Experimental Physics and
Industrial Control System

Mark Rivers via Tech-talk <tech-talk at aps.anl.gov> · Wed, 26 May 2021 12:16:21 +0000

Hi Terry,

> Question is that offset correction then simply held in memory and used for that session and needs to be captured fresh at the start of every session?

Yes the offset it just held in memory.  In practice you will probably want to acquire the offsets more frequently then just once when the IOC starts.  These detectors have a very large offset with quite different values in different regions of the detector, and the offset drifts with time/temperature.  You need to acquire the offset under the same conditions as the actual frames (acquire time, sync mode, etc.).  If you begin to see rectangular blocks in your images when you stretch the contrast to see the background, then it is time to acquire the offset again.

> Also, there appears to be thing in the gui  to load and apply a previously captured file.
Loading files is only supported for gain and bad pixels, not for offset.

> Is there a reason why using a previously captured one wouldn’t work?
The offset, gain, and bad pixel correction uses features in their SDK, which uses the FPGA on the frame grabber to do the corrections.  The SDK does not support loading offsets from a file.

> And is there a way to do that that just doesn’t appear on the gui?
> And a means of controlling the name of the captured offset file (other than the fields used for naming the normal datafiles which is what PEAcquireOffset  appears to do now?)

That is supported by the SDK for gain and bad pixels, but not for offset.

Mark

________________________________
From: Tech-talk <tech-talk-bounces at aps.anl.gov> on behalf of CORNALL, Terry via Tech-talk <tech-talk at aps.anl.gov>
Sent: Tuesday, May 25, 2021 11:08 PM
To: tech-talk at aps.anl.gov
Cc: BRAND, Helen
Subject: offset correction in PerkinElmer AreaDetector [SEC=OFFICIAL]

Hi All.

We have a Varex XRPAD detector and want to use the PerkinElmer Areadetector driver with it. So far it appears to work but we have noticed something we don’t understand about the ‘corrections’ part of the main medm gui.

I see in the PerkinElmer Areadetector medm gui that there is a button ( PV is something:PEAcquireOffset) to capture an offset correction which appears to capture to a TIFF file (if that plugin is enabled) using the filename specified for datafiles.

Question is that offset correction then simply held in memory and used for that session and needs to be captured fresh at the start of every session?

Also, there appears to be thing in the gui  to load and apply a previously captured file.

Is there a reason why using a previously captured one wouldn’t work? And is there a way to do that that just doesn’t appear on the gui? And a means of controlling the name of the captured offset file (other than the fields used for naming the normal datafiles which is what PEAcquireOffset  appears to do now?)

Thanks for any thoughts.

Terry

[cid:[email protected]]

OFFICIAL

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System