Description:
|
When the command "plot phase" has been run once, flattening iterations may be
initiated using the command "plot flatten" from the diagnostic monitor. The
number of iterations is specifed by <number>. Each iteration will write and
scan a 3.9 inch strip on the plate. Make sure that you don't ask for more
iterations than will fit on a plate as the software does not do any checking
for this. Each iteration needs 4 inches of sub scan space. Note that if you did
a previous plot phase or plot flatten on this plate you must set a sub scan
shift so as not to overwrite a previous strip. If required, the pattern is
specified by <pattern>. This must be solid or a high percentage screen. If
<pattern> is omitted, the solid pattern (12) is assumed. The flattening
algorithm will work to some extent with a 50% screen but with significantly
less signal to noise. At each iteration a 3.9 inch wide strip is plotted and
then scanned using the focus laser. The reflected intensity depends on the
unprocessed density on the plate. After scanning, the hdm NVS parameter
"bmslope" and the scorr table are adjusted to try and achieve the same density
for every channel on the next strip to be plotted. Generally about 4 iterations
are required to achieve the best obtainable results. Note that at the end of a
plot flatten series the last visible strip has been scanned and the scorr table
updated but nothing has yet been plotted using the latest scorr table. At the
end be sure to issue the commands "scorr save" and "nvs save hdm" to preserve
the changes.
Unfortunately, flattening the solid will not necessarily produce good results
on the middle screens. On some good heads, flattening the solids will produce
good results on the middle screens and as the heads improve we expect that this
technique will work better. If plate scan does not result in sufficiently high
quality plots then try flattening 50% screens.
|