An apparatus, comprising: a laser scanner (210, 302, 618, 706); an optical source (310, 640, 728) situated to produce a fiducial source beam (200, 312, 642, 730); an optical fiducial pattern generator (202, 314, 646, 732) situated to produce with the fiducial source beam at least one transient optical fiducial (102, 204a-f, 320a-i, 650a-d, 726) on a laser processing target (206, 308, 626, 714) that is in a field of view of the laser scanner (210, 302, 618, 706) situated to scan a laser processing beam across the laser processing target (206, 308, 626, 714), so that a positioning of the laser processing beam on the laser processing target (206, 308, 626, 714) becomes adjustable relative to the at least one transient optical fiducial (102, 204a-f, 320a-i, 650a-d, 726); an optical detector (212, 324, 656, 738) optically coupled to the laser processing target through the laser scanner to a subfield field of view (510a-d) of the field of view based on a scan position of one or more scan optics (322, 620a, 620b, 708a, 708b) of the laser scanner, wherein the optical detector (212, 324, 656, 738) is situated to detect the at least one transient optical fiducial (102, 204a-f, 320a-i, 650a-d, 726) in the subfield; and a controller (330, 630, 716) coupled to the optical detector (212, 324, 656, 738) and the laser scanner (210, 302, 618, 706) and configured to compare the detected position of the at least one transient optical fiducial (102, 204a-f, 320a-i, 650a-d, 726) to a position of the laser processing beam, to update a scan error correction table (637, 754) based on the comparison, and to scan the laser processing beam according to the updated scan error correction table (637, 754). a laser scanner (210, 302, 618, 706); an optical source (310, 640, 728) situated to produce a fiducial source beam (200, 312, 642, 730); an optical fiducial pattern generator (202, 314, 646, 732) situated to produce with the fiducial source beam at least one transient optical fiducial (102, 204a-f, 320a-i, 650a-d, 726) on a laser processing target (206, 308, 626, 714) that is in a field of view of the laser scanner (210, 302, 618, 706) situated to scan a laser processing beam across the laser processing target (206, 308, 626, 714), so that a positioning of the laser processing beam on the laser processing target (206, 308, 626, 714) becomes adjustable relative to the at least one transient optical fiducial (102, 204a-f, 320a-i, 650a-d, 726); an optical detector (212, 324, 656, 738) optically coupled to the laser processing target through the laser scanner to a subfield field of view (510a-d) of the field of view based on a scan position of one or more scan optics (322, 620a, 620b, 708a, 708b) of the laser scanner, wherein the optical detector (212, 324, 656, 738) is situated to detect the at least one transient optical fiducial (102, 204a-f, 320a-i, 650a-d, 726) in the subfield; and a controller (330, 630, 716) coupled to the optical detector (212, 324, 656, 738) and the laser scanner (210, 302, 618, 706) and configured to compare the detected position of the at least one transient optical fiducial (102, 204a-f, 320a-i, 650a-d, 726) to a position of the laser processing beam, to update a scan error correction table (637, 754) based on the comparison, and to scan the laser processing beam according to the updated scan error correction table (637, 754).