Diffractive Intraoral Scanner for Translucent Surface Topography
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Solution Overview
Problem
Existing intraoral scanners face challenges in achieving high recording accuracy and reliability for translucent dental objects due to light scattering and volume scattering, which affects the contrast and clarity of projected measuring patterns, leading to reduced recording accuracy and increased complexity.
Innovation Solution
The use of diffractive optical elements for generating measuring patterns through light diffraction, combined with linearly polarized light and a polarisation filter, allows for high-intensity, miniaturized, and cost-effective projection systems that enhance recording accuracy and depth of focus, enabling hybrid encoding to solve the correspondence problem.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional projection systems are used for structured illumination, then the system can project measuring patterns onto the surface, but light scattering and volume scattering in translucent dental objects reduce the contrast and clarity of the projected patterns, leading to reduced recording accuracy
Solution Approach 1:
The patent changes the wavelength parameter of the light source to blue light (400-480 nm) which has shorter wavelength and lower penetration depth, reducing volume scattering effects in translucent dental objects. This parameter change optimizes the interaction between light and the translucent material to improve measurement precision
Solution Approach 2:
The patent replaces conventional projection systems with diffractive optical elements (DOE) that use light diffraction to generate measuring patterns. This substitution creates higher intensity projected patterns with sharper edges, improving contrast and recording accuracy despite light scattering in translucent objects
2Ease of manufacture
If conventional projection systems are used, then the system can function, but the system size and cost increase
Solution Approach 1:
The patent replaces complex conventional projection systems with diffractive optical elements (DOE) that generate measuring patterns through light diffraction. This substitution significantly reduces system size, eliminates the need for spatial light modulators, and lowers manufacturing costs while maintaining functionality
Solution Approach 2:
The patent uses blue laser diodes with wavelength 400-480 nm, which allow for compact system design due to the small size of laser diodes at this wavelength. This parameter change enables miniaturization of the intraoral scanner while maintaining projection quality
3Productivity
If the scan tip is moved at high speed across the surface to improve productivity, then recording time is reduced, but recording accuracy may be compromised
Solution Approach 1:
The patent uses blue laser diodes that can be rapidly switched on and off at high frequencies, enabling periodic projection of measuring patterns. This allows for high-speed scanning while maintaining sufficient light intensity for accurate recording, as the laser can be pulsed synchronously with the scanning motion
Solution Approach 2:
The use of diffractive optical elements creates high-intensity projected patterns that expose the sensor more strongly, allowing for shorter exposure times during high-speed scanning. This enables maintaining recording accuracy even when the scan tip moves rapidly across the surface
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 achieves significantly improved recording accuracy, miniaturization of the scanner, and reduced costs while maintaining high movement speed and depth of focus, overcoming the limitations of light scattering and volume scattering in translucent dental objects.
Implementation Method 1
The use of diffractive optical elements for generating measuring patterns through light diffraction
Implementation Method 2
combined with linearly polarized light and a polarisation filter
Data Source
AI summary
A method and intraoral scanner are provided for detecting topography of the surface by at least partly superimposing a first and a second sub-topography. Each sub-topography is detected by projecting a total measurement pattern onto a respective sub-region of the surface by a projection device. The total measurement pattern has at least two different measurement patterns, each of which has parallel measurement lines, and each of the measurement patterns is assigned to a diffractive optical element, by means of which measurement lines can be generated by light diffraction. The method then provides a first and a second image of each sub-region, a first measurement pattern being projected onto the sub-region of the surface in the first image and a second measurement pattern being projected onto the sub-region of the surface in the second image, and detects the sub-topographies by triangulation in each case.