Abstract: An optical system configured to measure a raised or receded surface feature on a surface of a sample may comprise a broadband light source; a tunable filter configured to filter broadband light emitted from the broadband light source and to generate a first light beam at a selected wavelength; a linewidth control element configured to receive the first light beam and to generate a second light beam having a predefined linewidth and a predetermined coherence length; collimating optics optically coupled to the second light beam and configured to collimate the second light beam; collinearizing optics optically coupled to the collimating optics and configured to align the collimated second light beam onto the raised or receded surface feature of the sample, and a processor system and at least one digital imager configured to measure a height of the raised surface or depth of the receded surface from light reflected at least from those surfaces.

Abstract: A method of improving axial resolution of interferometric measurements of a 3D feature of a sample may comprise illuminating the feature using a first limited number of successively different wavelengths of light at a time; generating an image of at least the 3D feature based on intensities of light reflected from the feature at each of the successively different wavelengths of light; measuring a fringe pattern of intensity values for each corresponding pixel of the generated images; resampling the measured fringe patterns as k-space interferograms; estimating interference fringe patterns for a spectral range that is longer than available from the generated images using the k-space interferograms; appending the estimated interference fringe patterns to the respective measured fringe patterns; and measuring the height or depth of the 3D feature using the measured interference fringe patterns and appended estimated fringe patterns.

Abstract: An optical system configured to measure a raised or receded surface feature on a surface of a sample may comprise a broadband light source; a tunable filter configured to filter broadband light emitted from the broadband light source and to generate a first light beam at a selected wavelength; a linewidth control element configured to receive the first light beam and to generate a second light beam having a predefined linewidth and a predetermined coherence length; collimating optics optically coupled to the second light beam and configured to collimate the second light beam; collinearizing optics optically coupled to the collimating optics and configured to align the collimated second light beam onto the raised or receded surface feature of the sample, and a processor system and at least one digital imager configured to measure a height of the raised surface or depth of the receded surface from light reflected at least from those surfaces.

Abstract: A method of improving axial resolution of interferometric measurements of a 3D feature of a sample may comprise illuminating the feature using a first limited number of successively different wavelengths of light at a time; generating an image of at least the 3D feature based on intensities of light reflected from the feature at each of the successively different wavelengths of light; measuring a fringe pattern of intensity values for each corresponding pixel of the generated images; resampling the measured fringe patterns as k-space interferograms; estimating interference fringe patterns for a spectral range that is longer than available from the generated images using the k-space interferograms; appending the estimated interference fringe patterns to the respective measured fringe patterns; and measuring the height or depth of the 3D feature using the measured interference fringe patterns and appended estimated fringe patterns.

Abstract: An interferometer and an imager may include a tunable light source, a beam splitter, a digital imager, and a processor system. The tunable light source may be configured to emit a beam. The beam splitter may be configured to direct the beam toward a sample with a floor surface and a raised surface feature. The digital imager may be configured to receive a reflected beam and to generate an image based on the reflected beam. The reflected beam may be a coherent addition of a first reflection of the beam off a reference plate and a second reflection of the beam off the raised surface feature and third reflection of the beam off the floor surface. The processor system may be coupled to the digital imager and may be configured to determine a distance between the reference surface and the feature surface based on the image.

Abstract: An interferometer and an imager may include a tunable light source, a beam splitter, a digital imager, and a processor system. The tunable light source may be configured to emit a beam. The beam splitter may be configured to direct the beam toward a sample with a floor surface and a raised surface feature. The digital imager may be configured to receive a reflected beam and to generate an image based on the reflected beam. The reflected beam may be a coherent addition of a first reflection of the beam off a reference plate and a second reflection of the beam off the raised surface feature and third reflection of the beam off the floor surface. The processor system may be coupled to the digital imager and may be configured to determine a distance between the reference surface and the feature surface based on the image.