Auto-focus system
AssigneeOrbotech Ltd.
InventorsOfer Saphier, Doron Malka, David Fisch
Life of this patent
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Abstract
A distance measuring system is provided for auto focusing a camera of an inspection system for inspecting a planar surface that is patterned. The system includes a pattern generator, an image sensor, an optical element(s) and a processor. The pattern generator projects a spatially random pattern toward the planar surface at an oblique angle. The optical element(s) forms the image of the reflected pattern on the image sensor and the image sensor captures an image of the spatially random pattern reflected off the planar surface. The processor processes the image of the spatially random pattern and provides auto-focus information.
Claims25
A distance measuring system for auto focusing a camera of an inspection system for inspecting a planar surface that includes a patterned object, the distance measuring system comprising:
- a pattern generator that generates a spatially random pattern and projects the spatially random pattern toward the planar surface at an oblique angle;
- an image sensor that captures an image of the spatially random pattern reflected off the planar surface;
- at least one optical element that forms the image of the reflected pattern on the image sensor;
- and
- a processor that obtains distance information between the image sensor and the planar surface based on at least one of shifting and scaling of at least one feature of the spatially random pattern, and that provides auto-focus information based on the distance information,
- wherein the pattern generator is configured to project the spatially random pattern such that the shifting or scaling of the projected spatially random pattern captured in the image changes non-linearly in response to different distances between the image sensor and the planar surface,
- wherein the processor detects the nonlinear changes of the shifting or scaling of the spatially random pattern in the image and determines changes in distance between the image sensor and the planar surface using the nonlinear changes to determine the auto-focus information, and
- wherein the spatially random pattern is uncorrelated with the pattern of the patterned object.
A distance measuring system for auto focusing a camera of an inspection system for inspecting a planar surface that includes a patterned object, the distance measuring system comprising:
- a pattern generator that generates a spatially random pattern and projects the spatially random pattern toward the planar surface at an oblique angle;
- an image sensor that captures an image of the spatially random pattern reflected off the planar surface;
- at least one optical element that forms the image of the reflected pattern on the image sensor;
- a processor that processes the image of the spatially random pattern captured by the image sensor and provides auto-focus information based on at least one of shifting and scaling of at least one feature of the spatially-random pattern;
- and
- a memory for storing at least one calibration image of the spatially random pattern reflected off the planar surface, wherein the processor performs correlation between the image of the spatially random pattern and the calibration image of the spatially random pattern,
- wherein the pattern generator is configured to project the spatially random pattern such that the shifting or scaling of the projected spatially random pattern captured in the image changes non-linearly in response to different distances between the image sensor and the planar surface,
- wherein the processor detects the nonlinear changes of the shifting or scaling of the spatially random pattern in the image and determines changes in distance between the image sensor and the planar surface using the nonlinear changes to determine the auto-focus information, and
- wherein the spatially random pattern is uncorrelated with the pattern of the patterned object.
An auto-focus system for auto focusing a camera of an inspection system with respect to a planar surface having a patterned object for inspection comprises:
- a pattern generator that generates a spatially random pattern and projects the pattern generated toward a planar surface at an oblique angle;
- a camera that captures an image of the spatially random pattern reflected off the planar surface;
- a processor that obtains distance information between the image sensor and the planar surface based on at least one of shifting and scaling of at least one feature of the spatially random pattern, and that provides auto-focus information based on the distance information;
- an actuator for changing a working distance between the camera and the planar surface;
- and
- a controller that controls operation of the actuator in response to the auto-focus information provided by the processor,
- wherein the pattern generator is configured to project the spatially random pattern such that the shifting or scaling of the projected spatially random pattern captured in the image changes non-linearly in response to different distances between the image sensor and the planar surface,
- wherein the processor detects the nonlinear changes of the shifting or scaling of the spatially random pattern in the image and determines changes in distance between the image sensor and the planar surface using the nonlinear changes to determine the auto-focus information, and
- wherein the spatially random pattern is uncorrelated with the pattern of the patterned object.
An auto-focus system for auto focusing a camera of an inspection system with respect to a planar surface having a patterned object for inspection comprises:
- a pattern generator that generates a spatially random pattern and projects the pattern generated toward a planar surface at an oblique angle;
- a camera that captures an image of the spatially random pattern reflected off the planar surface;
- a processor that processes the image of the spatially random pattern captured by the camera and provides auto-focus information based on at least one of shifting and scaling of at least one feature of the spatially-random pattern;
- and
- a memory for storing at least one calibration image of the spatially random pattern reflected off the planar surface at a known actuator position, wherein the processor performs correlation between the image of the spatially random pattern and the calibration image of the spatially random pattern,
- wherein the pattern generator is configured to project the spatially random pattern such that the shifting or scaling of the projected spatially random pattern captured in the image changes non-linearly in response to different distances between the image sensor and the planar surface,
- wherein the processor detects the nonlinear changes of the shifting or scaling of the spatially random pattern in the image and determines changes in distance between the image sensor and the planar surface using the nonlinear changes to determine the auto-focus information, and
- wherein the spatially random pattern is uncorrelated with the pattern of the patterned object.
Dependencies are inferred from the claim text.