Scanning Hologram Camera for Automatic Optical Inspection
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Solution Overview
Problem
Existing automatic optical inspection systems require precise mechanical calibration and alignment to achieve high-resolution imaging, which is challenging due to limitations in depth of focus and mechanical control, especially when objects are rotated or defocused on a conveyor belt.
Innovation Solution
A scanning hologram camera system that captures a single-shot hologram of an object, allowing for the extraction of depth position and rotation angle without mechanical realignment, using monitoring-light and numerical processing to generate a rotated coordinate system for image restoration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If mechanical alignment and focus adjustment are used to obtain high-resolution images, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The patent replaces the mechanical alignment and focus adjustment system with a computational approach. Instead of using mechanical devices to physically align the objective plate and adjust focus, the system captures holographic data and uses numerical processing to computationally determine depth position and rotation angle, thereby eliminating complex mechanical control systems while maintaining high-resolution imaging capability
Solution Approach 2:
The patent changes the approach from mechanical parameter adjustment (physical alignment and focus position) to computational parameter extraction (depth position and rotation angle from holographic interference patterns). By capturing the full wavefront information through holography and numerically processing the interference patterns, the system extracts positional and orientational parameters without mechanical intervention
2Measurement precision
If mechanical realignment is performed to correct defocus and rotation, then measurement precision is improved, but productivity decreases
Solution Approach 1:
The patent replaces mechanical realignment operations with computational processing. The system captures holographic data containing depth and rotation information, then uses numerical algorithms to extract precise measurement data without any mechanical movement or realignment, thereby maintaining high measurement precision while achieving ultrahigh-speed inspection
Solution Approach 2:
The patent performs preliminary capture of all necessary information (depth position and rotation angle) in a single holographic exposure. By encoding the complete spatial and orientational information in the holographic interference pattern, the system eliminates the need for subsequent mechanical realignment steps, enabling both high precision and high productivity
3Manufacturing precision
If the depth of focus is reduced to several micrometers for high resolution, then manufacturing precision is improved, but ease of operation worsens
Solution Approach 1:
The patent replaces mechanical alignment operations with computational analysis. Instead of requiring operators to precisely align the objective plate within the narrow depth of focus, the system captures holographic data and uses numerical processing to determine the actual depth position and rotation angle, thereby maintaining high resolution while dramatically simplifying operation
Solution Approach 2:
The system performs self-alignment through computational processing. The holographic interference patterns inherently contain information about the objective plate's position and orientation, and the numerical processing automatically extracts this information without requiring manual alignment or operator intervention, making the system easy to operate despite the narrow depth of focus
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
Enables high-precision automatic optical inspection regardless of rotation and defocus, eliminating the need for precise mechanical calibration and enabling ultrahigh-speed inspection by obtaining focused images at inclined positions.
Implementation Method 1
taking a single-shot hologram of an imaging object using a scanning hologram camera
Implementation Method 2
using monitoring-light and numerical processing
Data Source
AI summary
Disclosed are a method and apparatus of automatic optical inspection using scanning holography. The apparatus for automatic optical inspection using scanning holography includes: a hologram capturer that takes a hologram of an object existing on an objective plate using a scanning hologram camera; a depth position/rotation angle extractor that extracts a depth position and a rotation angle about an objective surface of the objective plate on the basis of the hologram or the detected monitoring-light; a rotated coordinate system generator that generates a rotated coordinate system corresponding to the objective surface using the depth position and the rotation angle; and a hologram restorer that obtains an image of the object by restoring the hologram in a plane formed in a depth direction of the rotated coordinate system.