Question

我正在编写一个DigitalMicrograph脚本，以获取从ADF STEM探测器获得的散射电子强度的映射数据，在由手工脚本控制的各种入射光束条件下。但是，遗憾的是，我不知道在非STEM模式下（由DigiScan控制）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？

如果你有一些智慧，我们将不胜感激。非常感谢你提前。

Answer 1

当DigiScan单元处理STEM检测器信号时，无法独立读取检测器“信号”。

另外：您没有及时将信号视为“流”，而是由DigiScan提供时钟。也就是说，您必须使用DigiScan开始采集，并且不仅可以在没有探测器的情况下“监听”探测器。

但是，DigiScan的采集不与处于STEM模式有关。您可以在TEM模式下开始DigiScan采集。您可以选择这样的参数，即获取“图像”仅在非常小的区域内扫描光束，以使光束变为准静态。也许这可以帮到你？

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 )

是否有可能获得STEM探测器信号？

1 个答案: