Double Telecentric Optical System for 3D Tooth Imaging
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Solution Overview
Problem
Current 3-D imaging technologies for intra-oral surfaces, such as teeth, face challenges due to tooth translucency, light scattering, and high reflection levels, making it difficult to obtain accurate surface contour images without additional coatings or complex illumination setups, which increases costs and complexity.
Innovation Solution
A double telecentric optical system with a focus adjustment mechanism and image detector array that adjusts along an optical axis to capture 3-D surface contour data by calculating depth values from pixel contrast, allowing for accurate imaging without surface conditioning or complex illumination arrangements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If fringe projection imaging is used to obtain surface contour information, then surface contour imaging capability is improved, but the system becomes complex and costly due to the need for patterned light projection and phase shifting components
Solution Approach 1:
The patent extracts the essential function of obtaining surface contour information by using a simple camera to capture images at different focus positions, eliminating the need for complex fringe projection and phase shifting components. The depth information is derived from focus variations rather than projected patterns.
Solution Approach 2:
The patent replaces the mechanical complex illumination system (fringe projection, phase shifting) with a simpler optical approach using a camera and focus adjustment mechanism. The surface contour information is obtained through image processing of focus variations rather than through complex light modulation.
2Measurement precision
If confocal imaging methods are used to illuminate discrete spots on the tooth surface, then depth measurement capability is improved, but the system requires complex arrangement of illumination and sensing components
Solution Approach 1:
The patent uses a single camera to perform multiple functions: capturing surface contour information, obtaining depth data, and imaging the tooth surface. This eliminates the need for separate illumination and sensing components required in confocal methods.
Solution Approach 2:
The camera system captures images that inherently contain depth information through focus variations. The system uses the tooth surface itself as the object of interest, capturing its natural reflectivity and contour features without requiring external illumination patterns or complex optical arrangements.
3Measurement precision
If additional coatings are applied to tooth surfaces to enhance opacity, then imaging accuracy is improved, but the process time and cost increase
Solution Approach 1:
The patent captures the tooth surface as it naturally is, using the tooth's inherent optical properties (translucency, reflection) to obtain imaging information. The system processes the natural surface characteristics to extract contour and depth data without requiring external coatings or conditioning.
Solution Approach 2:
The patent converts the tooth's natural translucency and reflection properties, which were previously considered obstacles to imaging, into useful features for obtaining surface contour and depth information. The focus variation technique leverages these optical characteristics to derive accurate measurements.
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 accurate and cost-effective 3-D surface contour imaging of teeth by maintaining constant magnification and perspective, allowing for precise depth detection and surface reconstruction, reducing the need for additional coatings and simplifying the imaging process.
Implementation Method 1
obtain 3-D surface contour image data... by calculating depth values from pixel contrast... capturing light reflected back from the tooth surface
Data Source
AI summary
An apparatus for obtaining 3-D surface contour image data of a tooth has a double telecentric optical system disposed to form an image of the surface of the tooth onto an image detector array. A focus adjustment mechanism is actuable to adjust the position of either or both the double telecentric optical system and the image detector array along an optical axis to each of a sequence of focus positions. A control logic processor is in control signal communication with the focus adjustment mechanism to adjust focus position, and is in image data communication with the image detector array for receiving image data obtained by the image detector array and with a memory for storing the received image data corresponding to each of the sequence of focus positions. The control logic processor is further responsive to stored instructions for computing 3-D surface contour image data from the image data.