Optical device and method for changing the polarization of a polarized light beam

Abstract

The application also relates to an optical device (10) for changing the polarization of a polarized light beam (12).

Description

Technical Field

[0001] This invention relates to optical devices and methods for changing the polarization of polarized light beams. Background Technology

[0002] Optical devices for altering the polarization of a polarized light beam are known, taking the form of λ / 2 plates and / or λ / 4 plates. Typically, the λ / 2 or λ / 4 plates are made of a birefringent material through which the polarized light beam passes to change its polarization.

[0003] In the case of high-power polarized beams and / or at wavelengths of polarized beams where no birefringent material is available, polarization is typically altered by reflecting the polarized beam from a phase-shifting mirror.

[0004] A phase-shifting mirror can be understood as a mirror that reflects a light beam with a phase shift relative to the incident plane of the beam, between the P-polarization and S-polarization components of the beam. A phase-shifting mirror can, for example, have a 90° phase shift, although any other amount of phase shift is conceivable. A 90° phase shift can be understood as a phase shift of λ / 4. This allows a phase-shifting mirror with a 90° phase shift to reflect a linearly polarized beam incident on it with equal P-polarization and S-polarization components as a circularly polarized beam.

[0005] A phase-shifting mirror can be a mirror with a phase shift of at least 5°. A mirror with a phase shift of less than 5° cannot be a phase-shifting mirror. Summary of the Invention

[0006] The object of the present invention is to provide an optical device and method for changing the polarization of a polarized beam, the optical device and method each having improved characteristics, particularly enabling the change of polarization of a polarized beam in the case of a high-power polarized beam and / or at the wavelength of a polarized beam in which no birefringent material is available.

[0007] This invention achieves this objective by means of an optical device having the features of claim 1 and a method for changing the polarization of a polarized beam having the features of claim 9. Advantageous embodiments and further improvements of the invention arise from the dependent claims.

[0008] The optical device according to the invention is configured to change the polarization of a polarized light beam. The optical device includes an optical system having a first optical arrangement structure and a second optical arrangement structure. The first optical arrangement structure has a plurality of reflective optical elements for reflecting the light beam, such as 3, 4, 5, or 6 reflective optical elements. The first optical arrangement structure is rotatably mounted about a first rotation axis of the optical system. The second optical arrangement structure has a plurality of reflective optical elements for reflecting the light beam, such as 3, 4, 5, or 6 reflective optical elements. The second optical arrangement structure is rotatably mounted about a second rotation axis of the optical system. The first and second optical arrangement structures are arranged such that a polarized light beam passes through the first and second optical arrangement structures, particularly sequentially, for the purpose of changing its polarization. The optical system is configured to change the polarization of the polarized light beam by reflecting the polarized light beam by means of the plurality of reflective optical elements of the first optical arrangement structure, and by means of the plurality of reflective optical elements of the second optical arrangement structure, depending on the rotational position of the first and second optical arrangement structures.

[0009] Advantageously, the polarization of the polarized beam can be set by rotating the first optical arrangement about a first rotation axis and / or by rotating the second optical arrangement about a second rotation axis. For example, this allows the polarization of the polarized beam to be changed to a predetermined polarization using optical devices.

[0010] Another aspect of the invention is that, by using a first optical arrangement structure and a second optical arrangement structure, the setting of polarization changes in a polarized beam can be performed particularly quickly. Specifically, the polarization change can be set by rotating the first and / or second optical arrangement structures by a particularly small rotation angle. This allows for less space to be required to rotate the first and / or second optical arrangement structures, thereby achieving a particularly compact construction of the optical device for both the first and second optical arrangement structures.

[0011] More advantageously, even when the polarized beam has a wavelength with high power and / or no birefringent material is available, the optical device can change the polarization of the polarized beam by using reflective optics.

[0012] This allows the present invention to change the polarization of a polarized beam in a particularly simple and variable manner.

[0013] A polarized beam can be guided through multiple reflecting optical elements in a first optical arrangement and multiple reflecting optical elements in a second optical arrangement for the purpose of changing its polarization.

[0014] The polarization of a polarized beam, especially before it passes through an optical device, can be linear, elliptical, or circular. For example, an optical device can be used to change the linear polarization of a polarized beam to circular polarization. For example, an optical device can be used to change the elliptical polarization of a polarized beam to circular or linear polarization. For example, an optical device can be used to change the circular polarization of a polarized beam to linear polarization.

[0015] The beam can be a laser beam. The beam can be a beam from a CO2 laser. The power of the beam can be in a first range of 50 W to 300 W, particularly in a range of 100 W to 200 W, and / or in a second range of 8 kW to 50 kW, particularly in a range of 10 kW to 30 kW. The wavelength of the beam can be in a range of 9 μm to 12 μm, particularly in a range of 10 μm to 11 μm. For example, the wavelength of the beam can be 10.6 μm.

[0016] Each reflecting optical element in the first optical arrangement and / or the second optical arrangement can be constructed as a mirror, particularly a Bragg mirror.

[0017] The multiple reflecting optics in the first optical arrangement may have at least one phase-shifting mirror for changing the polarization of the beam. The multiple reflecting optics in the second optical arrangement may also have at least one phase-shifting mirror for changing the polarization of the beam. Each phase-shifting mirror in the optical system may have a phase shift in the range of 2.5° to 175°, particularly 3.5° to 120°, particularly 5° to 90°, and particularly 10° to 80°. The phase shift of the phase-shifting mirror can be a phase change between the fraction of the P-polarization component and the fraction of the S-polarization component of the polarized beam, which the polarized beam has after reflection at the phase-shifting mirror.

[0018] The first optical arrangement structure may have a housing rotatably mounted about a first rotation axis. The housing of the first optical arrangement structure may have an internal space in which a plurality of reflective optical elements of the first optical arrangement structure are arranged. The plurality of reflective optical elements of the first optical arrangement structure may be attached to the housing of the first optical arrangement structure.

[0019] The second optical arrangement structure may have a housing rotatably mounted about a second rotation axis. The housing of the second optical arrangement structure may have an internal space in which multiple reflective optical elements of the second optical arrangement structure are arranged. The multiple reflective optical elements of the second optical arrangement structure may be attached to the housing of the second optical arrangement structure.

[0020] A polarized beam can have an X-polarization component in the X direction and a Y-polarization component in the Y direction, which is orthogonal to the X direction. Changing the polarization of a polarized beam can be understood as changing the amplitude ratio between the X-polarization component and the Y-polarization component of the polarized beam and / or changing the phase shift between the X-polarization component and the Y-polarization component of the polarized beam.

[0021] When a polarized beam enters the reflecting optical component of an optical system, it can define the incident plane.

[0022] The proportions of the P-polarization component and the S-polarization component on each reflecting optical element of the first optical arrangement can depend on the rotational position of the first optical arrangement. By rotating the first optical arrangement about a first rotation axis, the proportions of the P-polarization component and the S-polarization component on each reflecting optical element of the first optical arrangement can be changed.

[0023] The proportions of the P-polarization component and the S-polarization component on each reflecting optical element of the second optical arrangement can depend on the rotational position of the second optical arrangement. By rotating the second optical arrangement about a second rotation axis, the proportions of the P-polarization component and the S-polarization component on each reflecting optical element of the second optical arrangement can be changed.

[0024] For example, in the case of elliptically polarized beams, the fractions of the P-polarization component and the S-polarization component on the reflecting optics of the first optical arrangement can be changed by rotating the first optical arrangement about a first rotation axis. This allows the amplitude ratio between the X-polarization component and the Y-polarization component, as well as the phase shift between the X-polarization component and the Y-polarization component, to be changed by rotating the first optical arrangement about the first rotation axis, provided that at least one reflecting optics of the first optical arrangement is configured as a phase-shifting mirror.

[0025] For example, in the case of elliptically polarized beams, the fractions of the P-polarization component and the S-polarization component on the reflecting optics of the second optical arrangement can be changed by rotating the second optical arrangement about the second rotation axis. This allows the amplitude ratio between the X-polarization component and the Y-polarization component, as well as the phase shift between them, to be changed by rotating the second optical arrangement about the second rotation axis, provided that at least one reflecting optics of the second optical arrangement is configured as a phase-shifting mirror.

[0026] Another aspect of the invention is that, by using a first optical arrangement structure and a second optical arrangement structure, the amplitude ratio between the X-polarized and Y-polarized components of the polarized beam and the phase shift between the X-polarized and Y-polarized components of the polarized beam can be set within a range having any combination. For example, the second optical arrangement structure can occupy a rotational position in which the change in amplitude ratio or phase shift caused by the first optical arrangement structure is partially or completely compensated.

[0027] The first optical arrangement structure can be rotatably mounted about a first rotation axis, independent of the rotational position of the second optical arrangement structure, and in particular, the rotational position of the second optical arrangement structure. The second optical arrangement structure can be rotatably mounted about a second rotation axis, independent of the rotational position of the first optical arrangement structure, and in particular, the rotational position of the first optical arrangement structure.

[0028] For example, a first optical arrangement can alter the amplitude ratio between the X-polarization and Y-polarization components of a polarized beam, and simultaneously cause an undesirable phase shift between the X-polarization and Y-polarization components. A second optical arrangement can be used to compensate for this undesirable phase shift.

[0029] For example, a first optical arrangement can alter the phase shift between the X-polarized and Y-polarized components of a polarized beam, and simultaneously cause an undesirable amplitude ratio between the X-polarized and Y-polarized components. A second optical arrangement can be used to compensate for this undesirable amplitude ratio.

[0030] In other words, after passing through the optical system, a polarized beam can exhibit the desired amplitude ratio between the X-polarized and Y-polarized components of the beam, as well as the desired phase shift between the X-polarized and Y-polarized components.

[0031] In a further improvement to the optical device, the multiple reflecting optical elements of the first optical arrangement, particularly in general, exhibit a phase shift in the range of 40° to 80°, especially 50° to 80°, and particularly 50° to 70°. Additionally or alternatively, the multiple reflecting optical elements of the second optical arrangement, particularly in general, exhibit a phase shift in the range of 40° to 80°, particularly 50° to 80°, and particularly 50° to 70°. This allows for alteration of the polarization of the polarized beam over a particularly large region.

[0032] The phase shift of the first optical arrangement can be the phase change between the fraction of the P-polarization component and the fraction of the S-polarization component of the polarized beam, which the polarized beam has after passing through the first optical arrangement.

[0033] The phase shift of the second optical arrangement can be the phase change between the fraction of the P-polarization component and the fraction of the S-polarization component of the polarized beam, which the polarized beam has after passing through the second optical arrangement.

[0034] The multiple reflective optics of the first optical arrangement can exhibit a phase shift of approximately 60° in general. Additionally or alternatively, the multiple reflective optics of the second optical arrangement can exhibit a phase shift of approximately 60°.

[0035] In a further improvement of the optical device, the plurality of reflective optical elements in the first optical arrangement have a first phase-shifting mirror and a second phase-shifting mirror. Additionally or alternatively, the plurality of reflective optical elements in the second optical arrangement have a first phase-shifting mirror and a second phase-shifting mirror.

[0036] The first phase-shifting mirror and the second phase-shifting mirror of the first optical arrangement may each have a phase shift equal to half the phase shift value of the first optical arrangement. Specifically, the first and second phase-shifting mirrors of the first optical arrangement may each have a phase shift in the range of 5° to 45°, particularly 20° to 40°. For example, the first and second phase-shifting mirrors of the first optical arrangement may each have a phase shift of approximately 30°.

[0037] The first phase-shifting mirror of the second optical arrangement and the second phase-shifting mirror of the second optical arrangement can each have a phase shift equal to half the phase shift of the second optical arrangement. Specifically, the first phase-shifting mirror of the second optical arrangement and the second phase-shifting mirror of the second optical arrangement can each have a phase shift in the range of 5° to 45°, particularly in the range of 20° to 40°. For example, the first phase-shifting mirror of the second optical arrangement and the second phase-shifting mirror of the second optical arrangement can each have a phase shift of approximately 30°.

[0038] In a further improvement of the optical device, a first optical arrangement structure for changing the polarization of a polarized beam has a rotational position in which the first optical arrangement structure is configured to change the amplitude ratio between the X-polarized component and the Y-polarized component orthogonal to the X-polarized component of the polarized beam more significantly than a second optical arrangement structure, and in this rotational position, the first optical arrangement structure is configured to change the phase shift between the X-polarized component and the Y-polarized component of the polarized beam less significantly than a second optical arrangement structure.

[0039] In a further improvement to the optical device, a plurality of reflecting optical elements in the first optical arrangement are arranged such that the beam axis of the polarized beam after passing through the first optical arrangement, in particular regardless of the rotational position of the first optical arrangement, forms a continuation of the beam axis of the polarized beam, particularly immediately preceding its passage through the first optical arrangement. Additionally or alternatively, a plurality of reflecting optical elements in the second optical arrangement are arranged such that the beam axis of the polarized beam after passing through the second optical arrangement, in particular regardless of the rotational position of the second optical arrangement, forms a continuation of the beam axis of the polarized beam, particularly immediately preceding its passage through the second optical arrangement. Advantageously, this allows the propagation direction of the polarized beam after passing through the first and / or second optical arrangements to be the same as the propagation direction of the polarized beam, particularly immediately preceding its passage through the first and / or second optical arrangements. In other words, a change in the propagation direction of the polarized beam does not occur upon the passing of the polarized beam through the first and / or second optical arrangements.

[0040] The polarized beam, particularly the beam axis immediately preceding its passage through the first optical arrangement, can be oriented parallel to the first rotation axis. The polarized beam, particularly the beam axis immediately preceding its passage through the second optical arrangement, can be oriented parallel to the second rotation axis.

[0041] The multiple reflecting optical elements of the first optical arrangement and the multiple reflecting optical elements of the second optical arrangement can be arranged such that the polarized beam forms a polarized beam on the beam axis after passing through the optical system, particularly a continuation of the beam axis immediately preceding the passing through the optical system.

[0042] In a further improvement to the optical device, the polarized beam has an X-polarization component in the X direction and a Y-polarization component in the Y direction, which is orthogonal to the X direction, before passing through the optical system. The phase shift of the first optical arrangement and the phase shift of the second optical arrangement are the same. The change in the amplitude ratio between the X-polarization component and the Y-polarization component of the polarized beam after passing through the optical system satisfies the condition... ,in, It is the change in the amplitude ratio between the X-polarization component and the Y-polarization component of the polarized beam. It is the phase shift of the first optical arrangement structure or the phase shift of the second optical arrangement structure. It is the rotation angle of the first optical arrangement structure relative to the X direction about the first rotation axis, and It is the rotation angle of the second optical arrangement structure relative to the X direction about the second rotation axis. The change in phase shift between the X-polarized component and the Y-polarized component of the polarized beam after passing through the optical system satisfies the condition. ,in, It is the phase shift change between the X-polarization component and the Y-polarization component of the polarized beam.

[0043] if If the magnitude has a value in the range of 0° to 10°, then the condition for the change in amplitude ratio... And / or conditions for phase shift changes It can be effective.

[0044] In a further improvement to the optical device, the first optical arrangement structure and the second optical arrangement structure are constructed identically. This advantageously simplifies the assembly of the first and second optical arrangement structures. Advantageously, by using the same components for both the first and second optical arrangement structures, costs can be saved due to economies of scale.

[0045] In a further improvement to the optical device, the first and second rotation axes are oriented parallel to each other. The first rotation axis can be arranged such that the second rotation axis becomes a continuation of the first rotation axis.

[0046] The method according to the invention is configured to change the polarization of a polarized beam. The method includes the following steps: a) generating a polarized beam; b) setting a rotational position of a first optical arrangement structure, wherein the first optical arrangement structure has a plurality of reflective optics for reflecting the beam; c) setting a rotational position of a second optical arrangement structure, wherein the second optical arrangement structure has a plurality of reflective optics for reflecting the beam; and d) changing the polarization of the polarized beam by reflecting the polarized beam using the plurality of reflective optics of the first optical arrangement structure and the plurality of reflective optics of the second optical arrangement structure, based on the rotational positions of the first and second optical arrangement structures.

[0047] This method can be adapted to operate the optical devices previously described.

[0048] Steps b) and c) can be performed simultaneously or in any desired order. Steps b) and c) can be performed before or after step a).

[0049] Steps b) and c) can each be performed for the purpose of changing the polarization of the polarized beam. For example, steps b) and c) can each be performed such that the polarization change of the polarized beam in step d) causes the desired polarization.

[0050] Step b) can be performed by rotating the first optical arrangement structure about a first rotation axis of the optical system. Step c) can be performed by rotating the second optical arrangement structure about a second rotation axis of the optical system. The optical system may include the first optical arrangement structure and the second optical arrangement structure.

[0051] In a further improvement to this method, the polarized beam has an X-polarization component in the X direction and a Y-polarization component in the Y direction, which is orthogonal to the X direction. The method includes the following steps: e) pre-setting a target amplitude ratio between the X-polarization and Y-polarization components; f) pre-setting a target phase shift between the X-polarization and Y-polarization components; g) measuring the actual amplitude ratio between the X-polarization and Y-polarization components; h) measuring the actual phase shift between the X-polarization and Y-polarization components; and i) determining the target rotation position of the first optical arrangement structure and the target rotation position of the second optical arrangement structure based on the target amplitude ratio, the target phase shift, the actual amplitude ratio, and the actual phase shift. Step b) is performed by setting the target rotation position of the first optical arrangement structure. Step c) is performed by setting the target rotation position of the second optical arrangement structure.

[0052] The measurements in step g) and / or step h) can be performed along the propagation direction of the polarized beam before the first optical arrangement structure or along the propagation direction of the polarized beam after the second optical arrangement structure.

[0053] For example, the measurements in step g) and step h) can be performed before the polarized beam passes through the first optical arrangement structure, wherein the target rotation position of the first optical arrangement structure obtained in step i) and the target rotation position of the second optical arrangement structure obtained in step i) are each absolute target rotation positions.

[0054] For example, the measurements in step g) and step h) can be performed after the polarized beam has passed through the second optical arrangement structure, wherein the target rotation position of the first optical arrangement structure obtained in step i) and the target rotation position of the second optical arrangement structure obtained in step i) are each relative target rotation positions. The relative target rotation positions can each represent the change in the rotation position of the first optical arrangement structure and the change in the rotation position of the second optical arrangement structure.

[0055] Steps e) and f) can be performed before steps b) and i). Steps g) and h) can be performed before steps b) and i). Step i) can be performed before step b).

[0056] The method may include the step: k) pre-given the phase shift of the first optical arrangement and the phase shift of the second optical arrangement. Step k) may be performed before step i).

[0057] The phase shift of the first optical arrangement and the phase shift of the second optical arrangement can be the same. Step i) can be based on the condition and Execution, among which, It is the target rotation position of the first optical arrangement structure. It is the target rotation position of the second optical arrangement structure. It is the difference between the actual amplitude ratio and the target amplitude ratio, and It is the difference between the actual phase shift and the target phase shift.

[0058] if If the value is in the range of 0° to 10°, then the condition for the target rotation position of the first optical arrangement structure is... And / or the condition for the target rotational position of the second optical arrangement structure It can be effective.

[0059] Further advantages and advantageous configurations of the invention can be derived from the drawings, their description, and the claims. All features disclosed in the drawings, their description, and the claims, whether individually or in any desired combination, may be essential to the invention. Attached Figure Description

[0060] Figure 1 A schematic diagram of the optical device is shown. Figure 2 A schematic diagram of the polarization of a polarized beam is shown. Figure 3 It shows Figure 1 A curve diagram of the rotation region of the first and second optical arrangement structures of the optical device. Figure 4 A schematic diagram of another exemplary embodiment of the first optical arrangement structure is shown. Figure 5 A schematic diagram of another exemplary embodiment of the first optical arrangement structure is shown, and Figure 6 It shows Figure 5 Another schematic diagram of the first optical arrangement structure. Detailed Implementation

[0061] Figure 1 An optical device 10 for changing the polarization of a polarized beam 12 is shown. The beam 12 is a laser beam from a CO2 laser. The power of the beam 12 is 100 W to 200 W, and the wavelength of the beam 12 is 10.6 μm.

[0062] Beam 12 can be an elliptically polarized beam 12. For example, the polarization of beam 12 can be affected by reflections from the optical components of the CO2 laser that generates beam 12, and by different reflection values ​​for the P-polarization component and the S-polarization component, causing beam 12 to exhibit elliptically polarization.

[0063] Figure 2The polarization ellipse 14 of the beam 12 is schematically shown. The polarized beam 12 has an X-polarization component 18 in the X direction 16 and a Y-polarization component 22 in the Y direction 20, which is orthogonal to the X direction 16. The Y-polarization component 22 is smaller than the X-polarization component 18. The amplitude ratio between the X-polarization component 18 and the Y-polarization component 22 is 1:0.8, or in other words, the amplitude ratio is 1.25. The principal axis of the polarization ellipse 14 is rotated by an angle 24 relative to the X direction 16. The phase shift between the X-polarization component 18 and the Y-polarization component 22 is 65°.

[0064] The optical device 10 is configured to change the polarization of the polarized beam 12 by altering the amplitude ratio and phase shift between the X-polarization component 18 and the Y-polarization component 22. For this purpose, the optical device 10 has an optical system 26 having a first optical arrangement structure 28 and a second optical arrangement structure 30.

[0065] The first optical arrangement structure 28 has a plurality of reflective optical elements 32 in the form of mirrors for reflecting the polarized beam 12. The reflective optical elements 32 of the first optical arrangement structure 28 are arranged in a plane. The beam 12 is guided by the plurality of reflective optical elements 32 of the first optical arrangement structure 28.

[0066] Each reflecting optic 32 of the first optical arrangement 28 is configured as a Bragg mirror. In general, the first optical arrangement 28 has four mirrors. However, it is also conceivable that the first optical arrangement has three, five, or six reflecting optics.

[0067] The beam 12 passes through the first optical arrangement structure 28. The beam 12 is first reflected by the first mirror 34 of the first optical arrangement structure 28, then reflected by the second mirror 36, then reflected by the third mirror 38, and then reflected by the fourth mirror 40.

[0068] The second mirror 36 and the third mirror 38 of the first optical arrangement 28 are configured as phase-shifting mirrors. Each of the second mirror 36 and the third mirror 38 of the first optical arrangement 28 has a phase shift of 30°. The phase shift is the phase angle generated between the P-polarization component and the S-polarization component of the beam 12 relative to the incident plane of the beam 12 on the respective mirrors 36 and 38 when the phase-shifting mirrors reflect the beam 12.

[0069] The first mirror 34 and the fourth mirror 40 of the first optical arrangement 28 are constructed as mirrors without phase shift. This results in an overall phase shift of 60° for the first optical arrangement 28.

[0070] The first optical arrangement structure 28 is rotatably mounted about a first rotation axis 42 of the optical system 26. The first rotation axis 42 is arranged such that it passes through the first mirror 34 and the fourth mirror 40 of the first optical arrangement structure 28. By rotating the first optical arrangement structure 28, the arrangement of the reflecting optical elements 32 of the first optical arrangement structure 28 relative to each other remains unchanged. By rotating the first optical arrangement structure 28 about the first rotation axis 42, the proportions of the P-polarization component and the S-polarization component of the beam 12 on the second mirror 36 and the third mirror 38 of the first optical arrangement structure 28 are changed. This changes the amplitude ratio and phase shift between the X-polarization component 18 and the Y-polarization component 22 of the polarized beam 12 according to the rotational position of the first optical arrangement structure 28. Therefore, the polarization of the beam 12 is changed by the first optical arrangement structure 28 according to its rotational position.

[0071] The plurality of reflective optical devices 32 of the first optical arrangement structure 28 are arranged such that the beam axis 44 after the polarized beam 12 passes through the first optical arrangement structure 28 forms a continuation of the beam axis 46 before the polarized beam 12 passes through the first optical arrangement structure 28, regardless of the rotational position of the first optical arrangement structure 28.

[0072] exist Figure 1 In the exemplary embodiment illustrated, the beam axis 46 of the beam 12 is oriented parallel to the first rotation axis 42 before passing through the first optical arrangement structure 28.

[0073] The second optical arrangement structure 30 is structurally the same as the first optical arrangement structure 28.

[0074] The first optical arrangement structure 28 and the second optical arrangement structure 30 are arranged relative to each other such that the polarized beam 12 passes through the first optical arrangement structure 28 and the second optical arrangement structure 30 in sequence.

[0075] The second optical arrangement structure 30 has a plurality of reflective optical elements 48 in the form of mirrors for reflecting the polarized beam 12. The reflective optical elements 48 of the second optical arrangement structure 30 are arranged in a plane. The beam 12 is guided on the plurality of reflective optical elements 48 of the second optical arrangement structure 30.

[0076] Each reflecting optic 48 of the second optical arrangement 30 is configured as a Bragg mirror. In general, the second optical arrangement 30 has four mirrors. However, it is also conceivable that the second optical arrangement has three, five, or six reflecting optics.

[0077] The beam 12 passes through the second optical arrangement structure 30. The beam 12 is first reflected by the first mirror 50 of the second optical arrangement structure 30, then reflected by the second mirror 52, then reflected by the third mirror 54, and then reflected by the fourth mirror 56.

[0078] The second mirror 52 and the third mirror 54 of the second optical arrangement structure 30 are configured as phase-shifting mirrors. The second mirror 52 and the third mirror 54 each have a phase shift of 30°.

[0079] The first mirror 50 and the fourth mirror 56 of the second optical arrangement 30 are constructed as mirrors without phase shift. This results in a phase shift of 60° for the second optical arrangement 30.

[0080] The second optical arrangement structure 30 is rotatably mounted about the second rotation axis 58 of the optical system 26. The second optical arrangement structure 30 is configured to rotate independently of the first optical arrangement structure 28 about the second rotation axis 58. The second rotation axis 58 is arranged such that it passes through the first mirror 50 and the fourth mirror 56 of the second optical arrangement structure 30. By rotating the second optical arrangement structure 30, the arrangement of the reflecting optics 48 relative to each other remains unchanged. By rotating the second optical arrangement structure 30 about the second rotation axis 58, the proportions of the P-polarization and S-polarization components of the beam 12 on the second mirror 52 and the third mirror 54 of the second optical arrangement structure 30 are changed. This changes the amplitude ratio and phase shift between the X-polarization component 18 and the Y-polarization component 22 of the polarized beam 12 according to the rotational position of the second optical arrangement structure 30. Therefore, the polarization of the beam 12 is changed by the second optical arrangement structure 30 according to its rotational position.

[0081] The plurality of reflective optical elements 48 of the second optical arrangement structure 30 are arranged such that the beam axis 60 after the polarized beam 12 passes through the second optical arrangement structure 30 forms a continuation of the beam axis 44 before the polarized beam 12 passes through the second optical arrangement structure 30, regardless of the rotational position of the second optical arrangement structure 30.

[0082] exist Figure 1 In the illustrated exemplary embodiment, the beam axis 44 of the beam 12 is oriented parallel to the second rotation axis 58 before passing through the second optical arrangement structure 30. The first rotation axis 42 and the second rotation axis 58 are oriented parallel to each other. The first rotation axis 42 and the second rotation axis 58 are arranged relative to each other such that the second rotation axis 58 forms a continuation of the first rotation axis 42.

[0083] The reflecting optical element 32 of the first optical arrangement structure 28 and the reflecting optical element 48 of the second optical arrangement structure 30 are arranged such that the propagation direction 62 of the polarized beam 12 before passing through the optical system 26 is equal to the propagation direction 64 of the polarized beam 12 after passing through the optical system 26. In other words, the optical system 26 does not cause any change in the propagation direction 62 of the polarized beam 12.

[0084] With the aid of the first optical arrangement structure 28 and the second optical arrangement structure 30, the optical system 26 is configured to change the polarization of the polarized beam 12 by reflecting the polarized beam 12 at the reflecting optical device 32 of the first optical arrangement structure 28 and the reflecting optical device 48 of the second optical arrangement structure 30, depending on the rotational position of the first optical arrangement structure 28 and the second optical arrangement structure 30.

[0085] The polarization of the polarized beam 12 can be changed by rotating the first optical arrangement structure 28 about the first rotation axis 42 and / or by rotating the second optical arrangement structure 30 about the second rotation axis 58.

[0086] Figure 3 The diagram shows the changes in the amplitude ratio and phase shift between the X-polarization component 18 and the Y-polarization component 22 after the illustrated polarized beam 12 passes through the optical system 26 with a 60° phase shift of the first optical arrangement structure 28 and a 60° phase shift of the second optical arrangement structure 30. In other words: and for different rotation angles of the first optical arrangement structure 28 and different rotation angles for the second optical arrangement structure 30 . Figure 3 The curves in the graph are calculated for linear input polarization in the Y direction and for circular output polarization. Figure 3 The changes shown in the graph are related to the circular output polarization.

[0087] For example, Figure 3 It is shown that at point A, the first optical arrangement 28 has a rotation angle of 154.5° relative to the X direction 16, and the second optical arrangement 30 has a rotation angle of 118°. At these rotation angles, the optical system 26 causes a polarization change in the polarized beam 12, such that after passing through the optical system 26, its amplitude ratio changes by 0.25 and its phase shift changes by 10°. This change in amplitude ratio and phase shift allows for circular output polarization of the beam 12.

[0088] Figure 3 It is also shown that the phase shift and amplitude ratio between the X-polarization component 18 and the Y-polarization component 22 of the polarized beam 12 can be set independently of each other by means of the optical system 26.

[0089] For example, optical system 26 causes a change in amplitude ratio of 0 and a phase shift of 10° at point B. In order to travel from point A to point B via optical system 26 without changing the phase shift, it is necessary to simultaneously adjust the rotation angles of the first optical arrangement structure 28 and the second optical arrangement structure 30.

[0090] In other words, by means of the optical system 26, the amplitude ratio between the X-polarization component 18 and the Y-polarization component 22 of the polarized beam 12 can be changed without changing the phase shift between the X-polarization component 18 and the Y-polarization component 22 of the polarized beam 12.

[0091] For example, optical system 26 causes a change in amplitude ratio of 0.25 and a phase shift of -20° at point C. In order to travel from point A to point C via optical system 26 without changing the amplitude ratio, it is necessary to simultaneously adjust the rotation angles of the first optical arrangement structure 28 and the second optical arrangement structure 30.

[0092] In other words, by means of the optical system 26, the phase shift between the X-polarization component 18 and the Y-polarization component 22 of the polarized beam 12 can be changed without changing the amplitude ratio between the X-polarization component 18 and the Y-polarization component 22 of the polarized beam 12.

[0093] In other words, the first optical arrangement structure 28 and the second optical arrangement structure 30 allow the amplitude ratio between the X-polarized component and the Y-polarized component of the polarized beam 12 and the phase shift between the X-polarized component and the Y-polarized component of the polarized beam 12 to be set independently of each other.

[0094] exist Figures 1 to 3 In the exemplary embodiment illustrated, the polarization of the elliptically polarized beam 12 is altered by means of the optical system 26, resulting in circular polarization of the beam 12. For this purpose, the polarization of the beam 12 is measured upstream of the optical system 26. The amplitude ratio between the X-polarized component 18 and the Y-polarized component 22 of the beam 12 is 1.25, and the phase shift between the X-polarized component 18 and the Y-polarized component 22 is 65°. Circular polarization requires an amplitude ratio between the X-polarized component and the Y-polarized component of 1, and a phase shift between the X-polarized component and the Y-polarized component of 90°.

[0095] Figure 3Point D shows that, with the rotation angle of the first optical arrangement structure 28 being 174° and the rotation angle of the second optical arrangement structure 30 being 118°, the optical system 26 reduces the amplitude ratio between the X-polarization component 18 and the Y-polarization component 22 of the beam 12 by 0.25 and increases the phase shift between the X-polarization component 18 and the Y-polarization component 22 by 25°. In other words, with a rotation angle of 174° for the first optical arrangement structure 28 and a rotation angle of 118° for the second optical arrangement structure 30, the optical system 26 changes the elliptical polarization of the beam 12 to circular polarization.

[0096] Optical device 10 is configured to perform a method for changing the polarization of polarized beam 12. The method includes the following steps: k) pre-setting the phase shift of the first optical arrangement structure 28 and the phase shift of the second optical arrangement structure 30; e) pre-setting a target amplitude ratio between the X-polarization component 18 and the Y-polarization component 22; f) pre-setting a target phase shift between the X-polarization component 18 and the Y-polarization component 22; a) generating polarized beam 12; g) measuring the actual amplitude ratio between the X-polarization component 18 and the Y-polarization component 22; h) measuring the actual phase shift between the X-polarization component 18 and the Y-polarization component 22; i) based on the phase shift of the first optical arrangement structure 28, the phase shift of the second optical arrangement structure 30, the target amplitude ratio, the target phase shift, the actual amplitude ratio, and... a) Obtain the target rotation position of the first optical arrangement structure 28 and the target rotation position of the second optical arrangement structure 30 by actual phase shift; b) Set the target rotation position of the first optical arrangement structure 28; c) Set the target rotation position of the second optical arrangement structure 30; d) According to the set target rotation position of the first optical arrangement structure 28 and the set target rotation position of the second optical arrangement structure 30, change the polarization of the polarized beam 12 by reflecting the polarized beam 12 by means of multiple reflecting optical devices 32 of the first optical arrangement structure 28 and by means of multiple reflecting optical devices 48 of the second optical arrangement structure 30.

[0097] In the illustrated exemplary embodiment, the phase shift of the first optical arrangement structure 28 is pre-defined in step k). Phase shift of the second optical arrangement structure 30 In step e), a target amplitude ratio of 1 is pre-defined. In step f), a target phase shift of 90° is pre-defined. In step g), an actual amplitude ratio of 1.25 is measured. In step h), an actual phase shift of 65° is measured.

[0098] Figure 4 Another exemplary embodiment of the first optical arrangement structure 28 is schematically shown, wherein, in Figures 1 to 3 In exemplary embodiments and in Figure 4In the exemplary embodiments, the same reference numerals are used for the same and functionally equivalent elements, and in this regard, reference can be made to the above regarding... Figures 1 to 3 The explanation given by the exemplary implementation is that it essentially only discusses... Figure 4 Existing differences in exemplary implementations.

[0099] exist Figure 4 In the exemplary embodiment shown, the incident angles of the light beam 12 on the first mirror 34 and the fourth mirror 34 are each greater than 45°. This results in the incident angles on the second mirror 36 and the third mirror 38 having values ​​less than 45°.

[0100] Large changes in phase shift can be achieved particularly easily at large incident angles.

[0101] Figure 4 The reflective optical element 48 of the first optical arrangement structure 28 is arranged such that the propagation path of the beam 12 from the first mirror 34 to the second mirror 36 and the propagation path of the beam 12 from the third mirror 38 to the fourth mirror 40 intersect each other.

[0102] Figure 5 and Figure 6 Another exemplary embodiment of the first optical arrangement structure 28 is schematically shown, wherein, in Figures 1 to 3 In exemplary embodiments and in Figure 5 and Figure 6 In the exemplary embodiments, the same reference numerals are used for the same and functionally equivalent elements, and in this regard, reference can be made to the above regarding... Figures 1 to 3 The explanation given by the exemplary implementation is that it essentially only discusses... Figure 5 and Figure 6 Existing differences in exemplary implementations.

[0103] exist Figure 5 In the exemplary embodiment shown, the incident angles of the light beam 12 on the first mirror 34 and the fourth mirror 34 are each less than 45°. The incident angles of the light beam 12 on the second mirror 36 and the third mirror 38 are each less than 45°.

[0104] In addition, Figure 5 and Figure 6 In the exemplary embodiment shown, the reflective optics 32 of the first optical arrangement structure 28 are not arranged in a single plane. The second mirror 36 is positioned further away from the third mirror 38. Figure 5 The observer. In other words, the second mirror 36 is perpendicular to... Figure 5 The plane shifts backward and away Figure 5 The observer. In Figure 5The rotational position of the first optical arrangement structure 28 shown is such that the second mirror 36 is spaced apart from the first mirror 34 by a distance in the X direction, wherein the distance is a positive value.

[0105] The third mirror 38 is perpendicular to Figure 5 The plane facing forward Figure 5 Observer offset. Figure 5 The rotational position of the first optical arrangement structure 28 shown is such that the third mirror 38 is spaced apart from the first mirror 34 by a distance in the X direction, wherein the distance is a negative value.

[0106] Figure 6 The first optical arrangement 28 is shown in a side view. The fourth mirror 40 is... Figure 6 The middle is hidden in the first shot 34, and therefore the fourth shot is in Figure 6 Invisible in the middle. Beam 12 enters the first mirror 34, which is arranged such that beam 12 is guided to the second mirror 36. The second mirror 36 guides beam 12 to the third mirror 38, and the third mirror 38 guides beam 12 to the fourth mirror 40.

Claims

1. An optical device (10) for changing the polarization of a polarized light beam (12), the optical device having: - an optical system (26) having a first optical arrangement (28) and a second optical arrangement (30), - wherein, the first optical arrangement (28) having a plurality of reflecting optics (32) for reflecting the polarized light beam (12), - wherein the first optical arrangement (28) is rotatably mounted about a first rotation axis (42) of the optical system (26), - wherein the second optical arrangement (30) has a plurality of reflecting optics (48) for reflecting the polarized light beam (12), - wherein the second optical arrangement (30) is rotatably mounted about a second rotation axis (58) of the optical system (26), - wherein the first optical arrangement (28) and the second optical arrangement (30) are arranged such that the polarized light beam (12) passes through the first optical arrangement (28) and the second optical arrangement (30) for the purpose of changing the polarization, - wherein the optical system (26) is configured to change the polarization of the polarized light beam (12) by reflecting the polarized light beam (12) by means of the plurality of reflecting optics (32) of the first optical arrangement (28) and by means of the plurality of reflecting optics (48) of the second optical arrangement (30) depending on a rotational position of the first optical arrangement (28) and a rotational position of the second optical arrangement (30).

2. The optical device (10) according to claim 1, - wherein, the plurality of reflecting optics (32) of the first optical arrangement (28) having a phase shift with a magnitude in the range of 50° to 80°, in particular in the range of 50° to 70°, preferably with a magnitude of 60°, and / or - wherein the plurality of reflecting optics (48) of the second optical arrangement (30) have a phase shift with a magnitude in the range of 50° to 80°, in particular in the range of 50° to 70°, preferably with a magnitude of 60°.

3. The optical device (10) according to claim 2, - wherein, the plurality of reflecting optics (32) of the first optical arrangement (28) having a first phase shift mirror (36) and a second phase shift mirror (38), and / or - wherein the plurality of reflecting optics (48) of the second optical arrangement (30) have a first phase shift mirror (52) and a second phase shift mirror (54).

4. The optical device (10) according to any one of the preceding claims, - wherein, The first optical arrangement (28) for changing the polarization of the polarized light beam (12) has a rotational position in which the first optical arrangement (28) changes the amplitude ratio between an X polarization component (18) of the polarized light beam (12) and a Y polarization component (22) of the polarized light beam (12) orthogonal to the X polarization component (18) more strongly than the second optical arrangement (30), and / or in which the first optical arrangement (28) changes the phase shift between the X polarization component (18) of the polarized light beam (12) and the Y polarization component (22) of the polarized light beam (12) less strongly than the second optical arrangement (30).

5. The optical device (10) according to any one of the preceding claims, - wherein, The plurality of reflective optics (32) of the first optical arrangement (28) is arranged such that a beam axis after the polarized light beam (12) has passed through the first optical arrangement (28) forms a continuation of a beam axis before the polarized light beam (12) has passed through the first optical arrangement (28), and / or - wherein the plurality of reflective optics (48) of the second optical arrangement (30) is arranged such that a beam axis after the polarized light beam (12) has passed through the second optical arrangement (30) forms a continuation of a beam axis before the polarized light beam (12) has passed through the second optical arrangement (30).

6. The optical device (10) according to any one of the preceding claims, - wherein, The polarized light beam (12) has an X polarization component (18) in an X direction and a Y polarization component (22) in a Y direction orthogonal to the X direction before passing through the optical system (26), - wherein the phase shift of the first optical arrangement (28) and the phase shift of the second optical arrangement (30) are equal, - wherein a magnitude ratio between the X-polarization component (18) and the Y-polarization component (22) of the polarized light beam (12) after passing through the optical system (26) varies in accordance with a condition wherein is a magnitude ratio between the X-polarization component (18) and the Y-polarization component (22) of the polarized light beam (12), is a phase shift of the first optical arrangement (28), is a rotation angle of the first optical arrangement (28) around the first rotation axis (42) with respect to the X-direction, and is a rotation angle of the second optical arrangement (30) around the second rotation axis (58) with respect to the X-direction, - wherein a variation of a phase shift between the X polarization component (18) and the Y polarization component (22) of the polarized light beam (12) after passing through the optical system (26) fulfills the condition wherein, is a variation of a phase shift between the X polarization component (18) and the Y polarization component (22) of the polarized light beam (12).

7. The optical device (10) according to any one of the preceding claims, - wherein, The first optical arrangement (28) and the second optical arrangement (30) are identically configured.

8. The optical device (10) according to any one of the preceding claims, - wherein, The first rotational axis (42) and the second rotational axis (58) are oriented parallel to one another.

9. A method for changing the polarization of a polarized light beam (12), the method having the following steps: a) generating the polarized light beam (12), b) setting a rotational position of the first optical arrangement (28), wherein The first optical arrangement (28) has a plurality of reflective optics (32) for reflecting the light beam (12), c) setting a rotational position of a second optical arrangement (30), wherein the second optical arrangement (30) has a plurality of reflective optics (48) for reflecting the light beam (12), and - wherein the plurality of reflective optics (48) of the second optical arrangement (30) is arranged such that a beam axis after the polarized light beam (12) has passed through the second optical arrangement (30) forms a continuation of a beam axis before the polarized light beam (12) has passed through the second optical arrangement (30). d) changing a polarization of the polarized light beam (12) by reflecting the polarized light beam (12) by means of the plurality of reflective optics (32) of the first optical arrangement (28) and by means of the plurality of reflective optics (48) of the second optical arrangement (30) depending on the rotational position of the first optical arrangement (28) and the rotational position of the second optical arrangement (30).

10. The method of claim 9, wherein, The polarized light beam (12) has an X-polarization component (18) in an X-direction and a Y-polarization component (22) in a Y-direction orthogonal to the X-direction, the method having the steps of: - predefining a target amplitude ratio between the X-polarization component (18) and the Y-polarization component (22), - predefining a target phase shift between the X-polarization component (18) and the Y-polarization component (22), - measuring an actual amplitude ratio between the X-polarization component (18) and the Y-polarization component (22), - measuring an actual phase shift between the X-polarization component (18) and the Y-polarization component (22), and - deriving a target rotational position of the first optical arrangement (28) and a target rotational position of the second optical arrangement (30) based on the target amplitude ratio, the target phase shift, the actual amplitude ratio and the actual phase shift, - wherein step b) comprises setting the target rotational position of the first optical arrangement (28), - wherein step c) comprises setting the target rotational position of the second optical arrangement (30).

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