Triangulation Profile Measurement Error Reduction
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Solution Overview
Problem
The line mode of displacement measuring apparatuses experiences measurement errors due to errors in pixel periods and surface conditions of measurement objects, leading to inaccurate results.
Innovation Solution
A displacement measuring apparatus that includes a light source, a converting optical system, a light guiding optical system, a light receiving section, and a driving section, where the light guiding optical system is minutely displaced to acquire multiple sub-profiles, which are then statistically processed to reduce measurement errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the line mode is used for measurement, then the irradiation angle of measurement light is constant and fewer error factors exist, but measurement errors still occur due to pixel period errors and surface conditions
Solution Approach 1:
The patent divides a single measurement into multiple sub-profiles by minutely displacing the light guiding optical system. Each sub-profile is measured at a slightly different position, and then all sub-profiles are statistically processed to obtain the final profile. This segmentation approach reduces the impact of pixel period errors and surface condition variations on the final measurement accuracy.
Solution Approach 2:
The patent performs measurements beyond the single required profile by acquiring multiple sub-profiles through minute displacements. This excessive action (measuring more than once) allows statistical processing to eliminate random errors and improve measurement precision, even though it requires additional measurement cycles.
2Measurement precision
If multiple sub-profiles are acquired by minutely displacing the light guiding optical system, then measurement errors are reduced through statistical processing, but the measurement time increases
Solution Approach 1:
The patent performs multiple measurements (excessive action) by acquiring several sub-profiles and then statistically processing them to reduce errors. While this increases measurement time compared to a single measurement, the trade-off is acceptable to achieve higher precision and eliminate pixel period errors.
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
This approach reduces measurement errors in the line mode by statistically processing multiple sub-profiles, improving the accuracy of the three-dimensional shape measurement of the measurement object.
Implementation Method 1
a light source which outputs light
Implementation Method 2
by reflecting the planar measurement light on the surface of the measurement object
Implementation Method 3
a light receiving section which receives reflected light from the measurement object
Data Source
AI summary
A displacement measuring apparatus acquires, based on a principle of triangulation and corresponding to an incident position of the reflected light in the light receiving section, a profile that is an aggregate of heights of reflection positions of the planar measurement light in the measurement object. The displacement measuring apparatus drives the light guiding optical system such that a plurality of reflection positions arranged in a line along a first direction on a surface of the measurement object are minutely displaced in a second direction different from the first direction by reflecting the planar measurement light on the surface of the measurement object. The displacement measuring apparatus acquires one profile by statistically processing a plurality of sub-profiles acquired by minutely displacing the light guiding optical system.