Handheld Dental Camera Chromatic Confocal 3D Measurement
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Solution Overview
Problem
Chromatic confocal measuring methods require large, unwieldy light sources for broad wavelength spectra, limiting depth measurement range, while classical scanning methods accumulate large data sets due to mechanical movement, making them inefficient for rapid 3D measurements of large objects like teeth.
Innovation Solution
A handheld dental camera combining chromatic and scanning confocal methods using a polychromatic light source and chromatic objective, allowing focal points to be distributed over the measurement depth and moved in steps to achieve an enlarged depth range with compact light sources like LEDs or SLDs, reducing data processing and mechanical steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a chromatic confocal measuring method is used with a broadband light source, then depth measurement range is extended, but the light source becomes large and unwieldy
Solution Approach 1:
The patent divides the depth measurement range into multiple discrete depth ranges, each corresponding to a specific wavelength range of the polychromatic light. By segmenting the measurement task across multiple wavelength bands, the system achieves an extended overall depth measurement range while using a compact light source that would be impossible if a single broadband source were required.
Solution Approach 2:
The patent changes the wavelength parameter of the polychromatic light source to correspond to different depth ranges. By tuning or selecting specific wavelength ranges within the polychromatic light, the system can measure different depth intervals, effectively extending the measurement range without requiring a physically larger light source.
2Measurement precision
If classical scanning confocal methods are used with mechanical movement, then measurement precision is maintained, but data set size increases and measurement efficiency decreases
Solution Approach 1:
The patent replaces the mechanical scanning system with an optical scanning approach using a polychromatic light source. Instead of mechanically moving the objective or sample to scan through different depths, the system uses different wavelength components of the light to optically access different depth ranges simultaneously, thereby maintaining precision while dramatically improving measurement efficiency.
Solution Approach 2:
The patent adds the wavelength dimension to the measurement process. By utilizing the spectral dimension of light, the system can encode depth information in the wavelength domain rather than requiring mechanical movement in the spatial domain. This dimensional transformation allows parallel depth measurement across multiple ranges without mechanical scanning.
3Adaptability or versatility
If a polychromatic light source is used with a chromatic objective, then multiple depth ranges can be measured, but the system complexity increases
Solution Approach 1:
The patent makes the chromatic objective serve multiple functions: it acts as both the focusing element and the depth-selective element. The chromatic objective's inherent property of having different focal lengths for different wavelengths is exploited to provide multi-depth-range measurement capability, eliminating the need for separate optical systems for each depth range and reducing overall system complexity.
Solution Approach 2:
The patent utilizes the natural chromatic aberration property of the chromatic objective to achieve depth differentiation. Instead of requiring additional corrective elements or complex mechanisms to manage the wavelength-dependent focal positions, the system allows the chromatic objective to self-generate the depth-range separation through its inherent optical characteristics, simplifying the overall system design.
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 rapid, efficient 3D measurement of large objects like teeth with reduced data rates and mechanical complexity, using compact light sources and fewer mechanical steps, while maintaining high resolution and depth measurement capabilities.
Implementation Method 1
The focal points of the different wavelengths of the illuminating beam form a chromatic depth measurement range
Implementation Method 2
the polychromatic light source emits an illuminating beam (8) that can be focused, at least in terms of one wavelength thereof, onto the surface of an object of interest
Implementation Method 3
The illuminating beam is reflected by the surface to form a monitoring beam, which is capable of being detected by means of the color sensor
Data Source
AI summary
A handheld dental camera performs three-dimensional, optical measurements. The camera includes a light source that emits an illuminating beam, a scanning unit, a color sensor, and a deflector. The scanning unit focuses the illuminating beam onto a surface of an object to be measured. The surface of the object reflects the illuminating beam and forms a monitoring beam, which is detected by the color sensor. Focal points of wavelengths of the illuminating beam form chromatic depth measurement ranges. The scanning unit stepwise displaces the chromatic depth measurement ranges by a step width smaller than or equal to a length of each chromatic depth measurement range, so that a first chromatic depth measurement range in a first end position of the scanning unit and a second chromatic depth measurement range in a second end position are precisely adjoined in a direction of a measurement depth, or are partially overlapped.