|Format||SCANV [X=start] [Y=stop] [Z=number_of_lines] [F=overshoot_factor]|
|Units||X and Y in mm, Z in integer, F in positive real|
|Remembered||Using SS Z|
|Format||[addr#]SCANV [X=start] [Y=stop] [Z=number_of_lines] [F=overshoot_time] [T=scan_overshoot]|
|Units||X and Y in mm, Z in integer, F in ms|
|Remembered||Using [addr#]SS Z|
Z parameters set up the slow-scan (vertical) start and stop positions, with the position values expressed in millimeters, and the number of lines. The stage will move to the start position before beginning the scan. The scan range will be divided into number_of_lines lines. Following a completed horizontal scan, the stage will move vertically to the next scan line. The processes will conclude when the stage has moved to the vertical stop position and completed the last horizontal scan. If the start and stop values are identical then a 1-D scan will occur, repeated number_of_lines times.
T parameters pertain to the fast-scan (horizontal scan) motion, and there is a difference between the behavior of the
F parameter on TG-1000 vs. MS-2000.
On MS-2000, overshoot_factor (
F) sets the amount of extra motion to account for the acceleration ramp at the start and stop of the trace. An overshoot_factor=1.0 (default) sets the pre and post move distances equal to the ramp up and down distances. Using a larger number will allow for more time to reach constant speed before the active sweep region.
On TG-1000, overshoot_time (
F) sets an additional settling time in ms for the stage velocity to settle before reaching the start position (beyond the always-required ramp time set by the
AC command). Thus the time required between scan line initiation and reaching the start position is given by summing the
AC time and the
NV F time. The same delay occurs after the stop position except for raster scans in firmware v3.20 and higher in which case the after-stop overshoot time is capped at 10ms. The default value is 50ms.
T parameter was partially implemented for TG-1000 firmware versions 3.17 and 3.18, absent in 3.19, and then present in 3.20 and greater. It is intended mostly for scan-optimized stages that have a significant amount of physical backlash. The default value is 0.02 when the SCAN_OPTIMIZED define is enabled and 0 otherwise. If the value is non-zero there are several changes to the scan operation: (1) There is an extra overshoot move performed (with amplitude specified by the parameter) before any scan move in either direction, which ensures that the physical backlash is removed correctly before beginning each scan pass. (2) Before the scan moves begin, an initialization move to the center of the range is made to ensure that the overshoot move happens correctly. (3) When the scan moves are complete, the stage moves to the center position (otherwise behavior is to move to the start position).