Optical Image Measurement Device Spatial Coherence Control
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Solution Overview
Problem
Conventional optical image measurement devices do not effectively improve measurement sensitivity by considering spatial coherence of light, which limits their resolving power in the horizontal direction.
Innovation Solution
An optical image measurement device that outputs light with low temporal and spatial coherence, splits it into signal and reference lights, and projects the interference light onto a 2-dimensional light receiving face with light receiving elements, ensuring the spatial coherent region is equal to or larger than the light receiving element size, enhancing measurement sensitivity without narrowing the measurement range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the size of the spatial coherent region is made larger to improve measurement sensitivity, then the resolving power in the horizontal direction is improved, but the measurement range may be narrowed
Solution Approach 1:
The patent applies local quality by making the spatial coherent region size match the light receiving element size at specific projection positions. The optical system is configured to project the interference light such that the spatial coherent region corresponds to each light receiving element's active area, optimizing measurement sensitivity locally without compromising overall measurement range. This is achieved through careful design of the optical system's projection characteristics across the light receiving face.
2Measurement precision
If coherent light with high spatial coherence is used to improve resolving power in the depth direction, then speckle noise increases and limits resolving power in the horizontal direction
Solution Approach 1:
The patent changes the coherence parameters of the light source, specifically using light with low temporal coherence and controlled spatial coherence. By selecting a light source with low temporal coherence (broad bandwidth) and configuring the optical system to achieve appropriate spatial coherence at the light receiving elements, the patent resolves the contradiction between depth resolving power and speckle noise suppression in the horizontal direction.
3Area of stationary object
If conventional optical systems project interference light without considering spatial coherence, then measurement range is maintained, but measurement sensitivity is insufficient
Solution Approach 1:
The patent applies preliminary action by pre-configuring the optical system to project the interference light with the appropriate spatial coherent region size before detection. The system is designed in advance to ensure that the spatial coherent region matches the light receiving element size at the projection position, so that when measurement is performed, the optimal sensitivity is achieved without requiring real-time adjustment, while maintaining the full measurement range.
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 configuration improves measurement sensitivity by efficiently detecting interference signals, maintaining resolving power, and preventing unnecessary light projection, which leads to higher signal-to-noise ratios and effective imaging without reducing the measurement range.
Implementation Method 1
it superimposes the signal light having passed through the measured object and the reference light having passed through the reference object to generate and detect an interference light
Implementation Method 2
a light receiver configured to receive the interference light and output an electric signal
Data Source
AI summary
An optical image measurement device comprises: a light source configured to output a light having low temporal coherence and low spatial coherence; an optical system configured to split the light into a signal light and a reference light and superimpose the signal light having passed through a measured object and the reference light, thereby generating an interference light; a light receiver configured to receive the interference light and output an electric signal; and a forming part configured to form an image of the measured object based on the electric signal, wherein: the light receiver has a light receiving face on which a plurality of light receiving elements are arranged 2-dimensionally; and the optical system projects the interference light onto the light receiving face so that a size of the spatial coherent region of the interference light becomes equal to or larger than a size of the light receiving element.