US 12,242,047 B2
Metrology system utilizing annular optical configuration
Paul Gerard Gladnick, Seattle, WA (US)
Assigned to Mitutoyo Corporation, Kanagawa-ken (JP)
Filed by Mitutoyo Corporation, Kanagawa-ken (JP)
Filed on Jun. 29, 2023, as Appl. No. 18/344,705.
Prior Publication US 2025/0004263 A1, Jan. 2, 2025
Int. Cl. G02B 21/24 (2006.01); G01N 21/88 (2006.01); G02B 21/06 (2006.01); G02B 21/36 (2006.01); H04N 23/55 (2023.01); H04N 23/56 (2023.01); H04N 23/67 (2023.01); H04N 23/74 (2023.01)
CPC G02B 21/248 (2013.01) [G01N 21/8806 (2013.01); G02B 21/06 (2013.01); G02B 21/365 (2013.01); H04N 23/55 (2023.01); H04N 23/56 (2023.01); H04N 23/67 (2023.01); H04N 23/74 (2023.01)] 25 Claims
OG exemplary drawing
 
1. A metrology system, comprising:
a variable focal length (VFL) lens;
a VFL lens controller that is configured to control the VFL lens to periodically modulate the optical power of the VFL lens over a range of optical powers at an operating frequency so as to vary a system focus position of the system over a plurality of positions within a focus range;
a camera configured to receive image light transmitted along an imaging optical path that passes through the VFL lens and to provide images of a workpiece;
an objective lens configuration that is configured to input image light arising from the workpiece and to transmit the image light along the imaging optical path that passes through the VFL lens, wherein the objective lens configuration is configured to include one of a plurality of interchangeable objective lenses at a time, the plurality of interchangeable objective lenses comprising at least a first objective lens with a first working distance and a corresponding first working distance focus position, and a second objective lens with a second working distance and a corresponding second working distance focus position;
an annular lighting configuration that is configured to provide source light for illuminating the workpiece for producing the image light; and
an annular optical configuration;
wherein:
the annular lighting configuration is configured to direct source light toward a first central volume which includes the first working distance focus position while the first objective lens is included in the objective lens configuration; and
the annular optical configuration is configured to be utilized in combination with the second objective lens while the second objective lens is included in the objective lens configuration and to be located in front of the annular lighting configuration to redirect the source light toward a second central volume which includes the second working distance focus position.