Abstract: The invention provides a wavelength tracking system comprising a wavelength tracking unit and an interferometer system. The wavelength tracking unit has reflection surfaces at stabile positions providing a first reflection path with a first path length and a second reflection path with a second path length. The first path length is substantially larger than the second path length.

Abstract: An interferometer system, including a heterodyne interferometer and a processing system. The heterodyne interferometer is arranged to provide a reference signal and a measurement signal. The reference signal has a reference phase. The measurement signal has a measurement phase and an amplitude. The processing system is arranged to determine a cyclic error of the heterodyne interferometer based on the reference phase, the measurement phase and the amplitude.

Abstract: The invention provides a wavelength tracking system comprising a wavelength tracking unit and an interferometer system. The wavelength tracking unit has reflection surfaces at stabile positions providing a first reflection path with a first path length and a second reflection path with a second path length. The first path length is substantially larger than the second path length.

Abstract: An alignment system configured to be substantially insensitive to thermal variations in its system during alignment measurements. The alignment system includes a sensor system, a support structure, a sensing element, a position measurement system, and an athermal interface between the sensing element and the support structure. The sensor system is configured to determine a position of an alignment mark on a substrate and the support structure is configured to support the sensor system. The sensing element is configured to detect an unintentional displacement of the support structure and the position measurement system is configured to measure the unintentional displacement relative to a reference element based on the detected unintentional displacement. The athermal interface is configured to prevent detection of temperature induced displacement of the support structure by the sensing element.

Abstract: An encoder includes an optical component and an enclosing device having a first surface portion and a second surface portion. The first surface portion is arranged to receive from an ambient environment a first radiation beam. The second surface portion is arranged to receive from the ambient environment a second radiation beam. The optical component is arranged to combine the first and second radiation beams. The enclosing device is arranged to propagate the first radiation beam along a first path. The first path is between the first surface portion and the optical component. The enclosing device is arranged to propagate the second radiation beam along a second path. The second path is between the second surface portion and the optical component. The enclosing device is arranged to enclose a space, so as to isolate the first path and the second path from the ambient environment.

Abstract: An interferometer system, including a heterodyne interferometer and a processing system. The heterodyne interferometer is arranged to provide a reference signal and a measurement signal. The reference signal has a reference phase. The measurement signal has a measurement phase and an amplitude. The processing system is arranged to determine a cyclic error of the heterodyne interferometer based on the reference phase, the measurement phase and the amplitude.

Abstract: An alignment system configured to be substantially insensitive to thermal variations in its system during alignment measurements. The alignment system includes a sensor system, a support structure, a sensing element, a position measurement system, and an athermal interface between the sensing element and the support structure. The sensor system is configured to determine a in position of an alignment mark on a substrate and the support structure is configured to support the sensor system. The sensing element is configured to detect an unintentional displacement of the support structure and the position measurement system is configured to measure the unintentional displacement relative to a reference element based on the detected unintentional displacement. The athermal interface is configured to prevent detection of temperature induced displacement of the support structure by the sensing element.

Abstract: A lithographic apparatus includes an optical sensor, a movable body, a support, a deflector system, a first drive system and a second drive system. The movable body is moveable relative to the sensor. The support is for holding the sensor. The first drive system is arranged to move the movable body relative to the sensor. The second drive system is arranged to move the first drive system relative to the sensor. The second drive system is arranged to move the deflector system relative to the sensor. A disturbance is induced by a movement of the movable body. The deflector system is arranged to create a deflecting area for reflecting the disturbance away from the support.

Abstract: A lithographic apparatus includes an optical sensor, a movable body, a support, a deflector system, a first drive system and a second drive system. The movable body is moveable relative to the sensor. The support is for holding the sensor. The first drive system is arranged to move the movable body relative to the sensor. The second drive system is arranged to move the first drive system relative to the sensor. The second drive system is arranged to move the deflector system relative to the sensor. A disturbance is induced by a movement of the movable body. The deflector system is arranged to create a deflecting area for reflecting the disturbance away from the support.

Abstract: A lithographic apparatus includes an optical sensor, a movable body, a support, a deflector system, a first drive system and a second drive system. The movable body is moveable relative to the sensor. The support is for holding the sensor. The first drive system is arranged to move the movable body relative to the sensor. The second drive system is arranged to move the first drive system relative to the sensor. The second drive system is arranged to move the deflector system relative to the sensor. A disturbance is induced by a movement of the movable body. The deflector system is arranged to create a deflecting area for reflecting the disturbance away from the support.

Abstract: A positioning system for positioning an object in a lithographic apparatus, including: a first and second object tables moveable in an operating area; a first position measurement system to provide an incremental position measurement of the second object table relative to a reference when in the operating area, wherein the first position measurement system is configured to provide an absolute position measurement of the first object table relative to the reference; a second position measurement system to provide an absolute position measurement of the first object table relative to the second object table, and wherein the first position measurement system is further configured to provide an absolute position measurement of the second object table relative to the reference based on the absolute position measurement of the first object table relative to the reference and on the absolute position measurement of the first object table relative to the second object table.

Abstract: A positioning system for positioning an object in a lithographic apparatus, including: a first and second object tables moveable in an operating area; a first position measurement system to provide an incremental position measurement of the second object table relative to a reference when in the operating area, wherein the first position measurement system is configured to provide an absolute position measurement of the first object table relative to the reference; a second position measurement system to provide an absolute position measurement of the first object table relative to the second object table, and wherein the first position measurement system is further configured to provide an absolute position measurement of the second object table relative to the reference based on the absolute position measurement of the first object table relative to the reference and on the absolute position measurement of the first object table relative to the second object table.

Abstract: A lithographic apparatus includes a position measuring system configured to measure a position of a moveable object with respect to a reference frame of the lithographic apparatus, in at least one direction of an orthogonal x-y-z coordinate system of the moveable object. The position measuring system includes an optical x-z-encoder configured to measure a displacement of a radiation source, a first grating, and a detector with respect to a second grating of the encoder. The first grating includes an alignment marker. A controller is configured to define a zero level of the moveable object with respect to the reference frame in at least one of the x- and z-direction by performing the scanning along the first grating, the alignment marker during the scanning step causing changes in the phase of the response of both the first positive and negative orders.

Abstract: A lithographic apparatus includes a position measuring system configured to measure a position of a moveable object with respect to a reference frame of the lithographic apparatus, in at least one direction of an orthogonal x-y-z coordinate system of the moveable object. The position measuring system includes an optical x-z-encoder configured to measure a displacement of a radiation source, a first grating, and a detector with respect to a second grating of the encoder. The first grating includes an alignment marker. A controller is configured to define a zero level of the moveable object with respect to the reference frame in at least one of the x- and z-direction by performing the scanning along the first grating, the alignment marker during the scanning step causing changes in the phase of the response of both the first positive and negative orders.