Abstract: Described are methods that enable rapid automated object classification of measured three-dimensional object scenes. Each method can be performed during a three-dimensional measurement procedure while data are being acquired or after completion of the measurement procedure using the acquired data. In various embodiments, an object scene is illuminated with an optical beam and an image is acquired. In some embodiments, the object scene is illuminated with a structured light pattern and a sequence of images of the object scene illuminated by the pattern at different spatial phases is acquired. Coordinates are determined for points in the one or more images and a translucence value is determined for each of the points. An object class is determined for each point based on the translucence value for the point. Optionally, additional information, such as grayscale or color image data for each point, is used to supplement the object class determination.

Abstract: Described are a method and apparatus for high-speed phase shifting of an optical beam. A transparent plate having regions of different optical thickness is illuminated by an optical beam along a path of incidence that extends through the regions. The transparent plate can be moved or the optical beam can be steered to generate the path of incidence. The optical beam exiting the transparent plate has an instantaneous phase value according to the region in which the optical beam is incident. Advantageously, the phase values are repeatable and stable regardless of the location of incidence of the optical beam within the respective regions, and phase changes at high modulation rates are possible. The method and apparatus can be used to modulate a phase difference of a pair of coherent optical beams such as in an interferometric fringe projection system.

Abstract: Described are embodiments of methods of obtaining three-dimensional (3D) surface data of an object scene such as an intra-oral cavity. For example, measured surfaces may include the enamel surface of teeth, the dentin substructure of teeth, gum tissue and various dental structures. The methods can also be applied in medical applications and other applications in which 3D measurement data are acquired with maneuverable 3D measurement devices. In certain embodiments, the measurement device is positioned and translated to enable 3D data to be acquired for a backbone 3D data set. Subsequent controlled motion of the measurement device enables additional 3D data to be acquired and accurately joined to the backbone 3D data set.

Abstract: Described are a method and apparatus for high-speed phase shifting of an optical beam. A transparent plate having regions of different optical thickness is illuminated by an optical beam along a path of incidence that extends through the regions. The transparent plate can be moved or the optical beam can be steered to generate the path of incidence. The optical beam exiting the transparent plate has an instantaneous phase value according to the region in which the optical beam is incident. Advantageously, the phase values are repeatable and stable regardless of the location of incidence of the optical beam within the respective regions, and phase changes at high modulation rates are possible. The method and apparatus can be used to modulate a phase difference of a pair of coherent optical beams such as in an interferometric fringe projection system.

Abstract: Described are an imaging device and method for determining three-dimensional position information of a surface of an object. The device includes a pair of optical fibers, a phase shifter, a detector array and a processor. The phase shifter is coupled to one of the optical fibers and is used to change a phase of optical radiation emitted from the optical fiber relative to a phase of optical radiation emitted from the other optical fiber. The detector array receives optical radiation scattered by the surface of the object. The processor communicates with the detector array and the phase shifter. Signals generated by the detector array are received by the processor and three-dimensional position information for the surface is calculated in response to the received optical radiation scattered by the surface of the object and the change in the relative phase of optical radiation emitted by the optical fibers.

Abstract: Described are a method and device for determining three-dimensional position information of a surface of a translucent object having a wavelength-dependent transmittance and reflectance characteristics. The method includes illuminating the surface of the translucent object with optical radiation at a predetermined wavelength emitted from a pair of optical sources. Radiation scattered from the surface and below the surface is detected, and a phase of the optical radiation from one of the optical sources relative to a phase of the optical radiation from the other optical source is changed before again detecting the scattered radiation. The predetermined wavelength is selected so that the optical radiation scattered from below the surface and detected provides a substantially constant background intensity with respect to the optical radiation scattered from the surface and detected. Three-dimensional position information of the surface is calculated in response to the detected radiation.

Abstract: Provided are a system and method for generating and displaying intra-oral measurement data. A measurement field of view of an intra-oral scanning device is directed at a first region of an object scene to acquire image data related to the first region. The intra-oral scanning device is moved from the first region along a path proximal to one or more surfaces of the object scene to a second region of the object scene. The intra-oral scanning device acquires image data corresponding to the object scene along the path. A set of 3D data is presented in a display. 3D data are generated from the image data acquired for the first region of the object scene to the second region of the object scene. Presented in a window of the display is a current video image of acquired image data of the object scene in the measurement field of view. The current video image overlays a respective portion of a graphical representation of accumulated data of the set of 3D data.

Abstract: Described are embodiments of methods of obtaining three-dimensional (3D) surface data of an object scene such as an intra-oral cavity. For example, measured surfaces may include the enamel surface of teeth, the dentin substructure of teeth, gum tissue and various dental structures. The methods can also be applied in medical applications and other applications in which 3D measurement data are acquired with maneuverable 3D measurement devices. In certain embodiments, the measurement device is positioned and translated to enable 3D data to be acquired for a backbone 3D data set. Subsequent controlled motion of the measurement device enables additional 3D data to be acquired and accurately joined to the backbone 3D data set.

Abstract: Described are methods that enable rapid automated object classification of measured three-dimensional object scenes. Each method can be performed during a three-dimensional measurement procedure while data are being acquired or after completion of the measurement procedure using the acquired data. In various embodiments, an object scene is illuminated with an optical beam and an image is acquired. In some embodiments, the object scene is illuminated with a structured light pattern and a sequence of images of the object scene illuminated by the pattern at different spatial phases is acquired. Coordinates are determined for points in the one or more images and a translucence value is determined for each of the points. An object class is determined for each point based on the translucence value for the point. Optionally, additional information, such as grayscale or color image data for each point, is used to supplement the object class determination.

Abstract: Described are a method and apparatus for generating a display of a three-dimensional (“3D”) metrology surface. The method includes determining a 3D point cloud representation of a surface of an object in a point cloud coordinate space. An image of the object is acquired in a camera coordinate space and then transformed from the camera coordinate space to the point cloud coordinate space. The transformed image is mapped onto the 3D point cloud representation to generate a realistic display of the surface of the object. In one embodiment, a metrology camera used to acquire images for determination of the 3D point cloud is also used to acquire the image of the object so that the transformation between coordinate spaces is not performed. The display includes a grayscale or color shading for the pixels or surface elements in the representation.

Abstract: Described are a method and apparatus for high-speed phase shifting of an optical beam. A transparent plate having regions of different optical thickness is illuminated by an optical beam along a path of incidence that extends through the regions. The transparent plate can be moved or the optical beam can be steered to generate the path of incidence. The optical beam exiting the transparent plate has an instantaneous phase value according to the region in which the optical beam is incident. Advantageously, the phase values are repeatable and stable regardless of the location of incidence of the optical beam within the respective regions, and phase changes at high modulation rates are possible. The method and apparatus can be used to modulate a phase difference of a pair of coherent optical beams such as in an interferometric fringe projection system.

Abstract: Described are methods and apparatus for reducing speckle noise in images, such as images of objects illuminated by coherent light sources and images of objects illuminated by interferometric fringe patterns. According to one method, an object is illuminated with a structured illumination pattern of coherent radiation projected along a projection axis. An angular orientation of the projection axis is modulated over an angular range during an image acquisition interval. Advantageously, shape features of the structured illumination pattern projected onto the surface of the object remain unchanged during image acquisition and the acquired images exhibit reduced speckle noise. The structured illumination pattern can be a fringe pattern such as an interferometric fringe pattern generated by a 3D metrology system used to determine surface information for the illuminated object.

Abstract: Described are an imaging device and method for determining three-dimensional position information of a surface of an object. The device includes a pair of optical fibers, a phase shifter, a detector array and a processor. The phase shifter is coupled to one of the optical fibers and is used to change a phase of optical radiation emitted from the optical fiber relative to a phase of optical radiation emitted from the other optical fiber. The detector array receives optical radiation scattered by the surface of the object. The processor communicates with the detector array and the phase shifter. Signals generated by the detector array are received by the processor and three-dimensional position information for the surface is calculated in response to the received optical radiation scattered by the surface of the object and the change in the relative phase of optical radiation emitted by the optical fibers.

Abstract: Described are a method and device for determining three-dimensional position information of a surface of a translucent object having a wavelength-dependent transmittance and reflectance characteristics. The method includes illuminating the surface of the translucent object with optical radiation at a predetermined wavelength emitted from a pair of optical sources. Radiation scattered from the surface and below the surface is detected, and a phase of the optical radiation from one of the optical sources relative to a phase of the optical radiation from the other optical source is changed before again detecting the scattered radiation. The predetermined wavelength is selected so that the optical radiation scattered from below the surface and detected provides a substantially constant background intensity with respect to the optical radiation scattered from the surface and detected. Three-dimensional position information of the surface is calculated in response to the detected radiation.

Abstract: Described is a multiple channel interferometric surface contour measurement system. The measurement system includes a multiple channel interferometer projector, a digital camera and a processor. The projector includes two or more interferometer channels. Each channel has an optical axis spatially separate from the optical axes of the other channels. Each channel projects a fringe pattern onto the surface of an object to be measured. Image data for the fringe patterns projected on the object surface are acquired by the digital camera. The processor controls the projection of the fringe patterns of different spatial frequencies, adjusts the phase of each fringe pattern and generates surface contour data in response to the camera image data. The multiple channel interferometric surface contour measurement system provides numerous advantages over conventional single channel interferometric systems, including reduced sensitivity to optical noise, improved stability and increased measurement accuracy.

Abstract: Described is a multiple channel interferometric surface contour measurement system. The measurement system includes a multiple channel interferometer projector, a digital camera and a processor. The projector includes two or more interferometer channels. Each channel has an optical axis spatially separate from the optical axes of the other channels. Each channel projects a fringe pattern onto the surface of an object to be measured. Image data for the fringe patterns projected on the object surface are acquired by the digital camera. The processor controls the projection of the fringe patterns of different spatial frequencies, adjusts the phase of each fringe pattern and generates surface contour data in response to the camera image data. The multiple channel interferometric surface contour measurement system provides numerous advantages over conventional single channel interferometric systems, including reduced sensitivity to optical noise, improved stability and increased measurement accuracy.

Abstract: Described is an interferometric surface contour measurement system for projecting structured light patterns onto an object. The measurement system includes an interferometric projector, an imager, and a processor. The imager is rigidly coupled to the projector to maintain a stable relationship to the projected, structured light pattern. The imager receives the structured light pattern and together with the processor, determines whether the projected image includes a positional error. In some embodiments, the projector is a multi-channel projector, each channel having an optical axis spatially separated from the others, one of the channels including the imager and dedicated for determining positional error. In other embodiments, the projector is a single-channel projector projecting a structured light pattern onto the object, a portion of the structured light pattern being tapped-off for determining positional error.

Abstract: Described are a multiple channel interferometric surface contour measurement system and methods of determining surface contour data for the same. The measurement system includes a multiple channel interferometer projector, a digital camera and a processor. Fringe patterns generated by spatially separate channels in the projector are projected onto an object surface to be measured. The digital camera acquires images of the fringe patterns and the processor determines surface contour data from the fringe patterns. More specifically, fringe numbers are determined for points on the object surface based on image data. The fringe numbers are modified according to collinear adjustment values so that the modified fringe numbers correspond to a common, collinear axis for the interferometer projector. After unwrapping the modified fringe numbers, the unwrapped values are modified by the collinear adjustment values to obtain accurate fringe numbers for the pixels in each interferometer channel.

Abstract: Described are a multiple channel interferometric surface contour measurement system and methods of determining surface contour data for the same. The measurement system includes a multiple channel interferometer projector, a digital camera and a processor. Fringe patterns generated by spatially separate channels in the projector are projected onto an object surface to be measured. The digital camera acquires images of the fringe patterns and the processor determines surface contour data from the fringe patterns. More specifically, fringe numbers arc determined for points on the object surface based on image data. The fringe numbers are modified according to collinear adjustment values so that the modified fringe numbers correspond to a common, collinear axis for the interferometer projector. After unwrapping the modified fringe numbers, the unwrapped values are modified by the collinear adjustment values to obtain accurate fringe numbers for the pixels in each interferometer channel.

Abstract: Described is an interferometric surface contour measurement system for projecting structured light patterns onto an object. The measurement system includes an interferometric projector, an imager, and a processor. The imager is rigidly coupled to the projector to maintain a stable relationship to the projected, structured light pattern. The imager receives the structured light pattern and together with the processor, determines whether the projected image includes a positional error. In some embodiments, the projector is a multi-channel projector, each channel having an optical axis spatially separated from the others, one of the channels including the imager and dedicated for determining positional error. In other embodiments, the projector is a single-channel projector projecting a structured light pattern onto the object, a portion of the structured light pattern being tapped-off for determining positional error.