Orthogonality determination method for direct writing system motion platform

The invention discloses an orthogonality determination method for a direct writing system motion platform. The method comprises the following steps: (1) designing a photolithography file, and forming positioning mark points at four corners; (2) fixing a substrate on the motion platform; (3) carrying out direct writing exposure on the substrate according to the photolithography file; (4) recording XY directions, corresponding to the motion platform, of various sides of the substrate and then carrying out developing, cleaning and drying; (5) rotating the substrate 90 degrees and then fixing the substrate on the motion platform of a direct writing system; (6) moving the motion platform, locating the four positioning mark points at the center positions of a CCD respectively, and recording the corresponding position coordinates; and (7) forming a parallelogram by connection lines of the position coordinates and calculating the orthogonality of the motion platform. Compared with the prior art, third-party equipment or tool is not needed, so that the method disclosed by the invention is short in period, simple, convenient, low in cost and suitable for correction of large-width platforms.