# US 2022/0035083 A1 · Spatial frequency filter device for use with a laser beam, spatial frequency filter assembly having such a spatial frequency filter device, and method for spatial frequency filtering of a laser beam > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2022/0035083 A1 - Document ID: US20220035083A1 - Status: Published application - Kind: A1 - Application number: 17/500,962 - Filed: 2021-10-14 - Published: 2022-02-03 - Earliest claimed: 2019-04-17 - Assignees: TRUMPF Laser- und Systemtechnik GmbH - Applicants: TRUMPF Laser- und Systemtechnik GmbH - Inventors: Malte Kumkar; Stefan Doerr; Daniel Flamm - Web page: https://patentgrep.com/patent/US20220035083A1 ## CPC - G02B 5/1814: {structurally combined with one or more further optical elements, e.g. lenses, mirrors, prisms or other diffraction gratings (G02B5/189 takes precedence)} - B23K 26/0648: {comprising lenses} - B23K 26/0652: {comprising prisms} - B23K 26/073: Shaping the laser spot - G02B 5/20: Filters (polarising elements G02B5/30) - G02B 27/0944: {Diffractive optical elements, e.g. gratings, holograms (gratings per se G02B5/18; holograms used as optical elements per se G02B5/32)} - G02B 27/095: {Refractive optical elements} - G02B 27/0988: {Diaphragms, spatial filters, masks for removing or filtering a part of the beam} - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS - B23K: SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM ## Abstract A spatial frequency filter device is for use with a laser beam. The device includes: a neutral region, which is configured to transmit or reflect the laser beam; and a deflecting region, which radially adjoins the neutral region and is configured to deflect beam components of the laser beam from a beam axis of the laser beam. The deflecting region has a constant portion, in which a deflecting effect on the beam components of the laser beam for each location in the constant portion is configured to be independent of a distance of a location from the neutral region. the deflecting region has a variation portion, in which the deflecting effect on the beam components of the laser beam is configured to vary, dependent on a distance from the neutral region. ## Claims ### Claim 1 A spatial frequency filter device for use with a laser beam, the spatial frequency filter device comprising: a neutral region, which is configured to transmit or reflect the laser beam; and a deflecting region, which radially adjoins the neutral region and is configured to deflect beam components of the laser beam from a beam axis of the laser beam, wherein the deflecting region has a constant portion, in which a deflecting effect on the beam components of the laser beam for each location in the constant portion is configured to be independent of a distance of a location from the neutral region, and wherein the deflecting region has a variation portion, in which the deflecting effect on the beam components of the laser beam is configured to vary, dependent on a distance from the neutral region. ### Claim 2 (depends on 1) The spatial frequency filter device as claimed in claim 1, wherein the neutral region is arranged centrally and is surrounded by the deflecting region on an outside, the variation portion being arranged between the neutral region and the constant portion. ### Claim 3 (depends on 1) The spatial frequency filter device as claimed in claim 1, wherein in the variation portion the deflecting effect on the beam components of the laser beam is configured to increase with increasing distance from the neutral region. ### Claim 4 (depends on 1) The spatial frequency filter device as claimed in claim 1, wherein the deflecting region has a phase influencing structure. ### Claim 5 (depends on 1) The spatial frequency filter device as claimed in claim 1, wherein the phase influencing structure is formed as a diffractive deflecting structure, the diffractive deflecting structure being periodic and having in the constant portion a constant modulation amplitude, the modulation amplitude of the diffractive deflecting structure varying in the variation portion. ### Claim 6 (depends on 1) The spatial frequency filter device as claimed in claim 1, wherein the deflecting effect on the beam components of the laser beam is configured to vary according to a specific function of the distance from the neutral region. ### Claim 7 (depends on 1) The spatial frequency filter device as claimed in claim 1, wherein the spatial frequency filter device has a filter body, on which the neutral region has been formed, the deflecting region having been applied to the filter body or incorporated in the filter body. ### Claim 8 (depends on 1) The spatial frequency filter device as claimed in claim 1, wherein the neutral region has a neutral width dimension, wherein: a) the neutral width dimension is from at least 5% to at most 130%, of a beam width dimension of a laser beam to be filtered, or b) a variation width dimension of the variation portion is from at least 10% to at most 150 of the neutral width dimension. ### Claim 9 (depends on 1) The spatial frequency filter device as claimed in claim 1, wherein the spatial frequency filter device is formed as a transmission stop, as a lens, as a protective glass, as a fiber end cap, or as a mirror. ### Claim 10 (depends on 1) The spatial frequency filter device as claimed in claim 1, wherein the diffractive deflecting structure has been etched into the filter body, or has been incorporated in the filter body as a volume modification. ### Claim 11 (depends on 1) A spatial frequency filter assembly for the laser beam, having the spatial frequency filter device as claimed in claim 1, and having a constant filter device. ### Claim 12 (depends on 11) The spatial frequency filter assembly as claimed in claim 11, comprising a first converging lens, which is arranged downstream of the spatial frequency filter device in a direction of beam propagation of the laser beam. ### Claim 13 (depends on 11) The spatial frequency filter assembly as claimed in claim 11, comprising a second converging lens, which is arranged upstream of the spatial frequency filter device in a direction of beam propagation of the laser beam. ### Claim 14 A method for spatial frequency filtering of a laser beam, the method comprising: a) passing the laser beam through a neutral region of a spatial frequency filter device; or b) reflecting the laser beam by the neutral region of the spatial frequency filter device; wherein beam components of the laser beam are deflected from a beam axis of the laser beam in a deflecting region radially adjoining the neutral region, wherein in a constant portion of the deflecting region, the beam components are deflected with a constant deflecting effect independently of a distance from the neutral region, and wherein in a variation portion of the deflecting region, the beam components are deflected with a varying deflecting effect in dependence on a distance from the neutral region. ### Claim 15 (depends on 14) The method as claimed in claim 14, wherein the deflecting region has a diffractive deflecting structure, a zero diffraction order being suppressed by the diffractive deflecting structure. ### Claim 16 (depends on 1) The spatial frequency filter device as claimed in claim 1, wherein the deflecting effect on the beam components of the laser beam is configured to vary according to a Gaussian function or according to a linear function.