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Merlin

The MerlinEM detector by Quantum Detectors is a fast pixelated detector capable of collecting electron diffraction data with virtually no noise and a high dynamic range (log scale 10^6).

Instamatic communicates with the Merlin control software via TCP/IP connection. This means that there is a fast connection with little overhead when collecting data.

In continous read/write mode, instamatic can achieve gapless data acquisition MerlinCamera.get_movie(). When continuously collecting single images using MerlinCamera.get_image(), there is a ~3 ms overhead per frame.

Setup

Enable merlin in settings.yaml:

camera: merlin

You can set up the parameters for the Merlin camera through camera/merlin.yaml in your config directory.

For an example config file, see: camera/merlin.yaml. Click here to go to the page with all common camera configuration parameters.

In addition, the Merlin camera has the following parameters to configure:

host
Set this to localhost or 127.0.0.1 if the Merlin control software runs on the same PC as instamatic. To make a remote connection over the network, pujt the IP of the PC where Merlin is running. For example: 
host: '10.0.0.123'
commandport
This is the port that instamatic uses to communicate with Merlin. Defaults to 6341.
dataport
This is the port that Merlin sends data. Defaults to 6342.
detector_config
The parameters under detector_config are directly sent to the Merlin software when instamatic starts. These can be used to put the Merlin in the desired state for data acquisition. Any command with a SET type can be adjusted. Check the Merlin EM documention for more information.
The default sets continuous read-write mode and 12-bit mode to minimize the gap between frames. It also disables automatic file writing (FILEENABLE) and image processing by Merlin, and enables headless RUNHEADLESS mode for faster throughput. If you don't want this, you can delete these lines or modify them.
detector_config:
  CONTINUOUSRW: 1
  COUNTERDEPTH: 12
  FILEENABLE: 0
  RUNHEADLESS: 1

You could for example also set the thresholds and bias in the instamatic config by adding these lines: 

detector_config:
  THRESHOLD0: 120
  THRESHOLD1: 40
  HVBIAS: 511

Notes on using instamatic with Merlin

  • Make sure the Merlin software is running before starting instamatic
  • When instamatic is running, it's advised not to change acquisition settings in the Merlin control software.
  • Changing exposure on the fly (for example, in the gui) incurs a small overhead (~300 ms).