Uniblitz Fast Shutter (25 mm)

The fast shutter at 2A is located just downstream of I0 (i.e. upstream of all in-hutch optics) and is used to limit the beam exposure of the sample optics. The spec command 'closes' causes the shutter to be closed except when data is being collected; on data acquisition, the shutter opens, data is collected, and then the shutter closes again until the next acquisition. In this manner the sample is not exposed while data is not being collected and thus the 'closes' state is the default state of the shutter. In limited instances, generally related to beam alignment, the shutter can be forced to remain open using the command 'opens', which will cause the shutter to be open regardless of data acquisition.

Changing the data acquisition delay

The off-the-shelf state of the fast shutter causes it to open shortly after data (~20 ms) acquisition has begun. This can lead to artifacts in the data, and so a delay between shutter opening and data acquisition can be introduced via the shutter.mac macro in the Macros folder. The delay is defined within this macro and is implemented by running the macro (udo /mnt/home/chess_id2a/Macros/shutter.mac) followed by setting the 'shutter_auto' variable to 0 and then to 1. Changes to this delay require these steps to be repeated. For convenience, the call to shutter.mac and the setting of shutter_auto are included in userlist.mac and so the inclusion of this delay should be the default behavior.

-- ChrisPollock - 08 Feb 2022