Patent application number | Description | Published |
20090185195 | INTERFERENCE OBJECTIVE FOR ANNULAR TEST SURFACES - An apparatus including: an interferometric objective comprising a beam splitter surface configured to separate input light into test light and reference light, and a reference surface configured to receive the reference light and direct it back to the beam splitter surface, which is configured to recombine the reference light with test light reflected from a test surface, the interferometric objective further comprising one or more optical elements positioned in the path of the input light and having positive or negative optical power, wherein the reference surface is curved and defines a window to pass the input light towards the beam splitter surface. | 07-23-2009 |
20090262362 | INTERFEROMETER FOR OVERLAY MEASUREMENTS - In general, in a first aspect, the invention features a system including an interferometer configured to direct test light to an overlay target and subsequently combine it with reference light to form an interference pattern, the test and reference light being derived from a common source, a multi-element detector, one or more optics to image the overlay target on the multi-element detector; and an electronic processor in communication with the multi-element detector. The overlay target includes a first pattern and a second pattern and the electronic processor is configured to determine information about the relative alignment between the first and second patterns. | 10-22-2009 |
20100128276 | COMPOUND REFERENCE INTERFEROMETER - Interferometry system are disclosed that include a detector sub-system including a monitor detector, interferometer optics for combining test light from a test object with primary reference light from a first reference interface and secondary reference light from a second reference interface to form a monitor interference pattern on a monitor detector, wherein the first and second reference interfaces are mechanically fixed with respect to each other and the test light, a scanning stage configured to scan an optical path difference (OPD) between the test light and the primary and secondary reference light to the monitor detector while the detector sub-system records the monitor interference pattern for each of a series of OPD increments, and an electronic processor electronically coupled to the detector sub-system and the scanning stage, the electronic processor being configured to determine information about the OPD increments based on the detected monitor interference pattern. | 05-27-2010 |
20100128278 | FIBER-BASED INTERFEROMETER SYSTEM FOR MONITORING AN IMAGING INTERFEROMETER - Apparatus include a microscope including an objective and a stage for positioning a test object relative to the objective, the stage being moveable with respect to the objective, and a sensor system, that includes a sensor light source, an interferometric sensor configured to receive light from the sensor light source, to introduce an optical path difference (OPD) between a first portion and a second portion of the light, the OPD being related to a distance between the objective lens and the stage, and to combine the first and second portions of the light to provide output light, a detector configured to detect the output light from the interferometric sensor, a fiber waveguide configured to direct light between the sensor light source, the interferometric sensor and the detector, a tunable optical cavity in a path of the light from the sensor light source and the interferometric sensor, and an electronic controller in communication with the detector, the electronic controller being configured to determine information related to the OPD based on the detected output light. | 05-27-2010 |
20100128280 | SCAN ERROR CORRECTION IN LOW COHERENCE SCANNING INTERFEROMETRY - In general, in one aspect, the invention features apparatus that includes a broadband scanning interferometry system including interferometer optics for combining test light from a test object with reference light from a reference object to form an interference pattern on a detector, wherein the test and reference light are derived from a common light source. The interferometry system further includes a scanning stage configured to scan an optical path difference (OPD) between the test and reference light from the common source to the detector and a detector system including the detector for recording the interference pattern for each of a series of OPD increments, wherein the frequency of each OPD increment defines a frame rate. The interferometer optics are configured to produce at least two monitor interferometry signals each indicative of changes in the OPD as the OPD is scanned, wherein the detector system is further configured to record the monitor interferometry signals. The apparatus also includes an electronic processor electronically coupled to the detection system and scanning stage and configured to determine information about the OPD increments with sensitivity to perturbations to the OPD increments at frequencies greater than the frame rate. | 05-27-2010 |
20100128283 | INTERFEROMETRIC SYSTEMS AND METHODS FEATURING SPECTRAL ANALYSIS OF UNEVENLY SAMPLED DATA - In certain aspects, interferometry methods are disclosed that include providing one or more interferometry signals for a test object, wherein the interferometry signals correspond to a sequence of optical path difference (OPD) values which are not all equally spaced from one another because of noise, providing information about the unequal spacing of the sequence of OPD values, decomposing each of the interferometry signals into a contribution from a plurality of basis functions each corresponding to a different frequency and sampled at the unequally spaced OPD values, and using information about the contribution from each of the multiple basis functions to each of the interferometry signals to determine information about the test object. | 05-27-2010 |
20110032535 | INTERFEROMETER FOR DETERMINING OVERLAY ERRORS - Systems are disclosed that include an interferometer configured to direct test light to an overlay test pad and subsequently combine it with reference light, the test and reference light being derived from a common source, one or more optics configured to direct at least a portion of the combined light to a multi-element detector so that different regions of the detector correspond to different illumination angles of the overlay test pad by the test light, the detector being configured to produce an interference signal based on the combined light, and an electronic processor in communication with the multi-element detector. The overlay test pad comprises a first patterned structure and a second patterned structure and the electronic processor is configured to determine information about the relative alignment between the first and second patterned structures based on the interference signal. | 02-10-2011 |
20110051147 | Measurement of Changes in Surfaces of Objects - Deformations of a surface of a test object can be measured by attaching mirrors to a surface of a test object, each mirror having a reflective surface with a dimension and a radius of curvature smaller than those of the surface of the test object. Light is directed towards the mirrors and a reference surface, and interference patterns are generated using light reflected from the mirrors and the reference surface. Changes in the surface of the test object are determined based on the interference patterns. | 03-03-2011 |
20120069326 | INTERFEROMETRIC METHODS FOR METROLOGY OF SURFACES, FILMS AND UNDERRESOLVED STRUCTURES - A method for determining information about a test object includes combining two or more scanning interference signals to form a synthetic interference signal; analyzing the synthetic interference signal to determine information about the test object; and outputting the information about the test object. Each of the two or more scanning interference signals correspond to interference between test light and reference light as an optical path length difference between the test and reference light is scanned, wherein the test and reference light are derived from a common source. The test light scatters from the test object over a range of angles and each of the two or more scanning interferometry signals corresponds to a different scattering angle or polarization state of the test light. | 03-22-2012 |
20120089365 | DATA INTERPOLATION METHODS FOR METROLOGY OF SURFACES, FILMS AND UNDERRESOLVED STRUCTURES - A method includes fitting a function to a subset of reflectivity data comprising values for the reflectivity of a test object for different wavelengths, different scattering angles, and/or different polarization states; determining values for the function at certain wavelengths and scattering angles and/or polarization states; and determining information about the test object based on the determined values. | 04-12-2012 |
20120224183 | INTERFEROMETRIC METROLOGY OF SURFACES, FILMS AND UNDERRESOLVED STRUCTURES - An interferometry method for determining information about a test object includes directing test light to the test object positioned at a plane, wherein one or more properties of the test light vary over a range of incidence angles at the plane, the properties of the test light being selected from the group consisting of the spectral content, intensity, and polarization state; subsequently combining the test light with reference light to form an interference pattern on a multi-element detector so that different regions of the detector correspond to different angles of the test light emerging from the test object, wherein the test and reference light are derived from a common source; monitoring the interference pattern using the multi-element detector while varying an optical path difference between the test light and the reference light; determining the information about the test object based on the monitored interference pattern. | 09-06-2012 |
20130114061 | DOUBLE PASS INTERFEROMETRIC ENCODER SYSTEM - An encoder head includes one or more components arranged to: i) direct a first incident beam to the diffractive encoder scale at a first incident angle with respect to the encoder scale; ii) receive a first return beam from the encoder scale at a first return angle, the first return angle being different from the first incident angle; iii) redirect the first return beam to the encoder scale as a second incident beam at a second incident angle; and iv) receive a second return beam back from the encoder scale at a second return angle, the second return angle being different from the second incident angle, in which a difference between the first incident angle and second incident angle is less than a difference between the first incident angle and the first return angle and less than a difference between the second incident angle and the second return angle. | 05-09-2013 |
20130114062 | COMPACT ENCODER HEAD FOR INTERFEROMETRIC ENCODER SYSTEM - An encoder system includes an encoder scale and an encoder head, in which the encoder head is configured to combine each twice-diffracted measurement beam of multiple twice-diffracted measurement beams with a corresponding reference beam to form multiple output beams, where the encoder head includes a monolithic optical component having multiple facets, the multiple facets being arranged to: receive multiple once-diffracted measurement beams from a surface of the encoder scale; and redirect the multiple once-diffracted measurement beams back towards the surface of the encoder scale, the encoder scale being positioned in a path of the once-diffracted measurement beams to produce the twice-diffracted measurement beams. | 05-09-2013 |
20130155413 | LOW COHERENCE INTERFEROMETRY WITH SCAN ERROR CORRECTION - A system includes an interference microscope having one or more optical elements arranged to image a test object to an image plane by combining test light from the test object with reference light from a reference object to form an interference pattern at the image plane, wherein the test and reference light are derived from a common broadband light source. The system includes a scanning stage configured to scan an optical path difference (OPD) between the test and reference light, a multi-element detector positioned at the image plane and configured to record the interference pattern for each of a series of OPD increments and to generate multiple interferometry signals each having a fringe carrier frequency indicative of changes in the OPD as the OPD is scanned, where there is phase diversity among the interferometry signals, and an electronic processor coupled to the multi-element detector and scanning stage and configured to process the interference signals based on the phase diversity to determine information about the OPD increments having sensitivity to perturbations to the OPD increments at frequencies greater than the fringe carrier frequency. | 06-20-2013 |
20140098375 | POSITION MONITORING SYSTEM WITH REDUCED NOISE - An interferometry system for monitoring changes in the position of an object, the system includes a spectrally broadband light source, a sensor module having an interferometer that direct portions of the light received from the source along separate paths. The system includes an intensity monitor having a detector configured to measure the intensity of additional light derived from the source and to produce a monitor output signal. The system includes an electronic processing module to process a sensor output signal based on the monitor output signal to account for intensity fluctuations in light output by the source, and determine information about the changes in the position of the object. The intensity monitor is configured to characterize the intensity fluctuations as a function of wavelength or intensity fluctuations that are spectrally correlated. | 04-10-2014 |