User`s manual

4-1
Positional Deviation Measurement
4
Chapter 4: Positional Deviation Measurement
4-1 Outline
Purpose
Example
Application
The gray scale search function and edge detection function* make possible measuring
positional deviation as well as the absolute position.
- 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).
[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
* Gray scale search / edge detection function
Gray scale search: Compares a workpiece image with the 256-level gray-scale
reference image to find an area that matches the reference image.
- See page G-6 of the User’s Manual (Hardware & Instruction).
Edge detection: Finds the boundary between light and dark areas in an image.
- See page G-3 of the User’s Manual (Hardware & Instruction).
- The deviation angle q, determined in the 2-point search, is used to readjust the
rotation of the image for measurements 1 to 4.
(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 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: q
Xa2-Xa1
Ya2-Ya1
q
Search area
(image a)
Yb2-Yb1
Xb2-Xb1
Search area (image b)
Anglar deviation: q
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)