Wavelength-Swept Optical Measurement for Surface Variation Correction
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Solution Overview
Problem
Existing optical measuring devices face inaccuracies in measuring distance due to variable factors on the measurement surface, such as differences in material, adhering substances, and surface structure, leading to errors in distance measurement.
Innovation Solution
An optical measuring device using a wavelength scanning interference method with a wavelength-swept light source, irradiation optical system, and information processing unit to correct spectrum information for variable factors, enabling accurate detection of steps and distances on the measurement surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If reflected light from the measurement surface is used directly for measurement, then the measurement process is simple, but measurement precision deteriorates due to variable factors on the measurement surface
Solution Approach 1:
The patent applies preliminary action by pre-acquiring reference spectrum information from a standard measurement surface and using it to correct measurements taken from surfaces with variable factors. The reference spectrum is obtained in advance and stored, then used during actual measurements to compensate for variations in surface properties, adhering substances, and material differences, thereby maintaining high measurement precision without complicating the measurement process.
2Measurement precision
If correction processing is applied to spectrum information, then measurement precision improves, but device complexity increases
Solution Approach 1:
The patent uses copying by creating a reference spectrum information copy from a standard measurement surface. This reference copy is stored and then used to correct actual measurement spectra through computational methods. The copying approach allows the system to maintain high measurement precision by comparing and correcting against the reference copy, while avoiding the need for complex real-time adaptive processing systems.
3Measurement precision
If wavelength scanning interference method is used, then measurement precision improves for low signal strength, but device complexity increases
Solution Approach 1:
The patent applies universality by implementing a wavelength scanning interference system that can measure both standard surfaces and surfaces with variable factors using the same optical hardware. The system uses a single wavelength-swept light source and interferometer that serves multiple measurement purposes, eliminating the need for separate optical systems for different measurement scenarios while maintaining high precision through the universal correction capability.
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 device can accurately measure distances and identify edge positions with higher resolution than spatial resolution determined by the measurement light spot diameter, correcting for errors caused by variable factors on the measurement surface.
Implementation Method 1
a wavelength-swept light source to output swept light whose wavelength continuously changes with time
Implementation Method 2
information regarding reflection and scattering from the object to be measured is extracted on the basis of interfering light in which the signal light reflected and scattered by the object to be measured and the reference light interfere with each other
Implementation Method 3
a measurement information acquirer to multiplex the reflected light for measurement from the irradiation optical system and the reference light from the reference light path, and output measurement information obtained by photoelectrically converting the multiplexed interfering light
Data Source
AI summary
An optical measuring device includes: a light source that outputs swept light an irradiation optical system that emits output light for measurement formed with the swept light in a space toward the measurement surface of a measurement target, receives reflected light reflected by the measurement surface of the measurement target, and outputs the reflected light a reference light path that outputs output light for reference formed with the swept light; a measurement information acquiring unit that multiplexes the reflected light for measurement and the reference light, and outputs measurement information obtained by photoelectrically converting the multiplexed interfering light; and an information processing unit that obtains spectrum information by performing Fourier transform on the measurement information corrects the obtained spectrum information using variable factor information, and obtain information about the distance to the measurement surface of the measurement target on the basis of the corrected spectrum information.