1D MEMS Scanner Structured Light for Intraoral 3D Imaging
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Solution Overview
Problem
Conventional structured light imaging techniques face challenges in accurately characterizing tooth surfaces due to tooth translucency, high reflection, and complex light interactions, leading to reduced signal-to-noise ratios and inaccurate height data, particularly in intraoral applications where compact and lightweight solutions are needed.
Innovation Solution
A compact intraoral imaging apparatus using a laser diode, collimator, beam-shaping optics, and a MEMS scanner to generate and scan a linear light pattern, allowing for high-speed surface contour characterization without the need for coatings or powders, with a control logic processor coordinating the light projection and image capture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional structured light imaging techniques are used for tooth surface imaging, then surface contour information can be obtained, but the signal-to-noise ratio is reduced and measurement accuracy deteriorates due to tooth translucency and subsurface scattering
Solution Approach 1:
The patent segments the structured light pattern into multiple discrete lines that can be independently controlled and scanned across the tooth surface. This segmentation allows for targeted illumination of specific surface areas while minimizing subsurface scattering effects, thereby improving signal-to-noise ratio and measurement accuracy simultaneously
Solution Approach 2:
The patent employs a dynamic scanning approach where the structured light pattern is rapidly swept across the tooth surface using a scanning mechanism. This dynamic illumination reduces the impact of tooth translucency by minimizing the time for light to penetrate and scatter within the tooth material, thereby maintaining high signal-to-noise ratio while achieving accurate surface contour measurements
2Measurement precision
If conventional structured light imaging is used for tooth imaging, then surface information can be captured, but the dynamic range is reduced due to high levels of reflection from tooth surfaces
Solution Approach 1:
The patent applies local quality control by adjusting the intensity and distribution of light in different regions of the structured light pattern. By locally adapting the illumination characteristics to match the reflective properties of different tooth surface areas, the system maintains adequate dynamic range while capturing accurate surface information from both highly reflective and less reflective regions
3Ease of manufacture
If a 2-D array of micromirrors or LCD matrix is used for pattern projection, then structured light patterns can be formed, but the device size and weight increase, making it unsuitable for intraoral applications
Solution Approach 1:
The patent extracts the essential pattern projection function from complex 2-D micromirror or LCD matrix systems and implements it using a simplified 1-D micromirror array combined with a scanning mechanism. This extraction maintains the capability to form structured light patterns while dramatically reducing the weight and size of the projection apparatus, making it suitable for intraoral applications
Solution Approach 2:
The patent replaces the static mechanical 2-D micromirror or LCD matrix system with a dynamic 1-D micromirror array system driven by a scanning mechanism. This substitution reduces the mechanical complexity and weight of the projection apparatus while maintaining pattern projection capability through the combination of 1-D mirror array and temporal scanning
4Measurement precision
If coatings or surface conditioning are applied to tooth surfaces for imaging, then imaging results can be improved, but the device complexity and procedure time increase due to angular and space limitations
Solution Approach 1:
The patent employs a self-service approach where the imaging system is designed to work effectively with the natural tooth surface properties without requiring external coatings or conditioning agents. By optimizing the structured light pattern design and scanning methodology, the system achieves high measurement precision while avoiding the complexity and procedure time associated with applying and removing surface coatings
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 apparatus provides high-resolution, 3-D imaging of teeth and dental features with improved scan speed and reduced size and weight, enabling accurate surface contour characterization and supporting video-capture at high frame rates without the use of special coatings.
Implementation Method 1
a laser diode energizable to emit a light beam
Implementation Method 2
a scanner that is disposed substantially at the focal plane and that is energizable to scan the formed linear light pattern
Data Source
AI summary
An apparatus for intraoral imaging has an intraoral camera that defines a field of view with a first dimension and a second dimension orthogonal to the first dimension. A projector has a laser diode energizable to emit a light beam; a collimator in the path of the emitted light beam; first beam-shaping optics disposed to shape the collimated light beam in the second dimension to form a linear light pattern; focusing optics disposed to focus the shaped collimated beam at a focal plane; and a scanner that is disposed substantially at the focal plane and that is energizable to scan the formed linear light pattern along the second dimension to successive positions of the field of view. A control logic processor coordinates energizing the laser diode and scanner with image capture by the intraoral camera.