Pulsed Light Optical Inspection for Sub-Micron Feature Detection
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Solution Overview
Problem
Current optical inspection methods are inefficient in capturing high-resolution micrographs of large area optics due to the need for repeated movement and long acquisition times, which prevents the detection of sub-micron features essential for high power laser systems, especially in industries like semiconductor manufacturing and at facilities like the National Ignition Facility.
Innovation Solution
An optical inspection system utilizing a controller, camera, high numerical aperture objective lens, and a pulsed light source to capture images during short light pulses while the sample is moving, allowing for continuous scanning and significantly reduced acquisition time without blurring, enabling sub-micron feature detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional optical microscopy with medium N.A. objective lenses is used to capture images of large area samples, then the inspection area can be covered, but the resolution is insufficient to detect sub-micron features
Solution Approach 1:
The patent segments the large area inspection into multiple smaller high-resolution fields of view by dividing the sample into regions that can be imaged sequentially with a high N.A. objective lens, allowing sub-micron feature detection across large areas through systematic scanning and image stitching
Solution Approach 2:
The patent introduces temporal dimension by using pulsed illumination synchronized with rapid sample scanning, enabling high-resolution imaging across large areas by capturing images at different time points during continuous sample movement rather than requiring the entire area to be in view simultaneously
2Measurement precision
If high N.A. objective lenses are used to detect sub-micron features, then the detection precision improves, but the time required to image the same area increases substantially
Solution Approach 1:
The patent uses periodic pulsed illumination synchronized with the scanning process, where light pulses are delivered at regular intervals during sample movement, allowing rapid sequential capture of high-resolution images across the entire sample area without requiring continuous illumination or repeated stopping
Solution Approach 2:
The patent maintains continuous sample scanning motion throughout the imaging process without stopping, while synchronizing pulsed illumination and camera capture to occur during movement, eliminating idle time between images and continuously advancing the inspection across the entire sample area
3Productivity
If the sample is moved during image capture to cover large areas, then the inspection efficiency improves, but image blur occurs due to motion
Solution Approach 1:
The patent employs periodic pulsed illumination with duration much shorter than the sample transit time across the field of view, so that each image is captured during a brief frozen moment of illumination, effectively freezing motion blur while maintaining continuous scanning for high productivity
Solution Approach 2:
The patent synchronizes the pulsed illumination and camera exposure to occur precisely when the sample is in the desired position within the field of view, anticipating and capturing the optimal imaging moment during continuous motion rather than attempting to stop the sample
4Measurement precision
If repeated stopping and starting of sample movement is performed to capture each micrograph, then image quality is maintained, but the total inspection time increases to an hour or more
Solution Approach 1:
The patent eliminates all stopping and starting by maintaining continuous sample scanning motion throughout the entire inspection process, with pulsed illumination and camera capture synchronized to occur during movement, removing all idle time between images and reducing total acquisition time from hours to minutes
Solution Approach 2:
The patent uses periodic pulsed illumination synchronized with continuous scanning to capture a sequence of images without interruption, where each pulse captures a portion of the sample during uninterrupted motion, eliminating the need to halt the scanning mechanism for image acquisition
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system achieves high-resolution imaging of large areas in a fraction of the time required by traditional methods, capturing sub-micron features with minimal image shift, thus enhancing the identification of damage precursors and reducing inspection costs and time, particularly beneficial for high power laser systems and semiconductor manufacturing.
Implementation Method 1
A pulsed light source is provided which generates light pulses
Implementation Method 2
The objective lens is used to image portions of the sample while at least a subplurality of the light pulses are being generated
Data Source
AI summary
An optical inspection system for detecting sub-micron features on a sample component. The system may have a controller, a camera responsive to the controller for capturing images, an objective lens able to capture submicron scale features on the sample component, and a pulsed light source. The pulsed light source may be used to generate light pulses. The camera may be controlled to acquire images, using the objective lens, only while the pulsed light source is providing light pulses illuminating a portion of the sample component. Relative movement between the sample component and the objective lens is provided to enable at least one of a desired subportion or an entirety of the sample component to be scanned with the camera.