Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
  • B24B13/00—Machines or devices designed for grinding or polishing optical surfaces on lenses or surfaces of similar shape on other work; Accessories therefor
  • B24B13/02—Machines or devices designed for grinding or polishing optical surfaces on lenses or surfaces of similar shape on other work; Accessories therefor by means of tools with abrading surfaces corresponding in shape with the lenses to be made
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B5/00—Optical elements other than lenses
  • G02B5/08—Mirrors
  • G02B5/0891—Ultraviolet [UV] mirrors
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B5/00—Optical elements other than lenses
  • G02B5/08—Mirrors
  • G02B5/10—Mirrors with curved faces
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
  • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
  • G03F7/70—Microphotolithographic exposure; Apparatus therefor
  • G03F7/70216—Mask projection systems
  • G03F7/70316—Details of optical elements, e.g. of Bragg reflectors, extreme ultraviolet [EUV] multilayer or bilayer mirrors or diffractive optical elements
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
  • B24B31/00—Machines or devices designed for polishing or abrading surfaces on work by means of tumbling apparatus or other apparatus in which the work and/or the abrasive material is loose; Accessories therefor
  • B24B31/10—Machines or devices designed for polishing or abrading surfaces on work by means of tumbling apparatus or other apparatus in which the work and/or the abrasive material is loose; Accessories therefor involving other means for tumbling of work
  • B24B31/112—Machines or devices designed for polishing or abrading surfaces on work by means of tumbling apparatus or other apparatus in which the work and/or the abrasive material is loose; Accessories therefor involving other means for tumbling of work using magnetically consolidated grinding powder, moved relatively to the workpiece under the influence of pressure
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B5/00—Optical elements other than lenses
  • G02B5/08—Mirrors
  • G02B5/0816—Multilayer mirrors, i.e. having two or more reflecting layers
• • G—PHYSICS
  • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
  • G21K—TECHNIQUES FOR HANDLING PARTICLES OR IONISING RADIATION NOT OTHERWISE PROVIDED FOR; IRRADIATION DEVICES; GAMMA RAY OR X-RAY MICROSCOPES
  • G21K2201/00—Arrangements for handling radiation or particles
  • G21K2201/06—Arrangements for handling radiation or particles using diffractive, refractive or reflecting elements
  • G21K2201/061—Arrangements for handling radiation or particles using diffractive, refractive or reflecting elements characterised by a multilayer structure
• • G—PHYSICS
  • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
  • G21K—TECHNIQUES FOR HANDLING PARTICLES OR IONISING RADIATION NOT OTHERWISE PROVIDED FOR; IRRADIATION DEVICES; GAMMA RAY OR X-RAY MICROSCOPES
  • G21K2201/00—Arrangements for handling radiation or particles
  • G21K2201/06—Arrangements for handling radiation or particles using diffractive, refractive or reflecting elements
  • G21K2201/064—Arrangements for handling radiation or particles using diffractive, refractive or reflecting elements having a curved surface
• • G—PHYSICS
  • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
  • G21K—TECHNIQUES FOR HANDLING PARTICLES OR IONISING RADIATION NOT OTHERWISE PROVIDED FOR; IRRADIATION DEVICES; GAMMA RAY OR X-RAY MICROSCOPES
  • G21K2201/00—Arrangements for handling radiation or particles
  • G21K2201/06—Arrangements for handling radiation or particles using diffractive, refractive or reflecting elements
  • G21K2201/067—Construction details

Definitions

• the invention relates to a method for polishing an optical surface by means of a polishing tool and an optical element.
• US Pat. No. 7,118,449 B1 discloses a method for producing an optical element which has an optical surface which extends in the vicinity of an edge of a substrate.
• a substrate is first provided which has a major surface extending beyond the edge of the optical surface.
• the substrate is also polished in the area where the major surface extends beyond the optical surface. After polishing, substrate material is removed that includes a portion of the surface that extends beyond the optical surface.
• a so-called overflow area ie a surface area adjacent to the optical surface, at least partially mitpoliert in the polishing of the optical surface.
• the reason for this approach is that it is typically required to polish the polishing tool at least partially into the overflow area to polish the optical surface in an edge area due to the size of the polishing tool used, in order to also include the edge area of the optical surface to polish the desired accuracy.
• Overflow area thus has an influence on the quality of the polish of the optical surface. If the overflow area for the polish is geometrically unsuitable, polishing errors or surface defects occur when polishing the optical surface. Such a polishing or surface defect, also referred to below as a polishing signature, generally leads to a significantly increasing correction effort on the optical surface. If the polishing defect is not correctable in subsequent correction processes, the optical surface can not be made in the specification, which means that the optical surface is unusable for the desired application.
• the object of the invention is to provide a method for polishing an optical surface and an optical element with reduced polishing defects.
• a method for polishing an optical surface by means of a polishing tool comprising: polishing the optical surface, which is designed as a free-form surface, by moving a polishing surface of the polishing tool over the optical surface and via a surface area adjoining the optical surface laterally,
• the typical manner is also designed as a free-form surface, wherein the
• Polierwerkmaschines is tuned that at any location of the surface area a threshold value of a polishing criterion is not exceeded, the
• Polishing criterion is a measure of a polishing error on the optical surface, which is generated by moving the polishing tool over the area adjacent to the optical surface area.
• the geometry of the surface area adjoining the optical surface be designed or adapted to the polishing tool used for polishing such that a polishing defect on the optical surface caused by the movement of the surface
• Polishing tool is generated over the adjacent surface area, as small as possible or is below a threshold, so that an optical surface can be produced, which meets the specification in terms of surface quality in terms of shape and roughness. This is guaranteed when at any location of the optical surface
• the polishing criterion is met, i. if at any location the (typically location-dependent variable) polishing criterion does not exceed a threshold, since in that case the polishing error can be corrected in subsequent correction processes so that an optical surface can be produced which meets the desired specification.
• Both the optical surface and the surface area are typically free-form surfaces, ie surfaces that are separated from one another spherical and deviate from a plan surface shape.
• Free-form surfaces may, for example, be so-called aspheric surfaces which have a radial symmetry about a central axis, but also free-form surfaces whose geometry has no (radial) symmetry, i. which are not rotationally symmetric.
• Free-form surface may have a peripheral edge which is circular, but it is also possible that the free-form surface has a peripheral edge deviating from a circular shape.
• a free-form surface typically has a minimum curvature at least two, usually at a plurality of locations, which differs from a maximum curvature at the respective location.
• both the maximum curvature and the minimum curvature of the freeform surface differ in at least two locations
• the polishing surface of the polishing tool performs a rotational movement about an axis of rotation when moving over the optical surface and over the adjacent surface region.
• the axis of rotation is typically aligned at each location substantially perpendicular to the optical surface or to the surface area.
• the polishing tool is pressed in the (reciprocating) movement over the optical surface and against the optical surface. The same applies if the polishing tool is at least partially moved into the adjacent surface area.
• the speed of the rotational movement may vary depending on the location on the optical surface or on the adjacent surface area or possibly be constant during the entire polishing process.
• the polishing surface is the surface of the
• Polishing tool which with the optical surface or with the adjacent area comes into contact.
• the polishing surface also has to be polished during the rotation of the polishing tool
• Polishing surface but also to a different removal behavior on the entire surface to be polished.
• Polishing signature designated polishing fault, which is essentially of the
• Geometry of the surface to be polished depends. This polishing signature can have steep gradients or high-frequency components, which presents a problem for subsequent correction processes which should make it possible to produce a surface with a precisely specified specification.
• Deformation or deviation of the surface to be polished determined by an example, planar polishing surface of the polishing tool at any location of the surface to be polished.
• the deviation or deformation between the polishing surface of the polishing tool and the optical surface is in any place in an orthogonal polynomial system, for example in Zemike polynomials, decomposed, typically only the lowest
• Coefficients of decomposition can be used as a measure of the polishability.
• Zernike coefficients are each assigned to different proportions of the deviation or different wavefront errors; such as e.g. the Zemike coefficient Z4 denotes a focus portion of the deviation while the Zernike coefficients Z5 / Z6 denote a local astigmatism or astigmatic portion of the deviation.
• a local astigmatism at a respective location of the surface area is selected as the polishing criterion. It has proven to be advantageous to use only the astigmatic part of the deviation as a measure of the polishability of a surface.
• the focus component Z4 also indicates how much the polishing surface has to bend, during one revolution the polishing surface or the polishing surface has to bend
• the deformation or deviation in the focus component Z4 is therefore to be regarded as static deformation.
• the astigmatic part Z5 / 6 of the deformation indicates how the polishing tool has to adapt dynamically during one revolution.
• the astigmatic part Z5 / 6 is called 'local astigmatism'. If the polishing tool or the polishing surface can not adjust dynamically during one revolution, strong local polishing defects are to be expected.
• the geometry of the surface area adjacent to the optical surface is chosen to be the local Astigmatism at any location of the area area the threshold
• threshold which represents a maximum value for the local astigmatism.
• the specification for the threshold which must not be exceeded, depends on a variety of parameters, such as the speed of the
• Polishing tool the surface area of the polishing surface of the polishing tool, the polishing removal to be achieved during polishing as well as the corrective capacity of the correction processes following the polishing.
• Threshold based on these parameters is an extensive one
• the threshold value for the polishing criterion in the form of the local astigmatism is therefore typically determined by a comparison with the polishing defects of already produced or already polished optical surfaces.
• the threshold of the polishing criterion typically should not be exceeded not only in the area adjacent to the optical surface but also on the optical surface itself.
• the optical surface itself is typically sufficiently smooth, i. this has no steep slopes or waste (gradients), so that this usually meets the polishing criterion.
• the local astigmatism ⁇ is determined or approximated at a respective location of the surface area by:
• Astigmatism has the unit of length and, according to the above definition, depends on the diameter of the typically rotationally symmetric
• Polishing surface of the polishing tool from.
• the polishing surface of the polishing tool forms a planar surface.
• polishing tools are used for polishing, the polishing surfaces are flat. If the polishing surface is rotated about an axis, the polishing surface typically has a circular geometry in order to generate no imbalance during the rotational movement. Is the
• Polishing surface plan formed this also simplifies the calculation of Deformation or the deviation of the surface to be polished from the polishing surface.
• the geometry of the optical surface and the geometry of the laterally adjacent surface area by means of a
• optical surface is used for reflection or transmission of radiation
• its geometry is typically used for optical design by analytical description, for example in the form of
• Geometry of the optical surface typically not on the
• the threshold value of the polishing criterion of the laterally adjacent surface area is taken into account in the determination of the (target) geometry of the optical surface.
• the fulfillment of the polishing criterion in the surface area is taken over as an additional boundary condition in the design of the (target) geometry of the optical surface.
• the geometry of the surface area is determined without an analytical surface description of the surface area.
• Suppress increases and optimally design the surface area as desired with respect to the polishing criterion. Rather disadvantageous in this method is that due to the lack of an analytical surface description on point clouds or similar area descriptions must be used.
• the method additionally comprises in a step preceding the polishing: mechanical processing of a substrate for producing the optical surface to be polished and the laterally adjacent surface area.
• the optical surface ie the region of the substrate which is to be used optically, is machined or shaped by mechanical pre-processing, for example by milling or grinding, if appropriate using loose abrasive grains.
• mechanical pre-processing for example by milling or grinding, if appropriate using loose abrasive grains.
• a geometry is generated by the mechanical processing, which at a given size or a predetermined size
• Diameter of the polishing surface of the polishing tool does not exceed the threshold of the polishing criterion.
• an optical surface with a replacement geometry that deviates from a target geometry of the optical surface is produced, wherein the target geometry of the optical surface consists of the replacement geometry in one on the polishing following correction process is made.
• the replacement geometry is first generated by grinding and polishing as described above, which deviates at the optical surface of the predetermined by the optical design target geometry.
• the deviation between the replacement geometry ie the geometry of the optical surface generated during mechanical processing and subsequent polishing, is adapted to the target geometry of the optical surface (among other things), so that in the end the target Geometry on the optical surface arises.
• the threshold value of the polishing criterion is selected such that the polishing error on the optical surface can be corrected in at least one subsequent correction process.
• the threshold value setting depends not only on parameters pertaining to the polish or polishing tool, but also on the correction capability of the correction processes following the polishing.
• the threshold value of the polishing criterion should be chosen such that the optical surface can be produced with the desired specification by one or possibly several subsequent correction processes.
• ion beam machining represents a correction method in which the optical surface is bombarded locally with ions or with an ion beam in order to remove material on the optical surface produce.
• magnetorheological polishing are performed.
• This correction process uses a magnetorheological fluid as a tool.
• the liquid is e.g. Applied to a rotating wheel and solidified in a magnetic field, so that upon contact with a machined
• a further aspect of the invention relates to an optical element, comprising: a substrate having an optical surface, which is formed as a free-form surface, and a laterally adjacent to the optical surface
• the local astigmatism approximated by the equation (1) next to the main curvatures at a respective location of the surface area depends only on the diameter of the polishing surface of the polishing tool used.
• the polishing surface of the polishing tool can not be chosen arbitrarily large, so that the value D is limited to a maximum value and whereby the threshold value Az s of the local astigmatism is limited to a maximum value independent of the diameter of the polishing tool.
• the optical surface steadily merges into the surface area adjacent to the optical surface.
• the surface area continuous, ie without a kink, adjacent to the edge of the optical surface.
• the optical surface has a
• a maximum extent of the surface is understood to mean the maximum length of a straight line which connects two points along the edge of the optical surface.
• the maximum extension represents the diameter of the optical surface
• the maximum extension represents the length of the major axis, i. of the largest diameter of the ellipse, etc. Due to the mechanical pre-processing, polishing and possibly subsequent subsequent correction processes, a desired quality or surface roughness can be generated on the optical surface both at small, medium and at large spatial wavelengths.
• the area of the optical surface does not extend more than a distance of 50 mm outwards.
• the surface area on the substrate in which the polishing criterion must be met does not typically extend farther outwardly of the optical surface than the diameter of the polishing surface of the one used
• polishing tool At longer distances from the optical surface, the polishing tool with its polishing surface no longer protrudes into the optical
• the optical element has at least on the optical surface a reflective coating, in particular a for EUV radiation reflective coating, on.
• Element is in this case typically a mirror, in particular an EUV mirror.
• a mirror in particular an EUV mirror.
• the substrate may also have, wholly or partially, a reflective coating in the adjacent surface region.
• the optical surface is that part of the surface of the substrate which is arranged in the beam path of an optical arrangement and is reflected at the useful radiation of the optical arrangement.
• the optical arrangement can be, for example, a lithography installation, in particular an EUV lithography installation, but the optical element can also be advantageously used in other optical arrangements.
• Fig. 1a is a schematic representation of a plan view of an optical
• Fig. 1d is a schematic representation of a following on the polishing
• Fig. 3a, b are schematic representations of a local deviation of
• FIGS. 1a-d schematically show a substrate 1, on the upper side of which an optical surface 2, ie a useful area, and a surface area 3 (overflow area) adjoining the optical surface 2 are formed laterally.
• the optical surface 2 has an elliptical edge 4, which is surrounded by the adjacent surface area 3 annular.
• the surface area 3 adjoining the optical surface 2 extends as far as the outer, likewise elliptical edge 5 of the substrate 1.
• the substrate 1 is a so-called zero-expansion material, for example Zerodur® or ULE®, ie, a substrate 1 which can be used for an EUV mirror.
• Both the optical surface 2, ie the optically used region of the substrate 1, and the adjacent surface region 3 each form a free-form surface, ie a non-radially symmetrical surface, which in the example shown is also not mirror-symmetrical to one of the axes of an xyz coordinate system.
• the geometry of the optical surface 2 ie the optically used region of the substrate 1, and the adjacent surface region 3 each form a free-form surface, ie a non-radially symmetrical surface, which in the example shown is also not mirror-symmetrical to one of the axes of an xyz coordinate system.
• Surface 2 is chosen to follow an optical specification after polishing and after further correction processes, i. deviates only within a predetermined tolerance of a target geometry, by the optical design of an optical arrangement
• the optical surface 2 is arranged. Also, the surface area 3 adjacent to the optical surface 2, which is continuous, i. without a transition in the form of a bend adjoins the edge 4 of the optical surface 2 is formed as a free-form surface.
• the geometry of the surface region 3 is selected such that a polishing criterion is maintained at each location P of the surface region, which will be described in more detail below.
• FIGS. 1 b and 1 c show a polishing process of the optical surface 2 by means of a polishing tool 6.
• the polishing tool 6 has a circular, planar polishing surface 7, on which the polishing tool 6 is pressed against the upper side of the substrate 1.
• the polishing tool 6 is set into a rotational movement about an axis of rotation 8 that acts centrally on the polishing surface 7, and the polishing tool 6, more precisely the polishing surface 7, is moved over the optical surface 2 (see FIG The movement is typically a back-and-forth motion.
• the polishing tool 6 at least partially in the
• Area 3 a part of the planar polishing surface 7 is also pressed against the optical surface 2.
• the geometry of the surface region 3 adjoining the optical surface 2 thus influences, in which way during polishing, the material of the substrate 1 on the optical surface 2
• the removal rate of the polishing tool 6 can thus be unfavorably influenced by an unfavorably selected geometry of the surface area 3 adjoining the optical surface 2, so that its geometry has to be suitably selected in order to minimize surface defects or polishing defects on the optical surface 2 caused by moving the polishing tool 6 into the optical surface 2
• Polishing surface 7 is tuned such that at each location P of the surface area 3, a threshold value Az s of the polishing criterion .DELTA. ⁇ is not exceeded.
• the polishing criterion ⁇ is a measure of the polishing error caused by the movement of the polishing tool 6 over the surface area 3 at the respective location P on the optical surface 2.
• the polishing error on the optical surface 2 or generally on a surface results from the deviation of the surface from the planar geometry of the polishing surface 7 in the example shown, wherein the deviation at a respective location P is dependent on the diameter D of the polishing surface 7.
• FIG. 3a shows a section through the substrate 1 along a section which is shown in FIG. 1a by a dashed straight line and runs in the Y-direction.
• Fig. 3a can be seen in the middle of the area of the optical surface 2 and to the right and left of it, the adjacent surface area 3.
• Fig. 3b the associated values for the local astigmatism are plotted, as in
• the local astigmatism Z5 / 6 thus represents a suitable polishing criterion, i. a measure of one caused on the optical surface 2
• 3b shows the local astigmatism ⁇ as a function of the location P both on the optical surface 2 and in the adjacent surface area 3.
• FIG. 3b also shows a threshold value Az s for the local astigmatism ⁇ , which should not be exceeded. to ensure that the optical surface 2 can be manufactured to the desired specification.
• the threshold value Azs is exceeded in a portion of the surface area 3, which is in the example shown on the left side of the section through the optical surface 2 in the Y direction, while the optical surface 2 itself every place P a local
• the surface area 3 is thus not adapted to the polishing tool 6, more precisely to the diameter D of the polishing surface 7, so that sufficiently small polishing defects are produced on the optical surface 2. It is therefore necessary to suitably change the geometry of the surface area 3 so that it satisfies the polishing criterion.
• the local astigmatism ⁇ at a respective location P can be approximated by the following formula: where D is the diameter of the polishing surface 7 of the polishing tool. 6
• k n mi minimal local curvature and k max, a maximum local curvature at a respective location P of the surface region 3 indicate.
• an analytical area description z (x, y) of the optical surface 2 may be e.g. in the form of polynomials or polynomial equations adjacent to the optical surface 2
• the geometry of the surface area 3 without an analytical surface description, for example by filling the surface area 3 between the outer edge 4 of the optical surface 2 and the outer edge 5 of the substrate 1 with a padding algorithm to avoid unfavorable rises or falls. Suppress gradients and optimally designed the surface area as desired for the fulfillment of the polishing criterion, so that the threshold value Az s of the polishing criterion .DELTA. ⁇ in the form of local astigmatism at any point of the surface area 3 is exceeded.
• Surface area 3 is for the optical surface 2 a
• the substrate 1 is processed by mechanical processing before polishing, e.g. by grinding, as well as polishing so processed that the optical surface 2 with one of the target geometry of the optical
• the optical surface 2 having the replacement geometry is post-processed after polishing in a correction process, as illustrated by way of example in FIG. 1d.
• the correction process is an ion beam machining in which a movable, controlled ion beam gun 9 directs an ion beam onto the optical surface 2 to be locally, i. in every place P of the optical
• the optical surface 2 can be adapted even at low spatial wavelengths to the target geometry to produce in this way an optical surface 2, in all spatial wavelength ranges meets the specification.
• the threshold ⁇ 5 of the polishing criterion ⁇ is chosen so that the
• Polishing error on the optical surface 2 can be corrected in subsequent correction processes at least so far that the optical
• a suitable threshold ⁇ z s can be determined by a comparison with polishing errors of already produced or already polished optical surfaces.
• the optical surface 2 may have a roughness R of less than 1 nm rms in a spatial wavelength range between 1 mm and a maximum extent L of the optical surface 2, the maximum extent L being as in FIG shown the length L of the major axis, ie the largest diameter of the elliptical shaped edge 4 of the optical surface 2 represents.
• a reflective coating 1 can be applied to produce an EUV mirror 10, as shown in FIG.
• the coating 11 is designed in the example shown to reflect EUV radiation 13 in the EUV wavelength range between about 5 nm and about 30 nm and has for this purpose at a wavelength of 13.5 nm, which the useful wavelength of the EUV Mirror 10 corresponds to a maximum of reflectivity.
• the reflective coating 11 has alternating layers 12a, 12b
• the first layers 12a are made of silicon (higher refractive index) and the second layers 12b are made of molybdenum (lower refractive index)
• Refractive index ⁇ Refractive index
• Other material combinations such as molybdenum and beryllium, ruthenium and beryllium or lanthanum and B 4 C are - depending on the useful wavelength in the EUV wavelength range - also possible.
• Surface area 3 which satisfies the polishing criterion typically does not extend outwardly by more than a distance d from the optical surface 2 corresponding to the diameter D of the polishing surface 7 of the polishing tool 6.
• the polishing surface 7 is laterally spaced from the optical surface 2, so that the polishing in this region no longer has any influence on the polishing defect on the optical surface 2.
• the outer edge of the surface region 3 does not necessarily have to coincide with the outer edge 5 of the substrate 1, but rather that the substrate 1 may continue beyond the outer edge of the surface region 3 may extend outside, where in the further outer region of the polishing criterion does not have to be met.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Grinding And Polishing Of Tertiary Curved Surfaces And Surfaces With Complex Shapes (AREA)
• Optical Elements Other Than Lenses (AREA)
• Optical Filters (AREA)
• Finish Polishing, Edge Sharpening, And Grinding By Specific Grinding Devices (AREA)
• Physical Vapour Deposition (AREA)

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• 2015
  • 2015-12-02 DE DE102015223983.7A patent/DE102015223983A1/de not_active Ceased
• 2016
  • 2016-11-16 JP JP2018528789A patent/JP2019505829A/ja active Pending
  • 2016-11-16 WO PCT/EP2016/077866 patent/WO2017093020A1/de active Application Filing
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• 2021
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