SQUAL
Address: 0x05
Access: Read
Reset Value: Undefined
Bit
7
6
5
4
3
2
1
0
Field
SQ7
SQ6
SQ5
SQ4
SQ3
SQ2
SQ1
SQ0
Data Type: Upper 8 bits of a 9-bit unsigned integer.
USAGE: SQUAL (Surface Quality) is a measure of the number of valid features visible by the
sensor in the current frame.
The maximum SQUAL register value is TBD. Since small changes in the current frame can result
in changes in SQUAL, variations in SQUAL when looking at a surface are expected. The graph
below shows 500 sequentially acquired SQUAL values, while a sensor was moved slowly over
white paper. SQUAL is nearly equal to zero, if there is no surface below the sensor. SQUAL is
typically maximized when the navigation surface is at the optimum distance from the imaging lens
(the nominal Z-height).
SQUAL Value (white Paper)
100
90
80
70
60
50
40
30
20
10
0
Count
Figure 21. SQUAL values (white paper)
Mean SQUAL vs Z (white paper)
60
50
40
30
20
10
0
-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
Delta from Nominal Focus (mm)
Figure 22. Mean SQUAL vs. Z (white paper)
19
AGILENT [ AGILENT TECHNOLOGIES, LTD. ]
