9-34Positional deviation measurement9PurposeExampleApplicationThe gray scale search function makes it possible to measure positional deviation aswell as the absolute position.· It is also possible to detect the position of sub-pixel units with great accuracy.[Determining the location of the positioning (the fiducial mark) mark that identifies theposition of the substrate](1) 1 point search: Detecting the deviation in position in X and Y directions· The deviation angle (θ), determined in the 2 point search, is used to readjust therotation of the image for measurements 1 to 3.For details about rotational adjustments, see section 9-2, item [5] Position correction.(2) 2 point search: Determining positional deviation in X and Y directions as wellas rotational deviationUsed to determine the position of machine parts and substrates.X2-X1Y2-Y1Search areaInspection Image: Center coordinates (X2,Y2)Reference image: Center coordinates (X1,Y1)[Measured result]Center coordinates: (X2,Y2)Amount of deviation: X2-X1, Y2-Y1[Measured result]· Center coordinates of image a: (Xa2,Ya2)· Amount of deviation of image a: Xa2-Xa1, Ya2-Ya1· Center coordinates of image b: (Xb2,Yb2)· Amount of deviation of image b: Xb2-Xb1, Yb2-Yb1· Deviation angle: (θ)Xa2-Xa1Ya2-Ya1Search area(image a)Yb2-Yb1Xb2-Xb1 Search area (image b)Anglar deviation: (θ)Inspection image a: Center coordinates(Xa2,Ya2)Reference image a: Center coordinates(Xa1,Ya1)Inspection image b: Center coordinates(Xb2,Yb2)Reference image b: Center coordinates(Xb1,Yb1)9-3 Positional deviation and absolute position measurement
