Form Measuring Apparatus Brightness Data Selection
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Solution Overview
Problem
Inadequate brightness variation data can contaminate measurements with higher contrast values, leading to measurement errors in phase distribution computation.
Innovation Solution
A form measuring apparatus and method that adjust shutter speed and capture multiple images with varying brightness conditions to select adequate brightness value sets within a predetermined effective range, ensuring accurate phase computation and reducing measurement errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple brightness variation data sets with different exposure light amounts are used to improve measurement reliability, then the likelihood of including inadequate brightness data increases, leading to measurement errors
Solution Approach 1:
The patent changes the exposure light amount parameter to capture multiple brightness variation data sets with different exposure levels. By varying this parameter, the system ensures that at least one data set falls within the effective brightness range, resolving the contradiction between reliability (having multiple data sets) and precision (avoiding inadequate data).
Solution Approach 2:
The patent performs preliminary evaluation of contrast values and brightness ranges before computing phase distribution. By预先 assessing the quality of brightness variation data sets, the system identifies and selects only those data sets that meet the effective brightness range criteria, preventing inadequate data from contaminating the measurement results.
2Measurement precision
If brightness variation data with higher contrast values are selected to improve signal quality, then inadequate brightness data may be included, causing saturated pixels and measurement errors
Solution Approach 1:
The patent implements a feedback mechanism where contrast values are evaluated and used to determine whether brightness variation data sets are adequate. The system adjusts its selection criteria based on this feedback, ensuring that only data sets with both high contrast and appropriate brightness levels (within effective range) are used for phase computation.
Solution Approach 2:
The patent evaluates brightness values as a secondary parameter after contrast evaluation. By checking whether brightness values fall within the effective brightness range, the system ensures that high-contrast data does not contain saturated pixels, thus maintaining both signal quality and data reliability.
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 approach reliably suppresses the influence of inadequate brightness data, enhancing measurement accuracy by selecting brightness value sets with better signal-to-noise ratios and maintaining linear input-output characteristics within the effective brightness range.
Implementation Method 1
an imaging element 26 which takes an image of the measuring object 11
Implementation Method 2
projects a fringe pattern having a sinusoidal intensity distribution onto a measuring object
Data Source
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AI summary
A form measuring apparatus is provided for the purpose of reliably suppressing the influence of inadequate data on a measurement result. The form measuring apparatus includes: a projection section configured to project patterns having a common repetitive structure and differing in phase onto a measuring object in sequence, an imaging section configured to acquire a plurality of image data sets by taking an image of the measuring object with a different exposure light amount every time each of the patterns is projected onto the measuring object, a selection section configured to select a data set as an adequate data set in which all data fall within an effective brightness range over which the imaging section has linear input and output characteristics from the plurality of image data sets in each area on the measuring object, and a form calculation section configured to find a form of the each area based on the selected adequate data set.