Abstract: Disclosed are systems and methods to extract information about the size and shape of an object by observing variations of the radiation pattern caused by illuminating the object with coherent radiation sources and changing the wavelengths of the source. Sensing and image-reconstruction systems and methods are described for recovering the image of an object utilizing projected and transparent reference points and radiation sources. Sensing and image-reconstruction systems and methods are also described for rapid sensing of such radiation patterns. A computational system and method is also described for sensing and reconstructing the image from its autocorrelation. This computational approach uses the fact that the autocorrelation is the weighted sum of shifted copies of an image, where the shifts are obtained by sequentially placing each individual scattering cell of the object at the origin of the autocorrelation space.

Abstract: Described is a fringe generator for an interferometric measurement system having improved fringe stability and reproducibility. The fringe generator includes a light source at a characteristic wavelength and a diffractive element to generate a pair of diffracted beams from light received from the light source. The fringe generator also includes a lens to receive the pair of diffracted beams and to image the plane of the diffractive element onto an object to be measured. The generated fringe pattern is substantially independent to a change in the position of the light source relative to the lens and a change in the characteristic wavelength of the light source. A broadband light source can be used and the resulting broadband fringe pattern is substantially independent to a change in the position of the light source relative to the lens and to a change in the spectral distribution of the broadband light source.

Abstract: Apparatus and methods of measuring three-dimensional position information of a onto a surface of an object including two sources of radiation separated by a distance, each source having a spectral distribution, and being coherent with respect to the other of the sources, a control system moving each of the sources relative to the other of the sources, and a detector positioned to receive radiation scattered from the point on the surface of the object. In another embodiment, the two sources of radiation include, an initial source of a beam of radiation having a spectral width, a beam separator in optical communication with the initial source of a beam of radiation generating a first optical beam and a second optical beam, and an imaging system optically connected to the beam separator.

Abstract: Described is a fringe generator for an interferometric measurement system having improved fringe stability and reproducibility. The fringe generator includes a light source at a characteristic wavelength and a diffractive element to generate a pair of diffracted beams from light received from the light source. The fringe generator also includes a lens to receive the pair of diffracted beams and to image the plane of the diffractive element onto an object to be measured. The generated fringe pattern is substantially independent to a change in the position of the light source relative to the lens and a change in the characteristic wavelength of the light source. A broadband light source can be used and the resulting broadband fringe pattern is substantially independent to a change in the position of the light source relative to the lens and to a change in the spectral distribution of the broadband light source.

Abstract: The present invention provides a method and apparatus for reducing error in interferometric fringe stability and reproducibility in an interference fringe generator. In one aspect, the method for reducing error in interferometric fringe stability and reproducibility includes providing a light source, positioning a grating to receive light from the light source and positioning a projection lens having a focal length F to receive light from the grating. The projection lens projects the received light upon an object of interest positioned substantially at a distance d1 from the lens. Typically the lens is positioned substantially at a distance d2 from the grating. The values of d1, d2, and F are related by d2 being approximately equal to d1F/(d1?F).

Abstract: Apparatus and methods of measuring three-dimensional position information of a point on the surface of an object. The invention also relates to an apparatus for projecting fringes onto a surface of an object including two sources of radiation separated by a distance, each source having a spectral distribution, and being coherent with respect to the other of the sources, a control system moving each of the sources relative to the other of the sources, and a detector positioned to receive radiation scattered from the point on the surface of the object. In another embodiment, the two sources of radiation include, an initial source of a beam of radiation having a spectral width, a beam separator in optical communication with the initial source of a beam of radiation generating a first optical beam and a second optical beam, and an imaging system optically connected to the beam separator.

Abstract: Apparatus and methods of measuring three-dimensional position information of a point on the surface of an object. The invention also relates to an apparatus for projecting fringes onto a surface of an object including two sources of radiation separated by a distance, each source having a spectral distribution, and being coherent with respect to the other of the sources, a control system moving each of the sources relative to the other of the sources, and a detector positioned to receive radiation scattered from the point on the surface of the object. In another embodiment, the two sources of radiation include, an initial source of a beam of radiation having a spectral width, a beam separator in optical communication with the initial source of a beam of radiation generating a first optical beam and a second optical beam, and an imaging system optically connected to the beam separator.

Abstract: In one aspect, the invention relates to an apparatus for monitoring thickness variations of an object having first and second opposing surfaces. The apparatus includes a first source positioned to project a first fringe pattern at a first location on the first surface and a second source positioned to project a second fringe pattern at a first location on the second surface. The apparatus further includes a first detector positioned to detect the first fringe pattern at the first location on the first surface, the first detector generating a first signal in response to the first fringe pattern at the first location. The apparatus also includes a second detector positioned to detect the second fringe pattern at the first location on the second surface, the second detector generating a second signal in response to the second fringe pattern at the first location.

Abstract: The present invention provides a method and apparatus for reducing error in interferometric fringe stability and reproducibility in an interference fringe generator. In one aspect, the method for reducing error in interferometric fringe stability and reproducibility includes providing a light source, positioning a grating to receive light from the light source and positioning a projection lens having a focal length F to receive light from the grating. The projection lens projects the received light upon an object of interest positioned substantially at a distance d1 from the lens. Typically the lens is positioned substantially at a distance d2 from the grating. The values of d1, d2, and F are related by d2 being approximately equal to d1F/(d1?F).

Abstract: Apparatus and methods of measuring three-dimensional position information of a point on the surface of an object. The invention also relates to an apparatus for projecting fringes onto a surface of an object including two sources of radiation separated by a distance, each source having a spectral distribution, and being coherent with respect to the other of the sources, a control system moving each of the sources relative to the other of the sources, and a detector positioned to receive radiation scattered from the point on the surface of the object. In another embodiment, the two sources of radiation include, an initial source of a beam of radiation having a spectral width, a beam separator in optical communication with the initial source of a beam of radiation generating a first optical beam and a second optical beam, and an imaging system optically connected to the beam separator.

Abstract: Apparatus and methods of measuring three-dimensional position information of a point on the surface of an object. In one embodiment, the method includes the steps of providing two sources of radiation having a spectral distribution, illuminating the surface with each of the sources to produce a first fringe pattern, moving the first fringe pattern to a second position, generating a first wrapped cycle map, estimating fringe numbers in the first fringe pattern, changing the first fringe pattern, moving the second fringe pattern to a second position, generating a second wrapped cycle map, estimating fringe numbers in the second fringe pattern, and determining position information in response to the estimated fringe numbers in the second fringe pattern and the second wrapped cycle map.

Abstract: In one aspect, the invention relates to an apparatus for monitoring thickness variations of an object having first and second opposing surfaces. The apparatus includes a first source positioned to project a first fringe pattern at a first location on the first surface and a second source positioned to project a second fringe pattern at a first location on the second surface. The apparatus further includes a first detector positioned to detect the first fringe pattern at the first location on the first surface, the first detector generating a first signal in response to the first fringe pattern at the first location. The apparatus also includes a second detector positioned to detect the second fringe pattern at the first location on the second surface, the second detector generating a second signal in response to the second fringe pattern at the first location.

Abstract: An apparatus and method for compensating for measurement uncertainty due to atmospheric effects. In one embodiment the apparatus includes two sources separated by a predetermined distance and two target locations separated by a predetermined distance. The radiation at the target locations is combined to form an interference pattern onto a detector which generates a signal corresponding to the measurement having a substantially reduced error due to atmospheric effects such as temperature variations. In another embodiment the radiation from the sources crosses somewhere in the measurement environment as it propagates toward the target locations. In yet another embodiment the separation between the two sources is substantially the same as the separation between the two target locations.

Abstract: An apparatus and method for compensating for measurement uncertainty due to atmospheric effects. In one embodiment the apparatus includes two sources separated by a predetermined distance and two target locations separated by a predetermined distance. The radiation at the target locations is combined to form an interference pattern onto a detector which generates a signal corresponding to the measurement having a substantially reduced error due to atmospheric effects such as temperature variations. In another embodiment the radiation from the sources crosses somewhere in the measurement environment as it propagates toward the target locations. In yet another embodiment the separation between the two sources is substantially the same as the separation between the two target locations.

Abstract: An apparatus and method for compensating for measurement uncertainty due to atmospheric effects. In one embodiment the apparatus includes two sources separated by a predetermined distance and two target locations separated by a predetermined distance. The radiation at the target locations is combined to form an interference pattern onto a detector which generates a signal corresponding to the measurement having a substantially reduced error due to atmospheric effects such as temperature variations. In another embodiment the radiation from the sources crosses somewhere in the measurement environment as it propagates toward the target locations. In yet another embodiment the separation between the two sources is substantially the same as the separation between the two target locations.

Abstract: Apparatus and methods of measuring position information of a point on the surface of an object. In one embodiment, the apparatus includes two sources of radiation positioned to illuminate the point on the surface of the object with radiation from each of the sources. The radiation from each of the sources is coherent with respect to the radiation from the other source. A control system moves each of the sources relative to the other and changes the phase of the radiation from at least one of the sources relative to the phase of the radiation from the other source as measured at the point on the surface of the object. A detector is positioned to receive radiation scattered by the point and a processor in communication with the detector calculates position information in response to the change in phase of the radiation from the source and the received radiation scattered by the point on the surface of the object.