Surface Shape Measuring System with Coaxial and Falling Illumination
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Solution Overview
Problem
Conventional surface shape measuring systems require separate apparatuses for two-dimensional and three-dimensional measurements, leading to inefficiencies and low inspection speed due to the need for scanning the entire object for three-dimensional data acquisition.
Innovation Solution
A surface shape measuring system using white-light scanning interferometry that integrates coaxial and falling illumination to obtain two-dimensional data and selectively performs three-dimensional inspections only on abstracted regions, utilizing a single apparatus with a main light source and subsidiary light source to optimize data acquisition and inspection speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single apparatus is used for both two-dimensional and three-dimensional measurements, then device complexity is reduced, but measurement precision may be compromised
Solution Approach 1:
The patent divides the measurement process into two distinct modes: a first mode for obtaining two-dimensional data (visual inspection) and a second mode for obtaining three-dimensional data (interferometric measurement). By segmenting the measurement functions and executing them sequentially rather than simultaneously, the system maintains the precision requirements of each measurement type while integrating them into a single apparatus, thus resolving the contradiction between device simplicity and measurement accuracy.
2Measurement precision
If three-dimensional inspection is performed on the overall dimensions of the target object, then complete shape data is obtained, but inspection speed decreases
Solution Approach 1:
The patent applies preliminary action by first obtaining two-dimensional data of the entire target object before performing three-dimensional inspection. This preliminary two-dimensional assessment allows the system to identify and focus subsequent three-dimensional measurements only on specific regions of interest, rather than scanning the entire object. This sequential approach ensures complete shape data is obtained where needed while significantly improving inspection speed by avoiding unnecessary full-object three-dimensional scanning.
3Measurement precision
If separate apparatuses are used for two-dimensional and three-dimensional measurements, then measurement precision is maintained, but ease of operation deteriorates
Solution Approach 1:
The patent merges the previously separate two-dimensional measurement apparatus and three-dimensional measurement apparatus into a single integrated system. The apparatus includes a light source, beam splitter, reference mirror, and detector that can operate in multiple modes - visual inspection mode for two-dimensional data and interferometric mode for three-dimensional data. This consolidation eliminates the need to switch between separate devices, significantly improving ease of operation while maintaining the measurement precision of both techniques through dedicated optical paths and processing modes.
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 simultaneous two-dimensional data collection and targeted three-dimensional inspections, simplifying the apparatus and significantly improving inspection speed by abstracting specific regions for detailed measurement.
Implementation Method 1
a beam splitter (2) which divides light from the main light source (11) into a reference beam and an object beam
Implementation Method 2
a reference mirror (4) which reflects the reference beam
Implementation Method 3
an objective lens (32) which focuses light onto a measurement surface (P) of a target object (3) to be measured and collects light reflected from the measurement surface (P)
Implementation Method 4
white-light scanning interferometry (WSI) has been proposed... generate an interference signal, a light detecting element (500) captures the interference signal
Implementation Method 5
moving the object at minute intervals in the optical axial direction with a transfer unit, such as a PZT actuator
Implementation Method 6
a light detecting element (500) captures the interference signal and then analyzes the signal
Data Source
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AI summary
The surface shape measuring system includes an illumination unit including a main light source, a focusing lens, and a projection lens; a beam splitter to split illumination light emitted respectively irradiated onto a reference surface and a measurement surface; a light detecting element to capture an interference pattern; and a control computer to obtain surface shape data through white-light interference pattern analysis from an image captured and detect whether or not the measurement surface is defective from the obtained data, wherein a subsidiary light source to provide falling illumination to the target object; and two-dimensional data and three-dimensional data regarding the surface shape of the target object are obtained by selectively intermitting the turning-on of the main light source and the subsidiary light source and the irradiation of the illumination light onto the reference surface.