The Time Stamp Form can be used to evaluate the timestamp data and
to to check the accuracy of the readout times.
The Time Stamp
Data is stored in the memory, while a drift scan image, a speckle
image, a fast scan image or a sub array image is taken.
There is
stored the time stamp data from maximal number of lines, which can be
set in Settings Computer, but it can be taken images with much more
lines
It is stored the time, a line is read out form the CCD.
The time at the start of the image is 0 .
To show the data in
the ListBox, press "Show Data".
To calculate the
standard deviation press "Calculate standard deviation".
The
data can be also saved to a file.
To save the ListBox, as it is
shown, chose: File , Save ListBox to file.
To save the raw data
chose: File, Save raw data to file.
The saved files are text
files and can be read in by other programs.
The decimal separator
in the ListBox can be changed. (affects only the ListBox in this
form, in the rest of the program the decimal separator is "."
)
The column separator can be used to separate the columns in the
ListBox. If the data saved form the ListBox is read in form example
by excel, decimal separator "." and column separator "tab"
should work.
Scale is used to show / save the data in seconds,
milliseconds or microseconds (ListBox, raw data is always in
seconds).
The "Hide" button will hide the form.
The
Edit field "Time per line (should be)" shows the time per
line, as set in the Settings Form
The Edit field "mean +
3*sigma (in sec) (Calculate standard deviation)" shows "mean
+ 3*sigma " after pressing "Calculate standard deviation".
This value can be copied and pasted in the "Time per line in
s " (Shiftime) Edit field in the Settings Form (for speckle or
fast scan images)
Examples, format of the data:
Drift
scan image, fast scan image:
time in ms :
Line Time Difference
Error (mean) Error(whole)
Line: the number of the line
Time:
the time the line is read out.
Difference = TimeLine[n] -
TimeLine[n-1];
Error(mean) First the mean time to read out a line
is calculated.
Error(mean)=mean - Difference;
Error(whole) The
whole error.
Error(whole) = TimeLine[n] - n * Shiftime;
Shifttime
is "Time per line in s" set in the Settings Form.
Speckle
image:
Like the data of a drift scan image, except, a new frame
is indicated with "n"
Sub frame image:
B
indicates the begin of a sub frame
E indicates the end of a sub
frame
In the next column the number of the sub frame is
shown.
Then the time is shown.
Then the difference of the time
and the time in the last line is shown
The difference in a "B"
line is the time it takes to shift the lines one sub frame, if this
time is to large, you will get some steaking. To avoid that, the
tracking CCD should be used.
The difference in a "E"
line is the time the sub frame is exposed
There are taken more
sub frames as fits on the CCD to avoid effects by opening the
Shutter, but of course there are only stored the last sub frames
which fits on the CCD.
Effect of the accuracy of the timing
in drift scan images:
Taking a drift scam image, every line must
be read out at a definite time.
If one line is read out a little
late, the next line will be read out earlier, that will be no problem
The first lines of the image may be read a little late, this will
only degrade the first lines of the image.
If there are read out
many lines to late, or if the necessary read out speed can not be
reached, the quality of the image will degraded.
This may happen,
if you use a very long focal length at 1 x 1 binning.
ST-7 > 4
m
ST-8 > 2 m
After taking an image, a message is shown, in
this message you can check also if the necessary read out speed is
reached.
If the focal length is to long, you will see this in the
data.
Do not run a second active program, which requires processor
time at the same time.
Don't select an other window, mousing
should be avoided while taking an image.
It can be selected 2 x 2
binning, you will have a faster readout speed and have to read out a
line half as often.
Or use the planetary mode (but this will
decrease the FOV)
Disabling brake while taking an image may also
increase the readout speed a little.