Large-area selective ablation methods

Patent metadata

Field	Value
Publication number	US-10363586-B2
Application number	US-201715397171-A
Country	US
Kind code	B2
Filing date	Jan 3, 2017
Priority date	Jan 3, 2017
Publication date	Jul 30, 2019
Grant date	Jul 30, 2019

Abstract

A method of using a laser ablation system to clean an area of a surface with a laser beam, having a target fluence and a target irradiance. The area comprises scan regions, each having a scan width. The method comprises determining a traverse scan speed, a laser-beam average power, a laser pulse repetition rate, a laser pulse width, and a laser-beam spot area of the laser beam for each one of the scan regions to achieve the target fluence and the target irradiance. The scan width of at least one of the scan regions is different from the scan width of another one of the scan regions. The method also comprises sequentially scanning, across the scan width, each one of the scan regions of the area with the laser beam at the target fluence and the target irradiance.

First claim

What is claimed is:

1. A method of using a laser ablation system to clean an area of a surface with a laser beam, having a target fluence and a target irradiance, the area comprising scan regions, each having a scan width, the method comprising:
using a controller of the laser ablation system to determine, based on one or more characteristics of the area of the surface, a traverse scan speed, a laser-beam average power, a laser pulse repetition rate, a laser pulse width, and a laser-beam spot area of the laser beam for each one of the scan regions to achieve the target fluence and the target irradiance of the laser beam when scanning each one of the scan regions with the laser beam, wherein a first scan width of at least one of the scan regions is different from a second scan width of another one of the scan regions; and
using the controller to cause a scanning head of the laser ablation system to sequentially scan each one of the scan regions of the area with the laser beam at the target fluence and the target irradiance, and wherein the controller causes the scanning head to:
scan the at least one of the scan regions with the first scan width, wherein the scanning head achieves the target fluence and the target irradiance when scanning the at least one of the scan regions; and
subsequently scan a different one of the scan regions with the second scan width, wherein the controller causes an adjustment in at least one of the traverse scan speed, the laser-beam average power, the laser pulse repetition rate, the laser pulse width, and the laser-beam spot area so that the scanning head achieves the target fluence and the target irradiance when scanning the different one of the scan regions.

2. The method according to claim 1 , wherein:
the laser beam has an initial laser-beam average power,
the scan regions comprise an adapted scan region,
determining the traverse scan speed, the laser-beam average power, the laser pulse repetition rate, the laser pulse width, and the laser-beam spot area for each one of the scan regions comprises determining that a projected traverse scan speed for the adapted scan region is greater than a maximum traverse scan speed,
the projected traverse scan speed for the adapted scan region is the initial laser-beam average power divided by a product of the scan width of the adapted scan region and the target fluence, and
the method further comprises determining an adapted laser-beam average power that is a product of the target fluence, the scan width of the adapted scan region, and the maximum traverse scan speed.

3. The method according to claim 2 , wherein:
the laser pulse repetition rate of the adapted scan region is the adapted laser-beam average power divided by a product of the target irradiance, the laser pulse width for the adapted scan region, and the laser-beam spot area for the adapted scan region; and
scanning the area of the surface comprises scanning the adapted scan region at the maximum traverse scan speed across the scan width of the adapted scan region while the laser beam has the adapted laser-beam average power, the laser pulse repetition rate for the adapted scan region, the laser pulse width for the adapted scan region, and the laser-beam spot area for the adapted scan region.

4. The method according to claim 2 , wherein:
determining the traverse scan speed, the laser-beam average power, the laser pulse repetition rate, the laser pulse width, and the laser-beam spot area for each one of the scan regions comprises determining that a projected laser pulse repetition rate for the adapted scan region is less than a minimum laser pulse repetition rate, and
the projected laser pulse repetition rate for the adapted scan region is the adapted laser-beam average power divided by a product of the target irradiance, the laser pulse width for the adapted scan region, and the laser-beam spot area for the adapted scan region.

5. The method according to claim 4 , wherein:
the laser pulse width for the adapted scan region is the adapted laser-beam average power divided by a product of the target irradiance, the minimum laser pulse repetition rate, and the laser-beam spot area for the adapted scan region; and
scanning the area of the surface comprises scanning the adapted scan region at the maximum traverse scan speed across the scan width of the adapted scan region while the laser beam has the adapted laser-beam average power, the minimum laser pulse repetition rate, the laser pulse width for the adapted scan region, and the laser-beam spot area for the adapted scan region.

6. The method according to claim 4 , wherein:
determining the traverse scan speed, the laser-beam average power, the laser pulse repetition rate, the laser pulse width, and the laser-beam spot area for each one of the scan regions comprises determining that a projected laser pulse width for the adapted scan region is less than a minimum laser pulse width;
the projected laser pulse width for the adapted scan region is the adapted laser-beam average power divided by a product of the target irradiance, the minimum laser pulse repetition rate, and the laser-beam spot area for the adapted scan region;
the laser-beam spot area for the adapted scan region is the adapted laser-beam average power divided by a product of the target irradiance, the minimum laser pulse repetition rate, and the minimum laser pulse width; and
scanning the area of the surface comprises scanning the adapted scan region at the maximum traverse scan speed across the scan width of the adapted scan region while the laser beam has the adapted laser-beam average power, the minimum laser pulse repetition rate, the minimum laser pulse width, and the laser-beam spot area for the adapted scan region.

7. The method according to claim 1 , wherein determining the traverse scan speed, the laser-beam average power, the laser pulse repetition rate, the laser pulse width, and the laser-beam spot area is performed at least partially concurrently with scanning the area of the surface.

8. The method according to claim 1 , wherein determining the traverse scan speed, the laser-beam average power, the laser pulse repetition rate, the laser pulse width, and the laser-beam spot area comprises determining the traverse scan speed in multiplicative inverse relation to the scan width for each one of the scan regions when the scan width is greater than or equal to a first critical scan width.

9. The method according to claim 1 , wherein:
determining the traverse scan speed, the laser-beam average power, the laser pulse repetition rate, the laser pulse width, and the laser-beam spot area comprises equating the traverse scan speed to a maximum traverse scan speed and determining the laser pulse repetition rate in proportion to the scan width for each one of the scan regions when the scan width is less than a first critical scan width and greater than or equal to a second critical scan width; and
the first critical scan width is greater than the second critical scan width.

10. The method according to claim 1 , wherein:
determining the traverse scan speed, the laser-beam average power, the laser pulse repetition rate, the laser pulse width, and the laser-beam spot area comprises equating the traverse scan speed to a maximum traverse scan speed, equating the laser pulse repetition rate to a minimum laser pulse repetition rate, and determining the laser pulse width in proportion to the scan width for each one of the scan regions when the scan width is less than a first critical scan width and greater than or equal to a second critical scan width; and
the first critical scan width is greater than the second critical scan width.

11. The method ac

Assignees

• Boeing Co

Inventors

• Barclay Richard Charles

Classifications

• B23K2101/006

  Vehicles · CPC title

• B23K26/0626

  Energy control of the laser beam (B23K26/0622 takes precedence) · CPC title

• B08B7/0042 Primary

  by laser · CPC title

• B23K26/361

  for deburring or mechanical trimming (B23K26/351 takes precedence) · CPC title

• B23K26/362

  Laser etching · CPC title