9-34
Positional deviation measurement
9
Purpose
Example
Application
The gray scale search function makes it possible to measure positional deviation as
well 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 the
position 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 the
rotation 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 well
as rotational deviation
Used to determine the position of machine parts and substrates.
X2-X1
Y2-Y1
Search area
Inspection 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-Xa1
Ya2-Ya1
θ
Search area
(image a)
Yb2-Yb1
Xb2-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
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