Abstract: An apparatus for measuring the surface contour of a target area of a substrate has a light source to emit a measurement light beam. A beam splitting element defines a measurement axis and a reference axis. A substrate holder disposes the target area along the measurement axis and tilted away from normal incidence, about a tilt axis that orthogonally intersects the measurement axis, according to a predetermined tilt angle that is a function of the measurement light beam wavelength. An imaging sensor records a fringe pattern generated from the measurement light beam and a reference light beam. A computer extracts frequency profiles from the recorded fringe pattern, each profile taken in a direction that is orthogonal to the direction of the tilt axis, wherein the programmed instructions further compute changes in the contour of the target area surface according to the frequency profiles.

Abstract: An apparatus for measuring the surface contour of a target area of a substrate has a light source to emit a measurement light beam. A beam splitting element defines a measurement axis and a reference axis. A substrate holder disposes the target area along the measurement axis and tilted away from normal incidence, about a tilt axis that orthogonally intersects the measurement axis, according to a predetermined tilt angle that is a function of the measurement light beam wavelength. An imaging sensor records a fringe pattern generated from the measurement light beam and a reference light beam. A computer extracts frequency profiles from the recorded fringe pattern, each profile taken in a direction that is orthogonal to the direction of the tilt axis, wherein the programmed instructions further compute changes in the contour of the target area surface according to the frequency profiles.

Abstract: A frequency-shifting interferometer is arranged for measuring an optical profile of a test object with a continuously tunable light source. A succession of the interference images of the test object are captured together with a measure of the beam frequencies at which interference images are formed. A limited number of the captured interference images of the test object are selected so that the monitored beam frequencies approximately match a predetermined beam frequency spacing pattern. Further processing proceeds based on the selected interference images.

Abstract: A frequency-shifting interferometer is arranged for measuring an optical profile of a test object with a continuously tunable light source. A succession of the interference images of the test object are captured together with a measure of the beam frequencies at which interference images are formed. A limited number of the captured interference images of the test object are selected so that the monitored beam frequencies approximately match a predetermined beam frequency spacing pattern. Further processing proceeds based on the selected interference images.

Abstract: A frequency scanning interferometer is arranged for simultaneously measuring multiple surfaces of a test object through a wide range of expected offsets. Knowledge of the expected locations of the test surfaces is compared with a sequence of ambiguity intervals based on a synthetic measurement wavelength to center the test surfaces within the ambiguity intervals.

Abstract: A wavelength tunable system including: a laser having a lasing cavity and an external cavity; a frequency-adjuster in the external cavity; and an adjustable current source to adjust the laser diode current, and a method of use as defined herein.

Abstract: A frequency scanning interferometer is arranged for simultaneously measuring multiple surfaces of a test object through a wide range of expected offsets. Knowledge of the expected locations of the test surfaces is compared with a sequence of ambiguity intervals based on a synthetic measurement wavelength to center the test surfaces within the ambiguity intervals.

Abstract: A wavelength tunable system including: a laser having a lasing cavity and an external cavity; a frequency-adjuster in the external cavity; and an adjustable current source to adjust the laser diode current, and a method of use as defined herein.

Abstract: Local data maps of an optical imaging system are stitched together into a composite global data map based on a merit function supporting closed-form processing. Overlapping regions of the local data maps are defined as difference maps that are given a parametric description. Corrective orientations of the local data maps are derived by collectively matching parametric descriptions of the corrective orientations for the overlapping local data maps to the parametric descriptions of the corresponding difference maps.

Abstract: An external cavity laser includes a lasing cavity and an optically coupled feedback cavity having differently spaced resonant lasing and feedback mode frequencies. The lasing modes can be collectively or individually matched to selected feedback modes. For example, a current driving the lasing cavity can be adjusted to shift individual lasing modes into alignment with the selected feedback modes.