MULTICHANNEL OPTOMECHANICAL ADDRESSING UNIT

Abstract

An optical device for imaging a first, object-side set of mutually parallel bundles of beams onto an image surface, includes

an optical beam expansion unit;
an optical rearrangement unit configured to rearrange the first set of mutually parallel bundles of beams while maintaining mutually parallelism to obtain a second set of mutually parallel bundles of beams;
an optical element configured to direct the second set of one or more bundles of beams onto the optical beam expansion unit by means of bundling, so that the optical beam expansion unit is reached by a third set of bundles of beams,
the optical beam expansion unit being configured to expand each bundle of beams of the third set to obtain a fourth set of expanded bundles of beams; and
an optical imaging unit configured to image the fourth set of expanded bundles of beams onto the image surface.

Claims

1. Optical device for imaging a first, object-side set of mutually parallel bundles of beams onto an image surface, comprising an optical beam expansion unit; an optical rearrangement unit configured to rearrange the first set of mutually parallel bundles of beams while maintaining mutually parallelism so as to achieve a second set of mutually parallel bundles of beams; an optical element configured to direct the second set of one or more bundles of beams onto the optical beam expansion unit by means of bundling, so that the optical beam expansion unit is reached by a third set of bundles of beams, the optical beam expansion unit being configured to expand each bundle of beams of the third set so as to achieve a fourth set of expanded bundles of beams; and an optical imaging unit configured to image the fourth set of expanded bundles of beams onto the image surface.

2. Optical device as claimed in claim 1, comprising a source for each bundle of beams of the first set of bundles of beams, from which the respective bundle of beams impinges upon the optical rearrangement unit.

3. Optical device as claimed in claim 2, wherein the source for each bundle of beams of the first set of bundles of beams comprises a monomode source or a multimode source.

4. Optical device as claimed in claim 3, comprising a collimator for each bundle of beams of the first set of bundles of beams through which the respective bundle of beams of the first set of bundles of beams passes in the direction of the optical rearrangement unit.

5. Optical device as claimed in claim 1, comprising, for each bundle of beams of the first set of bundles of beams, a monomode fiber comprising a GRIN lens as a collimator.

6. Optical device as claimed in claim 1, wherein the optical element is configured to bundle the second set of bundles of beams at a predetermined distance, which is smaller than double a focal length of an input-side optical element of the optical beam expansion unit in front of or behind the input-side optical element, so that the bundles of beams of the third set of bundles of beams superimpose one another.

7. Optical device as claimed in claim 6, wherein the predetermined distance amounts to between 0.5 and 1.5 times the focal length of the input-side optical elements.

8. Optical device as claimed in claim 6, wherein the predetermined distance amounts to between 0.5 and 1.5 times f.sub.T,1+Δ, with $\Delta =\frac{f_{T1}}{f_{T2}}\left(f_{T1}+f_{T2}\right)-f_{T1}=f_{T1}^2/f_{T2}$ wherein f.sub.T1 is the focal length of the input-side optical element, and f.sub.T2 is the focal length of the output-side optical element of the optical beam expansion unit, which together form a telescope.

9. Optical device as claimed in claim 5, wherein the optical imaging unit comprises a diameter larger than or equal to 1.5 times a cross-section of a bundle of beams of the fourth set of bundles of beams.

10. Optical device as claimed in claim 1, wherein the optical element is configured as a one- or multi-stage refractive optical element.

11. Optical device as claimed in claim 1, wherein the optical element is configured as a reflective optical unit.

12. Optical device as claimed in claim 1, wherein the optical rearrangement unit may be controlled to set rearrangement of the second set of bundles of beams as compared to the first set of bundles of beams.

13. Optical device as claimed in claim 1, wherein the optical rearrangement unit comprises mechanically adjustable mirrors.

14. Optical device as claimed in claim 13, comprising bearings by means of which the mechanically adjustable mirrors are linearly moveable.

15. Optical device as claimed in claim 1, wherein the optical rearrangement unit comprises mechanical and/or piezoelectric and/or magnetically drivable actuating elements.

16. Optical device as claimed in claim 1, wherein the optical rearrangement unit is configured to achieve rearrangement such that distances covered are maintained, so that each bundle of beams of the first set of bundles of beams, when passing through the optical rearrangement unit so as to become, or contribute to, a bundle of beams of the second set of bundles of beams, covers a distance that is independent of any setting of the rearrangement.

17. Optical device as claimed in claim 14, wherein the optical rearrangement unit comprises a rigid mirror arranged, along an optical path of the optical device, behind the adjustable mirrors.

18. Optical device as claimed in claim 1, wherein the optical rearrangement unit is configured to rearrange the first set of bundles of beams, that are parallel to the beam direction, while maintaining parallelism with one another and with the beam direction in such a manner that the second set of bundles of beams is parallel to the beam direction.

19. Optical device as claimed in claim 1, wherein the optical beam expansion unit is configured as a refractive telescope.

20. Optical device as claimed in claim 1, wherein the optical beam expansion unit is configured as a reflective telescope.

21. Optical device as claimed in claim 1, wherein the bundles of beams of the first set comprise monochromatic light.

22. Optical device as claimed in claim 1, wherein the optical beam expansion unit illuminates more than 50% of the optical imaging unit by means of each bundle of beams of the fourth set of bundles of beams.

23. Optical device as claimed in claim 1, wherein the bundles of beams of the first set impinge upon the optical element with a weak divergence which is not canceled out by the optical element, so that the bundles of beams of the third set of bundles of beams are weakly divergent.

24. Optical device as claimed in claim 1, wherein the bundles of beams of the first set have been generated to be weakly convergent with a waist in front of the optical element or have been generated to be weakly divergent.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Embodiments of the present invention will be detailed subsequently referring to the appended drawings, in which:

[0038] FIG. 1 shows a schematic diagram of an optical device in accordance with an embodiment,

[0039] FIG. 2 shows a schematic diagram for illustrating a conventional model of a Gaussian beam and/or Gaussian bundle of beams,

[0040] FIG. 3 shows a diagram of rearrangement unit with linearly arranged monomode fibers in accordance with an embodiment,

[0041] FIG. 4 shows a simplified diagram for illustrating bundle superposition of bundles of beams and beam expansion by means of an astronomic telescope for beam expansion in accordance with an advantageous embodiment,

[0042] FIG. 5 shows a simplified diagram for illustrating beam expansion by means of an astronomic telescope with disadvantageous superposition of bundles,

[0043] FIG. 6 shows a simplified diagram for illustrating superposition of bundles and beam expansion by means of an astronomic telescope for explaining an optimum condition for superposition of bundles of beams in accordance with an advantageous embodiment,

[0044] FIG. 7 shows a simplified diagram for illustrating superposition of bundles and beam expansion by means of an astronomic telescope for explaining non-optimum illumination of the objective with disadvantageously heavily collimated bundles of beams,

[0045] FIG. 8 shows a simplified diagram for illustrating beam expansion by means of an astronomic telescope in accordance with the embodiment of FIG. 1, comprising indications on the sizes of beam waists,

[0046] FIG. 9 shows a simplified diagram for illustrating the optical path of an optical device while using a refractive optical beam expansion unit in accordance with an embodiment,

[0047] FIG. 10 shows a simplified diagram for illustrating the optical path of an optical device while using reflective optical beam expansion unit in accordance with a further embodiment.

DETAILED DESCRIPTION OF THE INVENTION

[0048] In the following, embodiments will be described in more detail with reference to the figures, wherein elements having identical or similar functions have been provided with identical reference numerals.

[0049] FIG. 1 illustrates a schematic diagram of an optical device 100 in accordance with an embodiment. In this context, the optical device 100 corresponds to a multichannel optomechanical addressing unit for imaging a multitude of mutually parallel bundles of beams onto an image surface 190. Starting from a source 110, several bundles of beams, which form a first set S1 one bundle of beams, are directed onto the image surface 190 via the optical device 100. The individual bundles of beams of the first set S1 are aligned to be parallel to one another. In other words, different source points Y.sub.i.sup.source within an input plane are associated with, or imaged onto, specific target points Y.sub.i.sup.target within the image surface 190.

[0050] One or more monomode sources may serve as the source 110 for the bundles of beams of the first set S1 of bundles of beams. Light from a laser source is transmitted, e.g., via splitters, from one monomode fiber to several monomode fibers whose ends will then serve as sources of the individual bundles of beams of the set S1, or one uses several monomode lasers, without or with fiber coupling, for providing the set S1 of bundles of beams.

[0051] The bundles of beams of the first set S1 of bundles of beams are forwarded to a rearrangement unit 130, 140. This may be effected by means of a collimator 120 such as a gradient index lens, for example, for each bundle and/or channel.

[0052] The bundles of beams of the first set S1 may comprise monochromatic light. The monochrome property may be due to the technical field of application of the optical device 100, such as in a quantum computer, but may also be advantageous in other fields of application so as to avoid chromatic aberrations.

[0053] As an alternative to the above description, the bundles of beams of the first set S1 may also originate from multimode sources, i.e. from a multimode laser or a multimode fiber. For each channel and/or bundle of the set S1, a suitable collimator may be provided; in this case, the dimensions for collimating the bundles of beams might possibly be larger than with a monomode valiant. For example, each bundle of the set S1 stems from a multimode fiber, a VCSEL, or a channel of a VCSEL array. In the event of multimode production, the bundles of the set S1 might be generated by an array of VCSELs, followed by a microlens array and/or one more microlens for each VCSEL.

[0054] The rearrangement unit rearranges the first set S1 of mutually parallel bundles of beams while maintaining their mutually parallelism, so that a second set S2 of mutually parallel bundles of beams is obtained. Subsequently, embodiments will be described wherein the rearrangement unit is mechanically adjustable, or may be set to different rearrangements.

[0055] The second set S2 of mutually parallel bundles of beams is directed, via the rearrangement unit 130, 140, to an optical element 150 configured to direct the second set S2 of one or more bundles of beams onto an optical beam expansion unit 161, 162 by means of bundling, so that the optical beam expansion unit 161, 162 is reached by a third set S3 of bundles of beams. The optical element 150 is configured to bundle light, which impinges in parallel with the second set S2 of bundles of beams, toward a location of a point X at, or approximately at a distance f.sub.T,1+α smaller than double a focal length f.sub.T,1 of an input-side optical element T1 of the optical beam expansion unit 161, 162 in front of or behind, the input-side optical element T1. Because of the divergence which advantageously is inherent in each of the bundles of beams of the second set, the bundles of beams of the third set S3 will superimpose one another at the point X within an expanded area. In other words, each bundle of beams of the set S2 is bent by the optical element 150 and is directed toward the point X as one of the bundles of the set S3, so as to superimpose there with the other bundles of the set S3. Superposition takes place within an expanded surface area. The directions with which the bundles of the third set S3 are directed toward the point X bijectively depend on the lateral location where the corresponding bundle of beams of the set S2 impinges upon the optical element.

[0056] In the embodiment of FIG. 1, the optical element 150 is configured as a one-stage refractive optical unit. In accordance with further embodiments, the optical element 150 may also be configured as a multi-stage refractive optical unit or as a reflective optical unit.

[0057] In the present embodiment of FIG. 1, the point X of the superposition of the third set S3 of bundles of beams is located in front of the input-side optical element T1, for example a convergent lens of a telescope formed by the optical beam expansion unit 161, 162. The optical beam expansion unit 161, 162 is configured to expand each bundle of beams of the third set S3 of bundles of beams so as to obtain a fourth set S4 of expanded bundles of beams. In FIG. 1, the optical beam expansion unit 161, 162 is formed of a telescope which comprises a lens T1 on the input side and a lens T2 on the output side. The fourth set S4 of bundles of beams is imaged onto the image surface 190 via an optical imaging unit 170 arranged downstream from the optical beam expansion unit 161, 162. In this context, the optical imaging unit 170 is configured, in the embodiment of FIG. 1, to focus the fourth set S4 of expanded bundles of beams onto the image surface 190.

[0058] By means of the optical beam expansion unit 161, 162, which here is depicted as an astronomic telescope comprising two optical elements, or lenses, T1, T2, one manages to superimpose the bundles of beams—which are made to essentially superimpose one another at the point X in front of the telescope—of the third set S3 of bundles of beams on a plane, which here is an input-side surface of the optical imaging unit 170, to form a fourth set S4 of bundles of beams with a bundle diameter that is expanded as compared to the third set of bundles of beams, and with less variance in the bundle propagation direction among the bundles, the fourth set S4 of bundles of beams being focused onto the image plane 190 by the optical imaging unit 170.

[0059] Monomode Gaussian bundles suitable for focusing onto, e.g., ions, are subject to the laws of Gaussian beam optics. Embodiments of the present invention such as that of FIG. 1, for example, manage to produce waist sizes—of the bundles focused onto the image plane 190—which may be very small and essentially depend only on the size, or the diameter, of the optical imaging unit 170 and on the wavelength, but are essentially independent of the number of bundles of beams in the sets S1 to S4. To illustrate this, reference shall initially be made to FIG. 2.

[0060] FIG. 2 illustrates a conventional model of a Gaussian beam, or Gaussian bundle of beams, which is used for the purpose of approximation for calculating and depicting the behavior of bundles of beams in accordance with the embodiments listed here.

[0061] Accordingly, the bundles of beams of the wavelength are characterized by corresponding waists w.sub.0 and angles θ.sub.0 in accordance with

[00002]$\begin{array}{cc}{\theta }_0=\frac{\lambda }{\pi w_0}& \left(1\right)\end{array}$

and by beam radii in accordance with the distance z from the waist W

[00003]$\begin{array}{cc}W\left(z\right)=w_0\sqrt{1+{\left(\frac{z}{z_0}\right)}^2}& \left(2\right)\end{array}$

wherein z.sub.0 is the Rayleigh length

[00004]$\begin{array}{cc}{z}_0=\frac{\pi w_0^2}{\lambda }& \left(3\right)\end{array}$

by means of which the beam radius is enlarged to √2 times of the waist value W.

[0062] By means of optical elements, Gaussian waists are transformed to one another, the bundle cross-sections increasing in size away from a waist W, and tapering toward a waist W.

[0063] An illuminated area of an optical element located within the optical, or bundle, path is related to an angle of aperture θ.sub.0 of the bundle of beams and to a distance z from the waist plane. For a smaller waist size, the angle of aperture of the bundle becomes larger, which means that with a given distance from the optical element and the waist, the illuminated area of the optical element becomes accordingly larger. So as to ensure sufficient energy inclusion of >99% within the Gaussian bundle of beams, elements which are located in the optical path and which potentially have an effect of limiting bundles, additionally may have at least a diameter of three times the bundle radius present at this point.

[0064] In known technical approaches, abaxial bundles, or bundles which are markedly inclined toward an optical axis OA—indicated as a dotted line—have the tendency that requirements placed upon the respective size and quality of the optical elements increase, or that with limited sizes of the optical elements, transmission losses caused by partial cutting off of a Gaussian distribution—of the beam intensity—arise. Corresponding effects occur, for example, because of source-side arrangements or of beam deflections which are useful for associating source points Y.sub.i.sup.source with target points Y.sub.i.sup.target.

[0065] In accordance with an embodiment of the present invention, the diameter of the optical imaging unit 170, which is configured as an objective, for example, is not substantially larger, and the focal length is not substantially smaller, than may be used for producing a waist of the size w.sub.target—which enables spatially resolved addressing of the target points Y.sub.i.sup.target in the image surface 190—and than may be used for achieving transmission of >99% for Gaussian bundles. The objective 170 comprises a focal length f.sub.obj and a diameter D.sub.obj and transforms the bundle of beams within its focal plane, which corresponds to the image surface 190, to a Gaussian waist W.sub.target adapted to the requirements of the imaging task.

[0066] The aperture of the optical imaging unit 170, for example of an objective, in this context is referred to as the numeral aperture (NA), a size defined via

[00005]$\begin{array}{cc}NA=\sin \left(\theta \right)=\sin \left(\mathrm{atan}\left(\frac{D_{obj}/2}{f_{obj}}\right)\right).& \left(4\right)\end{array}$

[0067] In accordance with (1) and (4), while taking into account the demand of transmission of >99%, the angle of aperture that an objective may have as a minimum, is determined to be

[00006]$\begin{array}{cc}{\theta }_{\mathrm{oeff}}=\mathrm{atan}\left(\frac{D_{obj}/2}{f_{obj}}\right)=1.5.Math.\frac{\lambda }{\pi w_{target}},& \left(5\right)\end{array}$

wherein technical conditions of the setup such as the distance of the objective from the target plane and/or the expansion of the latter specify the focal length and/or the diameter of the objective.

[0068] Optomechanical beam bending by means of the optical rearrangement unit and beam expansion by means of the optical beam expansion unit may therefore be configured, in the embodiments of the optomechanical system, such that for each channel, the expanded bundle which impinges upon the objective remains within the diameter of the objective that is determined in accordance with the technical conditions, and almost fully illuminates the former.

[0069] In the above-described manner, embodiments of the present invention simultaneously enable highly precise association of a multitude of input-side light source points Y.sub.i.sup.source with output-side target points Y.sub.i.sup.target within a target plane, or image surface, the target points Y.sub.i.sup.target not necessarily being stationary. For example, load-dependent interionic distances or ion positions influenced by stray fields may be tracked in ion traps, for example. The optical overall arrangement, which is centered with regard to an optical axis OA by means of the objective and is set in terms of the diameter thereof, and which is enabled by suitable micro optomechanics, allows using objectives whose specifications with regard to a numerical aperture essentially depend only on the resolution requirements within the target plane and depend, with regard to their focal lengths, essentially only on the working distance that is due to construction-related reasons. In the event that, e.g., the image surface 190 lies within an ion trap, the above-mentioned working distance may be given, e.g., by a thickness of a vacuum window and by a distance of the trap from the window. Scaling operations toward larger ion numbers are thus not limited, as is the case with other optomechanical approaches, by clearly more expensive objectives having larger numerical apertures or larger diameters. In a similar manner, this also applies to other technical examples of applying the device 100. The limited numerical objective aperture, which may be used in the embodiments of the present invention, additionally limits, due to a larger depth of focus, the expenditure involved in longitudinally adjusting the objective with regard to the image surface 190, such as an ion plane, for example. Optical units which are folded and which, apart from the objective, are purely reflective enable compact setups which are also independent onf wavelengths and may thus be used for various cases of application, e.g. for ion traps comprising .sup.40Ca.sup.+, .sup.138Ba.sup.+ or other ions.

[0070] In a specific implementation, the device of FIG. 1 may be dimensioned as follows for realizing an optomechanical addressing unit, for simplicity's sake for linear arrangement in the image surface 190, for example for linear arrangement of .sup.40Ca.sup.+ ions within an ion trap, such as a Paul trap. As a source 110 of a first object-side set S1 of bundles of beams extending in a mutually parallel manner, an adequate linear arrangement of input-side monomode fibers may be used. For the distances of the sources 110, fiber diameters, diameters of the collimation lenses 120, and useful channel distances are to be taken into account on the part of the mechanical system. If one assumes a reference grid, determined by the mechanical system, of 500 μm, collimation lenses 120 having diameters below 500 μm are to be selected. If the sources can be arranged within different, e.g. oppositely located, planes, collimation lenses 120 having diameters below 1 mm are possible. For the distances of .sup.40Ca.sup.+ ions within the ion trap, an average value of approx. 5 μm, e.g., may be estimated, from which results a imaging scale of 100:1 for their distances. The wavelength for the optical device 100, or optical addressing unit, for .sup.40Ca.sup.+ ions amount to 729 nm. A mode field radius of a supplying monomode fiber 110 of approx. 2.5 μm may be considered, with good approximation, to be an input Gaussian waist. A rearrangement unit 130, 140, which is to be arranged within the optical path and whose side has an upper limit set by the channel distance, limits the bundle diameter of the beams. At this location, a bundle radius should therefore be kept below 150 μm. If individual interionic distances at the center of the ion trap are below 5 μm, it will be advantageous to select the size of a bending element, e.g. of an adjustable mirror 130, to be below 500 μm; i.e. advantageously, the bundle diameter W at the bending element 130, 140 will have to be selected to be smaller than 100 μm. FIG. 1 shows an advantageous implementation with a bundle that is weakly convergent behind the collimation lens 120.

[0071] For implementing the imaging scale, the optical beam expansion unit, the focal length f.sub.OE of the optical element 150, and the focal length f.sub.obj of the objective are to be suitably dimensioned. For the correlation between the distance of the source points Y.sub.i.sup.source and the distance of the target points Y.sub.i.sup.target without any loss of generality, in each case as a linear arrangement in the y direction, the following correlation may be found in the form of a formula, if the optical imaging element 150 has a focal length f.sub.OE and if the optical beam expansion unit 161, 162 is assumed to be a telescope having two lenses T1, T2 of the focal lengths f.sub.T,1 and f.sub.T,2:

[00007]$\begin{array}{cc}{Y}_i^{target}=Y_i^{source}.Math.\frac{f_{obj}}{f_{\mathrm{OE}}}.Math.\frac{f_{T,1}}{f_{T,2}}& \left(6\right)\end{array}$

[0072] If the optical imaging element 150 is configured as a parabolic mirror having a radius of curvature R.sub.c_mirr, (6) will result in the adequate correlation

[00008]$\begin{array}{cc}{Y}_i^{target}=Y_i^{source}.Math.\frac{f_{obj}}{R_{c_{-}mirr}/2}.Math.\frac{f_{T,1}}{f_{T,2}}& \left(7\right)\end{array}$

[0073] For (6) and/or (7) it shall be assumed that distances of fibers, aligned in parallel, as a source plane are translated, at a ratio 1:1, to distances from the optical axis OA of the imaging optical element 150, while maintaining parallelism, on the part of a suitable rearrangement unit 130, 140 and/or optomechanical system.

[0074] If the rearrangement unit 130, 140 enables—while maintaining the above-mentioned parallelism requirements—transformation of source positions Y.sub.i.sup.source to positions designated by Y.sub.i.sup.OE on the imaging optical element—which in turn describe distances from the optical axis OA—free associations of source and target points may be addressed by means of

[00009]$\begin{array}{cc}{Y}_i^{target}=Y_i^{c_{-}\mathrm{OE}}.Math.\frac{f_{obj}}{f_{\mathrm{OE}}}.Math.\frac{f_{T,1}}{f_{T,2}}& \left(8\right)\end{array}$

and/or, in case of the parabolic mirror as an imaging optical element, by means of

[00010]$\begin{array}{cc}{Y}_i^{target}=Y_i^{c_{-}mirr}.Math.\frac{f_{obj}}{R_{c_{-}mirr}/2}.Math.\frac{f_{T,1}}{f_{T,2}}.& \left(9\right)\end{array}$

[0075] Possible implementations of the association of source positions Y.sub.i.sup.source with positions Y.sub.i.sup.c_mirr are outlined in FIG. 3 by way of example. For the purpose of depicting the variability of the associations, various possibilities are shown in an illustrative manner: the case of application provides bijective association of N source channels, or source points, Y.sub.i.sup.source with N target channels, or target points, Y.sub.i.sup.target.

[0076] If, by way of example, one assumes an objective having an NA of 0.3, waist sizes <1.5 μm can be generated for the wavelength of 729 nm within the ion plane. Said waist sizes enable precise addressing of ion positions located at a distance of approx. 5 μm. If one continues to assume a focal length of 30 mm, which allows operation of the ion trap behind a vacuum window of a thickness of more than 10 mm, and if one uses a typical optical beam expansion unit 161, 162 for an imaging scale of 10:1, the imaging scale of 100:1, which corresponds to the ratio of the distances of the source points Y.sub.i.sup.source to the distances of the target points Y.sub.i.sup.target will be implemented with an optical element 150 having a focal length of 300 mm—for example with a mirror having a radius of curvature of 600 mm.

[0077] In the embodiments of the present application such as in FIG. 1, for example, e.g. the optical beam expansion unit 161, 162 is arranged at a suitable distance of f.sub.OE+f.sub.T1+Δ from the parabolic mirror. Thus, the location, or point, X of the superposition of the bundles lies, at a distance f.sub.T,1+Δ in front of the first lens T1 of the telescope, which in turn results in the bundles being centered on the output side of the telescope, as is shown, e.g., in FIG. 1 and FIG. 4. A possibility of determining A will be deduced hereinbelow.

[0078] Illumination of objective and/or output diameters of the optical beam expansion unit, which are given and/or demanded accordingly, is essentially set with the fiber-side optical collimation unit 120. If a conventional micro lens is used, the setting results from the fact that the object distance is selected to deviate several % from a nominal focal length f, so that the desired slight convergence, or divergence, is achieved. For example, the distance between the source, such as the laser or fiber output for example, and the collimator ranges between 0.9 and 1.1 times the nominal focal length.

[0079] An intended field of application of embodiments of the present invention are, as was already mentioned above, quantum technologies, wherein simultaneous addressing of a plurality of ions within an ion trap present a partial task that may be expediently performed. There are comparable tasks within various other fields of application—they might lie within communication technologies, within sensor systems, or within the field of beam guidance in industrial applications.

[0080] FIG. 3 illustrates an outline of a rearrangement unit 130, 140, comprising bundles of beams which stem from monomode fibers which here are linearly arranged by way of example. In the embodiment of FIG. 3, the respective monomode fibers comprise individual collimators 120a . . . d, which generate a bundle of beams which in an optical sense is weakly convergent and/or weakly divergent. The individual positions pos. 1 . . . 4 of the bundles of beams, which correspond to source points Y.sub.i.sup.source are associated with positions pos. 1′ . . . 4′ on the optical element 150 by means of a suitably moveable and/or adjustable mirror 130a . . . d per bundle of beams and a rigid mirror 140 provided for all of the bundles of beams. Within this context, individual bundles of beams may not only be mutually displaced, but also rearranged. In FIG. 3, the individual displacements of positions pos. 1 . . . 4 to pos. 1′ . . . 4′ are indicated by arrows. The adjustable mirrors 130a . . . b are advantageously supported to allow linear movement. Depending on the embodiment, the entire optical rearrangement unit 130, 140 or parts thereof may be controlled by means of mechanical and/or piezoelectric and/or magnetically controllable actuating elements. Along the optical path of the optical device 100, the optical rearrangement unit 130, 140 comprises a rigid mirror 140 which is arranged, in the optical path, behind the adjustable mirrors 130 and via which the bundles of beams are directed toward the optical element 150.

[0081] As illustrated by the example of FIG. 3, the optical rearrangement unit 130, 140 may be configured to achieve rearrangement of positions, here of pos. 1 . . . 4 to pos. 1′ . . . 4′, such that distances covered are maintained, so that each bundle of beams of the first set S1 of bundles of beams, when passing through the optical rearrangement unit 130, 140 so as to become, or contribute to, a bundle of beams of the second set S2 of bundles of beams, covers a distance that is independent of any setting of the rearrangement. In addition, the optical rearrangement unit 130, 140 is configured to rearrange the first set S1 of bundles of beams, which are parallel to the beam direction, while maintaining parallelism with one another and with the beam direction in such a manner that the second set S2 of bundles of beams is, or continues to be, parallel to the beam direction.

[0082] An advantageous setting with regard to individual optical components of the optical device 100, which enables optimum illumination of the target points Y.sub.i.sup.target, will be described below with reference to several consecutive diagrams.

[0083] FIG. 4 depicts a simplified diagram for illustrating bundle superposition of bundles of beams and their beam expansion by means of an astronomic telescope in accordance with an advantageous embodiment. In order to simplify matters, what is illustrated is the optical path starting from the collimators 120 of the individual bundles of beams—the rearrangement unit 130, 140 is not shown. The bundles of beams directed toward the optical element 150 exhibit only minor convergence, or divergence, and extend in parallel with an optical axis OA, which is indicated as a dotted line in the figures. The individual bundles of beams are deflected by the optical element 150. It is in the focal length f.sub.OE of the optical element 150 that the bundles of beams will then converge, a common center of all bundles of beams being defined by a point X, which is located in the focus of the optical element 150. Within this context, the location of the point X is arranged at a predetermined distance f.sub.T,1+α in front of the input-side optical element, or the input-side lens T1, of the optical beam expansion unit 161, 162. In the present embodiment, the distance of point X from the input-side lens T1 is set such that expansion of the bundles of beams by means of the optical beam expansion unit 161, 162 essentially fully illuminates the output-side lens T2 as well as the optical imaging unit 170—such as an objective, for example—arranged downstream from it, e.g., illuminates more than 50%, specifically, e.g., more than 50% with regard to each expanded bundle of beams. By means of the optical element 150, the original positions/orientations of the bundles of beams, i.e., various locations and identical angles of paraxial bundles of beams, are transferred into the same location and to various angles. The sources 110, e.g., monomode sources, may also be arranged in a one- or two-dimensional manner.

[0084] FIG. 5 depicts a shows a simplified diagram for illustrating bundle superposition of bundles of beams and their beam expansion by means of an astronomic telescope in accordance with a further embodiment. Unlike FIG. 4, in FIG. 5, the location of the point X at a distance from the input-side optical element, or the input-side lens T1, of the telescope is determined such that the bundles of beams do not necessarily superimpose one another in the output-side optical element, or the output-side optical lens T2, or the downstream objective 170. Accordingly, FIG. 5 illustrates the optical path of a bundle with a non-adapted distance between the optical element 150 and the input-side optical element 161 of the optical beam expansion unit 161, 162.

[0085] Advantageous setting, or dimensioning, of the optical device with a view to the fact that all bundles of beams which originate in parallel from sources at different distances from the optical axis OA, will perfectly superimpose one another in the output-side optical element 162, or the output-side lens T2, as well as in the objective 170 connected downstream from the optical beam expansion unit 161, 162, as will be explained by means of FIG. 6. When looking at FIG. 4 and FIG. 5, one may clearly discern a difference in the optical paths extending through the optical device 100.

[0086] By means of FIG. 6, the above-mentioned dimensioning for optimum superposition of bundles of beams in accordance with an embodiment is to be illustrated. To this end, by way of simplifying matters, only that section of FIGS. 4 and 5 is shown which includes the point X at the location of superposition of the individual bundles of beams as well as the optical beam expansion unit 161, 162. The condition to be demanded consists in that the bundle centers of the bundles of beams, which coincide at a distance f.sub.OE after the imaging optical element 150, will also coincide again within a plane of the output-side optical element, or the output-side lens T2, of the telescope. In FIG. 6, the individual beams represent the respective centers of the individual bundles of beams, which originate from different positions of the imaging optical element 150 and extend toward the optical beam expansion unit 161, 162. The condition may be formulated as an imaging task, for which the following applies:

[0087] The point X, or object point, is a position which is located on the optical axis OA and at which all of the centers of the bundles of beams, i.e. the bundle centers, coincide. The point X is imaged by the lens T1, at the image distance f.sub.T,1+f.sub.T,2, into an image point that is also located on the optical axis. A defining quantity for meeting the imaging task is the distance between the object point, or X, and T1

[0088] To this end, the following are to be inserted into the imaging equation

[00011]$\begin{array}{cc}\frac{1}{s}+\frac{1}{s^{\prime }}=\frac{1}{f}& \left(\mathrm{ED}1\right)\end{array}$ [0089] as the object width s, the quantity f.sub.T1+Δ [0090] as the image distance s′, the quantity f.sub.T1+f.sub.T2 [0091] and as the focal length f, the quantity f.sub.T1,
as a result of which the quantity A to be determined amounts to

[00012]$\begin{array}{cc}\Delta =\frac{f_{T1}}{f_{T2}}\left(f_{T1}+f_{T2}\right)-f_{T1}=f_{T1}^2/f_{T2}.& \left(\mathrm{ED}2\right)\end{array}$

[0092] In accordance with alternative embodiments, it shall suffice for A to be located within a range of ±50% of the value in accordance with ED 2.

[0093] For bundle superposition within the objective 170, minor modifications in A arise when a finite distance between T2 and the objective 170 is to be taken into account, e.g. when further optical elements are to be introduced into the optical path there.

[0094] FIG. 7 shows a simplified diagram for illustrating bundle superposition and beam expansion be means of an astronomic telescope comprising lenses T1, T2 by analogy with preceding FIGS. 4 to 6 for explaining insufficient illumination of the objective 170 in case of too heavily collimated bundles of beams. Illumination of the output-side optical element, or of the output-side lens T2, of the optical beam expansion unit 161, 162 and/or the objective 170 connected downstream from the optical beam expansion unit 161, 162 is set in that the parallel bundles of beams, which impinge on the imaging optical element 150, exhibit a certain convergence or divergence—in other words, they are not collimated in an ideal manner. This may be gathered, in FIG. 4, from the left of the imaging optical element 150, the curved lines of the individual bundles of beams indicating Gaussian bundles of beams.

[0095] One can recognize from FIG. 7 that in case of too heavily collimated bundles of beams, the bundles of beams will illuminate only a very small part of the output-side optical element T2 and/or of the objective 170 connected downstream from the optical beam expansion unit 161, 162.

[0096] FIG. 8 shows a simplified diagram for illustrating beam expansion by means of an astronomic telescope in accordance with an embodiment in connection with explaining the Gaussian beam in FIG. 2. FIG. 8 describes an embodiment wherein the distances of source points Y.sub.i.sup.source and target points Y.sub.i.sup.target differ by a factor of 100. Accordingly, there is also a reduction in size of a bundle of beams, or of a bundle waist, as may be gathered from the waist sizes in FIG. 8. The starting point for the reduction in size of 100:1 is not the waist of the bundle of beams of the source 110 but the waist which is generated by a collimation lens 120 that is not set to perform ideal collimation. In the embodiment, the latter amounts to 89 micrometers and is transformed, by the 100:1 reduction in size within the focal plane of the objective, to a waist size of 0.89 micrometers.

[0097] FIG. 9 shows a simplified diagram for illustrating the optical path of an optical device 100 while using a refractive optical beam expansion unit 161, 162 in accordance with an embodiment. Unlike the embodiment of FIG. 1, the embodiment of FIG. 9 comprises a reflective optical element 150. The reflective imaging optical element 150 may be a parabolic mirror, for example. In the embodiment comprising a reflective imaging optical element 150—parabolic mirror—the source 110, or the collimator 120, is arranged at a specific angle so that no shadowing may occur.

[0098] FIG. 10 shows a simplified diagram for illustrating the optical path of an optical device 100 while using a reflective optical beam expansion unit 165, 166. Unlike the above-explained embodiments of FIGS. 1 and 3 to 9, the embodiment of FIG. 10 comprises no rearrangement unit 130, 140. The individual parallel bundles of beams of the beam source 110 are guided, via collimator 120, directly to an imaging optical element 155, from where the bundles of beams are forwarded, via an optical beam expansion unit 165, 166 in the form of a reflective telescope including two parabolic mirrors, to the objective 170, via which the beams are focused into an image surface 190.

[0099] While this invention has been described in terms of several embodiments, there are alterations, permutations, and equivalents which fall within the scope of this invention. It should also be noted that there are many alternative ways of implementing the methods and compositions of the present invention. It is therefore intended that the following appended claims be interpreted as including all such alterations, permutations and equivalents as fall within the true spirit and scope of the present invention.

[0100] The research work that has led to these results has been supported by the European Union.