Abstract: A plate for use in an imaging system to determine at least two optical properties of an illumination beam of the imaging system, the imaging system configured to illuminate an illumination region with the illumination beam, the plate including a plurality of markers, wherein a first subset of the plurality of markers includes a first type of markers for determining a first optical property of the illumination beam, and a second subset of the plurality of markers includes a second type of markers for determining a second optical property of the illumination beam, wherein the plurality of markers are located within a marker region of the plate and the marker region generally corresponds to the illumination region.

Abstract: A method comprising determining aberrations caused by each lithographic apparatus of a set of lithographic apparatuses, calculating adjustments of the lithographic apparatuses which minimize differences between the aberrations caused by each of the lithographic apparatuses, and applying the adjustments to the lithographic apparatuses, providing better matching between the aberrations of patterns projected by the lithographic apparatuses.

Abstract: A method comprising determining aberrations caused by each lithographic apparatus of a set of lithographic apparatuses, calculating adjustments of the lithographic apparatuses which minimize differences between the aberrations caused by each of the lithographic apparatuses, and applying the adjustments to the lithographic apparatuses, providing better matching between the aberrations of patterns projected by the lithographic apparatuses.

Abstract: A projection system model is configured to predict optical aberrations of a projection system based upon a set of projection system characteristics and to determine and output a set of optical element adjustments based upon a merit function. The merit function comprises a set of parameters and corresponding weights. The method comprises receiving an initial merit function and executing an optimization algorithm to determine a second merit function. The optimization algorithm scores different merit functions based upon projection system characteristics of a projection system adjusted according to the output of the projection system model using a merit function having that set of parameters and weights.

Abstract: A method comprising illuminating a patterning device (MA?) comprising a plurality of patterned regions (15a-15c) of which each patterns a measurement beam (17a-17c), projecting, with a projection system (PL), the measurement beams onto a sensor apparatus (21) comprising a plurality of detector regions (25a-25c), making a first measurement of radiation when the patterning device and the sensor apparatus are positioned in a first relative configuration, moving at least one of the patterning device and the sensor apparatus so as to change the relative configuration of the patterning device to a second relative configuration, making a second measurement of radiation when the patterning device and the sensor apparatus are positioned in the second relative configuration in which at least some of the plurality of detector regions receive a different measurement beam to the measurement beam which was received at the respective detector region in the first relative configuration and determining aberrations caused by t

Abstract: A projection system model is configured to predict optical aberrations of a projection system based upon a set of projection system characteristics and to determine and output a set of optical element adjustments based upon a merit function. The merit function comprises a set of parameters and corresponding weights. The method comprises receiving an initial merit function and executing an optimization algorithm to determine a second merit function. The optimization algorithm scores different merit functions based upon projection system characteristics of a projection system adjusted according to the output of the projection system model using a merit function having that set of parameters and weights.

Abstract: A method comprising illuminating a patterning device (MA?) comprising a plurality of patterned regions (15a-15c) of which each patterns a measurement beam (17a-17c), projecting, with a projection system (PL), the measurement beams onto a sensor apparatus (21) comprising a plurality of detector regions (25a-25c), making a first measurement of radiation when the patterning device and the sensor apparatus are positioned in a first relative configuration, moving at least one of the patterning device and the sensor apparatus so as to change the relative configuration of the patterning device to a second relative configuration, making a second measurement of radiation when the patterning device and the sensor apparatus are positioned in the second relative configuration in which at least some of the plurality of detector regions receive a different measurement beam to the measurement beam which was received at the respective detector region in the first relative configuration and determining aberrations caused by t