and 570 nm with a central wavelength around 545 nm, and red (R) can be defined as the range between 610 nm and 660 nm with a central wavelength around 635 nm. Other colors with differently positioned ranges can be defined in the same way. In particular, the wavelength range of a color can also be narrower or wider.

[0126] The following is an exemplary selection of relationships between subbands and color.

[0127] The device can perform a) separation of subbands within a single color. For example, a color with a 30 nm bandwidth can be divided into N=10 subbands, each with a width of 3 nm; b) separation of, for example, three narrowband colors (R / G / B) (e.g., 3 nm per color), with each color assigned one, and in particular exactly one, subband; c) separation of all colors and subbands within a single color (a combination of variants a) and b). For example, three colors (R / G / B), each with a bandwidth of 30 nm, can be divided into N subbands, each with a bandwidth of, for example, 3 nm, so that a total of 30 subbands for three colors can be phase-encoded by the device.

[0128] According to a further embodiment of the invention, the object light a) comprises a continuous wavelength range – also referred to as color in the present specification – in particular wherein the wavelength range has a width of up to 50 nm, in particular up to 30 nm, in particular more than 10 nm, comprising a plurality of individual, in particular non-overlapping, subbands in this wavelength range. The subbands have, for example, a spectral width of 3 nm to 6 nm. b) is composed of a plurality of disjoint wavelength ranges (colors), in particular wherein there are gaps between the disjoint wavelength ranges, in particular wherein each gap is larger than 10 nm, in particular larger than 50 nm, wherein each disjoint wavelength range of a color is as wide as a subband, i.e., in particular 3 nm to 6 nm, or c) consists of a combination of variants a) and b), i.e.,A plurality of wavelength ranges with a width of up to 50 nm, in particular up to 30 nm per wavelength range, wherein the plurality of wavelength ranges are disjoint, in particular wherein the object light comprises three such wavelength ranges (colors) to cover three primary colors R / G / B. In particular, each wavelength range is wider than 10 nm. The subbands have a width of 3 nm to 6 nm, in particular up to 10 nm.

[0129] The system according to the invention thus allows the recording and reconstruction of digital holograms using broadband object light (variant a). The subbands can be processed independently of one another and subsequently reproduced individually or in combination. An object captured in the hologram exhibits a comparatively high sharpness, particularly when the subbands are processed individually and combined after scaling for each assigned color.

[0130] For example, object light with a spectral width of 30 nm can be resolved by the system into, for example, 5 sub-bands with a width of 6 nm each, which can then be reproduced individually or in combination, or processed as described in a previous embodiment, whereby this is limited to one color, i.e., one wavelength range. Until now, the recording of digital holograms with broadband object light has only been possible sequentially or by spatial separation with color filters.

[0131] Furthermore, the system according to the invention allows the recording and reconstruction of digital holograms with narrowband object light, i.e., in the subband width range, with multiple colors, e.g., narrowband RGB channels (variant b). The subbands can be processed individually and subsequently reproduced individually or in combination, or processed as described in a previous embodiment, whereby the summation across all subbands is omitted.

[0132] For example, object light with three regions in the red, green, and blue spectral ranges, each with a spectral width of up to 3 nm, can be resolved by the system into, for example, three subbands, each with a width of up to 3 nm. These subbands can then be reproduced individually or in combination. This variant can be of interest for applications in which, for example, different laser lines (e.g., 440 nm, 512 nm, 635 nm, 1024 nm) act as object light, with at least some of the laser lines being interpreted as different colors.

[0133] Another possibility is to combine variants a) and b), i.e., recording and reconstructing digital holograms using broadband object light, e.g., with a width of approximately 30 nm to 50 nm, using multiple colors, such as broadband RGB channels. The subbands can be processed individually and then reproduced individually or in combination.

[0134] Here, each of, for example, three spectral ranges, e.g., RGB, with a width of 30 nm, can be resolved into 5 subbands, each with a width of 6 nm, so that a total of 3 * 5 = 15 subbands can be resolved by the system. The subbands can be processed individually and then reproduced individually or in combination, or processed as described in a previous embodiment.

[0135] According to a further embodiment of the invention, the beam splitter comprises a beam splitter cube that includes the beam splitter surface, wherein the beam splitter cube has four faces that are assigned to the first to fourth sides. According to a further embodiment of the invention, the system has a converging lens on the first side, which is configured to collect object light from an object to be recorded and to project it through the first side onto the beam splitter surface.

[0136] In particular, if the object light originates from a focal plane of the converging lens, the converging lens collimates this part of the object light, so that object light from the focal plane hits the reference mirror and the retroreflector array in a collimated state.

[0137] According to another embodiment, the system includes an object light source which is configured to illuminate an object with object light.

[0138] According to another embodiment, the object light source comprises an LED which is configured to emit in a spectral range.

[0139] According to another embodiment, the object light source comprises a plurality of LEDs which are configured to emit in different spectral ranges.

[0140] According to another embodiment, the object light source comprises a plurality of laser sources which are configured to emit in different spectral ranges.

[0141] According to another embodiment, the system comprises one or more spectral filters suitable for filtering out one or more colors from the sunlight spectrum, wherein the filter(s) are arranged on the first side of the beam splitter, so that filtered sunlight serves or can serve as object light.

[0142] According to another embodiment, the system comprises a computer configured to determine object information from the interference pattern for each subband individually and to generate a digital hologram according to one of the preceding embodiments. The computer may include the processor.

[0143] According to a further development of the invention, an arrangement for adjustable focusing of a laser beam onto a target object is disclosed, comprising at least one combination module which has the following components: A first lens system comprising at least or exactly one first lens,

[0144] A 3D camera module arranged and configured to detect incident target object light via the first lens system, wherein the 3D camera module comprises the digital holographic imaging system according to the invention,

[0145] A light extraction module that has an optical fiber output, such as the output of a flexible optical fiber, as a laser light source, and is arranged and configured to extract laser light from the laser light source via the first lens system from the arrangement,

[0146] Beam shaping module arranged and configured to focus laser light from the light extraction module to an adjustable distance, the arrangement further being configured to use camera data from the 3D camera module to adjust the beam shaping module so that the laser light is focused to an adjustable distance, in particular via the first lens system.

[0147] This arrangement allows the distance to a target object to be determined based on the recorded camera data and a laser focus of the laser light to be shifted accordingly along an optical axis of the first lens system, so that the laser focus has a minimal area perpendicular to the direction of propagation of the laser light along an adjustable distance, for example on the target object, and thus a maximum energy density, e.g. #photons / cm² 2 , on which it can be deposited.

[0148] In particular, the combination module is designed to focus laser light emitted by the light source module via the first lens system into the focus zone determined by the 3D camera module.

[0149] The arrangement is therefore designed to determine the required distance using the 3D camera module and to focus the laser light accordingly on that distance, and in particular on a focal point at that distance on a target object. The beam path of the target object light and the laser light can be generally described as follows. In principle, the beam path of the combination module can be divided into a laser beam path and a detection beam path, which overlap at least in the area of ​​the first lens system.

[0150] In the detection beam path, target object light, also referred to as object light in the context of this specification, is captured by the first lens system of the combination module and propagated from the first lens system to the 3D camera module, which generates the camera data. In the laser beam path, the arrangement can emit laser light from the laser light source, for example, from a fiber output of an optical fiber. Typically, the laser beam path contains additional optical elements that act exclusively on the laser light and are therefore not located in a section of the laser beam path that overlaps with the detection beam path. Likewise, the detection beam path can comprise a multitude of optical elements that act solely on the collected object light and are therefore not located in a region of the detection beam path that overlaps with the laser beam path.At one point in the combination module, the detection beam path is superimposed on the laser light beam path, so that the laser light propagates through the first lens system and exits the assembly. This superposition can be achieved by a combining element, for example, a beam splitter, which, depending on wavelength and / or polarization, superimposes the beam paths of the target object light and the laser light.

[0151] Because the arrangement uses the first lens for both the detection of object light and the emission of laser light, a stable system can be provided through appropriate pre-adjustment that can robustly and reliably perform laser light focusing on a target object.

[0152] The beam shaping module comprises at least one adjustable optical element through which the laser light propagates. The optical element can, for example, adjust the wavefronts of the emitted laser light by mechanical adjustment and / or changes in position. A correspondingly positionable focusing lens can achieve this. Alternatively or additionally, the beam shaping module can comprise an electro-optical beam shaping module through whose optical element the laser light propagates, and where the wavefronts can be adjusted based on electro-optically variable properties of the optical element, particularly with respect to their curvature. Such an electro-optical beam shaping module requires no moving components and therefore generally has a faster response time. In particular, the beam shaping module adjusts the curvature of the wavefronts.In conjunction with the first lens system of the combination module, this results in a correspondingly adjustable focus distance of the laser light.

[0153] The arrangement may include a laser that is set up to generate laser light.

[0154] The arrangement can further be configured to feed the generated laser light into an optical fiber and supply it to the light extraction module via the optical fiber, whereby the optical fiber output, i.e. the light source, can be the fiber output of the optical fiber.

[0155] The laser light can be fed in and extracted using appropriate optical components.

[0156] According to a further embodiment of the invention, the arrangement further comprises a processor system, with one or more processors, which is configured to determine a distance to a target object based on the camera data, and wherein the processor system is further configured to transmit beam shaping data to the beam shaping module, which includes information about the distance to be set, and cause the beam shaping module to set the determined distance.

[0157] The processor system can be contained in one or more computers.

[0158] The distance to the target object can be determined, for example, in relation to the combination module or to a reference point in the combination module.

[0159] The camera data can, for example, include information about a three-dimensional image of the target object, and a distance value corresponding to the distance of the target object can also be determined from or is included in the camera data. The processor system is configured to evaluate the camera data to determine the distance to be set and to transmit beam shaping data to the beam shaping module, which then instructs the beam shaping module to set the distance to be set.

[0160] The processor system can include one or more non-transitory data stores in which the camera data and beamforming data are stored and from which the data can be retrieved.

[0161] According to a further embodiment of the invention, the arrangement is configured to receive target object light via the input aperture and to superimpose target object light reflected from the reference mirror and from the retroreflector array, so that interference patterns are created which can each be assigned to one of the retroreflector elements and wherein the array detector is arranged to detect the interference patterns, in particular to generate camera data and to transmit them to the processor system.

[0162] The 3D camera module, which incorporates such a digital holographic unit, is particularly compact and extremely robust, as it contains no moving parts. Furthermore, compared to other 3D imaging cameras, this module is significantly lighter, which is especially advantageous for various applications, such as equipping aircraft or other vehicles.

[0163] The arrangement can further be configured to determine a large number of images of the object space from the recording, wherein the focal planes assigned to the images are located at at least two or more different positions along the optical axis, and wherein the positions of the focal planes can be adjusted by appropriate evaluation of the holograms.

[0164] The first lens system, and in particular a magnifying optic comprising the first lens system, is configured to propagate light incident on the first lens system at an input angle to the beam splitter at an output angle, wherein the output angle is, in particular, significantly larger than the input angle, for example, at least five, ten, or more than ten times. Through the first lens system, and in particular through the magnifying optic, the arrangement captures a spatial volume along the optical axis. The wavefronts of the collected object light carry information about the entire captured spatial volume and are encompassed and captured in the form of the interference pattern attributable to a respective retroreflector element.

[0165] Through appropriate evaluation, it is now possible, in contrast to spatially operating imaging systems that project an image of an object directly onto the detector, such as cameras with zoom lenses, to define a focal plane in which a reconstruction of an image is to be or is to take place based on the interference patterns, so that this reconstructed image corresponds to an image that was set, i.e., focused on this focal plane, using a system operating in spatial space.

[0166] Moreover, the information in the interference patterns can now be used to simultaneously or alternatively reconstruct an image corresponding to a different focal plane, completely without mechanical refocusing.

[0167] This arrangement allows, similar to a wave field camera that operates in spatial space, the focal plane to be shifted or determined after the recording.

[0168] Furthermore, the arrangement does not require corrected optics, as aberrations or lens errors are compensated for due to the comparatively small apertures of the retroreflector elements, so that the arrangement is also improved in terms of size and complexity compared to systems operating in real space.

[0169] The inventor recognized that combining the system for digital holographic imaging, especially with a magnification optic at the entrance aperture, provides significant advantages in the field of zoom imaging that are not immediately obvious.

[0170] The apparent disadvantage that three-dimensional reconstruction of surfaces, for which such systems are typically used, is lost with distant objects, but can be "replaced" by focal plane selectivity, thus offering the aforementioned advantages compared to zoom systems operating in spatial space, is overcome by the invention. The arrangement according to the invention is therefore able to shift the focal plane with respect to which an image is to be generated along the optical axis of the arrangement by appropriately evaluating the interference patterns in a single image through algorithmic adaptations during the evaluation process.

[0171] According to a further embodiment of the invention, the arrangement has a magnifying optic in which the first lens system is included.

[0172] In particular, the magnifying optics have a magnification factor of more than five, especially more than ten, which corresponds in particular to a zoom range within the meaning of the invention.

[0173] In particular, the focal length(s) of the optics at the entrance aperture of the beam splitter is / are fixed.

[0174] According to a further embodiment of the invention, the magnifying optics comprises the first lens system with a first focal length ^ and a second lens system with a second focal length f2, wherein the first focal length is greater in magnitude than the second focal length.

[0175] A lens system according to the invention is an arrangement comprising at least one lens. In the lens system, one or more lenses can be arranged at predefined distances from each other, in particular forming an objective lens.

[0176] In particular, the lens systems each have a fixed focal length and are arranged at a fixed distance from each other.

[0177] According to another embodiment of the invention, the magnifying optics consist of the first and the second lens system.

[0178] According to a further embodiment of the invention, the first lens system comprises exactly one first lens.

[0179] The term "lens" in the context of this specification includes, in particular, composite lenses made up of several lens elements, such as achromats and apochromats, but also lenses made of only one material. Specifically, according to the specification, the lens has no air gap along the optical axis, even if it is made up of several lens elements.

[0180] This embodiment enables a particularly robust and simple implementation of the invention, without significantly impairing the image quality of a reconstructed image due to aberrations inherent in simple lenses (edge ​​effects, chromatic and spherical aberrations). An arrangement with only a first lens system can be built particularly compactly and lightweight.

[0181] In particular, the magnifying optics consist of a first lens and a second lens system comprising one or more lenses.

[0182] According to a further embodiment of the invention, the second lens system comprises a second lens, in particular exactly one second lens.

[0183] According to a further embodiment of the invention, the optics, in particular the magnifying optics, consist of the first lens and the second lens system, in particular the second lens. This embodiment allows for a particularly compact and lightweight design of the system.

[0184] An arrangement in which the second lens system comprises several lenses and the first lens system comprises only one lens can exhibit a particularly advantageous compromise between compactness, lightness, and optical imaging quality.

[0185] According to another embodiment of the invention, the first lens is a convex lens and the second lens is a concave lens.

[0186] According to a further embodiment of the invention, the optics, in particular the magnifying optics, comprise a fixed focal length ratio.

[0187] In particular, the focal length or magnification ratio is determined from the first and second focal lengths to — : Such an optic can therefore be designed in particular as a rigid, unchanging optic that does not allow any change in the focal length(s), at least as far as the detection side, i.e. the 3D camera module, is concerned.

[0188] Such an arrangement can be understood as an adaptive zoom system for digital holographic imaging with fixed magnification optics.

[0189] In this context, adaptive means that the focal plane, as far as the detection side is concerned, can be shifted without mechanical changes to the distance between lenses, solely through appropriate algorithmic evaluation, thus also allowing focusing on multiple planes.

[0190] According to a further embodiment of the invention, the components of the magnifying optics are fixedly spaced apart from each other.

[0191] According to a further embodiment of the invention, the magnifying optics have a preset, unchanging focal length.

[0192] According to a further embodiment of the invention, the beam shaping module comprises an electro-optical beam shaping module which is arranged to modify wavefronts of the laser light in such a way that the laser light is focused to the adjustable distance and / or a propagation direction of the laser light is adapted.

[0193] In particular, the electro-optic beam shaping module is arranged in such a way that the laser light propagates through it, i.e., it is a transmissive electro-optic beam shaping module.

[0194] This embodiment has the advantage that a device can be used to focus the laser light or to perform beam steering (i.e., to deflect the propagation direction of the laser light from the optical axis of the first lens system) without any elements that would need to be moved to adjust the focus or perform beam steering. Furthermore, electro-optical beam shaping modules have shorter response times compared to mechanical elements and can be used, in particular, to compensate for beam aberrations. The beam shaping module is arranged downstream of the laser light source in the propagation direction and is encompassed by the light extraction module. Thus, the beam shaping module lies entirely within the laser beam path. The beam shaping module can be arranged in transmission or reflection.

[0195] According to a further embodiment of the invention, the electro-optical beam shaping module is designed to be transmissive or reflective.

[0196] A reflective design favors a compact construction, while a transmissive variant is easier to implement.

[0197] According to a further embodiment of the invention, the electro-optic beam shaping module has a plurality of electro-optic elements whose optical properties, such as the refractive index, are variable, whereby the wavefronts of the laser light can be changed so that the laser light is focused at the adjustable distance and / or the propagation direction of the laser light is adapted.

[0198] The electro-optical elements can be arranged in layers, which are also referred to as layers in this specification, with each layer being set up for an aspect of wavefront deformation or wavefront matching.

[0199] A third first layer can be configured to adjust the wavefronts, and in particular the phases of the laser light, so that the individual segmentally generated phases are continuous at the transitions to adjacent segments. In this way, sidebands can be avoided when focusing the laser light, thus preventing a broadening of the focal point due to secondary maxima. This first layer is particularly located on a side of the beam shaping module facing the incident side of the laser light.

[0200] A second layer can be configured to deflect the propagation direction segment by segment along a first axis perpendicular to the optical axis. For each segment, i.e., each electro-optical element, a tilt angle of the propagation direction can be set over a defined range. A third layer can be configured to deflect the propagation direction along a second axis perpendicular to the optical axis. All or selected layers can be configured to compensate for aberrations in order to generate the smallest possible laser focus at the set distance.

[0201] If the electro-optic element is very small, for example in the range of a few micrometers (1 pm to 50 pm), the electro-optic beamforming module can have only one layer of electro-optic elements, with only an absolute phase being adjusted. However, in this configuration, approximately 1000 segments should be present across an aperture of, for example, 5 mm. With a three-layer electro-optic beamforming module, and considering that phase ramps can also be adjusted within an electro-optic element, the number of electro-optic elements across the aperture (e.g., 5 mm) drops drastically to, for example, 10–20 elements. The number of controlled electro-optic elements is therefore significantly lower.

[0202] According to a further embodiment of the invention, the electro-optic beam shaping module has three layers, each with several electro-optic elements, wherein a first layer is configured to increase or decrease a wavefront curvature so that the laser light is focused to the distance to be set, wherein a second and a third layer are each configured to deflect laser light in different directions, in particular perpendicular to each other, so that a laser light focus at the distance to be set is shifted laterally, i.e. with respect to the optical axis of the first lens system.

[0203] According to this embodiment, the second layer is configured, for example, to deflect the laser light by a first angle along a first direction, while the third layer is configured to deflect the laser light by a second angle along a second direction. The first and second angles are independently adjustable.

[0204] According to a further embodiment of the invention, the plurality of electro-optic elements can be controlled individually and independently of one another, wherein the beam shaping module is configured to impose a phase change, in particular a linearly increasing or decreasing phase change, on the laser light along a layer of electro-optic elements or to adjust the phase of the laser light individually in each electro-optic element.

[0205] According to a further embodiment of the invention, the combination module comprises a housing, in particular a spherical housing, which at least partially encloses the components, wherein the system includes an optical fiber configured to guide the laser light from a laser outside the housing to the light extraction module. The fiber can also be polarization-preserving.

[0206] According to a further embodiment of the invention, the arrangement comprises a laser for generating the laser light, in particular wherein the laser is arranged outside the housing and in particular is not rotatably mounted via the 2-axis gimbal, but is connected to the light extraction module by means of an optical fiber.

[0207] Furthermore, for the purposes of this specification, a distinction is made between a laser light source, which merely comprises an exit area of ​​laser light from the fiber output of an optical fiber, but not necessarily, and a laser light generating unit, such as the laser, which is therefore not necessarily defined as belonging to the laser light source.

[0208] The arrangement may further provide a power supply for the combination module, which is designed to supply the combination module with energy from a power source, such as a battery, located outside the housing, via a supply line that is at least partially flexible.

[0209] The arrangement can further include a data line for the combination module, configured to transmit data to the combination module, e.g., beam shaping data and / or beam steering data, or to transport data from the combination module. The data line is specifically connected to the processor system, which is located at least partially outside the housing. The data line is preferably an optical fiber, as this allows for the transmission of large amounts of data while maintaining high flexibility. Alternatively, data can also be transmitted wirelessly from the housing to the processor system.

[0210] This embodiment allows for a lightweight construction of the combination module, as it includes only essential optical components for detecting the object light and focusing the laser light. The housing can be movably mounted on a support structure.

[0211] According to a further embodiment of the invention, the arrangement has a 2-axis gimbal on which the housing is rotatably mounted such that the housing and thus the combination module can be rotated about two axes.

[0212] The 2-axis gimbal is attached to a support structure relative to which the housing can rotate.

[0213] The rotation axes of the 2-axis gimbal, and thus the rotation axes of the housing, correspond in particular to a pitch axis and a yaw axis with respect to the optical axis of the first lens system, which points in the direction of a roll axis.

[0214] This embodiment benefits considerably from a small and compact combination module, as the gimbal specification can be more generously dimensioned, energy consumption for rotation is kept low, and the reaction time for rotating the housing is also reduced the lighter the combination module and the housing are.

[0215] According to a further embodiment of the invention, the arrangement comprises one or more 2D cameras, each 2D camera having a field of view that is larger than that of the 3D camera module and that overlaps at least partially or completely with a field of view of the 3D camera.

[0216] However, to obtain a "rough" impression of the surroundings, the 2D cameras are sufficient; the 3D camera module, in conjunction with the [unclear text], delivers high detail.

[0217] According to a further embodiment of the invention, the arrangement comprises an aircraft, such as an unmanned aerial vehicle (UAV) like a multicopter, which includes the combination module and a laser connected to the combination module. The aircraft can be understood as a support structure for the 2-axis gimbal. This allows the combination module to be oriented relative to the aircraft in two axes.

[0218] This embodiment can be implemented as a mobile, in particular flying, optical weapon system. Such an optical weapon system comprises a laser with a specific minimum power, wherein the optics of the combination module, in particular the first lens system and, if applicable, a magnifying optic, are configured to generate a laser focus at a set distance, so that the laser power can be dissipated onto a target object over the area of ​​the laser focus. This allows the target object to be damaged by the delivered laser energy.

[0219] According to the invention, it is particularly provided that the arrangement is configured so that the laser focus at the set distance is within an area of ​​no more than 10 mm. 2 , especially of less than 5 mm 2, encompassing more than 50% of the total intensity, and the corresponding remaining intensity outside this area. In other words, the laser focus is limited to an area of ​​less than 10 mm. 2 , especially less than 5 mm 2 .

[0220] Due to the comparatively concentrated laser focus and the possibility of positioning the laser focus three-dimensionally with high precision with respect to distance via beam steering, the arrangement can operate with lower laser powers than conventional systems that generate focus sizes of 100 mm2 or more.

[0221] The setup is so light and compact that it can be housed in simple multicopters.

[0222] According to a further embodiment of the invention, the arrangement comprises a portable device, which can, for example, be designed as a handheld support structure or mounted on a helmet. The combination module is connected to the portable device via the 2-axis gimbal, in particular wherein a power supply, the processor system and / or the laser are housed in one or more modules connected to the portable device. The modularity of the arrangement allows for flexible, transportable use of the arrangement.

[0223] According to a further embodiment of the invention, the light extraction module comprises a collimation lens.

[0224] According to a further embodiment of the invention, the laser of the arrangement has an optical output power of at least 100W and / or at most 1kW- 5kW.

[0225] Description of the quillon and exemplary implementation forms

[0226] Further features and advantages of the invention are explained below with reference to the description of exemplary embodiments in the figures. These show:

[0227] Fig. 1 shows a first exemplary embodiment of the invention with a plurality of dispersion elements;

[0228] Fig. 2 shows a second exemplary embodiment of the invention with a plurality of dispersion elements;

[0229] Fig. 3 shows a second exemplary embodiment of the invention with a single dispersion element;

[0230] Fig. 4 shows a third exemplary embodiment of the invention without dispersion elements;

[0231] Fig. 5 shows an exemplary embodiment of the invention with layered system mirrors;

[0232] Fig. 6 shows an exemplary embodiment of the invention with layer system mirrors also in the reference mirror;

[0233] Fig. 7 shows a schematic representation of different optical path lengths in Bragg mirrors for different subbands;

[0234] Fig. 8 shows a schematic representation of the imposed wavelength-dependent phase relations for two different retroreflector elements. Fig. 9 shows a schematic representation of a first variant of an arrangement according to the invention, with a light extraction module, a beam shaping module, and magnification optics; and

[0235] Fig. 10 shows a schematic representation of a first variant of an arrangement according to the invention, with light extraction module, beam shaping module and magnification optics.

[0236] Fig. 1 shows a schematic representation of a first embodiment of the system 1 according to the invention.

[0237] System 1 comprises a beam splitter 2, here in the form of a beam splitter cube. The beam splitter cube 2 has four sides. A first side 21 is assigned to an entrance aperture, on which a converging lens 7 is arranged, which collects object light 100 originating from an object 200 to be examined.

[0238] The object light 100, provided it originates from a focal plane of the converging lens 7, is collimated by the converging lens 7. Object light 100 that does not originate from the focal plane is accordingly convergent or divergent.

[0239] The object light 100 propagates from the lens 7 to a beam splitter surface 2a of the beam splitter 2. The beam splitter surface 2a is oriented such that it reflects a portion of the object light 100 originating from the first side 21 of the beam splitter 2 towards a second side 22 of the beam splitter 2 and transmits another portion of the object light 100 along a third side 23 of the beam splitter 2. The second side 22 extends adjacent to the first side 21 on the beam splitter cube. The third side 23 is arranged opposite the first side 21 and extends adjacent to the second side 22.

[0240] Opposite the second side 22, a fourth side 24 of the beam splitter 2 extends. Each side of the beam splitter 2 defines a plane. The planes assigned to the adjacent sides extend at an angle of 90° to each other.

[0241] The beam splitter surface 2a forms a 45° angle with these planes. Each side, together with the beam splitter surface 2a, defines an associated arm that designates a beam path between the beam splitter surface and the respective side.

[0242] In the example of Fig. 1, a retroreflector array 3 is arranged on the second side 22 of the beam splitter 2 and a reference mirror 4 is arranged on the third side 23 of the beam splitter 2.

[0243] Alternatively, the retroreflector array 3 can be arranged on the third side 23 and the reference mirror 4 can be arranged on the second side 22. This variant is shown in Fig. 2, which is otherwise completely identical to Fig. 1. This interchange of the sides of the retroreflector array and the reference mirror is possible for every embodiment of the system 1 and is hereby explicitly disclosed.

[0244] The retroreflector array 3 comprises a plurality of retroreflector elements 30, each retroreflector element 30 comprising a lens 31 and an associated retroreflector mirror 32. In particular, the retroreflector mirrors 32 are arranged in a focal plane of the associated lens 31.

[0245] Each retroreflector element 30 is configured such that incident object light 100 is reflected back along the axis of incidence; that is, the object light is reflected along the same direction from which it strikes the retroreflector element. One can therefore say that the angle of incidence corresponds to the negative angle of reflection.

[0246] The beam path for object light 100, which essentially travels along the optical axis OA via the first side 21 onto the beam splitter 2, thus causes the object light 100 to pass on the second side 22 via the retroreflector array (Fig.

[0247] 1) or the reference mirror 4 (Fig. 2) is reflected towards the fourth side 4. At the same time, the object light 100 is reflected on the third side 23 via the

[0248] Reference mirror 4 (Fig. 1) or the retroreflector array 3 (Fig. 2) also reflects in the direction of the fourth side 24.

[0249] To minimize losses during passage through the beam splitter surface 2a, the object light 100 can undergo corresponding polarization reversals on the second and third sides, and the beam splitter surface can be designed to be polarization-dependent. This is known to those skilled in the art. Lambda-quarter plates at corresponding locations in the beam path can effect these polarization reversals. However, for the sake of simplicity, corresponding polarization elements are not shown, as they are not essential to the invention.

[0250] On page 24, the object light 100 from the second and third arms of the beam splitter 2 overlaps, resulting in interference. This interference produces an interference pattern on page 24 that provides information about the object 200 under investigation. The interference pattern is detected by an array detector 8 on page 24 and recorded as data.

[0251] The array detector 8 can be a digital monochrome camera.

[0252] The array detector 8 is connected to a computer 9, to which the data is transferred. The computer 9 is or includes an evaluation unit that is configured to reconstruct a structure of the object 200 under investigation from the interference pattern.

[0253] The invention relates to a particular configuration of system 1, such that the reconstruction for a plurality of subbands 100-1, 100-2, 100-3 of the object light 100 can be determined separately. That is, the invention makes it possible to determine color information about the object 200 in addition to the pure structural information. Due to the separate evaluation of the subbands, a calculated digital hologram exhibits no or only very minor losses in spatial sharpness. This is made possible by the separate evaluation of the subbands, since the interference information assigned to the subband can be scaled, thus resolving the similarity of the color and spatial information in the interference pattern. Subsequently, each subband can be assigned a color encompassing that subband, and a color-resolved digital hologram can be output.

[0254] How it is achieved that the sub-bands can be evaluated individually and independently of each other, and thus the similarity of the coloring and spatial information in the interference pattern is eliminated, will be explained in the following paragraphs for some exemplary implementations.

[0255] In Figures 1 and 2, a dispersion element 5 is positioned in front of each retroreflector element 30. That is, a dispersion element 5 is arranged in front of each lens 31 of a retroreflector element 30. Each dispersion element 5 is configured to impose wavelength-dependent phase shifts on the object light. This means, for example, that a first subband 100-1 of the object light experiences a phase delay relative to a second subband 100-2 of the object light, while the second subband 100-2 also experiences a phase delay relative to a third subband 100-3 of the object light. It should be noted that each subband 100-1, 100-2, 100-3 is assigned a central wavelength to which this phase delay refers.In this embodiment, each wavelength in the subband also experiences a phase delay. However, this phase delay within the subband is not taken into account during subsequent evaluation; typically, only the phase delay of the central wavelength is used for evaluation. This has only a marginal impact on the quality of the reconstructed hologram.

[0256] Each dispersion element 5 is now additionally set up so that the phase shifts of the subbands 100-1 , 100-2 , 100-3 are of different magnitudes for each retroreflector element 30.

[0257] That is, the dispersion elements 5 differ with respect to their wavelength-dependent phase delays.

[0258] This means that system 1 is set up to impose wavelength-dependent phase shifts on the object light 100 for each retroreflector element 30, which are different for each retroreflector element 30.

[0259] These wavelength-dependent phase shifts generate an interference pattern on page 24, which—provided the wavelength-dependent phase shifts for each retroreflector element are known—allows a reconstruction in which each subband can be resolved individually; that is, wavelength-dependent information can be extracted from the interference pattern. Due to the described design of the dispersion elements 5, the subband information is phase-encoded in the object light 100.

[0260] The term subband refers in particular to a narrowband

[0261] Wavelength range, for example, with a width of 0.5 nm to 10 nm. The subbands differ in the wavelengths they encompass. Typically, a subband is between 3 nm and 6 nm wide.

[0262] Regarding the phase shifts, the following should be added and explained:

[0263] The phase shifts that lead to the interference pattern on page 24 are phase shifts resulting from the phase relationship of the object light 100 from the second and third arms. The wavelength-dependent phase shifts caused by the dispersion elements 5 can therefore be specified, on the one hand, as a relative phase shift of the different subbands of the object light per retroreflector element 30, and on the other hand, as the phase shift of the individual subbands from the second and third arms, which is shown on page 24. The latter is essential for the shape of the interference pattern; however, the relative and differing phase positions of the individual subbands are primarily determined by the dispersion elements 5 and are further propagated by superposition with the object light 100 on page 24.

[0264] It is advantageous if the retroreflector array 3, including the dispersion elements 5, and / or the reference mirror 4 can be aligned or adjusted relative to each other. For this purpose, a corresponding actuator 6 is shown in Fig. 1, which is configured to set an angle and / or a distance between the retroreflector array 3 and the reference mirror 4. The actuator 6 can alternatively also be arranged on the reference mirror 4. It can be advantageous to assign an actuator to both the retroreflector array 3 and the reference mirror 4, so that they can be adjusted independently of each other (not shown). The actuators, and in particular the actuator system comprising the actuators, make it possible to reduce or eliminate the twin image and also the DC light by appropriately positioning the retroreflector array and / or the reference mirror.

[0265] In particular, each dispersion element 5 can consist of two (or more) different glasses 51, 52 (also referred to as layer elements in this specification), each exhibiting a different Abbe number. Depending on the design requirements, it may be advantageous for the glasses 51, 52 to have a refractive index as identical as possible in the green wavelength range (-535 nm). By selecting different thicknesses of the two glasses 51, 52 relative to each other, a resulting phase relationship can be set for each dispersion element 5 as a function of wavelength.

[0266] For example, the following glasses with nd = 1.62 have the same refractive index but different Abbe numbers, i.e., different dispersions: A glass consisting of N-F2 with an Abbe number Ai = 36.4 has a higher dispersion than a glass consisting of N-SSK8 with an Abbe number A2 = 49.8. Over the wavelength range of 170 nm (blue → red), this results in a refractive index difference of Am = 17*10⁻⁶ for Ai. -3 while for A2 the refractive index difference of An2 = 12*10' 3 This results in the difference between these refractive index differences – now denoted by the term refractive index delta – of An 170 = 5*10 -3 (for a wavelength spacing of 170 nm) for example, a refractive index delta of An = 3*10 can be calculated for a waveband spacing of 10 nm. -4The thickness can be calculated down. To estimate the necessary total thickness, assuming that only one or the other type of glass predominates in the externally arranged retroreflector elements, the following relationship for the thickness d of the dispersion element is valid when considering the double beam passage in the reflection arrangement, provided a phase shift of 2TT is assumed, which corresponds exactly to the displacement of an optical wave. Then the following applies:

[0267] For a wavelength n At 588 nm, a thickness d = 1 mm is required for the 2TT phase over the 10 nm wavelength band (see above). This is the extreme case achievable for the double lens under the above conditions. If, for example, only the TT phase is to be adjusted over 10 nm, both lenses would have to be approximately the same thickness, i.e., 0.5 mm each.

[0268] In this way, the dispersion elements 5 can be designed according to the requirements of the system.

[0269] The following section focuses primarily on the differences between the embodiments and the preceding embodiments, avoiding the repetition and redundant description of identical elements, components, or arrangements. These components are considered to be transferable unchanged or substantially unchanged from the previous embodiments.

[0270] Fig. 3 shows an alternative embodiment of the invention, which is essentially based on the same inventive concept as the system in Figs. 1 and 2.

[0271] Instead of assigning individual discrete dispersion elements 5 to each retroreflector element, a single dispersion element 5' can be used that extends over the entire retroreflector array 3. In this example, a dispersion element 5' is represented as a double wedge plate, where the wedges 51', 52' have different Abbe numbers.

[0272] As a result, the object light experiences 100 wavelength-dependent phase shifts, which are different for each retroreflector element 30 and therefore also produce the inventive effect.

[0273] It is noted that the wedges 5T, 52' also extend along a direction into the cross-sectional plane, wherein the wedges 5T, 52' are shaped in particular such that as many retroreflector elements 30 of the retroreflector array 3 as possible impose wavelength-dependent phase relations on the object light 100, which are different from one another. Retroreflector elements 30 of the retroreflector array 3 which impose the same phase relations on the object light 100 are redundant. This redundancy can be eliminated by tilting the reference mirror 4 with respect to the optical axis.

[0274] In the embodiments shown in Figures 1 and 2, it is possible that each retroreflector element 30 of the retroreflector array 3 imposes wavelength-dependent phase relations on the object light 100, which are different for each retroreflector element 30.

[0275] In Fig. 4, instead of one or more dispersion elements, the retroreflector array 3 is tilted at an angle 8 relative to the beam splitter surface 2a and, in particular, the reference mirror 4, so that the retroreflector elements 30 exhibit wavelength-dependent phase shifts due to their different optical path lengths. These phase shifts vary for a plurality of retroreflector elements 30. An actuator system 6, which may include one or more piezoelectric actuators, can be used to adjust the angle 6.

[0276] The actuators, and in particular the actuator system comprising the actuators, make it possible to reduce or eliminate the twin image and also the DC light by appropriately positioning the retroreflector array and / or the reference mirror.

[0277] As already explained in relation to Fig. 3, redundancies in the phase relations imposed by the retroreflector elements 30 may occur in this embodiment, since not all retroreflector elements may have different optical path lengths.

[0278] The angle 8 is comparatively small. It can be advantageous if the reference mirror 4 also includes an angle relative to the optical axis, especially an adjustable one.

[0279] Fig. 5 schematically shows an embodiment of the invention which effects the phase coding of the sub-bands using the retroreflector mirrors 32.

[0280] For this purpose, each retroreflector mirror 32 of a retroreflector element 30 is designed as a layer system mirror 320. Each layer system mirror 320 comprises a plurality of reflective layers 32-1, 32-2, 32-3, each reflective layer being configured to reflect object light 100 from a predefined subband 100-1, 100-2, 100-3 assigned to the respective reflective layer.

[0281] That is, the reflective layers are semi-transparent. The reflective layers are arranged in the layer system mirror 320 such that object light 100 from different subbands is reflected with a phase predefined for the respective retroreflector element 30. That is, the object light 100 travels a subband-dependent optical path length from entry into to exit from each layer system mirror 320, so that the layer system mirror 320 imposes a wavelength-dependent, in this case subband-dependent, phase relation on the reflected object light 100. For each retroreflector element 30, the layer system mirrors 320 contained therein are now designed such that a different phase relation is imposed on the object light 100 for a plurality of retroreflector elements 30, in particular for each retroreflector element 30.

[0282] The reflective layers 32-1,32-2,32-3 can be configured as Bragg mirrors, so that a layer system mirror 320 comprises a plurality of Bragg mirrors.

[0283] A Bragg mirror comprises a multitude of alternating dielectric thin layers (see magnification box in Fig. 5, depicted using dashed lines representing the reflection layers) with low and high refractive indices. The reflectivity for a particular wavelength is especially high when the layers have an optical thickness of one-quarter of the wavelength. Thus, by using a multitude of Bragg mirrors, the retroreflector mirror 32 can be made to reflect a multitude of wavelengths in a subband-specific manner, with a predefined phase.

[0284] It is possible to nest individual Bragg mirrors to a certain extent in order to minimize the installation space.

[0285] Figure 6 shows another embodiment in which the reference mirror 4 is also designed as a layered system mirror 40. In particular, the reference mirror also includes a plurality of Bragg mirrors. This allows the reference mirror 4 to impose wavelength-dependent, especially subband-dependent, phase relations on the object light 100. This can be advantageous in order to compensate for phase shifts that are too large due to the required installation space for the layered system mirrors 320 on the side of the retroreflector array 3, and to better meet the matching condition based on the coherence length. This is illustrated by way of example in Figure 7.

[0286] In Fig. 7, Panel A) shows exemplary optical path lengths for three subbands 100-1, 100-2, 100-3 in a retroreflector element 30. Panel B) shows exemplary optical path lengths for the same subbands 100-1, 100-2, 100-3 at the reference mirror 40, which, like the retroreflector element 30, is designed as a layered mirror 40. Each layer 32-1, 32-2, 32-3 (and 40-1, 40-2, 40-3) of the layered mirror 320, 40 acts as a wavelength-selective filter, reflecting a first subband 100-1 but transmitting a second and a third subband 100-2, 100-3. The second subband 100-2 is reflected by a second layer 32-2, 40-2 with a first optical separation from the first layer 32-1, 40-1, and the third subband 100-3 is transmitted. The third subband 100-3 is reflected by a third layer 32-3, 40-3, which has a second optical separation from the second layer 32-1, 40-2.

[0287] The diagram shows nearly identical layered mirror systems in the reference arm (comprising reference mirror 40) and in the object arm (comprising retroreflector mirror 320; a layered mirror system 320 of a retroreflector element is shown). In the object arm, greatly exaggerated distances between the individual layers are depicted. These additional path lengths As n (n= 2,3) move on the order of + / - 1 wavelength. This distance together with the wavelength then results in a phase. <P n = 2 / n ■ As n . In this embodiment, the phase coding has a phase range (0 ... 2TT).

[0288] Multiples of these can always be "mapped" to this phase range up to 2TT, which is generally known to experts.

[0289] Figure 8 shows an exemplary phase encoding for a multitude of subbands for two different retroreflector elements of a retroreflector array.

[0290] A first retroreflector element 30 of the retroreflector array 3 (panel A) imprints a phase of, for example, TT / 4 on each subband 100-1, 100-2, 100-3, so that the subbands have a first linear phase relationship, especially with respect to the central wavelengths of the subbands.

[0291] A second retroreflector element 30 of the retroreflector array 3 (panel B) imposes a phase of, for example, TT / 3 on the same subbands, so that the subbands have a second linear phase relationship, particularly with respect to the central wavelengths of the subbands.

[0292] The linear phase relationships are particularly advantageous because they are based on the idea of ​​the spectral Fourier transform.

[0293] In principle, it is possible to impose other phase relationships, including non-linear and / or irregular phase relationships, even statistically random ones. It is important that these phase relationships are known for each retroreflector element of the retroreflector array, which can be achieved, for example, by targeted measurements of the retroreflector elements.

[0294] The invention makes it possible to reconstruct digital holograms that are recorded with object light which is broadband, multicolored or both, wherein the recording of the object can take place simultaneously in all wavelength ranges of the object light and the reconstruction makes it possible to resolve the similarity of the spatial and color information in the interference pattern by phase coding of the subbands of the object light, which enables an improved, in particular sharper, holographic reconstruction of the recorded object over a wide wavelength range and multiple colors.

[0295] Fig. 9 now describes an arrangement 1000 for adjustable focusing of a laser beam on a target object 200.

[0296] The arrangement 1000 comprises a combination module 1-1 which includes the following components:

[0297] A light extraction module 60, comprising a laser light source 61 here in the form of a fiber output of an optical fiber 92,

[0298] A beam shaping module 80 for focusing and beam steering the laser light 300 onto a target point T at an adjustable distance A,

[0299] A 3D camera module 81 for capturing three-dimensional image data of a target object 200;

[0300] A magnifying optic 70 comprising a first, a second and a third lens system 71 , 72, 73.

[0301] The combination module 1-1 has an essentially spherical housing 94 in which these components are arranged. The housing 94 is rotatably mounted in a 2-axis gimbal (not shown) and can be rotated about two mutually perpendicular axes 93-1 and 93-2 (the direction of rotation is indicated by the curved arrows), which form a plane perpendicular to the optical axis OA. A first axis of rotation 93-1 is shown; the second axis of rotation 93-2 runs perpendicular to the plane of the figure and is only indicated by a black dot. The optical fiber 92, e.g., a single-mode fiber, can be guided from outside the housing 94 to the light extraction module 60 via the axis of rotation 93-1 or 93-2 of the housing 94, so that a laser 91, which can generate the laser light, can be arranged outside the housing 94. The laser light can be transported to the light extraction module 60 via the optical fiber 92.In principle, the optical fiber 92 can be implemented using a light guide which can be inflexible in some areas and flexible in others.

[0302] Similarly, a data and power supply 95 can be connected to the 3D camera module 81 via one of the rotary axes 93-1, 93-2. The light extraction module 60, in particular the beam shaping module 80, can also be supplied with power.

[0303] Data can be supplied via a data line 95, which is designed as a light guide, for example as an optical fiber.

[0304] Due to the small number of components, the 1-1 combination module can be designed to be very lightweight and compact.

[0305] In this example, the combination module 1-1 further includes - optionally - two 2D cameras 90, which are arranged so that they can take a wide-angle shot of the object space, in particular where the section of space captured by the two 2D cameras 90 overlaps with a field of view of the magnifying optics.

[0306] The 2D cameras 90 cover, in their peripheral areas, just the forward direction along the optical axis of the first lens system 71, but also a large area around it. Thus, depending on the orientation of the combination module 1-1 (by means of the rotation mechanism of the 2-axis gimbal), an extended spatial area can be captured. Additional 2D cameras (outside the image plane, not shown) can be mounted on the housing 94.

[0307] These wide-angle cameras 90 have the specific task of capturing the extended spatial area in order to then, using the described zoom arrangement 81, 70, identify details in the center of this spatial area around the optical axis. These details then have the high optical magnification. System 1 can rotate the 2-axis gimbal and thus the magnifying optics 70 by means of a control unit (not shown) and thereby adjust and stabilize the spatial section from which a three-dimensional image is to be created.

[0308] The light extraction module 60 comprises, in addition to the fiber output 61 (i.e., the laser light source), a collimation lens 62, which collimates the laser light 300 at least approximately. The collimated laser light 300 then propagates through the beam shaping module 80, which in this embodiment is included in the light extraction module 60.

[0309] The beam shaping module 80 is designed to adjust the wavefronts of the laser light 300 so that the laser light 300 is focused at a configurable distance A and, in particular, also in a configurable direction. This allows the arrangement 1000 to generate a precisely targeted, three-dimensional laser focus T with minimal area and to adjust it dynamically with very low latency.

[0310] The beam shaping module 80 features, in particular, an electro-optic beam shaping module that can adjust the wavefronts by means of electro-optically adjustable elements. The aim is a diffraction-limited focus spot on an object 200.

[0311] This has the advantage of very low latency. Furthermore, it eliminates the need for moving components that would have to be moved to adjust the laser focus T.

[0312] The manipulated laser light 300 propagates from the beam shaping module 80 via the combining element in the form of a chromatic beam splitter 74 to the second lens system 72, which in this example consists of a single diverging lens (concave lens), thus significantly increasing the beam diameter. The divergent laser light then strikes the first lens system 71, which—together with the second lens system 72 and the beam shaping module 80—causes the diffraction-limited focusing of the laser light 300 onto the focal point T at the set distance A and corresponding lateral position with respect to the optical axis OA. After leaving the arrangement 1000, the laser light 300 propagates further to the set focal point T, where it can strike the target object 200.

[0313] To generate the focal point T of the laser light 300 as close as possible to the diffraction limit, i.e., to keep it as small as possible, single lenses are generally not the right choice. Multiple lens systems in the area of ​​lens 71 are more suitable, but contribute to increased weight and space requirements. A non-mechanical electro-optical beam shaping module 80, as described previously, is better suited. When correctly positioned, the collimated laser beams point parallel to the optical axis at a common object point far away from the system; for example, at distances of 30 meters, 100 meters, or even 1000 meters.

[0314] Since a diffraction-limited effect is not expected with a simple lens system, the beam shaping module 60 is specifically designed to compensate for wavefront errors, i.e., to perform aberration correction, which leads to a smaller focal point T.

[0315] It is clear at this point that the second diverging lens 72 for the light extraction module 60 need not consist of just one element, but can also contain several lenses, since the small diameter contributes hardly to the overall weight. To this extent, the physical wavefront compensation in the beam shaping module 80 can be simplified.

[0316] The described beam path corresponds to a laser beam path that overlaps with a detection beam path between the combining element 74 and the first lens system 71.

[0317] The laser light 300 can have a wavelength in the near-infrared, making it invisible to the human eye.

[0318] The laser 91 should in particular be configured so that it emits laser light on average with an energy of at least 100 W - preferably 1 kW up to max. 5 kW - possibly also pulsed, so that the pulse energies are higher.

[0319] The magnifying optic 70 is arranged in the combination module 1-1 such that it collects object light 100 originating from an object 200 under investigation. The magnifying optic 70 also includes the first lens system 71 and the second lens system 72. These two lens systems are therefore also intended for imaging the object 200 in the 3D camera module 81 and result in a high magnification of the captured spatial area.

[0320] The first lens system 71 consists of a first lens.

[0321] Both beam paths, the laser beam path and the detection beam path, run via the first and lens system 71.

[0322] The magnifying optics 70 may include further optical components (not shown), such as filters or corrective lenses, which, however, do not primarily contribute to an angular magnification of the object light 100. The angular magnification is achieved by the magnifying optics 70 and its components 71, 72.

[0323] In general, the first lens 71 can also be designed as a first lens system 71, consisting of one or two lenses or even up to three lenses.

[0324] The second lens 72 can also be designed as a second lens system consisting of a multitude of lenses.

[0325] The first lens 71 has a first focal length fi, the second lens has a second focal length f2.

[0326] The first and second lenses are arranged at a distance along the optical axis OA that corresponds to the sum of the first and second focal lengths fi, f2. Thus, these lenses form a telecentric system.

[0327] The first and second lenses are fixed at this distance without any displacement mechanism, thus forming a rigid lens system without moving components.

[0328] The magnifying optic 70 is designed to magnify the angle at which object light 100 strikes the magnifying optic 70. In particular, the angular magnification assigned to the magnifying optic 70 is greater than three, especially greater than five or ten. The magnification can also be greater than 50 or, in exceptional cases, greater than 100. To make the magnifying optic 70 more compact, a so-called Galilean optic is preferably used, in which the second lens 72 is a concave lens with an associated negative focal length. The angular magnification is then given by: m = where the focal length of the first lens corresponds to |f21 corresponds to the absolute focal length of the second lens, where the first focal length is greater than the absolute value of the second focal length.

[0329] Since the distance between the first and second lenses 71, 72 is smaller in a Galilean optic than in a corresponding conventional (positive focal length) optic due to the negative focal length of the second lens, the magnifying optic 70 requires slightly less installation space.

[0330] It should also be explicitly noted here that both the first 71 and / or the second lens 72 can consist of a lens system, which can each comprise a multitude of lenses, with the second lens system in this case having a negative focal length.

[0331] The object light 100, provided it originates from a focal plane of the magnifying optics 70, is collimated by the magnifying optics 70 and directed onto the input aperture E of the 3D camera module 81, which comprises or corresponds to the system 1 according to the invention. Object light 100 that does not originate from the focal plane is convergent or divergent accordingly. Since the object 200 is located very far away compared to a lens aperture of the first lens 71, in particular more than 100 to 1000 times farther away than the lens aperture, any convergences of the wavefronts of the object light 100 that may occur are very small, only a few mrad or less, so that it can essentially be assumed that the object light 100 striking the magnifying optics of the arrangement 1000 is collimated.

[0332] The 3D camera module 81 (dashed box), which in this example and in all other exemplary embodiments is designed as a digital holographic recording system according to the invention – see Figures 1 to 8 – essentially comprises a beam splitter 2, a retroreflector array 3, a reference mirror 4, and an array detector 8. The 3D camera module 81 is also described below with reference to Figures 1 to 6.

[0333] The beam splitter 2 is designed here in the form of a beam splitter cube. The beam splitter cube 2 has four sides. A first side 21 is assigned to an input aperture E of the digital holographic recording system 81, on whose side the magnifying optics 70 are arranged.

[0334] The detector 8 can be a camera, in particular a digital monochrome camera. Such cameras are often implemented as CMOS or CCD cameras.

[0335] The detector 8 is connected to a processor system 9 (shown in Figs. 9 and 10), which comprises one or more processors, to which the camera data is transferred. The processor system 9 is or comprises an evaluation unit configured to reconstruct a hologram of the object 200 under investigation from the interference patterns.

[0336] The processor system 9 can also be connected to various components of the arrangement 1000 in such a way that the processor system 9 can communicate with these components and, in particular, control them. This applies, for example, to the beam shaping module and the control unit (not shown) for the 2-axis gimbal.

[0337] Furthermore, with reference to Fig. 9 and in detail to the digital holographic recording system 81 in Figs. 1 to 6, in order to determine the distance of a target object 200, an image of interference patterns is captured with the digital holographic recording system 81.

[0338] The recording can be captured by corresponding control commands from the processor system 9 to the detector 8 and transmitted to the processor system 9.

[0339] Alternatively, processor system 9 can also read the recording from a data storage device of system 1.

[0340] By evaluating the interference patterns, at least a two-dimensional image is determined from the recording along the optical axis OA of the arrangement 1000, which corresponds to an image of an assigned focal plane that can be positioned at an algorithmically adjustable distance A via the evaluation.

[0341] The image therefore corresponds to a focal plane or a focal surface in object space at a defined distance.

[0342] The computer program that processes the camera data in this way can be trained to output information about the position of the focal plane, for example via a user interface or to transmit it to other components, such as the beam shaping module.

[0343] This allows a multitude of images to be generated by repeatedly evaluating the recording at different focal plane distances, all of which depict these focal planes sharply, i.e., with focus on the focal plane. From the image with the highest sharpness, or the desired section of the target object, the system can be informed of the distance to be set, which corresponds to the distance associated with that image.

[0344] The expert knows which parameters can be used to determine image sharpness.

[0345] The multiple images can also be used to create a composite image, which, by combining the images, depicts a multitude of focal planes in focus, resulting in a greater depth of field compared to the individual images. The composite image can be two- or three-dimensional.

[0346] Additionally or alternatively, one or more of the images can be displayed on a screen.

[0347] In particular, the evaluation can be carried out in such a way that the assigned focal plane is shifted along the optical axis between at least a first and a second position, and a D is calculated for each position of the assigned focal plane.

[0348] The processor system or computer program is further configured to take the information about the subbands into account and process it in the evaluation, so that the image is corrected for the respective subband / and / or where a large number of color channels are generated during the reconstruction of the subband information, so that the image includes color channel information, e.g. RGB information, in particular where the image is a color image.

[0349] Typical dimensions of the components of the digital holographic recording system 81 are described below: With an aperture D of 1 mm of the retroreflector elements and a wavelength A of the object light of 500 nm, the following results from the relationship

[0350] A ß = — an angular resolution of the system of approximately 0.25 mrad.

[0351] A retroreflector element 30 with a larger aperture presents the challenge that the wavefronts no longer behave planarly across the aperture, which negatively affects the quality of the reconstructed pixels. Typically, an optimum diameter lies between a few mm at the upper edge and 100 pm at the lower edge. In particular, the range from D = 1 mm to 250 pm is especially favored.

[0352] The digital holographic recording system 81 allows the optical resolution to be significantly increased for a zoom range.

[0353] With regard to figures 9 and 10, the following applies, for example:

[0354] For a first focal length of = 100 mm, f2 = -4 mm, the resulting angular magnification is m = 25, and thus the angular resolution of the system is...

[0355] Aß = 0.25 mrad on increased.

[0356] With this angular resolution, objects at a distance of, for example, z = 100 m can be detected with a lateral resolution Ax of Ax = Aa ■ z = 1 mm.

[0357] For example, with 1024 object points, this would correspond to an image field of approximately 1 m.

[0358] This gives the zoom camera a field of view of approximately + / - 5 mrad or approximately + / - 0.3°. To achieve the above resolutions, the images must be algorithmically corrected for aberrations from the lenses and also precisely focused on the focal plane, which is also done algorithmically. Therefore, the zoom camera, which is realized through the 3D camera module in combination with the magnifying optics, is also referred to as a 3D zoom camera.

[0359] A certain technical challenge lies in keeping the focal length f2 of the second lens 72 short while simultaneously ensuring that the entrance aperture E of the digital holographic recording system 81 – typically a few millimeters – is still filled with light. Therefore, the second lens 72 can also be designed as an objective, i.e., as a lens system with lenses with a corresponding resulting focal length f2. The focal length of the first lens 71 is given in this example by = 100 mm significantly smaller than that of a typical 800 mm zoom lens. Therefore, this design is very compact. In particular, because the 3D camera module can be extremely compact and the second lens system, consisting of, for example, only a diverging lens, does not require any significant amount of installation space, almost the entire installation space of the combination module 1-1, or rather its housing 94, can be used for the focal length requirement of the first lens system.

[0360] The common first lens system 71, used on both the laser light and detection sides, has the advantage of generating a highly focused spot for the NIR laser light (NIR = near-infrared) via its diameter 71-1. This also maximizes the resolution for the 3D camera module 81, especially when the second lens system 72 is well-adjusted for aberrations and the 3D camera module 81 or the processor system 9 algorithmically corrects residual errors caused by the second lens system 72. For a given NIR power density, the overall power consumption is minimized due to the tight focusing to a few millimeters, and the zoom field aligned via the common first lens ensures that the object area is captured with high resolution.

[0361] A further advantage of the system according to the invention is the fact that the first lens or lens system 71, in combination with the second lens or lens system 72, exhibits wavefront aberrations, which, however, can be compensated for by the described self-interference method using algorithmic corrections via the processor system 9. In a "classic" zoom camera, the zoom lens must be optically corrected as perfectly as possible; otherwise, the image quality will be poor. This explains its size and weight, as up to 24 lenses can be used. Another advantage of the arrangement 1000 according to the invention is that the arrangement 1000 can dispense with mechanical focusing, since the position of the focal plane is controlled algorithmically during the subsequent evaluation of the interference patterns.This allows very rapid changes in distance to a target object to be sharply detected and - almost more importantly - changes in object depth in the image field can all be focused instantly.

[0362] For example, to compensate for the relative inertia of a UAV (unmanned aerial vehicle), such as a multicopter, during flight operation, the system 1 advantageously has a rotating mechanism, such as the 2-axis gimbal, which can very quickly stabilize and adjust the limited field of view of the 3D zoom camera 81, 70 in the selected spatial section.

[0363] Simultaneously, the non-mechanical beam shaping module 80 can briefly and with very low latency (lower than the 2-axis gimbal) stabilize the laser light 300 on a specific object point within the selected spatial area. However, if the target object 200 were to move without the aforementioned rotation mechanism, the laser light 300 could not be continuously tracked on the focal point T via the beam shaping module 80. Therefore, the combination of the 2-axis gimbal and the beam shaping module 80 is particularly advantageous.

[0364] In operation, the extremely fast tracking of the focal point T, in the range of milliseconds, cannot be achieved by the 2-axis gimbal alone, but can be achieved by the beam shaping module 80 with beam steering, while simultaneously correcting aberrations.

[0365] Figure 10 shows a further embodiment of the invention, differing from the embodiment in Figure 9 in that the beam splitter surface 2a of the digital holographic recording system 81 must be transparent to the laser light 300, and the reference mirror 4 must also be transparent to the wavelengths of the laser light and thus simultaneously serve as a combining element 74. In this way, the light extraction module 60 can be arranged on a side of the reference mirror 4, 74 that faces away from the digital holographic recording system 81. The light extraction module 60 is therefore arranged in the combining module 1-1 such that emitted laser light 300 propagates through the reference mirror 4, 74 and the beam splitter 2 and then strikes the magnifying optics 70 comprising the first and second lens systems 71, 72, as previously described.

[0366] If the reference mirror 4, 74 were to be arranged on the side of the retroreflector array 3, the beam splitter surface 2a of the beam splitter 2 would have to be designed to reflect the laser light 300 accordingly. However, the principle that the light extraction module 60 couples the laser light 300 via the reference mirror 4, 74 through the 3D camera module 81 into the magnifying optics 70 remains the same.

[0367] These embodiments, one of which is shown in Fig. 10, are the most compact and lightest, and are therefore preferred. However, the requirements for the selective coatings of the selectively reflective surfaces are particularly high, since the common beam-splitter layer 2a must transmit the NIR light spectrally selectively with high quality.

[0368] List of reference symbols

[0369] 1 system

[0370] 1-1 Combination module

[0371] 2 beam splitters

[0372] 2a Beam splitter area

[0373] 21 first side of the steel divider

[0374] 22 second side of the steel divider

[0375] 23 third side of the steel divider

[0376] 24 fourth side of the steel divider

[0377] 3 Retroreflector array

[0378] 30 Retroreflector element

[0379] 31 Lens of the retroreflector element

[0380] 32 retroreflector mirrors

[0381] 32-1 Reflective layer

[0382] 32-2 reflective layer 32-3 reflective layer

[0383] 320 layer system mirrors

[0384] 4 reference mirrors

[0385] 40-layer system mirror

[0386] 40-1 Reflective layer

[0387] 40-2 reflective layer

[0388] 40-3 reflective layer

[0389] 5 Dispersion element

[0390] 51, 52 layer elements

[0391] 5' large dispersion element

[0392] 5T, 52' wedge elements

[0393] 6 Actuator

[0394] 7 Converging lens / Optics

[0395] 70 Magnifying Optics

[0396] 71 first lens system / first lens

[0397] 71-1 Aperture diameter

[0398] 72 second lens system / second lens

[0399] 74 Combination element

[0400] 8 Array detector / camera

[0401] 80 Beam shaping module

[0402] 80-1, 80-2, 80-3 layers of the beam shaping module

[0403] 81 3D camera module / digital holographic recording system

[0404] 82 electro-optical element

[0405] 9 Computer / Processor system

[0406] 90 2D camera

[0407] 91 Laser

[0408] 92 optical fiber / light guide

[0409] 93-1 first axis of rotation of the 2-axis gimbal

[0410] 93-2 second axis of rotation of the 2-axis gimball

[0411] 94 cases

[0412] 94-1 Case diameter

[0413] 95 Data and power supply

[0414] 100 object light

[0415] 100-1 Subband

[0416] 100-2 Subband 100-3 Subband

[0417] 200 objects

[0418] 300 laser lights

[0419] 1000 Arrangement A Distance

[0420] OA optical axis

[0421] T Target point / Focus point

Claims

1. System (1) for digital holographic imaging, comprising at least the following components: a beam splitter (2) which, together with a beam splitter surface (2a), defines at least the following sides: (a) a first side (21) for collecting object light (100) comprising a plurality of sub-bands (100-1 , 100-2, 100-3), (b) a second side (22) to which the collected object light (100) is reflected, (c) a third page (23) opposite the first page (21) extends, (d) a fourth page (24) opposite the second page (22) extends such that object light (100) reflected from the second and third sides (22, 23) propagates to the fourth side (24) and forms an interference pattern on the fourth side (24), comprises a retroreflector array (3) arranged on the second or third side (22, 23) and a plurality of retroreflector elements (30), and a reference mirror (4) arranged on an adjacent side (23, 22) to the retroreflector array (3), wherein this adjacent side is the second or third side (22, 23), characterized in that the system (1) is configured to impose wavelength-dependent phase shifts on the object light (100) for a plurality of retroreflector elements (30), which are different for the plurality of retroreflector elements (30).

2. The system (1) according to claim 1, wherein each retroreflector element (30) comprises a lens (31) and an associated retroreflector mirror (32).

3. The system (1) according to one of the preceding claims, characterized in that the system (1) comprises one or more dispersion elements (5), each dispersion element (5) being configured to impose wavelength-dependent phase shifts on incident object light (100), which are suitable for a multitude of Retroreflector elements (30), in particular, are different for each retroreflector element (30).

4. The system (1) according to claim 3, wherein at least one (5') of the one or more dispersion elements (5) is arranged on the retroreflector array (3) and extends over several retroreflector elements (30), such that wavelength-dependent phase shifts are imposed on the object light (100) incident on these retroreflector elements (30), which are different for a plurality of these retroreflector elements (30).

5. The system (1) according to claim 4, characterized in that the at least one (5') or of the several dispersion elements (5) is each designed as a multiple wedge plate with a plurality of wedge elements (51 , 52), in particular as a double wedge plate with two wedge elements, wherein each wedge element has an Abbe number different from the other wedge elements.

6. The system (1) according to one of claims 3 to 5, characterized in that the system (1) has a plurality of dispersion elements (5), wherein each dispersion element (5) is associated with a retroreflector element (30), wherein each dispersion element (5) is configured to impose wavelength-dependent phase shifts on the incident object light (100), which are different for each dispersion element (5).

7. The system (1) according to any one of claims 3 to 6, characterized in that the one dispersion element (5') comprises N layer elements (51, 52), wherein each layer element (51, 52) has a respective Abbe number, wherein the Abbe numbers of each layer element (51, 52) are each different from each other, wherein N>1 is an integer, and / or wherein at least some dispersion elements of the plurality of dispersion elements (5) each comprise N layer elements (51, 52), wherein each layer element (51, 52) has a respective Abbe number, wherein the Abbe numbers of each layer element (51, 52) are each different from each other, wherein N>1 is an integer.

8. The system (1) according to one of the preceding claims, characterized in that the retroreflector array (3) extends along a retroreflector array plane (300) which forms an angle of intersection a = 45° + 8 with a beam splitter plane (400) extending along the beam splitter surface, wherein |<5| > 0° , so that object light reflected by the retroreflector array (3) is subjected to different wavelength-dependent phase shifts for a plurality of retroreflector elements (30).

9. The system (1) according to one of claims 2 to 8, characterized in that each retroreflector mirror (32) is configured such that wavelength-dependent phase shifts are imposed on incident object light (100) by the retroreflector mirror (32), which are different for a plurality of retroreflector elements (30), in particular for each retroreflector element (30) of the retroreflector array (3), in particular wherein the reference mirror (4) is also configured such that object light reflected at the reference mirror (4) experiences predefined wavelength-dependent phase shifts.

10. The system (1) according to claim 9, wherein each retroreflector mirror comprises or is configured as a layer system mirror (320), wherein each layer system mirror (320) is configured such that incident object light (100) is reflected in a wavelength-dependent manner such that object light (100) from different subbands (100-1 , 100-2, 100-3) travels a different optical path length (s2, s3) in the layer system mirror (320), in particular wherein the reference mirror (4) comprises or is configured as a layer system mirror (40).

11. The system (1) according to claim 10, wherein the layer system mirror (320) of each retroreflector element (30) comprises reflective layers (32-1, 32-2, 32-3), wherein each reflective layer (32-1, 32-2, 32-3) is configured to reflect object light (100) from a predefined subband (100-1, 100-2, 100-3) assigned to the respective reflective layer (32-1, 32-2, 32-3), wherein the reflective layers (32-1, 32-2, 32-3) in the layer system mirror (320) are arranged such that object light (100) from different sub-bands (100-1 , 100-2, 100-2) is applied with a frequency corresponding to the respective The retroreflector element (30) is reflected in a predefined phase, in particular wherein each layer system mirror (320) comprises a plurality of Bragg mirrors.

12. The system (1) according to any of the preceding claims, wherein the system (1) comprises one or more actuators (6), in particular piezo actuators, which are configured to adjust a position and / or an angle of the retroreflector array (3) and / or the reference mirror (4).

13. An arrangement (1000) for adjustable focusing of a laser beam on a target object (200) with at least one combination module (1-1) is disclosed, which has the following components: A first lens system (71), comprising at least or exactly one first lens, A 3D camera module (81) arranged and configured to detect incident target object light (100) via the first lens system (71), wherein the 3D camera module (81) comprises the system (1) for digital holographic imaging according to one of the preceding claims, A light extraction module (60) having an optical light guide output (61) as a laser light source, and arranged and configured to extract laser light (300) from the laser light source via the first lens system (71) from the arrangement (1000), Beam shaping module (80) which is arranged and configured to focus laser light (300) of the light extraction module (60) to an adjustable distance (A), wherein the arrangement is further configured to adjust the beam shaping module (60) using camera data from the 3D camera module (81) so that the laser light (300) is focused to an adjustable distance (A).

14. The arrangement (1000) according to claim 13, wherein the arrangement (1000) comprises a magnifying optic (70) comprising the first lens system (71) and a second lens system (72).

15. The arrangement (1000) according to claim 13 or 14, wherein the Beam shaping module (80) comprises an electro-optical beam shaping module (80) which is configured to modify wavefronts of the laser light (300) so that the laser light (300) is focused at the adjustable distance (A) and / or a propagation direction of the laser light (300) is adapted.

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