Specular Shape Acquisition Optics for Glossy Cylindrical Surfaces
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Solution Overview
Problem
Existing shape-data acquisition technologies struggle to efficiently and accurately measure the shape of glossy or transparent work surfaces with large surface irregularities, particularly when the workpiece has a columnar or cylindrical shape, due to noise generation and limited sensitivity to surface inclination.
Innovation Solution
A shape-data acquisition apparatus employing an obliquely incident specular optical system with a pattern illuminator and a multi-slit transmissive optical element, where the cyclic directions of the illuminator and transmissive optical element are parallel, allowing for high sensitivity and resolution in measuring surface shape by generating a cyclic pattern of light and shade.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional optical inspection methods are used to measure glossy or transparent work surfaces, then the measurement process can be simplified, but noise is generated and sensitivity to surface inclination is limited
Solution Approach 1:
The patent segments the optical measurement process into two distinct functional components: a pattern illuminator that projects cyclic luminance patterns onto the work surface, and a transmissive optical element (multi-slit) that selectively transmits specular reflected light. This segmentation allows each component to be optimized independently - the illuminator for pattern projection and the transmissive element for noise filtering - thereby improving surface inclination sensitivity while reducing noise from glossy surfaces
Solution Approach 2:
The patent introduces a transmissive optical element (multi-slit) as an intermediary component between the work surface and the imager. This intermediary selectively transmits only the specular reflected light that carries surface inclination information while blocking scattered light and noise from glossy or transparent surfaces. The multi-slit acts as a spatial filter that mediates between the complex reflected light field and the detection system, improving measurement precision
2Measurement precision
If the cyclic direction of the illuminator and transmissive optical element are not aligned, then the system configuration is simpler, but measurement resolution is reduced
Solution Approach 1:
The patent uses cyclic luminance patterns (alternating light and dark stripes) projected by the pattern illuminator, which interact with the cyclic transmittance pattern of the multi-slit to produce measurable intensity variations. This periodic pattern approach transforms surface inclination information into detectable optical intensity changes, enhancing spatial resolution through the interference and modulation of cyclic patterns
Solution Approach 2:
The patent establishes a specific mathematical relationship between the cyclic parameters of the illuminator and transmissive optical element: the cyclic direction of the first cycle of the illuminator and the cyclic direction of the second cycle of the transmissive optical element folded at a mirror image position on the work surface are parallel to each other. This parameter alignment optimizes the modulation of reflected light intensity, maximizing spatial resolution
3Measurement precision
If oblique incident angle is used to measure work surfaces, then sensitivity to surface inclination is improved, but the measurable area is reduced
Solution Approach 1:
The patent creates a multi-functional optical system where the same oblique illumination and specular reflection geometry serves multiple purposes: it provides high sensitivity to surface inclination, generates distinct cyclic patterns for shape measurement, and enables differentiation between specular and scattered light. This universal optical configuration achieves multiple measurement objectives simultaneously without requiring separate systems
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 achieves high-speed, high-sensitivity, and high-resolution shape data acquisition of glossy or transparent work surfaces with large irregularities, reducing noise and enabling accurate measurement of surface inclination and height with enhanced spatial resolution.
Implementation Method 1
The transmissive optical element faces specular reflected light of the illumination light reflected by the work surface
Implementation Method 2
The transmissive optical element faces specular reflected light of the illumination light reflected by the work surface and has a transmittance distribution of a second cycle in a cyclic direction
Data Source
AI summary
A shape-data acquisition apparatus obtains shape data of a work surface and includes an illuminator, a transmissive optical element, and an imager. The illuminator has a luminance distribution of a first cycle to irradiate the work surface. The transmissive optical element faces specular reflected light reflected by the work surface and has a transmittance distribution of a second cycle. The imager receives the specular reflected light to capture the work surface. The cyclic directions of the first cycle and the second cycle folded at a mirror image position on the work surface are parallel to each other. A relation of b=a×f2/f1 is satisfied when a is a distance between the illuminator and the work surface, b is a distance between the work surface and the transmissive optical element, f1 is the first cycle, and f2 is the second cycle.