# US 12,109,650 B2 · Planing-polishing apparatus and method using femtosecond pulsed laser > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,109,650 B2 - Document ID: US12109650B2 - Status: Granted - Kind: B2 - Application number: 17/403,989 - Filed: 2021-08-17 - Published: 2022-08-04 - Granted: 2024-10-08 - Earliest claimed: 2021-02-03 - Assignees: 21Th Century Co., Ltd - Applicants: 21Th Century Co., Ltd - Inventors: Sung Hwan Kim; Hyoung Shik Kang; Dong Bin You - Web page: https://patentgrep.com/patent/US12109650B2 ## CPC - B23K 26/0624: {using ultrashort pulses, i.e. pulses of 1 ns or less} - B23K 26/36: Removing material (B23K26/55, B23K26/57 take precedence) - B23K 26/03: Observing, e.g. monitoring, the workpiece - B23K 26/032: {using optical means} - B23K 26/3576: {Diminishing rugosity, e.g. by grinding, polishing or smoothing} - 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 Proposed is a planing-polishing apparatus 1 using a femtosecond pulsed laser and performing polishing of a planar workpiece to reduce surface roughness of the workpiece after performing planing of the workpiece using a femtosecond pulsed laser beam. ## Claims ### Claim 1 A planning-polishing apparatus using a femtosecond pulsed laser and performing polishing of a planar workpiece to reduce surface roughness of the workpiece after performing planning of the workpiece using a femtosecond pulsed laser beam, the apparatus comprising: a position fixing unit comprising a stage on which a workpiece is seated, a fixing jig for fixing the workpiece on the stage, and a transport means for moving the stage along X and Y axes, such that a surface of the workpiece is machined; a surface shape measurement unit digitalizing a surface shape of the workpiece into surface shape data by measuring heights at a plurality of measurement points on the surface of the workpiece and transmitting the surface shape data so that surface flatness of the workpiece is measured; a laser machining unit performing a planning process of planarizing for cutting only a convex portion of a machining area by selectively irradiating the machining area with a femtosecond pulsed laser beam in accordance with the surface shape data obtained from the surface shape measurement unit and, after the planning process, a polishing process of reducing irregularities formed on the surface of the workpiece by irradiating the irregularities with a femtosecond pulsed laser beam having a lower power level than the laser beam used in the laser planning step, wherein the surface shape data measured by the surface shape measurement unit is data regarding displacements along a Z-axis at the plurality of measurement points; and a controller converting the surface shape data into multiple-plane data, by which areas protruding to the same heights from virtual cross-sectional planes drawn by connecting points having the same heights from among the plurality of measurement points are determined to be planning areas, with the virtual cross-sectional planes being maintained to be arranged at predetermined distances in a height direction, transmitting machining parameters input for the planning process in accordance with the multiple-plane data, and controlling an operation of the laser machining unit. ### Claim 2 (depends on 1) The planning-polishing apparatus according to claim 1, wherein the surface shape measurement unit is a laser displacement sensor configured to measure heights of the measurement points by irradiating the measurement points on the surface of the workpiece with the laser beam and reading a state of the reflected laser beam. ### Claim 3 (depends on 1) The planning-polishing apparatus according to claim 1, wherein the laser beam radiated by the laser machining unit in the planning process is a femtosecond pulsed laser beam having a wavelength of 580 nm or shorter and a pulse length of from 270 fs to 700 fs. ### Claim 4 (depends on 3) The planning-polishing apparatus according to claim 3, wherein the planning process is sequentially performed from the planning area on an uppermost layer of the plane data to the planning area on a lowermost layer of the plane data by sequentially moving the laser machining unit downward or sequentially moving the stage upward along the Z-axis. ### Claim 5 (depends on 1) The planning-polishing apparatus according to claim 1, further comprising an optical camera disposed at a side of the laser machining unit, wherein the optical camera allows a state of alignment of the workpiece seated on the position fixing unit and a machining state obtained by the laser beam radiated by the laser machining unit to be visually observed in real time. ### Claim 6 (depends on 1) The planning-polishing apparatus according to claim 1, further comprising a process gas supply unit above the workpiece, the process gas supply unit being configured to control and supply a process gas that is used during laser machining performed by the laser machining unit. ### Claim 7 (depends on 1) The planning-polishing apparatus according to claim 1, further comprising a dust removing unit removing dust that is formed during laser machining performed by the laser machining unit. ### Claim 8 (depends on 7) The planning-polishing apparatus according to claim 7, wherein the dust removing unit comprises a negative pressure generator provided above the stage to generate a negative pressure around the workpiece and a filter filtering the dust drawn due to the negative pressure. ### Claim 9 (depends on 1) The planning-polishing apparatus according to claim 1, wherein the stage further comprises an elastic anti-vibration pad damping external vibration. ### Claim 10 (depends on 3) The planning-polishing apparatus according to claim 3, wherein the laser beam used in laser polishing is a femtosecond pulsed laser beam having a wavelength of 580 nm or shorter and a pulse length of from 270 fs to 700 fs. ### Claim 11 A planning-polishing method using a femtosecond pulsed laser and performing laser polishing of a planar workpiece to reduce surface roughness of the workpiece after performing laser planning to planarize a surface of the planar workpiece using a femtosecond pulsed laser beam, the method comprising: a machining preparation step of locating and fixing the workpiece at a machining origin on a stage in order to machine a surface of the workpiece; a surface shape measurement step of digitalizing a surface shape of the workpiece into surface shape data by measuring heights at a plurality of measurement points on the surface of the workpiece using a laser displacement sensor; a step of converting the surface shape data obtained by the surface shape measurement step into multiple-plane data in which virtual cross-sectional planes drawn by connecting points having same heights from among the plurality of measurement points are arranged at predetermined distances, determining areas protruding to same heights from the cross-sectional planes as planning areas, and determining and inputting machining parameters for a planning process; a laser planning step of planarizing for cutting only a convex portion of the surface of the workpiece by irradiating, by a laser machining unit, the planning area determined from the surface shape data with a laser beam in a predetermined pattern to which the machining parameters are applied; and a laser polishing step of reducing irregularities formed on the surface of the workpiece by radiating a femtosecond pulsed laser beam having a lower power level than the laser beam used in the laser planning step, thereby reducing surface roughness of the workpiece. ### Claim 12 (depends on 11) The planning-polishing method according to claim 11, wherein the machining preparation step, the surface shape measurement step, the laser planning step, and the laser polishing step are performed while a state of radiation of the laser beam to the workpiece is being visually observed in real time. ### Claim 13 (depends on 11) The planning-polishing method according to claim 11, wherein the laser planning step is sequentially performed from the planning area on an uppermost layer of the plane data to the planning area on a lowermost layer of the plane data while the laser machining unit is being sequentially moved downward or the stage is being sequentially moved upward along a Z-axis. ### Claim 14 (depends on 11) The planning-polishing method according to claim 11, wherein the laser beam radiated in the laser planning step is a femtosecond pulsed laser beam having a wavelength of 580 nm or shorter and a pulse length of from 270 fs to 700 fs. ### Claim 15 (depends on 11) The planning-polishing method according to claim 11, wherein the laser planning step and the laser polishing step are performed while dust formed during laser machining is being removed by a negative pressure. ### Claim 16 (depends on 11) The planning-polishing method according to claim 11, wherein the workpiece is a precision mold used in manufacture of stacked electronic ceramics. ### Claim 17 (depends on 11) The planning-polishing method according to claim 11, wherein the laser planning step and the laser polishing step are performed while a process gas is being supplied, the process gas preventing a change in mechanical properties of the surface of the workpiece and a surface residual stress in the workpiece from occurring from laser machining. ### Claim 18 (depends on 11) The planning-polishing method according to claim 11, wherein the laser beam used in the laser polishing step is a femtosecond pulsed laser beam having a wavelength of 580 nm or shorter and a pulse length of from 270 fs to 700 fs.