Chromatic Confocal 3D Surface Capture Device
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Solution Overview
Problem
Existing three-dimensional surface structure recording devices using chromatic-confocal optics are bulky and costly due to the requirement of complex combinations of prisms, gratings, and image converters with imaging optics as spectrometers.
Innovation Solution
A device that records differently colored spectral components in a chronological sequence instead of simultaneously, using a dispersive element and broadband light sources to generate a temporal sequence of illumination, allowing the time axis to replace the dispersion direction for determining the confocal condition, thereby simplifying the setup and reducing equipment complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a complex combination of prism or grating and image converter with imaging optics is used as a spectrometer, then spectral components can be detected simultaneously, but the device becomes bulky and costly
Solution Approach 1:
The patent applies periodic action by using a rotating diffraction grating to sequentially direct different spectral components to a single photodetector. The grating rotates at a controlled speed, allowing each wavelength component to be detected in turn, replacing the need for complex simultaneous detection systems while maintaining spectral analysis capability
Solution Approach 2:
The patent uses a camera to capture the grid of measurement points and creates a digital representation of the surface topology. This optical copy allows the three-dimensional information to be extracted from the image data without requiring physical scanning or complex spectral imaging equipment
2Measurement precision
If chromatic-confocal optics with high resolution are used, then measurement precision is improved, but the device size increases
Solution Approach 1:
The patent extracts only the essential spectral information needed for depth measurement by using a rotating grating to sequentially direct wavelengths to a single photodetector. This removes the need for large, complex spectral imaging systems while retaining the chromatic-confocal measurement capability
Solution Approach 2:
The camera serves multiple functions: it captures the grid pattern for topography determination, provides depth information through chromatic confocality, and enables three-dimensional reconstruction. This multi-functionality reduces the need for separate specialized components
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 enables a more compact, cost-effective three-dimensional surface structure recording by determining the distance to the surface structure based on the temporal sequence of illumination, achieving sufficient resolution without the need for complex dispersive elements, and allowing for a larger depth measurement range with hyperchromatic optics.
Implementation Method 1
the chromatic-confocal measurement arrangement is based on the knowledge that the refractive power of a lens is generally dependent on the wavelength of the light passing through. As a result, depending on the wavelength, a lens has spatially different focus areas and thus also image areas. In optical systems, this effect is known as chromatic aberration
Implementation Method 2
the light source has a grid of individual light sources spaced laterally to the optical axis, the optics imaging the individual light sources onto the surface structure in such a way that there is a grid generated from measurement points which are laterally spaced apart from one another
Data Source
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AI summary
The invention relates to a device (10) for the three-dimensional capturing of a surface structure (11; 11'; 11'') in particular for capturing teeth (13) having a chromatic confocal optical system (40, 42, 44), which comprises an optical axis (41), and having a light source (16), which has a grid of individual light sources (34) laterally spaced apart from the optical axis. The optical system displays the individual light sources (34) on the surface structure (11; 11'; 11'') such that a grid of measuring points (49) is generated there, which are laterally spaced apart from one another. An image-capturing unit (50) is arranged optically equivalent to the individual light sources (34) in order the capture the grid of measuring points (49). Furthermore, a control and evaluation device (70) is configured to control the light source (16) such that the individual light sources (34) emit light of a different spectral composition in chronological order, and, by means of the image-capturing unit (50), to capture the grid of measuring points (49) in correlation with the chronological order of the light emitted by the individual light sources (34).