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Click here to view actual size (1152 x 835) Ideal for real-time acquisition and analysis, Scan Mode allows you to select any number of windows and lines to extract data from the evolving RHEED pattern. In this way you can pull out and store the pertinent diffraction data and discard the rest, cutting down on data storage requirements and maximizing time resolution. Linescan data is "stacked " in time, forming Scan Mode images that beautifully and simply show the evolution of the diffraction pattern, while containing all the necessary diffraction information. Windows can be either stored in their entirety, forming "Area Images" similar to the Scan Mode images, or the windows can be analyzed on-the-fly, storing only the resultant window analysis data, (peak intensity, average intensity, centroid positions, tracking positions, etc.). Acquired image data can also be stored and played back as "movies", with full analysis capability. The live video window (2) shows the windows and lines that will be extracted during the run. Note that the tracking has been set to peak, so each window will "lock on" to and center itself on the peak intensity within the window during the run. (2) Scan Mode Region Selection The user has pre-selected 5 windows and 3 lines for extraction and analysis during this Scan Mode run. Note that the lines may be of any length and orientation. There is no limit to how many windows and lines are extracted. This plot shows the evolution of the peak intensity within each window in (2) during the Scan Mode run. The user may select what type of real-time window analysis to plot (for example, peak intensity, average intensity, or centroid intensity). This plot shows the real-time profiles of the lines in (2). In this manner the user can monitor the evolution of diffraction peaks, noise, etc. Note that there are additional real-time charts that may be displayed: for example, real-time lattice spacing, real-time FWHM/coherence length, and real-time analog input voltage. The kSA 400 offers a variety of image acquisition control settings, yielding a very powerful acquisition system. For example, CCD exposure time, image digitizer analog-to-digital conversion settings, frame adding, background subtraction, image filtering, and false coloring may all be applied to incoming images. Due to the multiple threading capabilities of the kSA 400, these various options may be applied on-the-fly, resulting in immediate visualization of the applied settings. One of the kSA 400 Plug In options the Staib Gun Control option. This option gives the user complete computer control of the Staib series of electron guns. Combined with the real-time image display on the computer monitor, the user may easily adjust all gun parameters and simultaneously see the results on the screen. In addition, user defined settings may be automatically set using a controlled ramp, and automated rocking scans may be obtained (for those users with the Staib Beam Rocking capability).
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