Area detector (2D CMOS)¶

The scattering camera is an Axis Photonique CMOS large-area detector on the same goniometer arm as the main photodiode. It replaced the earlier CCD camera on this station; control and analog labels may still use CCD in names (for example CCD Theta motors or CCD Temperature readbacks) even though the sensor is CMOS.

Physical role¶

• Position: set by CCD Theta, CCD X, and CCD Y (see Sample and detector geometry). Those names are legacy beamline axes for the detector arm, not a statement that the sensor is a CCD.
• Protection: the Beam Stop blocks the direct beam from hitting the sensor during scattering; align using the photodiode or beamstop diode instead of exposing the raw beam on the CMOS.
• Temperature: follow vendor and beamline practice for the CMOS head and readout electronics. Legacy analogs CCD Temperature and Camera Temp Setpoint still report cooling or setpoint for the camera stack; confirm limits against the Axis Photonique configuration in use.

Readout parameters¶

Region of interest (ROI) and binning motors (or equivalent software parameters) crop the sensor and reduce readout time at the cost of field of view or spatial resolution. Acquired frame height and width come from the instrument payload (they are not fixed to the old 2048 layout). Exposure is gated by shutter timing and optional CCD shutter control / inhibit lines so that motion does not blur images unintentionally.

Software integration¶

Application code treats the detector as an instrument (default name Axis Photonique in this repository) with acquire, status, and attribute access (vendor SDK behind the control layer). Quality metrics such as exposure time, mean intensity, max intensity, and histogram width are used to reject bad frames (for example shutter edge effects or saturation) before writing files or stacks.

Relation to other signals¶

• AI 6 BeamStop or Photodiode channels provide scalar flux concurrent with 2D frames for normalization or absorption estimates.
• Digital lines coordinate shutter, camera trigger, and pause during multi-point scans.

For API-level names used in Python helpers, see the API reference; this page describes hardware and experiment roles only.