EdgeMPE.spt is typically used to map the focus SUM and Error signals at the edge of the plate over a range of carriage positions, but at a fixed drum position. This is version assumes an MPE is hosting the head. It can be desirable to observe the edge of the plate for excessive plate curl and or SUM signal roll off at the edge. This script is supplied by the Thermal 2 group.

When to run this script:

• If you are investigating focus errors at the edge.
• If you are having edge detect problems and image shift in the sub-scan direction towards the away end of plate and you want to know how is the plate edge.
• Anytime a sub-scan slice map of the plate (or drum, for that matter) is desired.

Instructions:

1. Have the desired plate for observation mounted and know your carriage positions for the start and end of mapping (in "CAU" Creo Arbitrary Units. CAU's must be used because it is the only way to get high resolution sampling if required).
2. Decide on the desired resolution.
   Note: Typically, and for the case when you are going to map what the edge detect sequence would "see", you should do a "plot edge" first to set and hold the drum position. The script will ask if you want to move the drum or leave it where it is. However, you must then set up the focus relfectivity yourself because the head will have been set for the edge detect reflectivity which is different than for regular operation (use th2 "foc relfect 0.13", for example (note some MPE versions do NOT adjust the SR for edge detect)). The script will do the rest.
3. Observe the output graphs for the results. Note the plate edge in the enclosed examples changes about 15 or 20 microns in one swath width. This is very typical (we have seen 40 microns in one swath width) and by far exceeds the depth of focus of the write optics over one swath width. The SUM signal for the enclosed example is pretty good right to the plate edge [Doug: find an example of SUM signal roll off...].
   Sometimes the SUM signal rolls off at the plate edge which in turn can cause the edge detect signal to delay triggering. The first example had the SUM signal too low. In the second, it is higher.

>> carriage
Querying Carriage Status ...
Current Position: 9791 mil (117500 counts) (valid)  <<<< from here 9791 / 117.5 = 83 Mils / CAU
Home Sensor:      False
Away Sensor:      False
Current Speed:    0 mil/sec (0 synth)
Carriage state: Idle
Most recent plate edge: 9430939 pmil                <<<< from here 9430.939 /83 = 113.6 CAU = edge
*** State message: Carriage command (8) Complete