System and method for heterodyne interferometer high velocity type non-linearity compensation
AssigneeAgilent Technologies, Inc.
InventorDavid C. Chu
Life of this patent
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Abstract
A system and method for compensating non-linearity of the high-velocity type manifested in heterodyne interferometer position data includes receiving a plurality of groups of digital position values. A plurality of groups of digital phase values from a measurement channel are received. A first group of the digital position values and digital phase values are digitally processed to generate a plurality of block data values. The plurality of block data values are digitally processed to generate at least one quasi-static non-linearity parameter. A second group of the digital position values are compensated based on the at least one quasi-static non-linearity parameter.
Claims25
A method for compensating non-linearity of the high-velocity type manifested in heterodyne interferometer position data, the method comprising:
- receiving a plurality of groups of digital position values;
- receiving a plurality of groups of digital phase values from a measurement channel;
- digitally processing a first group of the digital position values and digital phase values to generate a plurality of block data values;
- digitally processing the plurality of block data values to generate at least one quasi-static non-linearity parameter;
- and
- compensating a second group of the digital position values based on the at least one quasi-static non-linearity parameter.
A compensation system for compensating a high velocity type of non-linearity in heterodyne interferometer position data, the system comprising:
- a first input for receiving a plurality of groups of digital position values, each digital position value including a whole number portion and a fractional number portion;
- a second input for receiving a plurality of groups of phase values from a measurement channel;
- a digital position-data processor for digitally processing a first group of the digital position values and measurement channel phase values and generating a plurality of data values;
- a digital data value processor for processing the plurality of data values and generating at least one non-linearity parameter;
- and
- a digital compensator for compensating a second group of the digital position values based on the at least one non-linearity parameter.
A displacement measuring heterodyne interferometer system comprising:
- a light source for generating at least one light beam;
- an interferometer for generating an optical measurement signal based on the at least one light beam;
- a receiver for receiving the optical measurement signal and an optical reference signal, the receiver configured to generate an analog measurement signal based on the optical measurement signal and configured to generate an analog reference signal based on the optical reference signal;
- a controller for generating a plurality of groups of digital position values and measurement channel phase values based on the analog measurement signal and the analog reference signal;
- and
- at least one digital signal processor coupled to the controller for digitally processing each group of the digital position values and measurement channel phase values and generating a plurality of data values for each processed group, the at least one digital signal processor configured to digitally process the plurality of data values for each processed group to generate at least one non-linearity parameter for each processed group, the at least one digital signal processor configured to non-linearity compensate digital position values based on the at least one non-linearity parameter, wherein the non-linearity being compensated is of a type occurring at relatively high velocities.
Dependencies are inferred from the claim text.