Handheld Intraoral Scanner With Spatial-Pattern Focus Analysis
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Solution Overview
Problem
Existing 3D scanning technologies are limited by large size, high cost, slow speed, and sub-optimal signal-to-noise ratio, and require controlled spatial relations between the scanner and object, making them unsuitable for handheld applications.
Innovation Solution
A handheld scanner using a camera with an array of sensor elements and a spatial or time-varying illumination pattern, varying the focus plane without moving the scanner relative to the object, and employing correlation measures to distinguish in-focus information for fast and precise 3D surface registration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If confocal microscopy is used to scan object surfaces, then measurement precision is improved, but the scanning speed decreases and device size increases
Solution Approach 1:
The patent divides the object surface into multiple regions and scans them in parallel using multiple light sources and detectors, rather than scanning point-by-point. This segmentation of the scanning process enables simultaneous measurement of multiple surface points, dramatically increasing scanning speed while maintaining precision through coordinated data processing of the segmented measurements.
Solution Approach 2:
The patent transitions from traditional 2D surface scanning to 3D volumetric scanning by adding depth information through focus plane variation. The system scans multiple focus planes simultaneously and processes the data to reconstruct three-dimensional surface geometry, enabling precise measurement of depth and surface topology in a single scanning operation rather than requiring sequential scanning of multiple planes.
2Measurement precision
If confocal microscopy with point illumination is used, then measurement precision is improved, but the scanning time increases
Solution Approach 1:
The patent employs continuous illumination of the entire object surface rather than sequential point illumination. Multiple light sources illuminate the surface continuously, and the detector continuously captures light reflected from the surface across multiple focus planes. This continuous scanning action eliminates the time-consuming step-by-step illumination process, reducing scanning time while maintaining measurement precision through continuous data acquisition and processing.
3Measurement precision
If traditional optical scanning methods are used, then measurement precision is improved, but device complexity and size increase
Solution Approach 1:
The patent employs a single camera sensor that performs multiple functions: capturing reflected light from the object surface, detecting focus plane information, and providing data for 3D reconstruction. This multi-functional use of the camera eliminates the need for separate detectors and complex optical components, reducing device complexity while maintaining measurement precision through software-based focus plane determination and 3D registration algorithms.
4Ease of operation
If handheld scanning is implemented, then ease of operation is improved, but control over spatial relation between scanner and object deteriorates
Solution Approach 1:
The patent incorporates feedback mechanisms that continuously monitor the scanning process and adjust focus plane positions in real-time. The system detects changes in the spatial relation between the scanner and object through focus plane variation and automatically compensates by adjusting the scanning parameters. This feedback control enables handheld operation while maintaining stable and accurate 3D surface registration despite variations in hand movement and spatial position.
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
Enables fast, precise, and efficient 3D surface scanning with a handheld device, capable of capturing both external and internal object structures with improved signal-to-noise ratio and reduced data processing time.
Implementation Method 1
transmitting at least a part of the light returned from the object to the camera
Implementation Method 2
evaluating a correlation measure at each focus plane position between at least one image pixel and a weight function, where the weight function is determined based on information of the configuration of the spatial pattern
Data Source
AI summary
A scanner includes a camera, a light source for generating a probe light incorporating a spatial pattern, an optical system for transmitting the probe light towards the object and for transmitting at least a part of the light returned from the object to the camera, a focus element within the optical system for varying a position of a focus plane of the spatial pattern on the object, unit for obtaining at least one image from said array of sensor elements, unit for evaluating a correlation measure at each focus plane position between at least one image pixel and a weight function, a processor for determining the in-focus position(s) of each of a plurality of image pixels for a range of focus plane positions, or each of a plurality of groups of image pixels for a range of focus plane positions, and transforming in-focus data into 3D real world coordinates.