Abstract: An interferometer system is disclosed which is configured to combine measurement light with reference light to form an optical interference pattern, where the interferometer system includes a modulator configured to repetitively introduce a sequence of phase shifts between the measurement and reference light; and a camera system positioned to measure the optical interference pattern, where the camera system is configured to separately accumulate time-integrated images of the optical interference pattern corresponding to the different phase shifts in the sequence during the repetitions of the sequence.

Abstract: An apparatus including a camera which includes a plurality of light-sensitive pixels each capable of accumulating electronic data in response to an incident light signal. Each light-sensitive pixel is electrically coupled to two or more storage cells in the camera to define a coupled set of elements, where the elements include the light-sensitive pixel and the storage cells. Each element in each set is capable of storing electronic data related to light incident on the light-sensitive pixel. For each set of elements, the camera further includes a switch between the light sensitive pixel and at least one of the storage cells and a switch between at least one pair of the storage cells. Each switch is configured to selectively transfer electronic data between the elements connected by the switch.

Abstract: An method for determining a surface profile of an object is described. The method typically includes providing a surface profile (e.g., a height profile) of a test object measured by an interferometric profiler. Information related to field- and object orientation-dependent systematic errors of the interferometric profiler is provided. The surface profile is corrected based on the field- and orientation-dependent errors. Also described is a method for determining the field- and orientation dependent errors of a profiler.

Abstract: Scanning interferometry methods and related systems are described in which scanning interferometry data for a test object is provided. The data typically include intensity values for each of multiple scan positions for each of different spatial locations of the test object. The intensity values for each spatial location typically define an interference signal for the spatial location. The intensity values for a common scan position typically define a data set for that scan position. Scan values are provided for each scan position. In general, scan value increments between various scan values are non-uniform (e.g., different). Information is determined about the test object based on the scanning interferometry data and scan values. Typically, the determination includes transforming at least some of the interference signals into a frequency domain with respect to the scan values.

Abstract: Scanning interferometry methods and related systems are described in which scanning interferometry data for a test object is provided. The data typically include intensity values for each of multiple scan positions for each of different spatial locations of the test object. The intensity values for each spatial location typically define an interference signal for the spatial location. The intensity values for a common scan position typically define a data set for that scan position. Scan values are provided for each scan position. In general, scan value increments between various scan values are non-uniform (e.g., different). Information is determined about the test object based on the scanning interferometry data and scan values. Typically, the determination includes transforming at least some of the interference signals into a frequency domain with respect to the scan values.

Abstract: An apparatus including: an interferometer comprising a series of three partially reflective reference surfaces, wherein the interferometer is configured to direct electromagnetic radiation to a test surface along a path through the series of three partially reflective reference surfaces, and direct the electromagnetic radiation reflected from each of the surfaces to form an optical interference pattern on a detector, wherein the interferometer comprises a first reference optic supporting the first reference surface and a second reference optic supporting the second and third reference surfaces, and wherein the second reference optic is configured to adjustably rotate to exchange an order of the second and third reference surfaces along the path relative to the first reference surface.

Abstract: Apparatus and means for calibrating optical gap-measuring instruments, including a preferred calibration standard (100) comprised of a substantially flat, transparent element (10) held in contact with the convex spherical surface (25) of a substantially opaque element (20) to provide an obvious and unambiguous region over which the gap is zero. The optical gap measuring tool that is to be calibrated is oriented so as to illuminate the interface. The calibration standard (100) is translated in position with respect the gap measuring tool in such a way as to vary the measured gap, while at the same time data storage means record the gap measurement as a function of relative position. This data is then compared to the predicted variation from the geometry of the calibration standard (100). Provided that the elements (10, 20) are of high optical quality, deviations of the measured data from an ideal parabolic curve are indicative of calibration errors.