[INSTRM-110] SpS Dither Flat sequence Created: 27/Apr/17  Updated: 17/May/17  Resolved: 09/May/17

Status: Done
Project: Instrument control development
Component/s: ics_spsaitActor
Affects Version/s: None
Fix Version/s: None

Type: Task Priority: Minor
Reporter: fmadec Assignee: arnaud.lefur
Resolution: Done Votes: 0
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Reviewers: fmadec

 Description   

For Arnaud:
implement the dither flat sequence within the spsaitActor.

For others:

according to past discussion we want to move the fiber by a quarter of fiber spacing (+/-60 microns).
some questions remains regarding the way to do it:
which are the inputs parameters you would like?
meaning: do we have a given dither step and a number of dither flat?
do we want a range and a number of dither flat?

do we want to talk in pix? in detector microns? in slit microns?

or is it fix, for example a dither flat is 3 images, one without moving the slit and one at +60 and -60 microns?

what do you think?

 Comments   
Comment by cloomis [ 28/Apr/17 ]

I vote for having two knobs: the spacing between images and the number of positions. In real life I think we will need to iterate a little to get the right numbers.

  • microns-on-detector is probably best, but microns-at-slit is also fine. The ratio probably comes from the procedure in any case....
  • #positions to the side of center (2 would give 5 positions) lets you not deal with even numbers, but I don't really care.
Comment by arnaud.lefur [ 28/Apr/17 ]

We had exactly the same opinion. Let's start with two parameters :

  • shift (microns) I will implement microns at slit first, but we'll able to calculate the ratio from the measures and check if it match theory
  • nb of positions Get rid of even number (1 gives -> 3, 2 gives ->5 ...)

For instance, with shift=60 and nb=2 would gives:
-120,-60,0,60,120

Comment by arnaud.lefur [ 09/May/17 ]

Code has been done and tested.
The shift is in the slit coordinate system for now.

Comment by arnaud.lefur [ 17/May/17 ]

The shift can now be specified in

  • microns in slit coordinates
  • pixels on detector

Merged in 0.8.0

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