US 5,668,665 AGranted

Telecentric, parfocal, multiple magnification optical system for videoinspection apparatus

AssigneeOptical Gaging Products, Inc.

InventorAlbert G. Choate

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Abstract

An objective lens is secured in an afocal mode to a support for movement vertically toward and away from a workpiece. An illumination collimator fixed on the support above the objective lens projects the image of a reticle downwardly and successively through a second lens assembly, a beamsplitter plate, and coaxially of the objective lens to the workpiece. A combined image of the reticle and workpiece is then projected by the objective lens upwardly onto the beamsplitter, and laterally to a mirror which projects the combined image upwardly along an axis spaced from and parallel to the axis of the objective lens, and through one of several different magnifying lens assemblies to the image detector of a video camera. The magnifying lens assemblies can be selectively indexed one at a time into registry with the camera, and each has a telecentric opening or stop which always registers with the rear focal point of the objective lens each time such assembly is indexed into its operative position.

Claims15

Dependent claims

A telecentric, multiple magnification optical system for projecting the combined images of a workpiece and reticle to the camera of associated video inspection apparatus, comprising,

a first lens assembly secured to a movable support for movement thereby along a first axis toward and away from a workpiece,
a beamsplitter mounted on said support adjacent the side of said first lens assembly remote from said workpiece,
reticle projection means including a second lens assembly fixed on said support coaxially of a second axis parallel to and approximately coaxially of said first axis, and operative to project the image of a reticle in one direction through said beamsplitter and said first lens assembly and onto said workpiece,
a video camera fixed to said support and having therein an image detector disposed coaxially of a third axis laterally spaced from and extending parallel to said first and second axes,
said first lens assembly including a fixed objective lens having front and back focal points, respectively, and operable in an afocal mode to project a combined image of said workpiece and said reticle in the opposite direction through said first lens assembly to said beamsplitter, and
means including a plurality of magnification lens assemblies movable selectively and one by one into an operative position between said beamsplitter and said camera to project a magnified image of said combined workpiece and reticle image along said third axis to said image detector in said camera,
each of said magnification lens assemblies having a telecentric stop disposed to be positioned at said back focal point of said objective lens when a respective magnification lens assembly is in its operative position.

4 more elements

In an optical system for projecting the combined images of a workpiece and a reticle to a video camera for inspection and autofocusing by an associated microprocessor (CPU) device,

an objective lens assembly having fixed front and rear focal points, respectively, and secured on a support for movement thereby coaxially of a first axis toward and away from a workpiece,
surface illuminator and reticle projection means on said support for simultaneously projecting in one direction through said objective lens assembly, and onto said workpiece, light from a source thereof and the image of a reticle, whereby a combined image of said workpiece and reticle is projected in an afocal mode in the opposite direction through said objective lens assembly,
a magnification lens assembly mounted on said support coaxially of a second axis spaced from and parallel to said first axis,
said magnification lens assembly registering at one end with the image detector of a video camera, and having in its opposite end a telecentric stop opening registering with the rear focal point of said objective lens assembly, and
means interposed between said objective lens assembly and said telecentric stop for projecting said combined image coaxially through said telecentric stop and said magnification lens assembly to the image detector of said camera,
said magnification lens assembly being one of several different magnification lens assemblies mounted on said support for movement selectively and one at a time into an operative position in which a respective one of said different assemblies is disposed coaxially of said second axis and has therein a telecentric stop opening registering with the rear focal point of said objective lens assembly.

3 more elements

Dependencies are inferred from the claim text.