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US 7,375,362 B2Granted
Method and apparatus for reducing or eliminating stray light in an optical test head
AssigneeWD Media, LLC
InventorsDavid Treves, Thomas A. O'Dell
Life of this patent
Estimating the term…
Abstract
An optical test head comprises one or more optical input paths by which a beam of light is communicated from a light source to a workpiece and one or more optical output paths by which light reflected off of the workpiece is communicated to a detector. The input optical path and the output optical path can include one or more mirrors and one or more lenses. At least one of the optical paths includes a layer for trapping and/or absorbing stray light. One or more of the lenses includes an anti-reflective coating for reducing noise caused by unwanted light reflection off of the lenses. The optical paths include one or more masks reducing stray light. The one or more masks can have an adjustable aperture (e.g. an iris).
Claims31
Apparatus comprising:
- at least one input path for receiving light from a light source and communicating said light to a workpiece;
- a light detector for receiving light and generating a signal in response thereto;
- at least one output path for receiving light reflected from said workpiece and communicating light to said detector;
- circuitry inspecting said workpiece for defects in response to said reflected light,
- wherein at least one of said at least one output path or at least one input path passes through a tube, said tube comprising a light-absorptive layer for absorbing and/or trapping stray light, said light-absorptive layer comprising dentritic material.
2 more elements
Method comprising:
- communicating light through at least one input path to a workpiece;
- communicating light reflected by said workpiece through at least one output path to a detector;
- inspecting said workpiece for defects in response to said reflected light;
- wherein at least one of said at least one output path or at least one input path passes through a tube, said tube comprising a light-absorptive layer for absorbing and/or trapping stray light, said light-absorptive layer comprising dentritic material.
1 more element
Apparatus comprising:
- at least one input path for receiving light from a light source and communicating said light to a workpiece;
- a light detector for receiving light and generating a signal in response thereto;
- at least one output path for receiving light reflected from said workpiece and communicating light to said detector;
- wherein at least one of said at least one output path or at least one input path passes through a tube a light-absorptive layer for absorbing and/or trapping stray light being plated onto said tube, and
- wherein light communicated in said at least one output path is light scattered by said workpiece within a selected range of angles, and said detector provides a signal indicating the amount of light scattered by said workpiece within said range.
2 more elements
Apparatus comprising:
- at least one input path for receiving light from a light source and communicating said light to a workpiece;
- a light detector for receiving light and generating a signal in response thereto;
- at least one output path for receiving light reflected from said workpiece and communicating light to said detector;
- wherein at least one of said at least one output path or at least one input path passes through a tube a light-absorptive layer for absorbing and/or trapping stray light being plated onto said tube, and
- wherein said at least one output path comprises a plurality of output paths, each of said output paths within said plurality communicating light scattered by said workpiece within an associated selected range of angles to an associated detector, each detector providing a signal indicating the amount of light scattered within said associated selected range of angles.
2 more elements
Apparatus comprising:
- at least one input path for receiving light from a light source and communicating said light to a workpiece;
- a light detector for receiving light and generating a signal in response thereto;
- at least one output path for receiving light reflected from said workpiece and communicating light to said detector;
- wherein at least one of said at least one output path or at least one input path passes through a tube a light-absorptive layer for absorbing and/or trapping stray light being plated onto said tube, and
- wherein light communicated in said at least one output path is specularly reflected by said workpiece, and said detector provides a signal indicative of the angle of specular reflection of said light.
2 more elements
Method comprising:
- communicating light through at least one input path to a workpiece;
- communicating light reflected by said workpiece through at least one output path to a detector;
- wherein at least one of said at least one output path or at least one input path passes through a tube a light-absorptive layer for absorbing and/or trapping stray light being plated onto said tube, and
- wherein the light communicated in said at least one output path is light scattered by said workpiece within a selected range of angles, said method further comprising generating a signal with said detector indicating the amount of light scattered within said range.
1 more element
Method comprising:
- communicating light through at least one input path to a workpiece;
- communicating light scattered by said workpiece through a plurality of output paths, each of said output paths within said plurality communicating light scattered by said workpiece at an associated range of angles to an associated detector which provides a signal indicative of the amount of light scattered within said selected range of angles,
- wherein at least one of said outputs paths or at least one input path passes through a tube a light-absorptive layer for absorbing and/or trapping stray light being plated onto said tube.
Method comprising:
- communicating light through at least one input path to a workpiece;
- communicating light reflected by said workpiece through at least one output path to a detector;
- wherein at least one of said at least one output path or at least one input path passes through a tube a light-absorptive layer for absorbing and/or trapping stray light being plate onto said tube,
- wherein light communicated in said at least one output path is specularly reflected by said workpiece, said method further comprising providing a signal with said detector indicating the angle of specular reflection of said light.
1 more element
Apparatus comprising:
- at least one input path for receiving light from a light source and communicating said light to a workpiece;
- a light detector for receiving light and generating a signal in response thereto;
- at least one output path for receiving light reflected from said workpiece and communicating light to said detector;
- a processor inspecting said workpiece for defects in response to said reflected light,
- wherein at least one of said at least one output path or at least one input path passes through a tube, said tube comprising a light-absorptive layer for absorbing and/or trapping stray light, said light-absorptive layer comprising dentritic material.
2 more elements
Dependencies are inferred from the claim text.