The concept of laser paint stripping has been around for a long time. Laser ablation is attractive because it can avoid damage to the part caused by abrasive methods of paint removal and does not require the use of toxic paint removal solvents.
NASA, the US Navy and the USAF have asked the industry for solutions. The USAF requirements have received a lot of attention.
Some of the challenges faced have been:
PAINT COLOR vs LASER WAVELENGTH
The ability to strip the paint depends on the absorption of the laser energy. Different color paints require different wavelengths to achieve high absorption!
STRIPPING THE PAINT WITHOUT PENETRATING THE PRIMER
This is especially important on aircraft. Removing the primer exposes the aluminum skin to oxidation. Aluminum primer is a different color from the top paint so this helps to avoid primer penetration. Another method is to use a camera which watches for primer or other substrate to appear and can regulate the laser accordingly.
HIGH SCAN RATES
Galvanometer (galvo) scanners were the original scanner of choice but galvos are not fast enough for the high power lasers of today. Polygon scanners can be 10 to 100 times faster than galvo scanners. Stripping paint and other thin film ablation applications require polygon speed to achieve the full potential of high power lasers.
LASER DAMAGE THRESHOLD
Polygon scanners are far superior to galvo scanners for laser damage threshold. Polygon scanners are essential to scan lasers at the multi KW power level. The laser spot is never stationery on a rotating polygon mirror so this eliminates hot spots. Polygon scanners act like a massive, self-cooling heat sink to pull heat from the facets to protect the coating from damage. See more information here on POLYGON LASER DAMAGE THRESHOLD.
It is not difficult to vacuum the paint residue away from the laser ablation area. At a minimum, some filtering is needed to contain the residue. Depending on the laser power and the scan speed, the residue may be gummy which presents some issues. Or the residue may be completely incinerated. An incinerated residue is easier to filter but will require some cooling of the high temperature exhaust.
I was at an ICALEO conference when Stan Ream of EWI (Edison Welding Institute) gave an amazing presentation to a packed audience. He gave detailed data on a very effective POLYGON SCANNER FOR LASER PAINT STRIPPING. Be sure to have a look at this very impressive VIDEO OF SELECTIVE PAINT ABLATION.
Precision Laser Scanning specializes in high speed laser scanning is a subject matter expert in POLYGON SCANNERS.