Line-scanning 3D Sensing System Using Dispersion Optical Module
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Solution Overview
Problem
Conventional line-scanning 3D sensing systems face challenges such as the shadow problem, limited resolution due to pinhole sizes, critical alignment requirements, and noise from diffractive elements, making it difficult to accurately measure deep holes, troughs, and surfaces with complex geometries.
Innovation Solution
A line-scanning 3D sensing system that chromatically disperses a polychromatic light beam into constituent narrowband linear light beams, which are focused on different heights to form a rainbow light pattern. This system uses a Dispersion Optical Module (DOM) with a first group of lenses for chromatic dispersion and focusing, and a second group of lenses for optically condensing the captured image-bearing color information into an elongated light pattern, which is then filtered to obtain a height profile of the scanned surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pinhole arrays or digital micro-mirrors device panels are used to measure deep holes and troughs, then measurement capability is improved, but alignment precision requirements increase and resolution is limited by pinhole sizes
Solution Approach 1:
The patent removes the pinhole array or digital micro-mirrors device panel from the optical system and replaces it with a tilted axis line-scanning configuration. This extraction eliminates the alignment precision problems associated with pinhole arrays while maintaining the ability to measure deep holes and troughs through the tilted illumination approach.
2Measurement precision
If cylindrical lenses are used for chromatic dispersion, then surface profile measurement is enabled, but rotation tolerance becomes critical and alignment requirements become stringent
Solution Approach 1:
The patent removes cylindrical lenses from the system and replaces them with a tilted axis line-scanning configuration using standard optical components. This eliminates the rotation tolerance and alignment precision problems associated with cylindrical lenses while maintaining surface profile measurement capability.
3Measurement precision
If diffractive elements are used for light modulation, then surface inspection is enabled, but zero-order and higher-order diffraction noise is introduced
Solution Approach 1:
The patent removes diffractive elements from the optical system and replaces them with a tilted axis line-scanning configuration. This extraction eliminates the zero-order and higher-order diffraction noise while maintaining surface inspection capability through the tilted illumination and line-scanning approach.
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 effectively measures surface profiles, including deep holes and troughs, with improved alignment ease and reduced noise, enabling accurate inspection of complex surfaces such as electronic components and automotive parts.
Implementation Method 1
The DOM is configured to perform a forward optical process of chromatically dispersing the PLLB received from the first slit into CNLLBs and focusing the CNLLBs respectively on different focal planes
Implementation Method 2
The backward optical process is an inverse of the forward optical process. The second slit is used for spatially filtering the elongated light pattern to form an output light line
Data Source
AI summary
A line-scanning three-dimensional sensing system measures a surface profile of an object. In the system, a dispersion optical module (DOM) performs a forward optical process of chromatically dispersing a polychromatic linear light beam into constituent narrowband linear light beams (CNLLBs) and focusing the CNLLBs on different focal planes to form a rainbow light pattern for illuminating a scanned surface of the object. The illuminated object displays an information-bearing color image (IBCI) containing height information of the scanned surface. The DOM captures the IBCI, and performs a backward optical process of optically condensing the captured IBCI to form an elongated light pattern. The backward optical process is an inverse of the forward one. A slit spatially filters the elongated light pattern to form an output light line. A height profile of the scanned surface is obtained by analyzing a spectral content at each point of the output light line.