Tomographic Scanning Device Using Dynamic Moiré Pattern Filtering
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing tomographic scanning devices struggle with imaging translucent or diffuse surfaces, such as dental teeth, due to weak Moiré patterns and interference from surface reflections, limiting their ability to scan steep flanks and achieving high resolution.
Innovation Solution
A device employing a light source, a first grid, an optical imaging assembly, and a second grid with a matching pattern, where the grids are moved to create fluctuations in the Moiré pattern intensity, allowing for bandpass filtering and improved signal-to-noise ratio, enabling focused imaging of translucent specimens, including perpendicular walls and interior details.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Moiré pattern imaging is used for translucent surfaces, then surface shape information can be obtained, but the Moiré pattern intensity is very weak compared to other reflected light
Solution Approach 1:
The patent introduces a moving element (either the object or the optical system) to create temporal variations in the Moiré pattern intensity. By moving the object through the focal plane or moving the optical assembly, the system converts spatial information into temporal signal variations that can be detected and filtered, thereby extracting weak Moiré signals from the background reflection.
Solution Approach 2:
The patent employs periodic motion of the object or optical system to generate periodic Moiré pattern fluctuations. This periodic action allows the use of narrow-band filtering at the specific modulation frequency to isolate the Moiré signal from aperiodic background reflections, significantly improving the signal-to-noise ratio for translucent surfaces.
2Measurement precision
If a large numerical aperture optical assembly is used to attain high resolution, then imaging resolution is improved, but the depth of focus becomes small
Solution Approach 1:
The patent uses dynamic focusing by moving the optical imaging assembly or the object through different axial positions. This allows the system to maintain a small depth of focus for high resolution while systematically scanning through the object's depth, building up three-dimensional information from a series of focused planes.
Solution Approach 2:
The patent transitions from two-dimensional surface imaging to three-dimensional volumetric imaging by adding the axial dimension through focal plane scanning. The moving element enables traversal through the depth dimension, allowing reconstruction of interior structures and three-dimensional surface topology from multiple focal planes.
3Device complexity
If scanning is performed on steep flanks with single-angle illumination, then simple illumination setup is maintained, but scanning of steep flanks is not possible
Solution Approach 1:
The patent introduces dynamic illumination by moving the light source or the object during scanning. This dynamic approach allows the illumination angle to change relative to the surface normal, enabling light to reach and reflect from steep flanks that would be invisible under fixed single-angle illumination, while maintaining a relatively simple illumination setup.
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 device achieves high-resolution, noise-reduced imaging of dental teeth and other translucent objects, allowing for accurate three-dimensional surface reconstruction and interior analysis without the need for opaque powdering or complex interferometry.
Implementation Method 1
a source of light generating a light beam for irradiating the object
Implementation Method 2
a pattern of the first grid is projected on the object... the sensor senses the light beam reflected by the object with a Moiré pattern resulting from overlying the pattern of the first grid and the pattern of the second grid
Data Source
AI summary
A device for tomographic scanning objects comprises a source of light for irradiating the object; a first grid arranged in the optical axis of the light beam so that a pattern of the first grid is projected on the object; an optical imaging assembly for imaging the object on a sensor; and a second grid provided in the optical axis of the reflected light beam having a pattern matching the first grid, through said second grid the reflected light beam having the pattern of the first grid being guided so that the sensor senses the light beam reflected by the object with a Moiré pattern resulting from overlying the pattern of the first grid and the pattern of the second grid. The device further comprises a means for moving the first grid and/or the second grid at a frequency causing fluctuations in the intensity of the resulting Moiré pattern.