peakAnalyser ¶

author:: Xiaoqiang Wang

Introduction ¶

This is an EPICS areaDetector driver for Scienta Omicron analysers using the PEAK API. It has been tested with PEAK software release 1.3.0 with a DA30L analyser. Due to the many changes in PEAK API, the minimum required PEAK version is 1.3.0.

The PEAK API uses JSON-RPC protocol and supports both HTTP and WebSocket. This driver will choose the implementation based on the host address, i.e. ws://127.0.0.1:8087 for WebSocket and http://127.0.0.1:8087 for HTTP.

Implementation of standard driver parameters ¶

The following table describes how the driver implements some of the standard driver parameters defined in ADDriver.

EPICS record name	EPICS record type	Description
$(P)$(R)AcquireTime, $(P)$(R)AcquireTime_RBV	ao, ai	Analyser dwell time.
$(P)$(R)NumImages, $(P)$(R)NumImages_RBV	longout, longin	Number of spectra to acquire in Multiple image mode.
$(P)$(R)NumExposures, $(P)$(R)NumExposures_RBV	longout, longin	Number of iterations to accumulate for each spectrum.
$(P)$(R)MaxSizeX_RBV	longin	Camera channel area size in X direction.
$(P)$(R)MaxSizeY_RBV	longin	Camera channel area size in Y direction.
$(P)$(R)MinX, $(P)$(R)MinX_RBV	longout, longin	Camera ROI in X direction, initialised with camera spatial calibration values.
$(P)$(R)SizeX, $(P)$(R)SizeX_RBV	longout, longin
$(P)$(R)MinY, $(P)$(R)MinX_RBV	longout, longin	Camera ROI in Y direction, initialised with camera spatial calibration values.
$(P)$(R)SizeY, $(P)$(R)SizeX_RBV	longout, longin
$(P)$(R)Manufacturer_RBV	stringin	“Scienta Omicron”
$(P)$(R)Model_RBV	stringin	Analyser model name
$(P)$(R)SerialNumber_RBV	stringin	Analyser serial number
$(P)$(R)SDKVersion_RBV	stringin	PEAK software release version
$(P)$(R)FirmwareVersion_RBV	stringin	PEAK server version

peakAnalyser specific parameters ¶

The peakAnalyser driver implements the following parameters in addition to those in ADDriver. The records are in peakAnalyser.template.

Acquisition information ¶

These values are estimated by the server about the current configured acquisition. Once the first step is acquired, $(P)$(R)STEPS_RBV might be updated again with the actual value.

EPICS record name	EPICS record type	Description
$(P)$(R)ETA	ai	Estimated time of acquisiton in seconds.
$(P)$(R)ETA_STR	stringin	ETA in hh:mm:ss format.
$(P)$(R)STEPS_RBV	longin	Number of steps that analyser acquires per iteration.
$(P)$(R)STEPS_COUNTER_RBV	longin	Number of steps that analyser has acquired for the current iteration.
$(P)$(R)PROGRESS	ai	The total progress in percentage of the current acquisition.

Analyser modes settings ¶

Note

These settings configure the next acquistion and do not immediately change the current analyser.

EPICS record name	EPICS record type	Description
$(P)$(R)ACQ_MODE, $(P)$(R)ACQ_MODE_RBV	mbbo, mbbi	Specify how analyser changes kinetic energy and theta Y Fixed Sweep Energy Sweep ThetaY Sweep Energy & ThetaY Theta Y sweeping is only possible if the lens mode supports.
$(P)$(R)ENERGY_MODE, $(P)$(R)ENERGY_MODE_RBV	bo, bi	Format of the energy input Kinetic Binding In case of Binding, $(P)$(R)EXCITATION_ENERGY must be valid. $(P)$(R)LOW_ENERGY, $(P)$(R)CENTER_ENERGY and $(P)$(R)HIGH_ENERGY are expected to be binding energy expressed in negative numbers.
$(P)$(R)WORK_FUNCTION, $(P)$(R)WORK_FUNCTION_RBV	ao, ai	Work function
$(P)$(R)EXCITATION_ENERGY, $(P)$(R)EXCITATION_ENERGY_RBV	ao, ai	Photon energy, used to calculate kinetic energy from binding energy input. i.e. `kinetic = excitation - work + binding`.
$(P)$(R)SLIT, $(P)$(R)SLIT_RBV	mbbo, mbbi	The current entrance slit.
$(P)$(R)FOCAL_POS_X, $(P)$(R)FOCAL_POS_X_RBV	ao, ai	The elctron optical focal position on the sample in X direction.
$(P)$(R)FOCAL_POS_Y, $(P)$(R)FOCAL_POS_Y_RBV	ao, ai	The elctron optical focal position on the sample in Y direction.
$(P)$(R)FOCAL_POS_Z, $(P)$(R)FOCAL_POS_Z_RBV	ao, ai	The elctron optical focal distance from the sample surface.
$(P)$(R)ELEMENT_SET_RBV	mbbi	Current analyser element set name.
$(P)$(R)LENS_MODE, $(P)$(R)LENS_MODE_RBV	mbbo, mbbi	Specify the analyser lens mode to be used in the acquisition. The list of lens modes are initialised from the current analyser configuration.
$(P)$(R)DETECTOR_MODE, $(P)$(R)DETECTOR_MODE_RBV	mbbo, mbbi	Specify the detector counting mode to be used in the acquisition. Image - Use camera counts Events - Detect electron events
$(P)$(R)PASS_ENERGY, $(P)$(R)PASS_ENERGY_RBV	mbbo, mbbi	Specify the pass energy to be used in the acquisition. The choice of pass energies are initialised from the current analyser configuration. And it can still be further limited in some lens modes.
$(P)$(R)WITH_SLICE_RBV	bi	Indicate whether the current lens mode supports Theta X.
$(P)$(R)WITH_THETA_Y_RBV	bi	Indicate whether the current lens mode supports Theta Y.
$(P)$(R)CHANNELS, $(P)$(R)CHANNELS_RBV	longout, longin	Specify the desired number of channels in X direction. This will not excceed the current camera width $(P)$(R)SizeX.
$(P)$(R)SLICES, $(P)$(R)SLICES_RBV	longout, longin	Specify the desired number of channels in Y direction. This will not excceed the current camera height $(P)$(R)SizeY.

Spectrum region definition ¶

For axis in sweeping mode, a low and a high value define the range, and then a step value defines the number of points

count = ceil((high-low-epsilon)/step) + 1

Once an input value is specified, the driver calls the to server to validate the range and updates readback values, which might differ from the inputs. And after the first step is acquired, the readback values are updated again to reflect the actual measured values.

EPICS record name	EPICS record type	Description
$(P)$(R)LOW_ENERGY, $(R)$(R)LOW_ENERGY_RBV	ao, ai	Specify the list of energies to acquire.
$(P)$(R)HIGH_ENERGY, $(R)$(R)HIGH_ENERGY_RBV
$(P)$(R)STEP_ENERGY, $(R)$(R)STEP_ENERGY_RBV
$(P)$(R)CENTER_ENERGY, $(R)$(R)CENTER_ENERGY_RBV
$(R)$(R)LOW_SLICE_RBV	ao, ai	Analyser theta X range. All values are readback only, except that the center value can be specified in certain lens mode.
$(R)$(R)HIGH_SLICE_RBV
$(R)$(R)STEP_SLICE_RBV
$(P)$(R)CENTER_SLICE, $(R)$(R)CENTER_SLICE_RBV
$(P)$(R)LOW_THETA_Y, $(R)$(R)LOW_THETA_Y_RBV	ao, ai	Specify the list of theta Y angels to acquire. These values are used only for lens modes that support Theta Y.
$(P)$(R)HIGH_THETA_Y, $(R)$(R)HIGH_THETA_Y_RBV
$(P)$(R)STEP_THETA_Y, $(R)$(R)STEP_THETA_Y_RBV
$(P)$(R)CENTER_THETA_Y, $(R)$(R)CENTER_THETA_Y_RBV

Live Spectrum ¶

During acquisition, the driver polls the live spectrum at maximum 1Hz. The NDArray image is available on addr=0. The following records describe the integrated spectrum.

EPICS record name	EPICS record type	Description
$(P)$(R)SPECTRUM	waveform	The integrated spectrum along the energy axis, updated at maximum 1Hz during acquistion.
$(P)$(R)ENERGY_SCALE_RBV	waveform	The scale array along the energy axis.
$(P)$(R)SLICE_SCALE_RBV	waveform	The scale array along the theta X axis.

Electronics control ¶

EPICS record name	EPICS record type	Description
$(P)$(R)ZERO_SUPPLIES	longout	Zero all electronics power supplies.

Configuration ¶

The peakAnalyser driver is created with peakAnalyserConfig command, either from C/C++ or from the EPICS IOC shell:

int peakAnalyserConfig(const char *portName,
                       const char *hostAddress)

portName: asym port name this driver creates
hostAddress: PEAK manager server address, e.g. ws://127.0.0.1:8087, http://127.0.0.1:8087

MEDM screen ¶