Data flow in Acquisition

Data acquisition from a detector in general is a continuous, repetitive process. It consists of several levels of recurring events (loops). This layout provides great flexibility in tuning cycle parameters to specific needs, but it may appear confusing at first. When learning xDSoft, read the overview and examine diagram to get conceptual idea of relationships between different parts of acquisition cycle. Once you try various acquisition cycles, return to this page and re-read description of cycle steps for better understanding of individual parameters.

Point or click on components for further details:

The core of acquisition involves requesting data (initiating acquisition) from a detector and reading these data after acquisition is complete. There are several possible timing scenarios depending on the specific detector used.

Detector itself can repeat elementary acquisition several times. One or several detector acquisitions constitute single detector accumulation event. Depending on the hardware, individual acquisitions can be combined differently within accumulation.

Accumulation events can, in turn, be repeated several times. Together they combine in an integration event. Initial accumulation events may be discarded to increase reproducibility of overall data if timing permits. Integration component wraps all underlying acquisition and accumulation events into a single step which occurs only once within overall cycle. This is the only step that generates data.

Once data have been generated, a series of optional on-line processing steps start. This processing is different from post-processing in that it has to occur in real-time. Therefore, processing should be limited to necessary as it can generate a significant overhead on the computer.       

Processing step involves most of numerical processing of raw data. In simplest form it can do nothing, but it can involve pooling data together according to selected algorithm, subtracting dark signal, calculating absorption etc. Specific operations are defined by Processing mode.

Once per cycle data may be displayed in the visual feedback (Display) plot. Depending on settings, data for Display may be picked up either before or after Processing. An option of choosing whether to display raw or processed data allows for much greater flexibility in optimizing and troubleshooting optical system, but require some caution from the operator because data that are displayed are not necessarily the same as data that are being streamed into a document. In some cases displaying current data may be suppressed to reduce overhead and to shorten cycle time.

The last data-related step in acquisition cycle involves delivery of processed data into Destination document. Spectral acquisition cycle streams data on every cycle, while serial acquisition may buffer several cycles of data before streaming data packet to the document.    

Cycle is completed by invoking additional, non-data generating hardware. Exposure or photolysis Shutter is the most common example. There is currently no additional hardware in serial acquisition, although it can be added as experiments require.