Configuring replication process of master holographic optical element to achieve variable intensity or polarization

Abstract

The present invention relates to techniques for producing holographic optical elements (HOEs) by replicating a master HOE. More specifically, the present invention relates to a technique for flexibly adjusting the diffraction efficiency of HOE. An adjustable optical element (54) may be used to vary the intensity and / or polarization of light during exposure.

Description

Technical Field

[0001] Different examples relate to techniques for producing holographic optical elements (HOEs) by replicating a master HOE. In particular, several examples relate to techniques for variably adapting the illumination of a master HOE during replication. Background Art

[0002] HOEs are used in various fields of application. For example, HOEs can be used to realize transparent screens. Application areas include, for example, use in head-up displays in cars or integration of holographic optical elements in mirrors. HOEs are used to generate holograms.

[0003] One technique for producing HOEs is based on the use of a master HOE, which is used during the exposure process of the HOE to form the HOE. An example of a master HOE is a reflection-free beam volume HOE.

[0004] During replication of the master HOE, the carrier layer of the master HOE (e.g., a photopolymer, which is arranged on a substrate) is arranged along the carrier layer of the HOE to be replicated (hereinafter referred to as "replicated HOE"). The diffraction structure of the master HOE can then be replicated in the replicated HOE by exposure.

[0005] This production method for manufacturing HOEs using replication of a master HOE can, for example, use a roll-to-roll process, in which the master HOE and the HOE are arranged on respective rolls which rotate synchronously with one another so that partial areas of the master HOE in each case extend along corresponding partial areas of the replicated HOE. Another technique is a flatbed process, in which the master HOE and the replicated HOE are fixed on respective planar or flat carriers so that the entire surfaces of the respective carrier layers extend along one another.

[0006] In such a production process, the diffraction efficiency of the replicated HOE may deviate from certain target specifications. This may reduce the quality of the hologram generated by the replicated HOE. In addition, in such a production method, it is conventionally not possible to have deviations between the replicated HOE and the master HOE, for example in order to allow for different color distributions. Summary of the invention

[0007] Therefore, there is a need for an improved HOE production process. In particular, there is a need for an improved production process that enables high quality of replicated HOEs.

[0008] This object is achieved by the features of the independent patent claim. The features of the dependent patent claims define exemplary embodiments.

[0009] A control device for an exposure device is described. The exposure device is used for producing an HOE. The HOE is produced by replicating a master HOE within the framework of an exposure process performed by the exposure device. During the exposure process, a carrier layer of the master HOE is arranged along a carrier layer of the HOE.

[0010] The control device includes at least one processor and a memory. The at least one processor is configured to load a program code from the memory and execute the program code.

[0011] The at least one processor is further configured to control at least one light source of the exposure device based on the program code so that the light source emits light of at least one wavelength along a beam path to a surface of the carrier layer of the master HOE.

[0012] For example, at least one light source may emit light in the visible spectrum. It may also emit radiation in the ultraviolet or infrared range of the electromagnetic spectrum. At least one light source may be a coherent laser source. For example, multiple light sources emitting light components of different wavelengths may be used. For example, the light source may have 3 channels, such as red-green-blue (multi-channel light source).

[0013] The at least one processor is further configured to control a beam moving unit of the exposure device based on the program code so that the beam moving unit moves the beam path relative to the surface of the carrier layer of the master HOE during the exposure process.

[0014] For example, the angle of incidence may be inclined. For example, the light spot may be moved on the surface of the carrier layer. A scanning movement may be performed. Line scanning would be conceivable. It is conceivable to use a galvanometer scanner that implements a stepping mode (i.e., remains in one position and then moves to the next stable position). The beam moving unit may scan the beam path of the light on the surface of the carrier layer of the master HOE. Alternatively or in addition, it is conceivable that the beam moving unit moves a reference point relative to the master HOE arranged along the beam path and spaced apart from the surface of the carrier layer along a curved path curve during exposure. The reference point may be arranged, for example, in a scanning mirror or a deflecting mirror. Specifically, the angle of incidence of the beam path on the surface of the carrier layer of the master HOE during exposure can be changed thereby. The beam moving unit may be used to move the light spot of the light on the master HOE. This means that the master HOE is not irradiated over a large area, but is gradually irradiated by moving the light spot. This means that the exposure of the HOE is not done in a "single shot" method but gradually.

[0015] In addition, at least one processor is configured to control at least one adjustable optical element of the exposure device arranged in the beam path based on the program code. Therefore, the at least one adjustable optical element changes the intensity and / or polarization of the light over time during the exposure process. Therefore, the at least one adjustable optical element can be a filter that changes the intensity or polarization.

[0016] The master HOE may be formed in a photopolymer as part of the carrier layer. The carrier layer may also additionally comprise a carrier material. The carrier layer may be film-based. A so-called volume HOE may be used.

[0017] The HOE may be formed in a photopolymer as part of a corresponding carrier layer. The carrier layer may also additionally comprise a substrate. The carrier layer may be film-based. So-called volume HOEs may be used.

[0018] Diffractive structures can be generated in the HOE by replication based on the diffractive structures in the master HOE. Replicas can be made, but 1:1 replicas are not required. The diffractive structures correspond to local variations in the refractive index, for example due to different chain lengths or different degrees of chain formation of the polymers in the corresponding layers.

[0019] Illuminating the master HOE enables exposure of the replicated HOE. A specific dose of light is used, which can produce a diffraction efficiency in the replicated HOE. The diffraction structure is copied from the master HOE to the replicated HOE. The replication efficiency of the master HOE describes the ratio between (i) the diffraction efficiency in the replicated HOE and (ii) the amount of light (dose) used to expose the replicated HOE. This means that the smaller / larger the replication efficiency, the larger / lower the light dose required to achieve a specific diffraction efficiency.

[0020] Diffraction efficiency of replicated HOE = replication efficiency x light quantity (1)

[0022] In the above equation, it should be taken into account that the ratio between the diffraction efficiency of the replicated HOE and the required amount of light is limited to a linear range (the so-called linear range of the material properties of the material of the replicated HOE, which relates the amount of light to the diffraction efficiency). The maximum achievable diffraction efficiency of the replicated HOE is typically in the range of 95% to 98% and is limited, for example, by the thickness of the HOE region (in which the refractive index is modulated). When this maximum diffraction efficiency is reached, additional exposures will not further increase the diffraction efficiency. As is known, this is described by the Kogelnik theory.

[0023] Replication efficiency can have multiple influencing variables. Some examples are summarized in the table. 1.

[0024]

[0025]

[0026]

[0027] Table 1: Various influencing variables of replication efficiency. The diffraction efficiency is explained in more detail below. Microscopically, the diffraction efficiency can be explained by the amplitude of the refractive index change, which amplitude can depend on, for example, the degree of chain formation of the polymer. Macroscopically, the diffraction efficiency can be defined by the portion of the diffracted light relative to the total incident (coherent) light:

[0028]

[0029] The more polymer chains there are, the higher the refractive index adjustment is, and the higher the diffraction efficiency is.

[0030] The dose of light used for exposing the replicated HOE is influenced by the dwell time of the light spot at the respective position on the surface of the carrier layer and by the intensity of the light.

[0031] By providing at least one adjustable optical element, the intensity and / or polarization of the light can be flexibly varied during the exposure process, i.e., as a function of the position of the light spot on the surface of the carrier material of the master HOE. For example, manufacturing fluctuations that produce locally variable replication efficiencies can be compensated (see Table 1: Example II). Alternatively or in addition, variations in the replication dose due to different angles of incidence and therefore different angles between the polarization plane of the light relative to the surface of the carrier layer of the master HOE can be compensated (see Table 1: Example III). Alternatively or in addition, it is conceivable to selectively use different intensities in order to obtain different diffraction efficiencies of the HOE, in particular deviations from the diffraction efficiency of the master HOE. In general, this effect can be used to ensure that the hologram generated by the HOE has a particularly high quality, i.e., has a specific diffraction efficiency corresponding to the target specifications. In particular, it can be ensured that the diffraction efficiencies of different wavelength components have a desired ratio relative to each other. Negative effects from replication can be reduced.

[0032] In general, the intensity can be changed in absolute terms. This means, for example, that the intensity can be increased or decreased from a reference level to a certain absolute level. This can be done separately for a plurality of components corresponding to different wavelengths of light. However, it is also conceivable that the intensity is changed equally for all components of the light. As a further general rule, it is conceivable to adjust the intensity of the different wavelength components of the light relative to each other. For example, if the intensity of the red-green-blue (RGB) components is 1:1:1 as a reference, it can be adjusted to, for example, 0.8:1.2:1.

[0033] For example, it is conceivable that the at least one processor is also configured to load control data based on the program code. For example, the control data can show changes in polarization and / or intensity over time. The control data can indicate a correlation between a movement of the beam path relative to the surface of the carrier layer and a change in the intensity and / or polarization of the light. The control of the beam moving unit and the control of the at least one adjustable optical element are then implemented in a synchronized manner based on the control data.

[0034] This means, therefore, that, depending on the position of the corresponding light spot on the surface of the carrier layer of the master HOE and / or depending on the angle of incidence of the beam path on the surface of the carrier layer of the master HOE, different intensities and / or different polarizations of the light can be set. This results in a temporal variation of the intensity and / or polarization, since the light spot moves accordingly over time, which means that the position of the beam path on the surface of the carrier layer and / or the angle of incidence vary as a function of time.

[0035] This synchronization can be used in a targeted manner for different locations on the surface of the carrier layer to compensate for undesired properties of the master HOE or the carrier layer. It is also possible to select local deviations between the master HOE and the HOE.

[0036] For example, if the beam moving unit implements a stepping mode, i.e., holds at each position and then moves stepwise between these positions (as opposed to continuous movement, such as occurs in a resonantly operated scanning mirror), then at least one tunable optical element can be controlled to change the intensity and / or polarization in conjunction with the stepping mode. For example, if a galvanometer scanner is moved, the intensity and / or polarization can be changed simultaneously.

[0037] For example, it is conceivable that at least one adjustable optical element and the beam displacement unit are controlled so that the influence of changes in the structural properties of the master HOE on the diffraction efficiency (and therefore on the replication efficiency, see Table 1: Example II) is reduced by changes in the light intensity during the exposure process. This means, for example, that a change in the diffraction efficiency of a certain value between two points on the surface of the carrier layer of the master HOE is not replicated or is replicated only to a lesser extent in the replicated HOE: if the diffraction efficiency between point A and point B in the master HOE varies by 10%, the diffraction efficiency of the HOE between the corresponding points A and B varies by only 5%.

[0038] For example, due to variable structural properties (e.g. caused by manufacturing fluctuations or aging or scratches), the diffraction efficiency at different locations on the surface of the carrier layer of the master HOE may vary. This actually means: if all locations on the surface of the carrier layer of the master HOE are irradiated with the same light dose, that is, for example, if the same intensity of light is used for exposure at all different locations on the surface of the carrier layer of the master HOE (while the light spot remains at different locations on the surface for an equal period of time), then these different diffraction efficiencies of the master HOE will also cause correspondingly different diffraction efficiencies in the HOE (because the replication efficiency varies correspondingly, see Table 1: Example 0). For example, the hologram generated by the replicated HOE will have different brightness or blurriness or color inhomogeneities, such as color fringes. This undesirable effect can be avoided by correspondingly adapting the intensity of the light during the exposure process so as to reduce or compensate for the variation of the diffraction efficiency. Therefore, at least one adjustable optical element and the beam moving unit can be controlled so that the influence of the variation of the structural properties of the master HOE on the diffraction efficiency is reduced by the variation of the light intensity during the exposure process. This enables compensation of defects of the master HOE. The master HOE can be used for a longer time.

[0039] Another factor that influences the replication efficiency is the orientation of the polarization plane of the light (for linearly polarized light) relative to the surface of the carrier material of the master HOE, see Table 1: Example III. For example, there may be s-polarization, p-polarization or a mixture of the above. When the incident angle of the light on the master HOE changes, the orientation of the polarization plane changes. If the light spot moves on the surface of the carrier layer of the master HOE during exposure, the incident angle may then change. This has an impact on the replication efficiency. At least one adjustable optical element and the beam moving unit may be controlled so that the orientation of the polarization relative to the surface of the carrier layer of the master HOE is stable. This means that control can be achieved so as to reduce the influence of the movement of the beam path during exposure on the change in the polarization orientation of the light relative to the surface of the carrier layer of the master HOE. In short, this therefore reduces the influence of the variable incident angle (due to the movement of the beam path) on the replication efficiency. This enables the beam path to be moved more flexibly by the beam moving unit. For example, this enables the replication of a curved master HOE.

[0040] This and other effects are also achieved by additional methods and apparatuses.

[0041] A method for configuring a production method for producing an HOE by replicating a master HOE within the framework of an exposure process performed by an exposure device is disclosed. During the exposure process, a carrier layer of the master HOE is arranged along a carrier layer of the HOE. The method comprises generating control data of at least one adjustable optical element of the exposure device, wherein the optical element is arranged in the beam path of the light used for the replication. With the aid of the control data, the at least one adjustable optical element can be controlled so that the at least one adjustable optical element changes at least one of the intensity and polarization of the light over time during the exposure process.

[0042] A device includes at least one processor and a memory. The at least one processor is configured to load and execute a program code from the memory. The at least one processor is also configured to execute a method for configuring the production process based on the program code.

[0043] A method for controlling an exposure device for producing an HOE by replicating a master HOE is disclosed. The replication is performed within the framework of an exposure process performed by the exposure device. During the exposure process, a carrier layer of the master HOE is arranged along the carrier layer of the HOE. The method comprises controlling at least one light source of the exposure device so that during the exposure process, the at least one light source emits light having at least one wavelength along a beam path toward the surface of the carrier layer of the master HOE. Furthermore, the method comprises controlling a beam moving unit of the exposure device so that the beam moving unit moves the beam path relative to the surface of the carrier layer of the master HOE during the exposure process. Furthermore, the method comprises controlling at least one adjustable optical element of the exposure device, wherein the adjustable optical element is arranged on the beam path so that the at least one adjustable optical element changes at least one of the intensity and polarization of the light over time during the exposure process.

[0044] A control device for an exposure device is disclosed, the exposure device being used to produce a holographic optical element HOE by replicating a master HOE within the framework of an exposure process performed by the exposure device. The exposure process uses light emitted from at least one light source of the exposure device along a beam path to a surface of a carrier layer of the master HOE during the exposure process. During the exposure process, the carrier layer of the master HOE is arranged along the carrier layer of the HOE. The control device includes at least one processor and a memory, wherein the at least one processor is configured to load a program code from the memory and execute the program code. The at least one processor is configured to control a beam moving unit of the exposure device based on the program code, so that the beam moving unit moves the beam path relative to the surface of the carrier layer of the master HOE during the exposure process. The at least one processor is further configured to control at least one of an adjustable optical element arranged on the beam path, at least one light source, and a beam moving unit of the exposure device, so that during the exposure process, at least one of the dose and polarization of the light changes over time.

[0045] A corresponding method is also disclosed.

[0046] For example, the diode current through the laser diode can be varied in order to change the intensity of the light.

[0047] For example, the scanning speed can be changed so that the dwell time of the light spot on the surface changes (eg the light intensity is the same), so that the dose is increased or decreased in this way.

[0048] The features explained above and the features described below can be used not only in the corresponding combination explicitly stated but also in further combinations or alone, without departing from the scope of protection of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 A flow chart of an exemplary method for producing a HOE is shown.

[0050] Figure 2 A system for exposing a HOE in the framework of replication of a master HOE according to various examples is schematically illustrated.

[0051] Figure 3 A flow chart of an exemplary production method is shown.

[0052] Figure 4 Schematically illustrated is the illumination of a master HOE based on a corresponding map according to different examples.

[0053] Figure 5 Schematically illustrated is the illumination of a master HOE based on a corresponding map according to different examples.

[0054] Figure 6 A flow chart of an exemplary method for producing HOEs by replicating a master HOE is shown.

[0055] Figure 7 Schematically illustrates illuminating a master HOE with a target surface shape according to various examples.

[0056] Figure 8 Schematically illustrating irradiation with an exposure surface shape different from a target surface shape according to various examples Figure 7 The master HOE.

[0057] Fig. 9 Schematically illustrates the Figure 8 Exposure surface shape irradiation Figure 7 A master HOE in which the reference point of the light beam path moves along the trajectory.

[0058] Fig.10 A roll-to-roll process is shown.

[0059] Fig.11 A flatbed replication process for exposing a HOE by replicating a master HOE according to various examples is schematically illustrated.

[0060] Fig.12 Schematically illustrates the shape of a surface illuminated by a plane according to various examples Fig.12 The master HOE.

[0061] Fig.13 yes Fig.11 Side view of the master HOE.

[0062] Fig.14 yes Fig.11 Another side view of the mother HOE.

[0063] Fig.15 Aspects related to a beam moving unit according to various examples are illustrated.

[0064] Fig.16 The p-polarization is schematically illustrated.

[0065] Fig.17 The s-polarization is schematically illustrated.

[0066] Fig.18 Exposure apparatuses according to various examples are schematically illustrated.

[0067] Fig.19 Exposure apparatuses according to various examples are schematically illustrated.

[0068] Fig. 20 Exposure apparatuses according to various examples are schematically illustrated.

[0069] Fig.21 An exposure device with a sensor according to various examples is schematically illustrated.

[0070] Fig. 22 An exposure device with a sensor according to various examples is schematically illustrated.

[0071] Fig.23 An exposure device with a sensor according to various examples is schematically illustrated.

[0072] Fig.24 is a flow chart according to various examples that allows, for example, stabilizing intensity to a time-varying target intensity value during an exposure. DETAILED DESCRIPTION

[0073] The characteristics, features and advantages of the present invention described above and the manner in which they are achieved will become clearer and more clearly appreciated in conjunction with the following description of exemplary embodiments, which are explained in more detail in conjunction with the accompanying drawings.

[0074] The present invention is explained in more detail below with reference to the accompanying drawings based on preferred embodiments. In the accompanying drawings, the same reference numerals represent the same or similar elements. The accompanying drawings are schematic representations of various embodiments of the present invention. The elements illustrated in the accompanying drawings are not necessarily illustrated in true scale. Alternatively, the various elements illustrated in the accompanying drawings are presented in a manner that makes their functions and general purposes easy for those skilled in the art to understand. The connection and coupling between the functional units shown in the figures and the elements can also be implemented as indirect connections or couplings. Connections or couplings can be implemented in a wired or wireless manner. The functional units can be implemented as hardware, software, or a combination of hardware and software.

[0075] The following will describe techniques for producing HOEs. For example, volume HOEs or surface HOEs may be produced with the aid of the techniques described herein.

[0076] The technology described herein is based on replicating a master HOE to produce a replicated HOE. To produce a master HOE, a corresponding exposure process may be used before it. Several examples described herein specifically relate to exposing a replicated HOE by replicating a master HOE.

[0077] The replication can be performed, for example, by a scanning method. Here, the laser spot is transformed into a line or other shape by a fast scanning element (such as a scanning mirror) and then moved on the master HOE. Thus, in a snapshot, the laser spot moves on the master. More generally, the beam path of the light (which may include a plurality of components corresponding to different wavelengths) is moved on the surface of the carrier material of the master HOE by a beam moving unit during the exposure process. In other words, during the exposure process, different areas of the replicated HOE are gradually exposed by the movement of the light spot.

[0078] The different examples described herein are based on the finding that it may be desirable to change the intensity and / or polarization of the light used for exposure during the exposure process by means of an adjustable optical element for different reasons. Some scenarios are listed in Table 2.

[0079]

[0080]

[0081]

[0082] Table 2: Several exemplary scenarios for varying the intensity and / or polarization over time during exposure. In practical examples, different scenarios can be combined. For example, it would be conceivable to combine the polarization adaptation for large angles of incidence from scenario II with a local intensity adaptation according to scenario III, with the result that the Fresnel losses are additionally achieved by increasing the power at large angles of incidence.

[0083] It is therefore apparent from Table 2 that a distinction is made between a scenario in which an imperfect master HOE (e.g. inhomogeneous mixing of the RGB components of the light) is to be compensated (scenario I) and a scenario in which a perfect master HOE is exposed differently (spatially resolved) for other reasons, e.g. in order to compensate for inhomogeneities of the copy material and / or the later illumination (scenario V). A mixture of both scenarios is also conceivable.

[0084] A modulation frequency in the kHz or MHz range can be used to vary the intensity of the light during the exposure process, which can be realized, for example, by means of an acousto-optic element (such as an acousto-optic modulator (AOM) or an acousto-optic filter (AOTF) as examples of an adjustable optical element for varying the intensity). Such a modulation frequency is high enough to vary the intensity rapidly compared to the movement of the light spot on the surface of the carrier material of the master HOE. Typically, the beam moving unit is controlled in the kHz range, i.e., for example, with a few 100 Hz. In general, the beam moving unit can be controlled with a smaller signal bandwidth than the signal bandwidth used for controlling the adjustable optical element, for example, there can be a multiple of 3 to 4 between the signal bandwidths. In summary, the corresponding signal bandwidth for controlling the adjustable optical element can be in the megahertz range, for example, when the beam moving unit is controlled with a signal bandwidth in the kilohertz range.

[0085] In some variants, it is conceivable to vary the intensity with a control loop during the exposure process. This means that (using a suitable sensor, such as a photodiode) a measurement indicating the intensity of the light of the master HOE used for replication can be obtained. This measurement can then be used to check whether the actual intensity of the light deviates from a target intensity. As mentioned above, this target intensity can be varied during the exposure process. Such a control loop can be implemented in software and / or hardware. For example, the target intensity can be output as a program output of a software program; the control loop can then be implemented in hardware.

[0086] Modulation frequencies in the MHz range can also be used to change the polarization of the light during exposure, which can be achieved, for example, by means of a Pockels cell or a λ / 2 wave plate which can be flexibly introduced into the beam path.

[0087] As described above in connection with the control loop for intensity, it is alternatively or additionally conceivable to use a control loop to vary the polarization during exposure.

[0088] Figure 1 Methods for producing replicated HOEs according to various examples are illustrated.

[0089] In block 3005, a master HOE is produced. For this purpose, a corresponding photopolymer located in or on a carrier layer of the master HOE is exposed. For the exposure, an object beam and a reference beam of corresponding light can be used, which are formed phase-coherently with respect to each other. An analog exposure can be performed, in which the object generates the object beam. Digital exposure using a pixelated light modulator and a stitching method can also be used.

[0090] Figure 1 It is shown that in block 3005, when exposing the master HOE, the master HOE (or more precisely, the carrier material of the master HOE) has a target surface shape 911. The target surface shape 911 is, for example, Figure 1 It is schematically shown as being curved, but may have any shape.

[0091] The replicated HOE is then exposed by replicating the master HOE in block 3010. A roll-to-roll process or a flatbed replication process may be used.

[0092] In block 3010, the carrier material of the master HOE and the carrier material of the replicated HOE have an exposed surface shape 912; Figure 1 , is shown as being flat by way of example, but may also have a curvature.

[0093] In some examples, the exposure surface shape 912 may differ from the target surface shape 911. This may be compensated by moving a reference point on the beam path on a curved trajectory during exposure. Specifically, a change in the angle of incidence of the beam path on the surface of the carrier material may be achieved thereby.

[0094] In box 3015 , after the exposure process, the carrier layer of the replicated HOE is fixed again in the target surface shape 911 .

[0095] Figure 2 The system 50 is illustrated in relation to aspects of a system that can be used to produce a replicated HOE 96 from a replicated master HOE 92. Thus, the system 50 can be used in conjunction with a method according to Figure 1 Box 3010 of the method is used.

[0096] The system 50 includes an exposure device 59 and a control device 51 for the exposure device 59. The control device 51 (or simply referred to as the controller 51) includes a processor 191 and a memory 192. The processor 191 can load and execute program codes from the memory 192, and then implement the control of the exposure device 59 based thereon.

[0097] The exposure device 59 includes a light source 52, such as a laser. The light source 52 is configured to emit light along the beam path 41. The exposure device 59 may, for example, include multiple light sources (not shown) for different components of light associated with different wavelengths. The exposure device 59 may, for example, include three light sources 52 for RGB components of light. The light source may emit coherent light. The "light" may be in the visible spectrum or in an adjacent wavelength range, such as in the infrared portion or ultraviolet portion of the electromagnetic spectrum.

[0098] Light is directed to the master HOE 92 so that the replicated HOE 96 is exposed in this manner. Figure 2 The carrier layer of the master HOE 92 is schematically illustrated arranged along the carrier layer of the HOE 96 .

[0099] The exposure device 59 has an optical element 54 in the beam path. The optical element 54 can change the intensity and / or polarization of the light. The optical element is adjustable, that is, the change of the intensity and / or polarization of the light can be adjusted, that is, in particular over time during the exposure process. Examples of adjustable optical elements 54 are shown in Table 3 below.

[0100]

[0101]

[0102]

[0103] Table 3: Several examples of embodiments of the adjustable optical element 54. In general, the exposure device 59 may also have a plurality of such adjustable optical elements, for example in a series loop on the beam path 41 (but this is not the case in Figure 2 (not shown in the figure).

[0104] In addition, the system 50 also includes a beam moving unit 55. The beam moving unit may include, for example, one or more motorized actuators and optical elements (e.g., mirrors and / or prisms and / or lens elements and / or scanning mirrors) that are arranged on the beam path and may be passive or active, i.e., adjustable or fixedly oriented. The motorized actuator may position the optical element according to a plurality of degrees of freedom. One or more degrees of freedom of translational movement may be achieved. Alternatively or in addition, one or more degrees of freedom of rotational movement may be achieved. This allows the beam path of the light to be moved. The actuator may be implemented, for example, by a mechanical arm having a plurality of adjustable axes. It is also conceivable that the actuator is implemented by a multi-axis optical linear adjustment stage. The actuator may be controlled by a controller 51. By means of the beam moving unit 55, the beam path 41 may be moved relative to the surface of the carrier layer of the master HOE 96 during the exposure process. For example, the beam path 41 may be scanned by the beam moving unit 55, which is illustrated by a corresponding exit angle or scanning angle 85. Alternatively or additionally, a reference point 84 arranged along the beam path 41 may be moved by the beam moving unit 55 along a curved path curve 61 (indicated by a dash-dotted line).

[0105] The position of the corresponding light spot 42 on the surface of the carrier layer of the master HOE 96 is changed during the exposure process by the movement of the beam path 41 .

[0106] By moving the beam path 41 relative to the master HOE 96 , the angle of incidence 89 of the beam path 41 on the surface of the carrier layer of the master HOE 96 can be changed during the exposure process.

[0107] Figure 2 Also illustrated is a sensor 57 that is configured to measure the intensity of light in the region of the beam path 41. The sensor 57 is optional. For example, the sensor 57 may be a photodiode. The sensor 57 may output a signal indicative of the light intensity. Thus, the sensor 57 may, for example, measure the light flux or the light output. Figure 2 In the example of the embodiment of the invention, the sensor 57 is connected to the controller 51. The sensor 57 may also be directly connected to the light source 52 and / or another adjustable element for setting the intensity (e.g. a Pockels cell or an AOTF). Based on the measurement signal of the sensor 57, a monitoring of the exposure may be achieved. This means that in particular the light output of the exposure of the HOE 92 may be monitored. A closed control loop may be implemented which adapts the control signal for the adjustable optical element in order to control the actual value of the light output to be at a target value of the light output.

[0108] The controller can use the control data 401 to control the adjustable optical element 54 and / or the light source 52 and / or the beam moving unit 55. In particular, a (time) synchronous control of the adjustable optical element 54 and the beam moving unit 55 and optionally the light source 52 can be achieved. This means that a time-dependent control is achieved so that, for example, different settings of the adjustable optical element 54 are selected depending on the position of the light spot on the surface of the carrier material of the master HOE. These control data 401 can be specifically assigned to a specific master HOE 96. This means that different control data 401 can be used for different master HOEs. This is because the control data 401 can specifically compensate for specific characteristics of the master HOE. Details related to the generation of the control data 401 are described below.

[0109] Figure 3 is a flow chart of an exemplary method. Figure 3 Illustrated are aspects related to the configuration of a production process for producing HOEs by replicating a master HOE. Figure 3 Specifically illustrated are aspects related to the generation of control data for an exposure device, by which a master HOE can be replicated. The control data may be, for example, control data 401 of the exposure device 59. Specifically, reference is made below to the generation of control data 401, which allows control of at least one adjustable optical element, see Table 3. By generating control data 401, the intensity and / or polarization of light used by the exposure device to expose the master HOE for replication can be changed. This can be done based on one or more scenarios, such as the scenarios listed in Table 2.

[0110] In particular, the control data may couple the control of the beam moving unit and of the at least one tunable optical element, ie the light spot is moved on the surface of the carrier layer of the master HOE and the polarization and / or intensity is changed in connection therewith.

[0111] First, one or more input data are received in block 3805. Based on the input data, control data may then be generated in block 3810. The control data includes instructions for at least an adjustable optical element such that the control data changes the intensity and / or polarization of light over time during an exposure process to replicate a master HOE.

[0112] Different types of input data may be used to determine control data. Specifically, depending on the scenario of Table 2, different input data may be considered. Below, in Table 4, several examples of considering input data that may be obtained in block 3805 are described.

[0113]

[0114]

[0115]

[0116]

[0117] Table 4: Different examples of input data that may be used to generate control data for an adjustable optical element. The different examples may also be combined.

[0118] In general, the control data in block 3810 may be determined at different stages. This is described in conjunction with Table 5.

[0119]

[0120]

[0121]

[0122] Table 5: Various variants of the stage at which control data can be generated for a customized diffraction efficiency of a replicated HOE. Such variants can also be combined. In particular, a distinction can be made between the case where the manufacturer of the master HOE performs measurements to characterize the master HOE in order to generate control data in this way, which are for example provided together with the master HOE (see example I from Table 5), and the case where the control data are generated before the production of the replicated HOE and after the master HOE is delivered to the user at the same time (see examples II and III of Table 5). These cases can also be combined with each other, for example, to address different scenarios according to Table 2.

[0123] use Figure 4 With the technique described in , the control data can be generated in an optimized way; for example, if too high a dose is used in the exposure in case of a bad master HOE and resulting poor interference contrast (due to too high a chosen intensity or incorrect change of polarization), a back-effect in the replicated HOE and a drop in the diffraction efficiency can occur locally, since the refractive index modulation of the material "revealed" again. This can be avoided by appropriately determining the control data.

[0124] Once the control data has been determined, the HOE can be exposed by replicating the master HOE. Figure 6 Disclosed.

[0125] Figure 6 An exemplary method is illustrated. Figure 6 The method in was used to produce replicated HOEs. Specifically, Figure 6 The methods in involve the replication process, see Figure 1 : Frame 3010. For example, Figure 6 The method in can be implemented by a controller, for example by Figure 2For example, the processor may load and execute program code 191 from memory 192 to perform Figure 6 method.

[0126] In block 3105, a light source, such as a laser, is controlled to emit light along a beam path to the master HOE. For example, the light source may be controlled in such a way that it continuously emits light at a specific light intensity during the exposure process. The light source may also be turned on and off alternately. This may be helpful, for example, when implementing a stepping mode for moving the beam path on the surface of the carrier layer, that is, in this example, moving the light spot between two different positions or two scan lines.

[0127] In block 3110, a beam movement unit (see beam movement unit 55) may be controlled to move the beam path relative to the surface of the carrier layer of the master HOE. For example, the angle of incidence together with the position may change as the scanning mirror passes over the scan line. More complex movements may also occur, in which the reference point moves along a curved trajectory. For this purpose, for example, a robotic arm may be controlled.

[0128] In block 3115, the adjustable optical element may be controlled to change the intensity and / or polarization of the light. For example, the intensity and / or polarization may be changed between two finite values ​​> 0. There may be a step-like change whenever the light source is turned off and / or the beam path is or has been moved, see block 3105. Thus, blocks 3105, 3110, and 3115 may be performed synchronously.

[0129] To set the intensity, it is conceivable to adapt the target specification of the intensity taken into account in conjunction with a control loop. However, it is not necessary to use a control loop in all variants: intensity variations that are not controlled by a control loop are also conceivable. Fig.24 Aspects related to variations with a control loop are described below. Aspects related to a beam moving unit are explained below. In some examples, the beam moving unit can generate a curved path curve 61 of a reference point 84 (see Figure 2 ; Block 3110). The curved path curve 61 can be different depending on the master HOE 92. This changes in particular the angle of incidence 89, but also, for example, the position of the light spot on the surface of the carrier material of the master HOE. This dependence of the curved path curve 61 on the master HOE used results from the fact that, depending on the master HOE 92, different target surface shapes 911 can be used (wherein the exposure process for replication can in each case be carried out with the same exposure surface shape 912, since this is determined by the replication process used). Therefore, different compensations are achieved by the curved path curve 61. This will be described below in conjunction with Figure 7 , Figure 8 and Fig. 9 Explain this.

[0130] Figure 7 Aspects related to target surface shape 911 are illustrated. Figure 7 A master HOE 92 having a target surface shape 91 is illustrated on a corresponding carrier layer 91 .

[0131] exist Figure 7 In the example of , the master HOE 92 implements the optical function of an off-axis parabolic mirror illuminated by a point light source. An incident divergent light beam 81 is converted into a parallel light beam 82. This is only an exemplary optical function, and in principle many different optical functions are conceivable.

[0132] In any case, if the replicated HOE 96 has the same target surface shape 911, the replicated HOE 96 should implement the corresponding optical function.

[0133] However, during the exposure of the replicated HOE 96 (see Figure 1 : Box 3010), the replicated HOE 96 and the master HOE 92 have an exposure surface shape 912. This Figure 8 Shown in.

[0134] The transformation between the target surface shape 911 and the exposure surface shape 912 causes a change in the diffraction structure of the master HOE 92; this change in the diffraction structure can be correspondingly converted into a change in the light of the incident light beam 81# and the light of the reflected light beam 82#: these light beams 81# and 82# are "drawn" in the drawing plane, just like the diffraction structure.

[0135] The different examples are based on the following finding: for producing a replicated HOE 96 when using exposure surface shape 912, if there is a target surface shape 911, the beam path 41 of the light used for exposure should simulate the rays of the adapted beam 81# (see Figure 8 ) in order to ensure in this way that Figure 7 (The figure shows the optical function of the master HOE 92) The optical function of the replicated HOE 96. Fig. 9 Shown in.

[0136] Fig. 9 Aspects related to a flatbed replication process for replicating a master HOE 92 to expose a replicated HOE 96 are illustrated. Fig. 9 The diagram shows that during the exposure of the replicated HOE 96, the carrier layer 91 of the master HOE 92 extends parallel to the carrier layer 95 of the replicated HOE 96. To expose the replicated HOE 96, the master HOE 92 is illuminated with light along the ray 81#; Fig. 9 As is apparent from the figure, the angle of incidence 89 of these light rays 81# varies depending on the position of the corresponding light spot on the master HOE 92, which is achieved by using a curved path curve 61 of the reference point 84 along the beam path 41 and optionally by changing the exit angle of the light from the reference point 84 (e.g., by using a scanning mirror). If the replicated HOE 96 is in use and has a target surface shape 911, then ( Fig. 9 The irradiation of other light beams (indicated by the dashed arrow in the middle) is as shown in the above combination Figure 7 and Figure 8 described.

[0137] Fig.10 Aspects related to a roll-to-roll replication process for replicating a master HOE 92 (that is, exposing a replicated HOE 96) are illustrated. Fig.10 The left side of FIG. 1 shows that if the master HOE 92 has a target surface shape 911 (ie, when the master HOE is produced (see Figure 1 3005) in the cross section of the master HOE. In addition, the corresponding rays 81-1 to 81-4 of the light beam for exposure are shown, which light beam is later used to illuminate the replicated HOE 96 when the replicated HOE 96 is used.

[0138] In the roll-to-roll replication process (see Figure 1 3010 in FIG. 30 ), the master HOE 92 is applied to the roll 71, and as the rotation of the roll 71 increases, corresponding rays 81#-1 to 81#-4 of the beam path 41 of the light used to illuminate the master HOE 92 are realized by the movement 21 of the reference point 84 and the corresponding change of the angle of emission 85 of the light from the reference point 84 (e.g., by tilting 22 a corresponding mirror arranged at the reference point 84). Thus, in the case of the replicated HOE (which is applied to another roll 72 and is not shown in FIG. 30 ), the master HOE 92 is applied to the roll 71, and as the rotation of the roll 71 increases, corresponding rays 81#-1 to 81#-4 of the beam path 41 of the light used to illuminate the master HOE 92 are realized. Fig.10 During the exposure process (shown in FIG), the curvature of the carrier material 91 of the master HOE 92 is compensated by a curved path curve.

[0139] Techniques related to the movement of the reference point 84 have been explained above. It has also been explained how to vary the exit angle 89. Optionally, the movement of the reference point 84 along the curved path curve 61 can be synchronized with the scanning of the light beam 41. In contrast to the variation of the exit angle 89 as discussed above, the scanning of the light beam 41 can be implemented by a periodic scanning movement.

[0140] For example, reference point 84 may mark the midpoint of scanning movement 53. Fig.11 and Fig.12 The diagram illustrates aspects related to scanning.

[0141] Fig.11 A master HOE 92 is shown, which implements the optical function of an off-axis parabolic mirror as an example. Fig.11 A master HOE 92 is shown in the shape of a target surface 911; Fig.12 The same master HOE 92 is shown with an exposure surface shape 912. Fig.11 It is apparent that the master HOE 92 in the target surface shape 911 has a one-dimensional curvature along the axis of curvature 199 .

[0142] This means that adjustment can be made between the target surface shape 911 and the exposure surface shape 912 by a one-dimensional curvature operation along the curvature axis 199 (the curvature perpendicular to the curvature axis 199 does not change). The same applies (in reverse form) to Figure 8 In general, a transition occurs between the one-dimensional curvature of the carrier layer 91 of the master HOE and the planar configuration of the carrier layer 91 of the master HOE 92.

[0143] The scanning direction 36 of the scanning movement 53 of the light spot 49 scanned by the scanning mirror on the master HOE 92 is oriented perpendicularly to the axis of curvature 199, see Fig.12 This is due to the fact that the origin of the scanning movement 53 does not have to be displaced perpendicularly to the axis of curvature 199 , since there is no transformation of the curvature of the corresponding surface in this direction 36 .

[0144] therefore, Fig.12 The examples in correspond to a line scanner.

[0145] Overlapping with the scanning movement 53 along the scanning direction 36, the movement of the reference point 84 takes place along the curved path curve 61. This displaces the light spot 49 along the direction 37. The corresponding movement 21 has a component along the axis 37 which is oriented along the direction 37 perpendicularly to the scanning direction 36 (and therefore parallel to the axis of curvature 199).

[0146] Fig.12 Also shown is a (non-scanned) variation of the exit angle 85 that occurs by corresponding control of the beam moving unit. In some examples, a two-dimensional scanning mirror can be used to simultaneously implement scanning along the scanning direction 36 (i.e., periodic movement around the scanning center) and non-scanning variation of the exit angle 85 (e.g., by corresponding tilt 22 at the reference point 84). Figure 2 A similar situation is discussed; the scanning mirror can then be arranged at the reference point 84 .

[0147] exist Fig.12In the example of , the scanning can be performed with a fixed scanning frequency with a fixed scanning amplitude, with the result that the entire area between the two edges of the master HOE 92 is scanned by the light spot 49. In this example, in particular, a resonantly driven scanning mirror can be used.

[0148] Not all examples require the implementation of the scanning movement 53. For example, at least one optical element can also be arranged at the reference point 84, which causes the light spot 49# to expand along the direction 36 on the master HOE 92 (compare light spot 49 with light spot 49#). Thus, the line originally to be scanned is exposed in an integral manner.

[0149] Fig.13 and Fig.14 is from Fig.10 A side view of the situation viewed at perpendicular angles to each other.

[0150] Fig.15 An exemplary embodiment of the beam moving unit 55 is shown. The beam moving unit 55 includes a robotic arm 231. The optical fiber 212 guides the light from the laser 52 to the moving end of the robotic arm 231. At the moving end, the light is coupled out by an output coupling unit 281, which may include, for example, a corresponding lens element (GRIN lens), etc. The output coupling unit 281 can be designed to maintain polarization. In addition, a two-dimensional galvanometer scanner 261 is arranged at the moving end of the robotic arm 231; it implements a tilt 22 for non-scanning variation of the exit angle 85 of the light leaving the reference point 84; and a scanning movement.

[0151] Fig.15 It is also shown how the angle of incidence 89 changes during the exposure process, because the beam path 41 is moved over the surface of the carrier layer of the master HOE by the beam moving unit 55. As a result, the orientation of the polarization 641 of the light relative to the surface of the carrier layer of the master HOE 92 can change. For example, p-polarization can occur instead of s-polarization, see Fig.16 and Fig.17 (If the beam path is rotated about an axis of rotation which does not coincide with the polarization direction, the angle of the polarization direction changes relative to the surface normal of the surface of the carrier layer of the master HOE.) This will affect the replication efficiency and can be compensated by adapting the polarization and / or intensity as described above.

[0152] Fig.18 Schematically illustrates an exposure device 59 according to different examples. In the example shown, the exposure device 59 comprises a plurality of lasers 311-313 for different wavelength components of light. The lasers 311-313 implement a polychromatic light source. The corresponding components of light are guided via optical waveguides to a beam combining element 331, which then combines the corresponding partial beam paths.

[0153] The AOTF 332 implementing an adjustable optical element is then arranged downstream of the beam combining element 331 on the beam path beam. In addition, a Pockels cell 333 is provided, which also implements an adjustable optical element. This allows the intensity or polarization of the light to be adapted. A wave plate 334 is also provided, followed by a scanning mirror 261 and deflection mirrors 336, 337. (For example, in Fig.17 The robotic arm (if used) is not shown.

[0154] The AOTF 332 uses acoustic waves to filter light. This is achieved through a process of acoustic-optical interaction in a suitable medium, usually a crystal. As the acoustic waves propagate through the crystal, they induce periodic density variations in the material. These density variations induce periodic variations in the refractive index of the medium. As light passes through a crystal with a periodic variation in refractive index, it is diffracted, similar to light passing through a grating. Several components of light are formed; these components correspond to different diffraction orders, in particular the zeroth order and the first order. Typically, only the first order diffraction is used to replicate the master HOE.

[0155] Instead of Fig.18 In the example of FIG. 3 , a single Pockels cell 333 is shown, but it is conceivable to provide a plurality of Pockels cells, for example one Pockels cell for each beam path between the beam combining element 331 and the light sources 311 - 313 . The polarization of different wavelength components of the light can then be adjusted individually.

[0156] Fig.19 Shows Fig.18 A variation of the exposure device 59. Instead of the AOTF 332, AOMs 341, 342, 343 are now used. These are arranged upstream of the beam combining element 331 and are assigned in each case to the lasers 311-313 (in Fig. 20 , AOMs 341, 342, 343 are integrated into lasers 311-313).

[0157] although Fig.19 and Fig. 20 A Pockels cell is not shown, but could be used as well.

[0158] Aspects related to power monitoring are described below. Power monitoring can be used to ensure that the light intensity during exposure meets specifications. The intensity of the light can be changed according to a time-varying target value. The light intensity can be controlled in a control loop.

[0159] To ensure that the light intensity is set correctly, the light intensity can be checked during the copy process / exposure process.

[0160] The different examples are based on the finding that, during a running exposure, it is not easy to measure the used light beam: conventional sensors block the light beam during the measurement. There are several variants that still enable measuring the light intensity.

[0161] In one variant, part of the power of the used light beam is redirected via a beam splitter (e.g. a 90:10 beam splitter) or via another optical unit and used for the measurement. A corresponding sensor is then arranged in the redirected partial beam (see Figure 1 : sensor 57). However, this will result in a power loss of the light beam used.

[0162] It may be desirable to measure the intensity of the used beam indirectly. This avoids reducing the power of the used beam (ie the component of the light used to replicate the master HOE). This variant is shown below.

[0163] Fig.21 A variation of the exposure device 59 is shown in FIG. Fig.21 In principle it corresponds to Fig.18 (No more explanation of what has already been said about Fig.18 Element explained). In the case of AOTF 332, the incident superimposed beam is split into a zero-order diffraction 800 and a first-order diffraction 801 (reference numerals 800, 801 indicate the relevant beam paths). The first-order diffraction 801 is the desired power set, while the remaining power is the zero-order diffraction 800. Depending on the type and design, the AOTF 332 can be configured so that, for example, the first-order diffraction 801 (i.e., the used beam) is dispersion corrected. That is, all wavelengths of the first-order diffraction 801 exit the AOTF 332 at the same angle. The zero-order diffraction 800 contains the remaining power, where the angles of the wavelengths are slightly different. Another characteristic of the filter is the polarization state of the two diffraction orders 800, 801, which are linearly polarized at 90° to each other. In Fig.21 In the example of , the first order diffraction 801 is p-polarized relative to the window, while the zeroth order is s-polarized.

[0164] One way to monitor the power without interfering with the used beam (i.e., the first order diffraction 801) is to measure the light of the zeroth order diffraction 800 during the exposure process. Since the zeroth order diffraction 800 lacks the power in the first order diffraction 801, there is an inverse relationship between the used power and the sensor 57 measurement of the zeroth order diffraction 800. By adjusting (calibrating) these two diffraction orders 800, 801, the first order diffraction 801 can be controlled in a control loop based on the measurement of the zeroth order diffraction 800. Thus, an indirect measurement of the intensity of the used beam (first order diffraction 801) is used.

[0165] However, since the angular difference between the zeroth order diffraction 800 and the first order diffraction 801 is small (maybe a few degrees), a long beam path is required to separate the beams sufficiently. Fig.21 , where the sensor 57 is located at a greater distance from the AOTF 332 so that the light of the first-order diffraction 801 can pass through the sensor 57.

[0166] Fig.21 Not shown are further optical elements (which are located downstream of the beam path of the light of the first-order diffraction 801), such as Pockels cells or deflection mirrors (see Fig.18 : Pockels cell 333, deflection mirror 261, etc.). Different additional optical elements may be designed according to the different variants described herein.

[0167] Fig. 22 The ratio is shown in Fig.21 A more compact variant of the invention has a sensor 57 with an exposure device 59. Here, Fig. 22 Basically corresponds to Fig.21 .exist Fig. 22 In FIG. 8 , the polarization beam splitter 820 is located downstream of the AOTF 332 along the beam path of the light. The AOTF 332 is oriented so that the first-order diffraction 801 is vertically polarized. Therefore, the light of the first-order diffraction 801 is deflected and coupled into the rest of the optical system ( Fig.21 801 ), while the zeroth order diffraction 800 passes directly through the polarizing beam splitter 820 to the power measurement head of the sensor 57. Therefore, the intensity of the first order diffraction light can be determined without intervening the first order diffraction 801 during the exposure process by measuring the intensity of the zeroth order diffraction 800 light (i.e., again indirectly measuring). Fig. 22 The disadvantages of this variant occur at particularly high laser powers, for example laser powers greater than several 100 mW: it may be necessary to use a sensor 57 for thermally determining the intensity; the measuring frequency is then very low. In some cases, a neutral density filter or the like may be used, which produces back reflections or may be destroyed in the case of an absorptive filter. In order to mitigate or eliminate these disadvantages, it may be possible to use Fig.23 Variations in .

[0168] Fig.23 The variation corresponds in principle to Fig.21 A variation of or Fig. 22 variants.

[0169] Along the beam path of the light downstream of the AOTF 332, an optical sheet 811 (i.e., a window made of, for example, BK7, quartz glass, etc.) is positioned at an angle such that the first order diffraction 801 is incident on the optical sheet with p-polarization at the Brewster angle (about 57° for BK7). This allows the first order diffraction to pass through the window with almost no reflection losses (this is represented by the crossed-out reflected ray 815). On the other hand, the zeroth order diffraction 800 has no Brewster effect due to its polarization and changed angle, and is reflected according to the general Fresnel equations. About 5%-15% of the reflection can be detected with the sensor 57, because it is only a part of the high laser power. Therefore, a fast sensor is available. The rest of the power passes through the window and can be safely diverted to a dedicated beam trap / absorber 812. If necessary, the angles of the zeroth order diffraction 800 and the first order diffraction 801 can be increased relative to each other by the wedge-shaped design of the optical sheet 811 in order to achieve faster separation of the beams.

[0170] Several aspects have been described above in connection with the implementation of the tunable element by means of an AOTF 332. However, it is also conceivable that the tunable element is implemented by means of an AOM. Here too, different diffraction orders occur, which can be used for replication and intensity measurement as described above.

[0171] Fig.24 A flow chart of an exemplary method is illustrated. Fig.24 The method in is used to control the light intensity during the exposure process, which is used to replicate the master HOE. Fig.24 The method can be based on Figure 1 Part of box 3010.

[0172] For example, Fig.24 The method can be executed by the controller. For example, Fig.24 The method can be Figure 2 The controller 51 is implemented. It is conceivable that Fig.24 The method may be implemented partly in software, partly in hardware, or only in software or only in hardware. For example, it may be implemented in hardware if a particularly fast closed-loop control of the light intensity during the exposure process is desired.

[0173] The exposure process starts in block 5005. This means that the light source (see e.g. Figure 2 : The light source 52) is controlled to emit light. The light beam moving unit and / or at least one optical element may also be controlled. Figure 6 The method mentioned the corresponding aspects.

[0174] A current target intensity value is received in block 5010. For example, the corresponding target intensity value of the control data may be displayed. Several aspects related to the control data 401 are described above.

[0175] In block 5015, the actual intensity value of the light used to replicate the master HOE is measured. For this purpose, appropriate measurements can be obtained from a sensor (e.g., a photodiode). The sensor is preferably positioned near the HOE to be exposed. Figure 2 as well as Fig.21 , Fig. 22 and Fig.23 The variants describe aspects related to the corresponding sensor 57.

[0176] In block 5020, a control signal may then be set based on the deviation between the target intensity value of the current iteration of block 5010 and the actual intensity value of the current iteration of block 5015. In particular, the control signal may be adjusted to reduce the deviation. For example, a PID controller may be used to determine the control signal. The control signal may be used to control the intensity in several ways. For example, a Pockels cell may be controlled. However, alternatively or in addition, the light source itself may also be controlled. The AOTF (see Fig.21 , Fig. 22 , Figure 3 :AOTF 332) or AOM.

[0177] Block 5025 checks whether the exposure process is complete. If the exposure process is not complete, another iteration 5026 is performed. In another iteration 5026 of block 5010, another target intensity value is obtained, etc. When the exposure process in block 5025 ends, the process in block 5030 ends.

[0178] In summary, the following examples are described in particular:

[0179] Example 1. A control device (51) for an exposure device (59) for producing a holographic optical element HOE (96) by replicating a master HOE (92) within the framework of an exposure process performed by the exposure device (59), wherein the exposure process uses light emitted from at least one light source (52) of the exposure device along a beam path (41) to the surface of a carrier layer of the master HOE (92), wherein during the exposure process the carrier layer of the master HOE (92) is arranged along a carrier layer of the HOE,

[0180] The control device (51) comprises at least one processor (191) and a memory (192), wherein the at least one processor (191) is configured to load a program code from the memory (192) and execute the program code, wherein the at least one processor (191) is configured to perform the following steps based on the program code:

[0181] - controlling the beam moving unit (55) of the exposure device (59) so that the beam moving unit moves the beam path (41) relative to the surface of the carrier layer of the master HOE (92) during the exposure process, and

[0182] - controlling at least one adjustable optical element (54) of the exposure device (59), wherein the at least one adjustable optical element is arranged on the beam path (41) so that the at least one adjustable optical element (54) changes at least one of the intensity and polarization of the light over time during the exposure process.

[0183] Example 2. The control device (51) according to Example 1, wherein the at least one processor (191) is further configured to perform the following steps based on the program code:

[0184] - loading control data (401) indicating a correlation between a movement of the beam path (41) relative to the surface of the carrier layer and a change in at least one of the intensity and polarization of the light,

[0185] The control of the beam moving unit (55) and the control of the at least one adjustable optical element (54) are realized in a synchronous manner based on the control data (401).

[0186] Example 3. The control device (51) according to Example 1 or 2,

[0187] wherein the at least one adjustable optical element (54) varies the intensity of the light,

[0188] The at least one adjustable optical element (54) and the beam moving unit (55) are controlled so that the influence of the change of the structural characteristics of the master HOE (92) on the replication efficiency of the master HOE is reduced by changing the intensity of the light during the exposure process.

[0189] Example 4. The control device (51) according to Example 3,

[0190] The at least one adjustable optical element (54) and the beam moving unit are controlled so that the effect of changes in the structural characteristics of the master HOE (92) on the diffraction efficiency of the master HOE is reduced by changing the intensity of the light during the exposure process.

[0191] Example 5. A control device (51) according to any one of the preceding examples,

[0192] wherein the at least one tunable optical element (54) changes the polarization of the light,

[0193] The at least one adjustable optical element (54) and the beam moving unit (55) are controlled so as to reduce the effect of the movement of the beam path (41) during the exposure process on the change of the polarization orientation of the light relative to the surface of the carrier layer of the master HOE.

[0194] Example 6. A control device (51) according to any one of the preceding examples,

[0195] wherein the at least one tunable optical element (54) changes the polarization of the light,

[0196] The at least one adjustable optical element (54) is controlled so as to compensate for the effect of the variable incident angle of the beam path (41) on the change of the replication efficiency during the exposure process caused by the movement of the beam path (41).

[0197] Example 7. A control device (51) according to any one of the preceding examples,

[0198] wherein the at least one wavelength comprises a plurality of wavelengths,

[0199] The at least one tunable optical element (54) is controlled such that the at least one tunable optical element varies the intensities of the components of the light corresponding to the plurality of wavelengths relative to each other during the exposure process.

[0200] Example 8. A control device (51) according to any one of the preceding examples,

[0201] wherein the beam moving unit (55) is controlled using a first signal bandwidth in the kilohertz range,

[0202] Wherein, the tunable optical element (54) is controlled using a second signal bandwidth that is greater than the first signal bandwidth.

[0203] Example 9. A control device (51) according to any one of the preceding examples,

[0204] wherein the beam moving unit (55) is controlled to move the beam path in a stepping mode,

[0205] wherein the at least one adjustable optical element (54) is controlled to vary the at least one of the intensity and the polarization in conjunction with a step size of the stepping pattern.

[0206] Example 10. A control device (51) according to any one of the preceding examples,

[0207] The control device (51) is further configured to change the intensity of the light over time through a control loop during the exposure process.

[0208] Example 11. A system (50) comprising:

[0209] - a control device (51) according to any of the preceding examples, and

[0210] - The exposure device (59).

[0211] Example 12. The system (50) according to Example 11,

[0212] The at least one adjustable optical element (54) comprises at least one acousto-optic modulator, and the at least one acousto-optic modulator is used to change the intensity of the light by adjusting the transmittance.

[0213] Example 13. The system (50) according to Example 12,

[0214] wherein the at least one wavelength comprises a plurality of wavelengths,

[0215] The at least one tunable optical element (54) comprises an acousto-optic modulator for each of the plurality of wavelengths.

[0216] Example 14. The system (50) according to Example 13,

[0217] The control device is further configured as follows:

[0218] The at least one light source (52) includes a plurality of light sources for components of the light corresponding to the plurality of wavelengths.

[0219] The exposure device (59) further comprises a beam combining element, which combines partial beam paths of the components of the light corresponding to the multiple wavelengths of the multiple light sources.

[0220] Therein, the acousto-optic modulators are arranged upstream along the partial beam paths relative to the beam combining element.

[0221] Example 15. The system (50) according to any one of Examples 11 to 14,

[0222] The at least one adjustable optical element (54) comprises an acousto-optic multi-channel filter, and the acousto-optic multi-channel filter is used to change the intensity of the light by adjusting the transmittance.

[0223] Example 16. The system (50) according to Example 15,

[0224] wherein the at least one wavelength comprises a plurality of wavelengths,

[0225] The filtering curve of the acousto-optic filter can be adjusted individually for each of the multiple wavelengths.

[0226] Example 17. The system (50) according to Example 16,

[0227] The at least one light source (52) includes a plurality of light sources for components of the light corresponding to the plurality of wavelengths.

[0228] The exposure device (59) further comprises a beam combining element, which combines partial beam paths of the components of the light corresponding to the multiple wavelengths of the multiple light sources.

[0229] Therein, the acousto-optic filter is arranged downstream along the partial beam paths based on the beam combining element.

[0230] Example 18. The system (50) according to any one of Examples 11 to 17,

[0231] wherein the at least one tunable optical element separates the light into at least a first component (800) and a second component (801),

[0232] The system (50) comprises a sensor (57) configured to measure the intensity of the first component.

[0233] Wherein, the exposure device (59) is configured to implement the exposure process using the second component.

[0234] Example 19. The system (50) according to Example 18,

[0235] wherein the first component corresponds to a diffraction order having a first polarization,

[0236] wherein the second component corresponds to another diffraction order having a second polarization,

[0237] wherein the diffraction order is different from the other diffraction order,

[0238] Wherein, the first polarization is optionally different from the second polarization.

[0239] Example 20. The system (50) according to example 18 or 19, further comprising:

[0240] - a polarization beam splitter (820) arranged on the beam path of the first component and on the beam path of the second component.

[0241] Example 21. The system (50) according to Example 17 or 18, further comprising:

[0242] - an optical sheet (811) arranged on the beam path of the first component (800) and on the beam path of the second component (801),

[0243] The optical sheet is arranged tilted relative to the beam path of the second component (801) so that the second component is incident on the optical sheet at a Brewster angle.

[0244] Example 22. The system (50) according to any one of Examples 11 to 21,

[0245] Therein, the at least one tunable optical element (54) comprises a Pockels cell for changing the polarization by rotating the polarization plane.

[0246] Example 23. The system (50) according to any one of Examples 11 to 22,

[0247] The at least one adjustable optical element (54) comprises one or more λ / 2 wave plates which can be alternately introduced into the beam path (41) by a motor.

[0248] Example 24. A method for controlling an exposure device (59) for producing a holographic optical element HOE (96) by replicating a master HOE (92) within the framework of an exposure process performed by the exposure device (59), wherein the exposure process uses light emitted from at least one light source (52) of the exposure device along a beam path (41) to the surface of a carrier layer of the master HOE (92), wherein during the exposure process the carrier layer of the master HOE (92) is arranged along a carrier layer of the HOE (96),

[0249] The method comprises the following steps:

[0250] - controlling the beam moving unit (55) of the exposure device (59) so that the beam moving unit moves the beam path (41) relative to the surface of the carrier layer of the master HOE (92) during the exposure process, and

[0251] - controlling at least one adjustable optical element (54) of the exposure device (59), wherein the at least one adjustable optical element is arranged on the beam path (41) so that the at least adjustable optical element (54) changes at least one of the intensity and polarization of the light over time during the exposure process.

[0252] Example 25. The method according to Example 24,

[0253] Therein, at least the control of the at least one adjustable optical element (54) and / or the beam shifting unit (55) is based on control data.

[0254] Example 26. The method according to Example 24 or 25,

[0255] The at least one adjustable optical element (54) is controlled based on a closed control loop that minimizes a deviation between a target intensity and an actual intensity of the light.

[0256] Example 27. The method according to any one of Examples 24 to 26,

[0257] The method is performed by a control device (51) according to any one of Examples 1 to 10.

[0258] Example 28. A method for configuring a production method for producing a holographic optical element HOE by replicating a master HOE (92) within the framework of an exposure process performed by an exposure device (59), wherein during the exposure process the carrier layer of the master HOE (92) is arranged along the carrier layer of the HOE (96),

[0259] The method comprises the following steps:

[0260] - generating (3810) control data (401) for at least one adjustable optical element (54) of the exposure device (59), wherein the optical element is arranged in the beam path (41) of the light used for carrying out the replication,

[0261] The at least one adjustable optical element (54) can be controlled by the control data (401) so that the at least one adjustable optical element changes at least one of the intensity and polarization of the light over time during the exposure process.

[0262] Example 29. The method according to Example 28, wherein the method further comprises:

[0263] - obtaining a map (799) of the master HOE (92), wherein the map (799) indicates the diffraction efficiency as a function of the position on the surface of the carrier layer of the master HOE (92),

[0264] Therein, the control data (401) is determined based on the graph (799).

[0265] Example 30. The method according to Example 29,

[0266] wherein the control data (401) is determined using a predetermined transfer function based on the map (799),

[0267] wherein the predetermined transfer function assigns a relatively high intensity of the light to a first region (701, 702, 703) on the surface of the carrier layer having a relatively low diffraction efficiency,

[0268] The predetermined transfer function assigns a relatively low intensity of the light to a second region (701, 702, 703) on the surface of the carrier layer having a relatively high diffraction efficiency.

[0269] Example 31. The method according to any one of Examples 28 to 30, wherein the method further comprises:

[0270] - obtaining exposure configuration data describing the movement of the beam path (41) relative to the surface of the carrier layer of the master HOE (92) during the exposure process,

[0271] The control data (401) is generated based on the exposure configuration data.

[0272] Example 32. The method according to Example 31,

[0273] The exposure configuration data describes the change of the incident angle of the beam path (41) relative to the surface of the carrier layer of the master HOE (92) during the exposure process,

[0274] The control data (401) causes a rotation of the polarization plane to maintain s-polarization or p-polarization during a change in the incident angle of the beam path (41).

[0275] Example 33. The method according to any one of Examples 28 to 32, wherein the method further comprises:

[0276] - obtaining a target specification for the diffraction efficiency of the HOE (96),

[0277] The control data (401) is generated based on a target specification of the diffraction efficiency of the HOE (96).

[0278] Example 34. The method according to Example 33,

[0279] Wherein the target specification indicates a local variation in the diffraction efficiency of the HOE (96) relative to a local variation in the diffraction efficiency of the master HOE.

[0280] Example 35. The method according to any one of Examples 28 to 34, wherein the method further comprises:

[0281] - obtaining synchronous measurement data collected in conjunction with the production of the HOE (96),

[0282] Therein, the control data (401) is generated based on the synchronous measurement data.

[0283] Example 36. The method according to Example 35,

[0284] Therein, the synchronous measurement data describes the diffraction efficiency of the test instance of the HOE (96).

[0285] Example 37. A device comprising at least one processor and a memory, wherein the at least one processor is configured to load program code from the memory and execute the program code,

[0286] Wherein, the at least one processor is configured to execute the method described in any one of Examples 28 to 36 based on the program code.

[0287] It goes without saying that the features of the embodiments and aspects of the present invention described above can be combined with each other. In particular, without departing from the scope of the present invention, these features can be used not only in the described combinations, but also in other combinations or alone.

[0288] For example, techniques have been described above in which light intensity variation occurs via an adjustable optical element disposed in the beam path. Similarly, a light source (such as a laser) may also be controlled to vary the intensity of the light. For example, the supply current of a laser diode may be reduced to reduce the intensity. In such variations, it may sometimes be unnecessary to provide a separate adjustable optical element in the beam path.

[0289] Further, the technique of achieving light intensity variation via an adjustable optical element arranged in the beam path has been described above. This causes a variation in the dose of light used for exposure. Alternatively or in addition, the residence time of the light spot on the surface of the master HOE or the replicated HOE can be adapted to vary the dose.

[0290] For example, techniques related to implementing a closed control loop of light intensity during exposure have been described above (see, e.g., Fig.24 ). Alternatively or in addition to such a closed control loop for the light intensity, a closed control loop for the light polarization can also be implemented.

[0291] Although techniques have been described above by which intensity or polarization sensor values ​​can be used to close a control loop, the corresponding sensor values ​​can also be used to monitor whether the sensor values ​​are within a specified range. If they are not within the tolerance range, the replication process can be aborted.

Claims

1. A method for configuring a production method for producing a holographic optical element (HOE) by replicating a master HOE (92) within the framework of an exposure process performed by an exposure device (59), wherein: During the exposure process, the carrier layer of the master HOE (92) is arranged along the carrier layer of the HOE (96). The method comprises the following steps: - generating (3810) control data (401) for at least one adjustable optical element (54) of the exposure device (59), wherein the optical element is arranged in the beam path (41) of the light used for carrying out the replication, The at least one adjustable optical element (54) can be controlled by the control data (401) so that the at least one adjustable optical element changes at least one of the intensity and polarization of the light over time during the exposure process.

2. The method according to claim 1, wherein: The method further includes: - obtaining a map (799) of the master HOE (92), wherein the map (799) indicates the diffraction efficiency as a function of the position on the surface of the carrier layer of the master HOE (92), Therein, the control data (401) is determined based on the graph (799).

3. The method according to claim 2, in, determining the control data (401) using a predetermined transfer function based on the map (799), wherein the predetermined transfer function assigns a relatively high intensity of the light to a first region (701, 702, 703) on the surface of the carrier layer having a relatively low diffraction efficiency, The predetermined transfer function assigns a relatively low intensity of the light to a second region (701, 702, 703) on the surface of the carrier layer having a relatively high diffraction efficiency.

4. A method according to any one of the preceding claims, wherein: The method further includes: - obtaining exposure configuration data describing the movement of the beam path (41) relative to the surface of the carrier layer of the master HOE (92) during the exposure process, The control data (401) is generated based on the exposure configuration data.

5. The method according to claim 4, in, The exposure configuration data describe the change in the angle of incidence of the beam path (41) relative to the surface of the carrier layer of the master HOE (92) during the exposure process, The control data (401) causes a rotation of the polarization plane to maintain s-polarization or p-polarization during a change in the incident angle of the beam path (41).

6. A method according to any one of the preceding claims, wherein: The method further includes: - obtaining a target specification for the diffraction efficiency of the HOE (96), The control data (401) is generated based on a target specification of the diffraction efficiency of the HOE (96).

7. The method according to claim 6, in, The target specification indicates a local variation in the diffraction efficiency of the HOE (96) relative to a local variation in the diffraction efficiency of the master HOE.

8. A method according to any one of the preceding claims, wherein: The method further includes: - obtaining synchronous measurement data collected in conjunction with the production of the HOE (96), Therein, the control data (401) is generated based on the synchronous measurement data.

9. The method according to claim 8, in, The synchronous measurement data describes the diffraction efficiency of the test instance of the HOE (96).

10. A device comprising at least one processor and a memory, wherein: The at least one processor is configured to load program code from the memory and execute the program code, The at least one processor is configured to execute a method according to any one of the preceding claims based on the program code.

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