hardware-interface - 是否可以获得 STEM 检测器信号？

Question

我正在编写一个 DigitalMicrograph 脚本，以获取在由手工脚本控制的各种入射光束条件下从 ADF STEM 检测器等获得的散射电子强度的映射数据。但是，不幸的是，我不知道在非 STEM 模式（由 DigiScan 控制）下获取 STEM 检测器信号的命令。在这种情况下我应该使用什么命令？

如果您分享一些智慧，将不胜感激。非常感谢您提前。.

Answer 1

由于 STEM 检测器信号由 DigiScan 单元处理，因此无法独立读取检测器“信号”。

另外：您不会及时将信号作为“流”获得，而是由 DigiScan 计时。也就是说，您必须使用 DigiScan 开始采集，并且不能仅在没有一台的情况下“收听”检测器。

但是，DigiScan 采集与 STEM 模式无关。您可以在 TEM 模式下开始 DigiScan 采集。您可以选择参数，以便获取“图像”仅在非常小的区域内扫描光束，从而使光束变为准静止。也许这可以帮助你？

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这是我的意思的一个例子：但是，我没有在硬件上测试过这个：

// Create "Scan" parameters for an overview
// This image will stay as survey. Its content is not important
// as you're in TEM mode, but we need it as reference
number paramID
number width    = 1024 // pixel
number height   = 1024 // pixel
number rotation = 0   // degree
number pixelTime= 2   // microseconds
number lSynch   = 0   // no-linesync 
paramID = DSCreateParameters( width, height, rotation, pixelTime, lSynch )

number signalIndex, dataDepth, selected, imageID
signalIndex = 0 // HAADF (most likely) ?
dataDepth    = 4 // 4 byte data
selected    = 1 // acquire this signal
imageID     = 0 // create new image
DSSetParametersSignal( paramID, signalIndex, dataDepth, selected, imageID )

number continuous  = 0 // 0 = single frame, 1 = continuous
number synchronous = 1 // 0 = return immediately, 1 = return when finished

// Capture the "survey" image
DSStartAcquisition( paramID, continuous, synchronous )
image survey := DSGetLastAcquiredImage( signalIndex )
survey.SetName("Survey")
if ( !DSIsValidDSImage( survey ) ) Throw( "Something wrong..")
DSDeleteParameters( paramID ) // remove parameters from memory

// Now we create a "subscan" image for a quasi-stationary beam...
// The size has a minimum size (16x16?) but as we keep the beam 
// "stationary" this will rather define your "time-resolution" of 
// data. Scan 'speed' is taken from our reference...
number sizeX = 1024     
number sizeY = 1024
image Static := IntegerImage( "Static", dataDepth, 0, sizeX, sizeY )
Static.ShowImage()
// defeine "ROI" on the survey. Just the center pixel!
number t,l,b,r
t = height/2
l = width/2
b = t + 1
r = l + 1
DSScanSubRegion( survey, Static, t, l, b, r )