Stratus OCT User Manual PN 2660021134133 A
Analysis Protocols
6-41
Each A-scan consists of 1024 data points on the longitudinal axis (from 1 to 1024 anterior
to posterior) over 2 mm of depth. There are two vertical cursors. You can drag the red
cursor 1 or green cursor 2 along the 1024 data points. At lower right, the signal value at
the indicated data point appears in decibels. For example, the green “Cursor 2 Value is
31.3 dB at [data point] 10.” At bottom right, “Difference is” and “Distance is” give,
respectively, the signal value difference and distance between the red and green cursors.
The blue horizontal cursor has a particular purpose described next.
Signal Offset Threshold Comparison
The blue cursor 3 enables you to make threshold comparisons among the signal values in
the A-scan. The blue cursor has a second horizontal line offset from it by 36.2 decibels by
default. You can change the offset value by clicking in the “Offset is” field, typing a new
number and clicking the Change button next to it. The offset value range is -56 to +56
decibels. By aligning the blue cursor or its offset line with a particular signal value—
usually a signal peak or trough on the graph—you can visually identify data points that
cross or fail to cross the chosen offset threshold.
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