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(2) Positional deviation measurement
The gray scale search function and edge detection function* make possible measuring
positional deviation as well as the absolute position.
Purpose
- It is also possible to detect the position of sub-pixel units with great accuracy.
- A rotation angle of 360° can be detected. (When a one point gray search is selected).
Application
Used to determine the position of machine parts and substrates.
[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
Reference image: Center coordinates (X1,Y1)
(2) 2 point search: Determining positional deviation in X and Y directions as well
as rotational deviation
Example
Reference image b:
Center coordinates (Xb1,Yb1)
Inspection image b: Center coordinates (Xb2,Yb2)
* Gray scale search / edge detection function
Gray scale search: Compares a workpiece image with the 256-level gray-scale
Edge detection:
- The deviation angle θ, determined in the 2-point search, is used to readjust the
rotation of the image for measurements 1 to 4.
Inspection Image: Center coordinates (X2,Y2)
Y2-Y1
Search area
X2-X1
Reference image a: Center coordinates (Xa1,Ya1)
Ya2 Ya1
Search area
Xb2 Xb1
(image a)
reference image to find an area that matches the reference image.
- See G-6.
Finds the boundary between light and dark areas in an image.
- See G-3.
1-9
[Measurement result]
Center coordinates: (X2,Y2)
Amount of deviation: X2-X1, Y2-Y1
Xa2-Xa1
Inspection image a:
Center coordinates (Xa2,Ya2)
θ
θ
Anglar deviation:
[Measurement results]
- 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
Outline
Yb2 Yb1
Search area (image b)
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