OPTICAL SYSTEM, LITHOGRAPHY SYSTEM WITH AN OPTICAL SYSTEM AND METHOD FOR PRODUCING AN OPTICAL SYSTEM

Abstract

An optical system for a lithography system comprising a plurality of optical elements has: a number N1 of arrangements, with N1≥1, wherein each of the N1 arrangements comprises a number of actuator / sensor devices, wherein the respective actuator / sensor device is assigned to one of the optical elements, and a number N2 of local control units for controlling the number N1 arrangements, wherein each of the N1 arrangements comprises a ring network with N3 network devices arranged in a ring and connected by N3 primary connections, wherein the N3 network devices comprise a number N4 of the actuator / sensor devices and N5 bridges, with N5≥0 and N3=N4+N5, wherein the N4 actuator / sensor devices comprise a first subset N6 with a respective connection to one of the local control units and a second subset N7 without a connection to one of the local control units, with N4=N6+N7,wherein each group member of the group comprising the N5 bridges and the N7 actuator / sensor devices is connected to another group member of the group by means of a secondary connection, wherein the respective secondary connection bridges at least one adjacent group member in the group.

Description

The present invention relates to an optical system and a lithography apparatus having such an optical system. The present invention further relates to a method for producing an optical system for a lithography apparatus.Microlithography is used for producing microstructured components, such as integrated circuits. The microlithography process is carried out with a lithography apparatus which has an illumination system and a projection system. The image of a mask (reticle) illuminated by means of the illumination system is projected by means of the projection system onto a substrate, for example a silicon wafer, coated with a photosensitive layer (photoresist) and arranged in the image plane of the projection system, in order to transfer the mask structure to the photosensitive coating of the substrate.Driven by the desire for increasingly smaller structures in the production of integrated circuits, EUV lithography apparatuses are currently being developed which use light with a wavelength in the range from 0.1 nm to 30 nm, in particular 13.5 nm. Since most materials absorb light of this wavelength, reflective optics, i.e. mirrors, must be used in such EUV lithography apparatuses instead of refractive optics, i.e. lenses, as before.In lithography apparatuses, a multiplicity of actuator / sensor devices, such as sensors and actuators, are installed. In general, an actuator / sensor device is suitable for displacing an optical element, such as a mirror, associated with the actuator / sensor device and / or for detecting a parameter of the associated optical element, such as a position of the associated optical element or a temperature of the associated optical element. For the purpose of activation and evaluation, such an actuator / sensor device is to be electrically connected to an electronic component, in particular to an integrated circuit (IC).The number of actuator / sensor devices in optical systems of lithography apparatuses increases steadily. In conventional star-shaped wirings of the actuator / sensor devices, the length of the cable paths increases linearly. Cables suitable for clean rooms are expensive and also consume the tight installation space available in the lithography apparatus. Bus systems, on the other hand, involve a lower wiring complexity, but are susceptible to failures of individual connected devices and can thus lead to failures of an entire group of connected devices if the bus system itself has a fault.Document DE 10 2015 224 742 A1 proposes a lithography apparatus which comprises a radiation source for generating radiation, a plurality of optical components for guiding the radiation in the apparatus, a number of arrangements, wherein each of the arrangements comprises at least one actuator / sensor device which is assigned to one of the optical components, a plurality of local control units for controlling the number of arrangements and a number of central control units for controlling the local control units. By the distributed control of the actuator / sensor devices by means of the local control units and the central control units, it is possible to distribute the heat arising from the control. As a result, heat spots, for example in the vacuum housing of the lithography apparatus, are avoided and the heat distribution is harmonized and optimized. The respective arrangement is connected for data exchange via a connection to one of the local control units. However, it is possible that such a connection fails after a certain time or is subject to a fault.The exchange of electronic components, such as, for example, such connections involving errors between an actuator / sensor device and a drive unit, in an optical system of a lithography apparatus, in particular within the vacuum range, requires a great deal of time until the system is again in operative operation. Although a modular construction as described, for example, in the above-cited document DE 10 2015 224 742 A1 enables a reduction in the maintenance time and the maintenance costs, with an increasing number of connections between the modules, that is to say in particular the actuator / sensor devices and the control units, the frequency of faults also increases, in particular in the presence of several hundred electrical connections between the modules.The document DE 10 2022 211 696 A1 describes an optical system for a lithography apparatus comprising a plurality of optical elements, which optical system has: a number of arrangements, each of the arrangements comprising at least one actuator / sensor device which is assigned to one of the optical elements, a plurality of local drive units for driving the number of arrangements and a number of central drive units for driving the local drive units, wherein each of the arrangements is connected to at least one of the N2 local drive units by means of a primary connection and a secondary connection redundant to the primary connection, wherein one of the connections can be used as an active connection for data transmission and the other of the connections is inactive, wherein each of the local driving units comprises a plurality of interface means for establishing the primary connection or the secondary connection to one of the arrangements respectively, a fault detecting unit for detecting a fault of one of the active connections of a particular one of the arrangements, and a providing unit for providing switching information for switching the active connection having a detected fault to the inactive connection of the particular arrangement.In view of the foregoing, it is an object of the present invention to provide an improved optical system.According to a first aspect, an optical system for a lithography apparatus comprising a plurality of optical elements is proposed, which comprises:a number N1 of arrays, where N1≥1, each of the N1 arrays comprising a number of actuator / sensor devices, the respective actuator / sensor device being associated with one of the optical elements, anda number N2 of local drive units for driving the number N1 of arrays,wherein each of the N1 arrangements comprises a ring network with N3 network devices arranged in a ring and connected by N3 primary connections, wherein the N3 network devices comprise a number N4 of the actuator / sensor devices and N5 bridges, with N5≥0 and N3=N4+N5, wherein the N4 actuator / sensor devices comprise a first subset N6 with respective connection to one of the local drive units and a second subset N7 without connection to one of the local drive units, with N4=N6+N7,wherein each group member of the group of the N5bridges and the N7 actor / sensor devices is connected to another group member of the group by means of a secondary connection, wherein the respective secondary connection bridges at least one adjacent group member in the group.An arrangement is in particular designed as a printed circuit board, which integrates, for example, a plurality of MMUs with a respective mirror array of mirrors as network devices. The present ring network of the network devices in the respective arrangement comprising the primary connections and the secondary connections creates a wiring scheme which is constructed redundantly in such a way that it is robust with respect to individual errors in the ring network of the arrangement. The next element in the ring network is considered to be the adjacent group member in particular. The physical placement on the printed circuit board can be arbitrary.The use of the primary connections and the secondary connections results in particular in redundant connections between all network devices of the ring network of the arrangement. Thus, a failure of a connection in the ring network can be tolerated. If a certain active connection, which is used for data transmission between two of the network devices of the ring structure, fails, then the associated redundant secondary connection can be switched over.The network devices are connected to one another in a redundant manner locally in the ring network, in particular, and thus meet the highest requirements with regard to reliability, real-time capability and latency during the communication within the arrangement.The present ring network with the primary and secondary connections provides robust communication against single faults in a network topology with point-to-point connections between the participating network devices. This creates high system availability with a simultaneous saving in costs and installation space due to low wiring complexity in the arrangement. Overall, this also advantageously allows the length of expensive cables suitable for clean rooms and the associated installation space to be saved.The present condition that the respective secondary connection bridges at least one adjacent group member in the group maintains the following rules: 1. during bridging in the ring network by the respective secondary connection, at least one adjacent space in the ring network is always skipped. 2. such skipping does not involve actuator / sensor devices which have a connection to one of the local activation units. Consequently, when skipping, only those actuator / sensor devices which do not have a connection to one of the local activation units and bridges are included. 3. the positions in the ring network which have a connection to one of the local control units are always occupied by an actuator / sensor device, and not by a bridge.Thus, each network device of the group has at least one alternative connection to a non-immediately adjacent network device of the group in order to be able to tolerate the failure of individual network devices in the ring network. The N2 local drive units, where N2≥1, are configured to control the network devices in the ring network of the arrangement from a higher hierarchy level. The N6 actuator / sensor devices with a respective connection to one of the local activation units implement the data exchange between the arrangement and the higher hierarchical level of the local activation units. A hierarchy level above the local control units can also be provided with a number of central control units.The respective bridge can also be referred to as an adapter bridge, bridge device, bridge or device bridge and is suitable for forwarding data in any direction of the ring network. In this case, the respective one of the N5bridges comprises, in particular, a respective electrical through-connection in each direction of the ring network. The ring network can also be referred to as a ring topology network or network.In particular, if a space of the ring network is not occupied by an actuator / sensor device, for example when the arrangement is designed as a printed circuit board having N3 slots, the free slots are bridged by the adapter bridges, in particular purely electrically without packet routing, in order thus to keep the ring of the ring network closed. In particular, adapter bridges are not used in successive plug-in locations.The optical system is preferably a projection optical unit of the lithography apparatus or projection exposure apparatus. However, the optical system may also be an illumination system. The projection exposure apparatus can be an EUV lithography apparatus. EUV stands for "extreme ultraviolet" and denotes a wavelength of the working light between 0.1 nm and 30 nm. The projection exposure apparatus can also be a DUV lithography apparatus. DUV stands for deep ultraviolet and denotes a wavelength of the working light between 30 nm and 465 nm.The respective actuator / sensor device is, for example, an actuator (or actuator) for actuating an optical element, a sensor for sensing an optical element or an environment in the optical system, or an actuator and sensor device for actuating and sensing in the optical system. The sensor is, for example, a temperature sensor. The actuator is, for example, an actuator that uses the electrostrictive effect or an actuator that uses the piezoelectric effect, for example, a PMN actuator (PMN; lead magnesium niobate) or a PZT actuator (PZT; lead zirconate titanate). The actuator may also be a MEMS (microelectromechanical system) actuator. The actuator is configured in particular to actuate an optical element of the optical system. Examples of such an optical element include lenses, mirrors, and adaptive mirrors.In the description of the present optical system, the following parameters are used: N1 number of arrangements N2 number of local drive units N3 number of network devices of the ring network N3 number of primary connections of the ring network N4 number of actuator / sensor devices of the ring network N5 number of bridges of the ring network N6 number of actuator / sensor devices of the ring network connected to one of the local drive units N7 number of actuator / sensor devices of the ring network without connection to one of the local drive units N8 number of central drive unitsAccording to one embodiment, the respective primary connection is a point-to-point connection between two of the network devices arranged in the ring network.According to a further embodiment, the group members form a ring structure by means of the N3precursive compounds and the N6actuator / sensor devices. In the ring structure, each group member is connected to each of two adjacent group members via one of the primary compounds, or via two of the primary compounds and one of the N6 actor / sensor devices.According to a further embodiment, the respective secondary compound is a point-to-point compound between two of the non-adjacent group members arranged in the ring structure.According to a further embodiment, the N4 actor / sensor devices of the ring network are identical. The N4 actor / sensor devices are in particular identical according to the common part principle. By using identical actuator / sensor devices, costs in the production of the optical system can be reduced.According to another embodiment, each of the N3network devices has at least two inputs and at least two outputs. Preferably, each of the N3network devices has exactly two inputs and exactly two outputs. In alternative embodiments, each of the N3 network devices has exactly four inputs and exactly four outputs.According to a further embodiment, the N6 actor / sensor devices are connected to N6 different local control units, where 2≤N6≤N2. This advantageously brings about redundancy in the data-technology coupling of the arrangement and in this case in particular of its actuator / sensor devices having the higher hierarchy level, in the present case the local activation units.According to a further embodiment, each of the N6 actor / sensor devices is connected to a specific one of the N6 different local drive units via a downlink connection for transmitting commands from the specific local drive unit to the connected actor / sensor device and via an uplink connection for transmitting data from the actor / sensor device to the connected local drive unit.According to a further embodiment, the respective primary connection is designed as a unidirectional connection. According to a further, alternative embodiment, the respective primary connection is designed as a bidirectional connection.According to a further embodiment, the respective secondary connection is designed as a unidirectional connection. According to a further, alternative embodiment, the respective secondary connection is designed as a bidirectional connection.According to a further embodiment, the respective one of the N5bridges has a respective electrical via in each direction of the ring network.According to a further embodiment, each of the N1 arrangements is formed as a printed circuit board. The respective printed circuit board comprises in particular N3 slots which are connected to one another via the N3 primary connections for forming the ring network.According to a further embodiment, each slot of a subset N 6 of the N 3 slots is connected to one of the N 2 local driver units, where N 6≤N 3, in particular via a dedicated downlink connection and a dedicated uplink connection. In this case, each of the N6 slots is equipped with one of the N6 actuator / sensor devices. Thus, those slots with a connection to one of the local control units are equipped with actuator / sensor devices which are set up for communication with one of the hierarchically higher local control units.According to a further embodiment, the N3 network devices are configured to transmit and receive data packets of a specific communication protocol via the ring network. The respective data packet has, in particular, a first frame with packet routing information, a second frame with header information and a third frame with payload data.According to another embodiment, the packet routing information of the first frame determines a path in the ring network. The path is in particular a complete path in the ring network. Here, the packet routing information for each forwarding step of the data packet in the ring network includes a bit group of a predetermined bit length. Here, each bit group is assigned to one of the network devices determining the path in the ring network.According to a further embodiment, the respective network device has a first output connected to the respective primary connection and a second output connected to the respective secondary connection. The respective bit group of the packet routing information has a first coding for forwarding the data packet via the first output of the respective network device of the path. For forwarding the data packet via the second output of the respective network device of the path, the respective bit group of the packet routing information has a second coding. The last bit group of the packet routing information has a third encoding for indicating the termination of the data packet at the network device associated with the last bit group.If the respective network device has more than two outputs, the encodings of the packet routing information are correspondingly adapted, so that the respective assignment of one of the outputs to a respective encoding is one-to-one.For example, the packet routing information is configured as:In this example, the packet routing information has five bit groups each having a bit length of 2 bits. The first coding for forwarding over the primary link is 01, the second coding for forwarding over the secondary link is 10, and the third coding for terminating the data packet at the associated network device is 00. Thus, in this example, there is one transmitting network device and three relaying network devices, ultimately terminating the data packet at the network device designated 00. With this packet routing information in the first frame of the data packet, the transmitter of the data packet defines the path through the network by means of instructions on packet forwarding, namely by means of the different encodings of the bit groups, to the other network subscribers. Because the packet routing information is provided in the first frame of the data packet, each network subscriber can already analyze the data packet header, in the present case comprising the first and the second frame, before receiving the entire data packet. The packet routing information contained therein is followed by the receiving network subscriber accordingly, and the data packet header can be adapted so that the next network subscriber receives the routing instructions intended for it.According to a further embodiment, the data transmission takes place in the ring network on a time slot basis. By means of a time-slot-based data transmission within the ring network, it can also be ensured that data packets always arrive at the respective receiver with the same delay time, so that sensor data can be transmitted in real time, for example. As stated above, the data packet header includes the transmission path through the ring network. Consequently, a constant, predictable latency in the transmission of data packets can be achieved. Thus, a simplified transmission protocol can be used as the communication protocol, in which the network devices of the ring network do not require any information about the ring network itself.According to a further embodiment, the respective network device is configured to analyze only the respective foremost bit group and subsequently consume it, so that the respective network device always only needs to analyze the first bit group. The respective bit group can also be referred to as a symbol. In other words, the foremost symbol can thus be consumed during forwarding and deleted from the packet routing information, so that each actuator / sensor device always only has to evaluate the foremost symbol. As a result, the actuator / sensor devices do not require any knowledge about the network itself and can have an identical evaluation unit. In order to keep the length of the routing information constant, any symbol may be appended at the back or even the foremost deleted bit. With the latter, the receiver can reconstruct the routing path to the transmitter.According to a further embodiment, the local drive unit is configured to analyze the ring network by sending data packets of the determined communication protocol configured for network analysis via the network devices of the ring network and, on the basis thereof, to define a number of ring paths, in particular logic ring paths, in the ring network.According to a further embodiment, the local drive unit is configured to set the ring paths in the ring network such that each point-to-point connection between two of the network devices per ring path is used at most once.At least one local drive unit analyzes the ring network of the arrangement for existing devices and connections by systematically sending data packets according to the source-driven routing principle and establishes one or more ring paths through the ring network, in which each direct connection between two network subscribers per ring path is used at most once. This advantageously results in redundant communication connections in the analyzed ring network of the arrangement. After defining the ring paths, data can be exchanged between the local drive unit and the network subscribers of the ring network, in particular in a time-division multiplex method. The local control unit can in particular send data packets according to the source-driven routing principle, wherein each sent data packet again has the local drive unit itself as a destination, so that the data packets can pass through the defined ring path. For example, in each circulating data packet, each network subscriber is allocated a fixed data block in which data can be received and sent by overwriting the received data.According to a further embodiment, the optical system further comprises a number N8 of central drive units for driving the N2 local drive units, where N8≥1.According to a further embodiment, the optical system is arranged in a vacuum housing of the lithography apparatus.According to a further embodiment, the optical system is designed as an illumination optical unit or as a projection optical unit of a lithography apparatus.According to a second aspect, a lithography apparatus is proposed, which has an optical system according to the first aspect or according to one of the embodiments of the first aspect.According to a third aspect, a method for producing an optical system for a lithography apparatus comprising a plurality of optical elements is proposed. The method comprises:providing a number N1 of arrangements, with N1≥1, wherein each of the N1 arrangements comprises a number of actuator / sensor devices, wherein the respective actuator / sensor device is assigned to one of the optical elements,providing a number N2 of local drive units for driving the number N1 of devices,wherein in each of the N1 arrangements, N3 network devices are arranged in a ring and primary connections are connected by N3 to form a ring network, wherein the N3 network devices comprise a number N4 of the actuator / sensor devices and N5 bridges, with N5≥0 and N3=N4+N5, wherein a first subset N6 of the N4 actuator / sensor devices is connected by means of a respective connection to one of the local control units and a second subset N7 of the N4 actuator / sensor devices is provided without connection to one of the local control units, with N4=N6+N7,wherein each group member of the group of the N5bridges and the N7 actor / sensor devices is connected to another group member of the group by means of a secondary connection, wherein the respective secondary connection bridges at least one adjacent group member in the group.The embodiments described for the proposed optical system apply correspondingly to the proposed method. Furthermore, the definitions and explanations relating to the optical system also apply correspondingly to the proposed method."An" is not necessarily to be understood as limiting to exactly one element. Rather, a plurality of elements, such as two, three or more, can also be provided. Any other counting word used here is also not to be understood as being limited to exactly the number of elements mentioned. Instead, numerical deviations upwards and downwards are possible, unless indicated to the contrary.Further possible implementations of the invention also include combinations, not explicitly mentioned, of features or embodiments described above or below with respect to the exemplary embodiments. In this case, the person skilled in the art will also add individual aspects as improvements or additions to the respective basic form of the invention.Further advantageous embodiments and aspects of the invention are the subject matter of the dependent claims and of the exemplary embodiments of the invention described below. The invention is explained in more detail below on the basis of preferred embodiments with reference to the enclosed figures. FIG. 1 shows a schematic meridional section of a projection exposure apparatus for EUV projection lithography; FIG. 2 shows a schematic illustration of a first embodiment of an optical system having a central drive unit, local drive units and an arrangement having actuator / sensor devices; FIG. 3 shows a schematic illustration of a second embodiment of an optical system; FIG. 4 shows a schematic illustration of a third embodiment of an optical system; FIG. 5 shows a schematic illustration of a data packet that can be transmitted via the ring network of the arrangement; FIG. 6 shows a schematic illustration of a fourth embodiment of an optical system; FIG. 7 is a schematic illustration of ring paths in the ring network of the optical system arrangement; and FIG. 8 shows a schematic flow diagram of a method for producing an optical system for a lithography apparatus.In the figures, identical or functionally identical elements have been provided with the same reference symbols, unless indicated to the contrary. It should also be noted that the representations in the figures are not necessarily to scale.FIG. 1 shows an embodiment of a projection exposure apparatus 1 (lithography apparatus), in particular an EUV lithography apparatus. An embodiment of an illumination system 2 of the projection exposure apparatus 1 has, in addition to a light or radiation source 3, an illumination optical unit 4 for illuminating an object field 5 in an object plane 6. In this case, the illumination system 2 does not include the light source 3.A reticle 7 arranged in the object field 5 is exposed, and the reticle 7 is held by a reticle holder 8. The reticle holder 8 can be displaced via a reticle displacement drive 9, in particular in a scanning direction.For the purpose of explanation, FIG. 1 shows a Cartesian coordinate system with an x-direction x, a y-direction y and a z-direction z. The x-direction x extends perpendicularly into the plane of the drawing. The y-direction y runs horizontally and the z-direction z runs vertically. In FIG. 1, the scanning direction extends along the y-direction y. The z-direction z extends perpendicular to the object plane 6.The projection exposure apparatus 1 comprises a projection optical unit 10. the projection optical unit 10 serves for imaging the object field 5 into an image field 11 in an image plane 12. the image plane 12 runs parallel to the object plane 6.A structure on the reticle 7 is imaged onto a light-sensitive layer of a wafer 13 arranged in the region of the image field 11 in the image plane 12, the wafer 13 being held by a wafer holder 14. The wafer holder 14 is displaceable via a wafer displacement drive 15, in particular along the y-direction y. The displacement of the reticle 7 via the reticle displacement drive 9 on the one hand and of the wafer 13 via the wafer displacement drive 15 on the other hand can take place in synchronization with one another.The light source 3 is an EUV radiation source. The light source 3 emits in particular EUV radiation 16, which is also referred to below as useful radiation, illumination radiation or illumination light. The useful radiation 16 has in particular a wavelength in the range between 5 nm and 30 nm. The light source 3 can be a plasma source, for example a LPP (laser produced plasma) source or a DPP (gas discharged produced plasma) source. It can also be a synchrotron-based radiation source. The light source 3 can be a free-electron laser (FEL).The illumination radiation 16 emanating from the light source 3 is focused by a collector 17. The collector 17 can be a collector with one or more ellipsoidal and / or hyperbolic reflection surfaces. The illumination radiation 16 can be applied to the at least one reflection surface of the collector 17 in the case of a scattering incidence (GI), that is to say with angles of incidence greater than 45°, or in the case of a normal incidence (NI), that is to say with angles of incidence less than 45°. The collector 17 can be structured and / or coated on the one hand for optimizing its reflectivity for the useful radiation and on the other hand for suppressing false light.After the collector 17, the illumination radiation 16 propagates through an intermediate focus in an intermediate focus plane 18. the intermediate focus plane 18 can represent a separation between a radiation source module, comprising the light source 3 and the collector 17, and the illumination optical unit 4.The illumination optical unit 4 comprises a deflection mirror 19 and, downstream thereof, a first facet mirror 20 in the beam path. The deflection mirror 19 can be a planar deflection mirror or alternatively a mirror having an effect influencing the beam beyond the pure deflection effect. Alternatively or additionally, the deflecting mirror 19 can be designed as a spectral filter which separates a used light wavelength of the illumination radiation 16 from false light of a wavelength deviating therefrom. If the first facet mirror 20 is arranged in a plane of the illumination optical unit 4 which is optically conjugate to the object plane 6 as a field plane, this is also referred to as a field facet mirror. The first facet mirror 20 comprises a multiplicity of individual first facets 21, which can also be referred to as field facets. Of these first facets 21, only some are illustrated by way of example in FIG. 1.The first facets 21 can be designed as macroscopic facets, in particular as rectangular facets or as facets with an arcuate or part-circular edge contour. The first facets 21 can be embodied as planar facets or alternatively as convexly or concavely curved facets.As is known, for example, from DE 10 2008 009 600 A1, the first facets 21 themselves can also each be composed of a multiplicity of individual mirrors, in particular a multiplicity of micromirrors. The first facet mirror 20 can be designed, in particular, as a microelectromechanical system (MEMS system). For details, reference is made to DE 10 2008 009 600 A1.Between the collector 17 and the deflecting mirror 19, the illumination radiation 16 extends horizontally, that is to say along the y-direction y.Arranged downstream of the first facet mirror 20 in the beam path of the illumination optical unit 4 is a second facet mirror 22. The second facet mirror 22 can also be arranged at a distance from a pupil plane of the illumination optical unit 4. In this case, the combination of the first facet mirror 20 and the second facet mirror 22 is also referred to as a specular reflector. Specular reflectors are known from US 2006 / 0132747 A1, EP 1 614 008 B1 and U.S. Pat. No. 6,573,978 B1.The second facet mirror 22 comprises a plurality of second facets 23. the second facets 23 are also referred to as pupil facets in the case of a pupil facet mirror.The second facets 23 can likewise be macroscopic facets, which can be round, rectangular or else hexagonally bordered, for example, or alternatively facets composed of micromirrors. In this respect, reference is likewise made to DE 10 2008 009 600 A1.The second facets 23 can have planar or alternatively convexly or concavely curved reflection surfaces.The illumination optics 4 thus form a double faceted system. This basic principle is also referred to as a honeycomb capacitor (Fly's Eye Integrator).It may be advantageous not to arrange the second facet mirror 22 exactly in a plane which is optically conjugate to a pupil plane of the projection optical unit 10. In particular, the second facet mirror 22 can be arranged tilted with respect to a pupil plane of the projection optical unit 10, as is described, for example, in DE 10 2017 220 586 A1.With the aid of the second facet mirror 22, the individual first facets 21 are imaged into the object field 5. The second facet mirror 22 is the last beam-forming mirror or indeed the last mirror for the illumination radiation 16 in the beam path in front of the object field 5.In a further embodiment of the illumination optics 4, not shown, a transmission optics can be arranged in the beam path between the second facet mirror 22 and the object field 5, which in particular contributes to the imaging of the first facets 21 into the object field 5. The transmission optics can have exactly one mirror, but alternatively also two or more mirrors, which are arranged one behind the other in the beam path of the illumination optics 4. The transmission optics can comprise in particular one or two mirrors for perpendicular incidence (NI mirror, Normal Incidence mirror) and / or one or two mirrors for fringe incidence (GI mirror, Growing Incidence mirror).In the embodiment shown in FIG. 1, the illumination optical unit 4 has exactly three mirrors downstream of the collector 17, namely the deflecting mirror 19, the first facet mirror 20 and the second facet mirror 22.In a further embodiment of the illumination optical unit 4, the deflecting mirror 19 can also be omitted, so that the illumination optical unit 4 can then have exactly two mirrors downstream of the collector 17, namely the first facet mirror 20 and the second facet mirror 22.The imaging of the first facets 21 by means of the second facets 23 or with the second facets 23 and a transmission optical unit into the object plane 6 is regularly only an approximate imaging.The projection optical unit 10 comprises a plurality of mirrors Mi, which are numbered according to their arrangement in the beam path of the projection exposure apparatus 1.In the example illustrated in FIG. 1, the projection optical unit 10 includes six mirrors M 1 to M 6. Alternatives with four, eight, ten, twelve or another number of mirrors Mi are also possible. The projection optical unit 10 is a double-obscured optical unit. The next-to-last mirror M 5 and the last mirror M 6 each have a passage opening for the illumination radiation 16. The projection optical unit 10 has an image-side numerical aperture which is greater than 0.5 and which can also be greater than 0.6 and which can be, for example, 0.7 or 0.75.Reflection surfaces of the mirrors Mi can be designed as free-form surfaces without a rotational symmetry axis. Alternatively, the reflection surfaces of the mirrors Mi can be designed as aspherical surfaces with exactly one axis of rotational symmetry of the reflection surface shape. The mirrors Mi, like the mirrors of the illumination optical unit 4, can have highly reflective coatings for the illumination radiation 16. These coatings can be designed as multilayer coatings, in particular with alternating layers of molybdenum and silicon.The projection optical unit 10 has a large object image offset in the y direction y between a y coordinate of a center of the object field 5 and a y coordinate of the center of the image field 11.The projection optical unit 10 can be designed in particular anamorphically. It has in particular different imaging scales βx, βyin the x- and y-directions x, y. The two imaging scales βx, βyof the projection optical unit 10 are preferably (βx, βy)=(+ / - 0.25, / +-0.125). A positive imaging scale β means imaging without image reversal. A negative sign for the imaging scale β means image reversal imaging.The projection optical unit 10 thus leads in the x-direction x, i.e. in the direction perpendicular to the scanning direction, to a reduction in the ratio 4:1.The projection optical unit 10 leads to a reduction of 8:1 in the y-direction y, i.e. in the scanning direction.Other imaging scales are also possible. Identical-sign and absolutely identical imaging scales in the x- and y-directions x, y, for example with absolute values of 0.125 or of 0.25, are also possible.The number of intermediate image planes in the x- and y-directions x, y in the beam path between the object field 5 and the image field 11 can be the same or can be different depending on the embodiment of the projection optical unit 10. Examples of projection optics with different numbers of such intermediate images in the x and y directions x, y are known from US 2018 / 0074303 A1.In each case one of the second facets 23 is assigned exactly to one of the first facets 21 for forming in each case an illumination channel for illuminating the object field 5. This can result in particular in illumination according to the Kohler principle. The far field is broken down into a plurality of object fields 5 with the aid of the first facets 21. The first facets 21 generate a plurality of images of the intermediate focus on the second facets 23 assigned to them in each case.The first facets 21 are imaged onto the reticle 7 in each case by an associated second facet 23 in a manner overlapping one another in order to illuminate the object field 5. The illumination of the object field 5 is in particular as homogeneous as possible. It preferably has a uniformity error of less than 2%. The field uniformity can be achieved by superimposing different illumination channels.By arranging the second facets 23, the illumination of the entry pupil of the projection optical unit 10 can be geometrically defined. By selecting the illumination channels, in particular the subset of the second facets 23, which guide light, the intensity distribution in the entrance pupil of the projection optical unit 10 can be adjusted. This intensity distribution is also referred to as illumination setting or illumination pupil filling.A likewise preferred pupil uniformity in the region of sections of an illumination pupil of the illumination optical unit 4 that are illuminated in a defined manner can be achieved by redistribution of the illumination channels.Further aspects and details of the illumination of the object field 5 and in particular of the entry pupil of the projection optical unit 10 are described below.The projection optical unit 10 can have, in particular, a homocentric entry pupil. This can be accessible. It may also be inaccessible.The entrance pupil of the projection optical unit 10 cannot be illuminated exactly with the second facet mirror 22 as a rule. In an imaging of the projection optical unit 10, which images the center of the second facet mirror 22 telecentrically onto the wafer 13, the aperture beams often do not intersect at a single point. However, an area can be found in which the paired distance of the aperture beams becomes minimum. This surface represents the entry pupil or a surface in the spatial domain which is conjugated to it. In particular, this surface exhibits a finite curvature.It can be that the projection optical unit 10 has different positions of the entry pupil for the tangential and for the sagittal beam path. In this case, an imaging element, in particular an optical component of the transmission optics, should be provided between the second facet mirror 22 and the reticle 7. With the aid of this optical element, the different position of the tangential entry pupil and of the sagittal entry pupil can be taken into account.In the arrangement of the components of the illumination optical unit 4 illustrated in FIG. 1, the second facet mirror 22 is arranged in a surface conjugate to the entry pupil of the projection optical unit 10. The first facet mirror 20 is arranged tilted with respect to the object plane 6. The first facet mirror 20 is arranged tilted with respect to an arrangement plane which is defined by the deflecting mirror 19. The first facet mirror 20 is arranged tilted with respect to an arrangement plane which is defined by the second facet mirror 22.FIG. 2 shows a schematic illustration of an embodiment of an optical system 100 for a lithography apparatus or projection exposure apparatus 1, as is shown for example in FIG. 1. In addition, the optical system 100 of FIG. 2 can also be used, for example, in a DUV lithography apparatus.The optical system 100 comprises a number N 1 of arrangements 200, with N 1≥1, wherein each of the N 1 arrangements 200 comprises a number of actuator / sensor devices 201, 202 (see for example FIG. 3 ). The number of actuator / sensor devices 201, 202 of the respective arrangement 200 is part of a respective ring network 210. The respective arrangement 200 is preferably designed as a printed circuit board.The actuator / sensor device 201, 202 is, for example, an actuator device for displacing the optical element, a sensor device for determining a position of the optical element or an actuator and sensor device for displacing the optical element and for determining a position of the optical element.Furthermore, the optical system 100 comprises a plurality N 2 of local drive units 300 for driving the number N 1 of arrangements 200, with N 2≥2.In addition, the optical system 100 has a number N 8 of central drive units 400 for driving the local drive units 300, with N 8≥1. In this case, N 1, N 2, N 8 are in particular natural numbers. Without limitation of generality, N8=1 in FIG. 2.Details of the ring network 210 of the arrangement 200 are illustrated in FIG. 3. Without limiting generality, the optical system 100 of FIG. 3 comprises an arrangement 200 (with N=1) and two local drive units 300 (N2=2). In general, each of the N1 arrangements 200 has a number of actuator / sensor devices 201, 202, wherein the respective actuator / sensor device 201, 202 is assigned to one of the optical elements of the optical system 100. The N2 local drive units 300 are configured to drive the number N1 of arrangements 200, as discussed above with respect to FIG. 2.As already explained with reference to FIG. 2, each of the N1 arrangements 200 has a ring network 210. This ring network 210 is shown in detail in FIG. 3. The ring network 210 of FIG. 3 comprises N3 network devices 201, 202, 203 arranged in a ring. In the example of FIG. 3, N3=12, and thus the ring network 210 of FIG. 3 includes twelve network devices 201, 202, 203.The N3 ringed network devices 201, 202, 203 are connected by N3 primary connections V3. Since N3=12, the ring network 210 has twelve primary connections V1. The respective primary connection V 1 is in particular a point-to-point connection between two of the network devices 201, 202, 203 arranged in the ring network 210. For example, the respective primary connection V 1 is designed as a unidirectional connection. Alternatively, the respective primary connection V 1 can also be designed as a bidirectional connection.The N 3 network devices 201, 202, 203 comprise a number N 4 of actuator / sensor devices 201, 202 (with N 4=10 in FIG. 3 ) and N 5 bridges 203 (with N 5=2 in FIG. 3 ). The N4 actor / sensor devices of FIG. 3 comprise two actor / sensor devices with the reference symbol 201 and eight actor / sensor devices with the reference symbol 202. The actuator / sensor devices with the reference number 210 are those actuator / sensor devices which have a connection to one of the local control units 300. In contrast, the actuator / sensor devices with the reference sign 202 are those actuator / sensor devices which have no connection to one of the local activation units 300. In general, the N4 actor / sensor devices 201, 202 (with N4=10in FIG. 3 ) have a first subset N6(with N6=2in FIG. 3 ) of actor / sensor devices 201 with a respective connection V3, V4to one of the local control units 300 and a second subset N7(with N7=8in FIG. 3 ) without a connection to one of the local control units 300.The respective bridge 203 can also be referred to as an adapter bridge, bridge device, bridge or device bridge and is suitable for forwarding data in predetermined directions of the ring network 210. In this case, the respective one of the N5bridges 203 comprises in particular a respective electrical through-connection in each direction of the ring network 210. The respective bridge 203 is configured to connect the primary input and output as well as the secondary input and output or to connect the primary input to the secondary output as well as the secondary input to the primary output.Furthermore, each group member of the group 202, 203 of the N bridges 203 (with N5=2 in FIG. 3 ) and the N7 actuator / sensor devices 202 is connected without a connection to one of the local drive units 300 by means of a secondary connection V 2 to another group member of the group 202, 203, wherein the respective secondary connection V 2 bridges at least one adjacent group member in the group 202, 202.The following example may illustrate: The actuator / sensor device 202 at the bottom left in FIG. 3 has, in the ring network 210 following clockwise via the primary connections V 1 as the adjacent network device in the ring, the actuator / sensor device 201 at the top left, which is not a group member of the group 202, 203.In the clockwise direction, this actuator / sensor device 201 is followed by a bridge 203 (the left bridge 203 of the two bridges 203 in FIG. 3 ), which is a group member of the group 202, 203. The left bridge 203 is followed by two actuator / sensor devices 202.As FIG. 3 shows, a secondary connection V 2 is provided between the actuator / sensor device 202 on the lower left to the right of the two actuator / sensor devices 202 in the upper row of the network devices. Thus, this secondary connection V 2 bridges two group members of the group 202, 203, namely the left bridge 203 and the actuator / sensor device 202 following the left bridge 203 in the clockwise direction.In particular, the group members 202, 203 form a ring structure by means of the N3precursive compounds V1(with N3=12in FIG. 3 ) and by means of the N6actuator / sensor device 201 by means of connection to a local drive unit 300 (with N6=2in FIG. 3 ). In the ring structure, each group member 202, 203 is connected to two adjacent group members 202, 203, respectively, via one of the primary compounds V 1 or via two of the primary compounds V 1 and one of the N 6 actuator / sensor devices 201.Analogously to the primary compound V1, the respective secondary compound V2is in particular a point-to-point connection between two of the non-adjacent group members 202, 203 arranged in the ring structure. Likewise analogously to the primary connection V 1, the respective secondary connection is designed as a unidirectional connection or alternatively as a bidirectional connection.Due to the present condition that the respective secondary connection V 2 bridges at least one adjacent group member in the group 202, 203, the following rules are complied with. 1. bridging in the ring network 210 by the respective secondary connection V 2 always causes at least one adjacent space in the ring network 210 to be skipped. 2. such skipping does not include actuator / sensor devices (presently the actuator / sensor device with the reference symbol 201) which have a connection to one of the local control units 300. 3. the positions in the ring network 210 which have a connection to one of the local control units 300 are always occupied by an actuator / sensor device 201 (and not by a bridge 203).FIG. 4 shows a schematic illustration of a third embodiment of an optical system 100. The third embodiment of the optical system 100 according to FIG. 4 is based on the second embodiment according to FIG. 3 and comprises all features of FIG. 3. In the third embodiment according to FIG. 4, the arrangement 200 is designed as a printed circuit board having N3 slots 221, 222 (with N3=12). These N3 slots 221, 222 are connected to one another via N3 primary connections V1 for forming the ring network 210. Those slots which have a connection to one of the local drive units 300 are provided with the reference symbol 221. In contrast, those slots which do not have a connection to one of the local drive units 300 are provided with the reference symbol 222. Consequently, the slots with the reference sign 221 are equipped with an actuator / sensor device 201, whereas the slots 222 are equipped either with an actuator / sensor device 202 or with a bridge 303.In general, each slot 221 of a subset N 6 (N 6=2 in FIG. 4 ) of the N 3 slots 221, 222 (N3=12 in FIG. 4 ) is connected to one of the N 2 local drive units 300 (N2=2 in FIG. 4 ). As Fig. 4 illustrates, such a connection may consist of a dedicated downlink connection and a dedicated uplink connection. In general, each of the N6 slots 221 is equipped with one of the N6 actuator / sensor devices 201.In addition, the N3 network devices 201, 202, 203 are configured in particular to transmit and receive data packets DP of a specific communication protocol via the ring network 210. An example of such a data packet DP is shown in FIG. 5. The data packet DP has a first frame R 1 with packet routing information, a second frame R 2 with header information and a third frame R 3 with payload data. The packet routing information of the first frame R 1 determines in particular a complete path for the data packet DP in the ring network 210. The respective network device 201, 202, 203 has in particular a first output connected to the respective primary connection V 1 and a second output connected to the respective secondary connection V 2.Generally, the packet routing information includes, at least for each forwarding step of the data packet DP in the ring network 210, a bit group of a predetermined bit length. In the example of FIG. 5, the packet routing information is configured as: 01|01|01|10|00.Thus, in this example, the packet routing information has five bit groups of the respective bit length of two bits. Each bit group is associated with one of the network devices 201, 202, 203 determining the path in the ring network 210. A first coding, 01 in the present example, indicates that the data packet is to be forwarded via the first output of the respective network device 201, 202, 203 of the path and thus via the primary connection V 1. A second coding 10 indicates that the data packet DP is to be forwarded via the second output of the respective network device 201, 202, 203 of the path and thus via the secondary connection V 2. The last bit group of the packet routing information has a third encoding 00 for indicating the termination of the data packet DP at the network device 201, 202 assigned to the last bit group. The first coding 01, the second coding 10 and the third coding 00 are in the present case exemplary, but generally different from one another.The respective network device 201, 202, 203 is preferably configured to analyze only the respective frontmost bit group and subsequently consume it, so that the respective network device 201, 202, 203 always only needs to analyze the first bit group 201, 202, 203. The respective bit group can also be referred to as a symbol. In other words, the foremost symbol can thus be consumed during forwarding and deleted from the packet routing information, so that each actuator / sensor device 201, 202 always only has to evaluate the foremost symbol at any time. As a result, the actuator / sensor devices 201, 202 do not require any knowledge about the network itself and can have an identical evaluation unit.In order to keep the length of the packet routing information constant, any symbol may be appended at the back or even the foremost deleted bit. With the latter, the receiver can reconstruct the routing path to the transmitter.An exemplary transmission of a data packet DP with the packet routing information 01|01|01|10|00 shown in FIG. 5 is shown in FIG. 6 ; assuming, by way of example, that the actuator / sensor device 202 at the top left in FIG. 6 is the source and thus transmitter of the data packet DP in the ring network 210, the first bit group, namely 01, is assigned to the packet routing information 01|01|01|10|00 of this actuator / sensor device 201. In FIG. 6, this actuator / sensor device 201 is marked with the letter A.The bit group with the first coding 01 therefore means that the data packet is transmitted from the actuator / sensor device 201 with the letter A via the primary connection V 1 to the bridge 203, which is marked with the letter B. Since the second bit group is also 01, the data packet DP is forwarded from the bridge 203, denoted by the letter B, via the primary connection V 1 to the actuator / sensor device 202, which is denoted by the letter C.Since the third bit group is 01 as well, the data packet DP is forwarded from the actuator / sensor device 202 with the letter C via the primary connection V 1 to the actuator / sensor device 202, which is marked with the letter D.Since the fourth bit group is 10, the data packet DP is forwarded from the actuator / sensor device 202 with the letter D via the secondary connection V 2 to the actuator / sensor device 202, which is marked with the letter E.Since the fifth and last bit group is 00, the data packet DP terminates at the actuator / sensor device 202 with the letter E.FIG. 7 shows a schematic illustration of ring paths P 1, P 2 in the ring network 210 of the arrangement 200 of an optical system 100. In this case, the respective local drive unit 300 is preferably configured to analyze the ring network 210 by sending data packets DP of the specific communication protocol configured for network analysis via the network devices 201, 202, 203 of the ring network 210, in order to define a number of ring paths P 1, P 2 in the ring network 210 on the basis thereof. Specifically, the ring paths P 1, P 2 in the ring network 210 are set such that each point-to-point connection, which is either a primary connection V 1 or a secondary connection V 2, is used between two of the network devices 201, 202, 203 per ring path P 1, P 2 at most once. For reasons of clarity, the network devices of the arrangement 200 in FIG. 7 are numbered through and thus carry the numbers 1 to 12.In the example of FIG. 7, two ring paths P 1 and P 2 are set. Thus, the ring path P 1 is formed by the right local drive unit 300 and the network devices 4, 5, 6, 7, 8, 9, 12. The ring path P 2 separated therefrom is formed by the left local drive unit 300 and the network devices 1, 2, 3, 6, 10, 11, 12.FIG. 8 shows a schematic flow diagram of a method for producing an optical system 100 for a lithography apparatus 1 comprising a plurality of optical elements. Examples of such optical systems 100 are shown in FIGS. 2 to 7.The method of FIG. 8 includes steps 801-805:In step 801, a number N 1 of arrangements 200, with N 1≥1, is provided, wherein each of the N 1 arrangements 200 comprises a number of actuator / sensor devices 201, 202, wherein the respective actuator / sensor device 201, 202 is assigned to one of the optical elements.In step 802, a number N 2 of local drive units 300 is provided for driving the number N 1 of arrays 200.In step 803, in each of the N1 arrangements 200, N3 network devices 201, 202, 203 are arranged in a ring and primary connections V1 are connected by N3 to form a ring network 210. In this case, the N3network devices 201, 202, 203 comprise a number N4of the actuator / sensor devices 201, 202 and N5bridges, with N5≥0and N3=N4+N5.In step 804, a first subset N 6 of the N 4 actuator / sensor devices 201, 202 is connected to one of the local activation units 300 by means of a respective connection V 3, V 4, and a second subset N 7 of the N 4 actuator / sensor devices is provided without connection to one of the local activation units 300, with N4=N6+N7.In step 805, each group member of the group 202, 203 comprising the N5bridges 203 and the N7 actor / sensor devices 202 is connected to another group member of the group 202, 203 by means of a secondary connection V 2, wherein the respective secondary connection V 2 bridges at least one adjacent group member in the group 202, 203.Although the present invention has been described on the basis of exemplary embodiments, it can be modified in various ways.LIST OF REFERENCE CHARACTERS1 Projection exposure apparatus 2 Illumination system 3 Light source 4 Illumination optical unit 5 Object field 6 Object plane 7 Reticle 8 Reticle holder 9 Reticle displacement drive 10 Projection optical unit 11 Image field 12 Image plane 13 Wafer 14 Wafer holder 15 Wafer displacement drive 16 Illumination radiation 17 Collector 18 Intermediate focal plane 19 Deflection mirror 20 First facet mirror 21 First facet 22 Second facet mirror 23 Second facet 100 Optical system 200 Arrangement 201 Actuator / sensor device with connection to local drive unit 202 Actuator / sensor device without connection to local drive unit 203 Bridge 210 Ring network 221 Slot with connection to local drive unit 222 Slot without connection to local drive unit 300 Local drive unit 400 Central drive unit M 1 Mirror M 2 Mirror M 3 Mirror M 4 Mirror m5 mirror M6 mirror P1 ring path P2 ring path R1 first frame with packet routing information R2 second frame with header information R3 third frame with user data V1 primary connection V2 secondary connection V3 downlink connection to local drive unit V4 uplink connection to local drive unit 801-805 method step 01 first coding 10 second coding 00 third coding

Claims

An optical system (100) for a lithography apparatus (1) comprising a plurality of optical elements, having a number N1 of arrangements (200), with N1≥1, wherein each of the N1 arrangements (200) comprises a number of actuator / sensor devices (201, 202), wherein the respective actuator / sensor device (201, 202) is associated with one of the optical elements, and a number N2 of local drive units (300) for driving the number N1 arrangements (200), wherein each of the N1 arrangements (200) comprises a ring network (210) with N3 network devices (201, 202, 203) arranged in a ring and connected by N3 primary connections (V1), wherein the N3 network devices (201, 202, 203) comprise, 203) comprise a number N4 of the actuator / sensor devices (201, 202) and N5 bridges (203), with N5≥0 and N3=N4+N5, wherein the N4 actuator / sensor devices (201, 202) comprise a first subset N6 (201) with respective connection (V3, V4) to one of the local drive units (300) and a second subset N7 (202) without connection to one of the local drive units (300), with N4=N6+N7, wherein each group member of the group (202, 203) of the N5 bridges (203) and the N7 actuator / sensor devices (202) comprises a secondary connection (V2) to another group member of the group (202, 203), 203), wherein the respective secondary link (V2) spans at least one adjacent group member in the group (202, 203).The optical system according to claim 1, wherein the respective primary connection (V1) is a point-to-point connection between two of the network devices (201, 202, 203) arranged in the ring network (210).The optical system according to claim 1 or 2, wherein the group members (202, 203) form a ring structure by means of the N3 primary compounds (V1) and the N6 actuator / sensor devices (201), in which each group member (202, 203) is respectively connected to two adjacent group members (202, 203) respectively via one of the primary compounds (V1) or via two of the primary compounds (V1) and one of the N6 actuator / sensor devices (201).The optical system of claim 3, wherein the respective secondary compound (V2) is a point-to-point connection between two of the non-adjacent group members (202, 203) arranged in the ring structure.The optical system according to any one of claims 1 to 4, wherein the N4 actuator / sensor devices (201, 202) of the ring network (210) are identical.The optical system according to any one of claims 1 to 5, wherein each of the N3 network devices (201, 202, 203) has at least two inputs and at least two outputs, wherein preferably each of the N3 network devices (201, 202, 203) has exactly two inputs and exactly two outputs, or wherein each of the N3 network devices (201, 202, 203) has exactly four inputs and exactly four outputs.Optical system according to one of Claims 1 to 6, wherein the N6 actuator / sensor devices (201) are connected to N6 different local control units (300), where 2≤N6≤N2.The optical system according to claim 7, wherein each of the N6 actuator / sensor devices (201) is connected to a particular one of the N6 different local driver units (300) via a downlink connection (V3) for transmitting commands from the particular local driver unit (300) to the connected actuator / sensor device (201) and via an uplink connection (V4) for transmitting data from the actuator / sensor device (201) to the connected local driver unit (300).Optical system according to one of Claims 1 to 8, wherein the respective primary connection (V1) is designed as a unidirectional connection or as a bidirectional connection and / or wherein the respective secondary connection (V2) is designed as a unidirectional connection or as a bidirectional connection.The optical system of any of claims 1 to 9, wherein the respective one of the N5 bridges (203) comprises a respective electrical via in each direction of the ring network (210).The optical system according to any one of claims 1 to 10, wherein each of the N1 arrangements (200) is configured as a printed circuit board having N3 slots (221, 222) which are connected to one another via the N3 primary connections (V1) for forming the ring network (210).The optical system according to claim 11, wherein each slot (221) of a subset N6 of the N3 slots is connected to one of the N2 local driver units (300), with N6≤N3, in particular via a dedicated downlink connection (V3) and a dedicated uplink connection (V4), wherein each of the N6 slots (221) is populated with one of the N6 actuator / sensor devices (201).The optical system according to any one of claims 1 to 12, wherein the N3 network devices (201, 202, 203) are configured to transmit and receive data packets of a specific communication protocol over the ring network (210), wherein the respective data packet (DP) comprises a first frame (R1) with packet routing information, a second frame (R2) with header information and a third frame (R3) with payload data.The optical system according to claim 13, wherein the packet routing information of the first frame (R1) determines a path, in particular a complete path, in the ring network (210), wherein the packet routing information comprises, at least for each forwarding step of the data packet (DP) in the ring network (210), a bit group of a predetermined bit length, wherein each bit group is associated with one of the network devices (201, 202, 203) determining the path in the ring network (210).Optical system according to claim 14, wherein the respective network device (201, 202, 203) has a first output connected to the respective primary connection (V1) and a second output connected to the respective secondary connection (V2), wherein the respective bit group of the packet routing information for forwarding the data packet (DP) via the first output of the respective network device (201, 202, 203) of the path has a first coding (01), wherein the respective bit group of the packet routing information for forwarding the data packet (DP) via the second output of the respective network device (201, 202, 203) of the path has a second coding (10), and wherein the last bit group of the packet routing information for indicating the termination of the data packet (DP) on the network device (201, 202) assigned to the last bit group has a third coding (00).The optical system according to claim 15, wherein the respective network device (201, 202, 203) is configured to analyze and subsequently consume only the respective foremost bit group.The optical system according to any one of claims 13 to 16, wherein the local drive unit (300) is configured to analyze the ring network (210) by sending data packets (DP) of the determined communication protocol configured for network analysis via the network devices (201, 202, 203) of the ring network (210) and to set a number of ring paths (P1, P2) in the ring network (210) based thereon.The optical system according to claim 17, wherein the local drive unit (300) is configured to set the ring paths (P1, P2) in the ring network (210) such that each point-to-point connection between two of the network devices (201, 202, 203) per ring path (P1, P2) is used at most once.The optical system according to any one of claims 1 to 18, further comprising a number N8 of central driving units (400) for driving the N2 local driving units (300), where N8 ≥ 1.Lithography apparatus (1) having an optical system (100) according to one of Claims 1 to 19.Method for producing an optical system (100) for a lithography apparatus (1) comprising a plurality of optical elements, comprising providing (801) a number N1 of arrangements (200), with N1≥1, wherein each of the N1 arrangements (200) comprises a number of actuator / sensor devices (201, 202), wherein the respective actuator / sensor device (201, 202) is associated with one of the optical elements, providing (802) a number N2 of local drive units (300) for driving the number N1 arrangements (200), wherein in each of the N1 arrangements (200) N3 network devices (201, 202, 203) are arranged in a ring and are connected (803) by N3 primary connections (V1) to form a ring network (210), wherein the N3 network devices (201, 202, 203) comprise a number N4 of the actuator / sensor devices (201, 202) and N5 bridges (203), with N5≥0 and N3=N4+N5, wherein a first subset N6 (201) of the N4 actuator / sensor devices (201, 202) is connected (804) to one of the local drive units (300) by means of a respective connection (V3, V4) and a second subset N7 (202) of the N4 actuator / sensor devices (201, 202) is provided (804) without connection to one of the local drive units (300), with N4=N6+N7, wherein each group member of the group (202, 202, 202, 203) of the N5 bridges (203) and the N7 actuator / sensor devices (202) is connected (805) to another group member of the group (202, 203) by means of a secondary connection (V2), wherein the respective secondary connection (V2) bridges at least one adjacent group member in the group (202, 203).

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