Spatial accuracy correction method and apparatus

A spatial accuracy correction apparatus comprising:

• a positioning machine that displaces a displacer to a predetermined set of spatial coordinates, the positioning machine comprising a retroreflector mounted to the displacer, the positioning machine being configured to measure a measurable value of the spatial coordinates of the retroreflector;
• a laser interferometer having a reference point and configured to measure a measurable length value that is a distance from the reference point to the retroreflector;
• and
• a controller operably connected to the positioning machine and the laser interferometer, the controller comprising a processor and a memory that stores an instruction, the processor further comprising, as a configuration when the processor executes the instruction stored in the memory:
• a measurement controller that divides a plurality of measurement points into a plurality of measurement lines, displaces the displacer to the plurality of measurement points, and acquires the measured length value and the measured value at each of the measurement points;
• and
• a correction value calculator that performs parameter calculation that calculates a correction parameter based on the measured value, the measured length value, and the coordinates of the reference point, wherein the correction value calculator applies a first correction constant to the measured length value for each measurement line, and applies a second correction constant different from the first correction constant to the coordinates of the reference point for each measurement line to calculate the correction parameter.