Intraoral scanner with a scanning reflector and a method for calibration of a scanning reflector
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Publication Number
US-12082909-B2
Publication Date
2024-09-10
Expiration Date
Abstract
An intraoral scanner (90) is disclosed for use with a dental optical coherence tomography system. The scanner has a scanning reflector that is energizable to direct a scanning beam in a raster pattern toward a sample (S) surface. The scanning reflector is further to direct a reflected beam from the sample surface toward a detector (60). The scanning reflector is calibrated to direct the scanning and reflected beams in an open-loop control mode. A dental optical coherence tomography system and a method for calibration of a scanning reflector are also disclosed.
Core Innovation
The invention concerns an intraoral scanner for use with a dental optical coherence tomography system. The scanning reflector is energizable to direct a scanning beam toward a surface in a raster pattern and to direct a reflected beam toward a detector, and the detector is in signal communication with a processor that calibrates the detector to detect variations in the reflected beam from a sample target.
The scanning reflector is calibrated to direct the scanning beam and the reflected beam in an open-loop control mode through calculation of scanner nonlinearity by the processor according to a linear fitting error of a measured scanning trajectory determined using optical coherence tomography images of the sample target. The processor further operates to configure the scanning reflector to operate at a natural frequency determined based at least in part on the calculated scanner nonlinearity.
A calibration target is defined with paired target features in which the target features in each pair alternate between a light-absorbing feature and a reflective or scattering feature. Scanning along the calibration target provides a measured scanning trajectory determined using optical coherence tomography images, and scanner nonlinearity is corrected by tuning one or more scanning reflector parameters according to a natural frequency of the scanning reflector and by optimizing a cost function defined by a linear fitting error of the measured scanning trajectory.
Claims Coverage
The document contains three independent claims. Across these claims, the inventive features total three main clusters: open-loop calibration using OCT-determined linear fitting error from a measured scanning trajectory, operation at a natural frequency based on calculated scanner nonlinearity, and a calibration target architecture with paired alternating light-absorbing and reflective or scattering features.
Open-loop scanner calibration from OCT-measured scanning trajectory linear fitting error
The scanning reflector is calibrated to direct the scanning beam and the reflected beam in an open-loop control mode through calculation of scanner nonlinearity by the processor according to a linear fitting error of a measured scanning trajectory determined using optical coherence tomography images of the sample target.
Natural frequency operation based on calculated scanner nonlinearity
The scanning reflector is configured to operate at a natural frequency determined based at least in part on the calculated scanner nonlinearity.
Calibration target with paired alternating absorbing and reflective or scattering features
The calibration target has paired target features, and the target features in each pair alternate between a light-absorbing feature and a reflective or scattering feature, with scanner nonlinearity corrected by tuning one or more scanning reflector parameters according to a natural frequency of the scanning reflector.
The independent claims collectively cover intraoral raster scanning with a scanning reflector operating in an open-loop control mode, where calibration is derived from OCT images to obtain a measured scanning trajectory and a linear fitting error cost. The calibration nonlinearity is handled by tuning parameters and configuring operation at a natural frequency determined based on the calculated scanner nonlinearity, using a calibration target having paired alternating light-absorbing and reflective or scattering features.
Stated Advantages
Not explicitly described in patent.
Documented Applications
Not explicitly described in patent.
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