Mitutoyo Corporation

Robert Kamil Bryll

Mark Lawrence Delaney

Michael Nahum

Paul Gerard Gladnick

Shannon Roy Campbell

Yuhua Ding

William Todd Watson

Tatsuya Nagahama

Casey Edward Emtman

Benjamin K Jones

Kozo Ariga

Vidya Venkatachalam

Joseph Andrew Summers

Karl Gustav Masreliez

Benjamin Keith Jones

A workpiece inspection and defect detection system includes a light source, a lens that inputs image light arising from a surface of a workpiece, and a camera that receives imaging light transmitted along an imaging optical path. The system utilizes images of workpieces acquired with the camera as training images to train a defect detection portion to detect defect images that include workpieces with defects. Anomaly detector classification characteristics are determined based on features of the training images. Run mode images of workpieces are acquired with the camera, and based on determined features from the images, the anomaly detector classification characteristics are utilized to determine if the images of the workpieces are classified as anomalous. In addition, the defect detection portion determines if images are defect images that include workpieces with defects and for which additional operations may be performed (e.g., metrology operations for measuring dimensions of the defects, etc.)

Workpiece inspection and defect detection system including monitoring of workpiece images

A workpiece inspection and defect detection system includes a light source, a lens that inputs image light arising from a surface of a workpiece, and a camera that receives imaging light transmitted along an imaging optical path. The system utilizes images of workpieces acquired with the camera as training images to train a defect detection portion to detect defect images that include workpieces with defects, and determines a performance of the defect detection portion as trained with the training images. Based on the performance of the defect detection portion, an indication is provided as to whether additional defect images should be provided for training. After training is complete, the camera is utilized to acquire new images of workpieces which are analyzed to determine defect images that include workpieces with defects, and for which additional operations may be performed (e.g., metrology operations for measuring dimensions of the defects, etc.)

Workpiece inspection and defect detection system indicating number of defect images for training

A metrology system is provided with a transparent workpiece surface mode, for which the system is configured to vary a focus position over a plurality of positions along a Z height direction proximate to a workpiece. An image stack is acquired, wherein each image of the image stack includes a first surface (e.g., an upper surface of the workpiece) that is transparent or semi-transparent and at least a second surface that is at least partially viewable through the first surface. A plurality of focus curves are determined based on the image stack (e.g., with pattern projection utilized for improved contrast), from which first, second, etc. local focus peaks may be determined from each focus curve that correspond to the first, second, etc. surfaces, respectively. An image is displayed (e.g., extended depth of field, 3D) including a selected surface and for which features of the selected/displayed surface may be measured.

Metrology system with transparent workpiece surface mode

A variable focal length (VFL) lens system is provided including a VFL lens, a VFL lens controller, an objective lens, a camera and an optical power monitoring configuration. During a standard workpiece imaging mode, the objective lens transmits workpiece light along an imaging optical path through the VFL lens to the camera, which provides a corresponding workpiece image exposure. During an optical power monitoring mode, the optical power monitoring configuration produces a monitored beam pattern which travels along at least a portion of the imaging optical path through the VFL lens to the camera, which provides a monitoring image exposure. Different monitoring image exposures are acquired at different phase timings of the periodic modulation of the VFL lens, and a dimension of the monitored beam pattern is measured in each monitoring image exposure as related to an optical power of the VFL lens at the corresponding phase timing.

Variable focal length lens system with optical power monitoring

A focus state reference subsystem comprising a focus state (FS) reference object is provided for use in a variable focal length (VFL) lens system comprising a VFL lens, a controller that modulates its optical power, and a camera located along an optical path including an objective lens and the VFL lens. Reference object image light from the FS reference object is transmitted along a portion of the optical path through the VFL lens to the camera. Respective FS reference regions (FSRRs) of the FS reference object include a contrast pattern fixed at respective focus positions. A camera image that includes a best-focus image of a particular FSRR defines a best-focus reference state associated with that FSRR, wherein that best-focus reference state comprises a VFL optical power and/or effective focus position of the VFL lens system through the objective lens.

Variable focal length lens system including a focus state reference subsystem

A method for providing an extended depth of field (EDOF) image includes: Periodically modulating an imaging system focus position at a high frequency; using an image exposure comprising discrete image exposure increments acquired at discrete focus positions during an image integration time comprising a plurality of modulation periods of the focus position; and using strobe operations having controlled timings configured to define a set of evenly spaced focus positions for the image exposure increments. The timings are configured so that adjacent focus positions in the set are acquired at times that are separated by at least one reversal of the direction of change of the focus position during its periodic modulation. This solves practical timing problems that may otherwise prevent obtaining closely spaced discrete image exposure increments during high frequency focus modulation. Deconvolution operations may be used to improve clarity in the resulting EDOF image.

Machine vision inspection system and method for obtaining an image with an extended depth of field

A focus state reference subsystem comprising a focus state reference object (FSRO) and reference object optics (ROO) is for use in a variable focal length (VFL) lens system comprising a VFL lens, a controller that modulates its optical power, and a camera located along an imaging path including an objective lens and the VFL lens. The ROO transmits image light from the FSRO along a portion of the imaging path through the VFL lens to the camera. Respective FS reference regions (FSRRs) of the FSRO include a contrast pattern fixed at respective focus positions relative to the ROO. A camera image that includes a best-focus image of a particular FSRR defines a best-focus reference state associated with that FSRR, wherein that best-focus reference state comprises a VFL optical power and/or effective focus position of the VFL lens system through the objective lens.

An imaging system including a tunable acoustic gradient (TAG) lens is associated with a user interface including a live display of an extended depth of field (EDOF) image. The TAG lens is utilized to produce a raw EDOF image, which may include defocus blur (e.g., resulting in part from the periodically modulated optical power variation of the TAG lens). The live EDOF image is repetitively updated in the user interface based on a translation state signal at a current time (e.g., indicating a speed of translation of the workpiece across a field of view of the imaging system, etc.) In response to a current state of the translation state signal, a corresponding type of live EDOF image of the workpiece is displayed in the user interface corresponding to an EDOF image data set that is based on a corresponding level of image processing to remove defocus blur.

Variable focal length lens system with multi-level extended depth of field image processing

A system for providing an automatically focused image comprises an imaging system including a high speed periodically modulated variable focal length (VFL) lens, a VFL lens controller, a VFL-projected light source, a focus determining portion, an exposure timing adjustment circuit, and an exposure strobe time controller. The focus determining portion comprises an optical detector that inputs reflected VFL-projected light that is projected to, and reflected from, a workpiece through the VFL lens, and provides a focus deviation signal. The exposure timing adjustment circuit provides an exposure timing adjustment signal based on the focus deviation signal, which indicates a time when the imaging system focus Z-height approximately coincides with the workpiece surface Z height. The exposure strobe time controller uses the exposure timing adjustment signal to adjust the image exposure time so the imaging system focus Z-height coincides with the workpiece surface Z height at the adjusted image exposure time.

Autofocus system for a high speed periodically modulated variable focal length lens

A variable focal length (VFL) imaging system comprises a camera system, a first high speed variable focal length (VFL) lens, a second high speed variable focal length (VFL) lens, a first relay lens comprising a first relay focal length, a second relay lens comprising a second relay focal length, and a lens controller. The first relay lens and the second relay lens are spaced relative to one another along an optical axis of the VFL imaging system by a distance which is equal to a sum of the first relay focal length and the second relay focal length. The first high speed VFL lens and the second high speed VFL lens are spaced relative to one another along the optical axis on opposite sides of an intermediate plane which is located at a distance equal to the first relay focal length from the first relay lens. The lens controller is configured to provide synchronized periodic modulation of the optical power of the first high speed VFL lens and the optical power of the second high speed VFL lens.

Variable focal length imaging system

A method is provided for defining operations for acquiring a multi-exposure image of a workpiece including first and second regions of interest at different Z heights. The multi-exposure image is acquired by a machine vision inspection system including strobed illumination and a variable focal length lens (e.g., a tunable acoustic gradient index of refraction lens) used for periodically modulating a focus position. During a learn mode, first and second multi-exposure timing values for instances of strobed illumination are determined that correspond with first and second phase timings of the periodically modulated focus position that produce sufficient image focus for the first and second regions of interest. Data indicative of the multi-exposure timing difference is recorded and is subsequently utilized (e.g., during a run mode) to define operations for acquiring a multi-exposure image of first and second regions of interest on a current workpiece that is similar to the representative workpiece.

Multi-level image focus using a tunable lens in a machine vision inspection system

An image acquisition system is operated to provide an image that is relatively free of the effect of longitudinal chromatic aberration. The system includes a variable focal length lens (e.g., a tunable acoustic gradient index of refraction lens) that is operated to periodically modulate a focus position. First, second, third, etc., wavelength image exposure contributions are provided by operating an illumination system to provide instances of strobed illumination of first, second, third, etc., wavelengths (e.g., green, blue, red, etc.) timed to correspond with respective phase timings of the periodically modulated focus position which focus the respective wavelength image exposure contributions at the same focus plane. The respective phase timings of the periodically modulated focus position compensate for longitudinal chromatic aberration of at least the variable focal length lens. An image is produced that is relatively free of the effect of longitudinal chromatic aberration by combining the image exposure contributions.

Chromatic aberration correction in imaging system including variable focal length lens

A method for programming a three-dimensional (3D) workpiece scan path for a metrology system comprising a 3D motion control system, a first type of Z-height sensing system, and a second type of Z-height sensing system that provides less precise surface Z-height measurements over a broader Z-height measuring range. The method comprises: placing a representative workpiece on a stage of the metrology system, defining at least a first workpiece scan path segment for the representative workpiece, determining preliminary actual surface Z-height measurements along the first workpiece scan path segment, and determining a precise 3D scan path for moving the first type of Z-height sensing system to perform precise surface Z-height measurements. The precise 3D scan path is based on the determined preliminary actual surface Z-height measurements. The precise 3D scan path may be used for performing precise surface Z-height measurements or stored to be used in an inspection program.

Method for programming a three-dimensional workpiece scan path for a metrology system

A variable focal length (VFL) lens system is utilized to determine surface Z-height measurements of imaged surfaces. A controller of the system is configured to control a VFL lens (e.g., a tunable acoustic gradient index of refraction lens) to periodically modulate its optical power and thereby periodically modulate a focus position at a first operating frequency, wherein the periodically modulated VFL lens optical power defines a first periodic modulation phase. A phase timing signal is synchronized with a periodic signal in the controller that has the first operating frequency and that has a second periodic modulation phase that has a phase offset relative to the first periodic modulation phase. A phase offset compensating portion is configured to perform a phase offset compensating process that provides Z-height measurements, wherein at least one of Z-height errors or Z-height variations that are related to a phase offset contribution are at least partially eliminated.

Phase difference calibration in a variable focal length lens system

A method for operating an imaging system of a machine vision inspection system to provide an extended depth of field (EDOF) image. The method comprises (a) placing a workpiece in a field of view; (b) periodically modulating a focus position of the imaging system without macroscopically adjusting the spacing between elements in the imaging system, the focus position is periodically modulated over a plurality of positions along a focus axis direction in a focus range including a workpiece surface height; (c) exposing a first preliminary image during an image integration time while modulating the focus position in the focus range; and (d) processing the first preliminary image to remove blurred image contributions occurring in the focus range during the image integration time to provide an EDOF image that is focused throughout a larger depth of field than the imaging system provides at a single focal position.

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Bothell, WA, United States of America

Robert Kamil Bryll