3D Shape Measuring Apparatus Using Diffraction Grating
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional three-dimensional shape measuring apparatuses face challenges in accurately measuring the depth and shape of narrow and deep via holes, particularly in semiconductor packaging, due to issues with light convergence, image distortion, and difficulty in focusing inclined surfaces using single-camera systems.
Innovation Solution
A three-dimensional shape measuring apparatus utilizing a diffraction grating that splits light into different paths, allowing multiple image sensors to capture images with varying parallax information through a single lens, enabling accurate measurement of inclined surfaces and reducing measurement errors by using diffraction gratings on light paths between the light source, splitter, and image sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single camera is used for measurement, then the device complexity is reduced, but the measurement precision deteriorates due to difficulty in measuring inclined surfaces and holes
Solution Approach 1:
The patent divides the measurement function into multiple cameras positioned at different angles. Each camera captures images from its specific viewpoint, and the measurement system segments the analysis by processing images from each camera separately to extract depth and shape information from inclined surfaces and holes that would be invisible or distorted in a single viewpoint.
Solution Approach 2:
The patent transitions from a single 2D image capture to multi-dimensional observation by positioning multiple cameras at different spatial angles. This creates a three-dimensional measurement capability where each camera provides a different perspective, allowing the system to reconstruct the complete geometry of inclined surfaces and holes by combining data from multiple dimensional viewpoints.
2Measurement precision
If multiple cameras are used to observe side surfaces of holes, then the measurement precision improves, but the device complexity increases due to focusing and distortion issues
Solution Approach 1:
The patent designs each camera to serve multiple functions: capturing images of inclined surfaces, observing hole side walls, and providing depth information. The same camera system that measures external inclined surfaces also captures internal hole geometry, eliminating the need for separate specialized sensors for different measurement tasks and reducing overall system complexity.
Solution Approach 2:
The patent introduces a beam splitter as an intermediary optical element that directs light from the measurement target to multiple cameras simultaneously. This intermediary component enables a single illumination source and target area to be observed from multiple angles without requiring separate lighting systems or complex mechanical positioning, thereby reducing device complexity while maintaining multi-camera measurement precision.
3Measurement precision
If a confocal scheme is used to measure hole depth, then the measurement precision improves, but the device complexity increases and light convergence is blocked in narrow holes
Solution Approach 1:
The patent replaces the mechanical confocal focusing system with a computational imaging approach. Instead of using a single point-focused optical system that requires precise mechanical alignment and suffers from light blockage, the system uses multiple cameras capturing images from different angles, and the depth information is extracted through image processing and geometric reconstruction algorithms, eliminating the need for complex confocal optical mechanics.
4Measurement precision
If cameras are positioned to view inclined surfaces, then the measurement precision improves, but image distortion increases due to inclined image formation surfaces
Solution Approach 1:
The patent implements a feedback mechanism where the system captures images from multiple cameras at different angles, detects distortions in each image, and uses this information to iteratively refine the three-dimensional reconstruction. The measurement algorithm receives feedback from the distorted images and compensates for the distortion mathematically, allowing the system to maintain high measurement precision on inclined surfaces while accounting for the inevitable image distortion.
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 apparatus effectively measures and inspects blind spots, reduces measurement errors, and enhances inspection speed, suitable for very thin and deep via holes with high aspect ratios, achieving precise multi-view imaging without distortion.
Implementation Method 1
a diffraction grating disposed on at least one light path among a light path between the light source unit and the light splitter, a light path between the measurement target and the light splitter, and a light path between the measurement target and the image sensor unit
Implementation Method 2
a light splitter installed in a traveling direction of a light generated from a light source unit and configured to reflect a portion of the light along a first path and transmit a portion of the light along a second path
Data Source
AI summary
Disclosed is a three-dimensional shape measuring apparatus using a diffraction grating, comprising: a light splitter installed in a traveling direction of a light generated from a light source unit and configured to reflect a portion of the light along a first path and transmit a portion of the light along a second path; an image sensor unit configured to receive a light traveling along the first path and reflected from a measurement target having at least one hole, and measure the shape of the measurement target; and a diffraction grating disposed on at least one light path among a light path between the light source unit and the light splitter, a light path between the measurement target and the light splitter, and a light path between the measurement target and the image sensor unit.