1. Using SMART A quick guide to using the SMART (Scanning Microscopy Analysis and Resolution Testing) Macro in conjunction with SCION Image or NIH Image to measure SEM resolution, imaging performance and drift. Problems, questions, suggestions for improvements ? - please let me know ……... djoy@utk.edu

2. What does SMART do? zSMART currently provides three options 4(1) Automatic Resolution measurement using Fourier analysis of the micrograph 4(2) Autocorrelation which provides both a resolution and a signal to noise estimate 4(3) Two Image Analysis which measures resolution, drift, and instability For more details read the paper “Metrics of SEM performance” included (courtesy of SPIE) as a Microsoft Word document in this download.Metrics of SEM performance

3. and please note... zAlthough the MACRO language of IMAGE is good there are some things I could not make it do. If you can help improve the interface and usability of SMART please let me know how. zThis is a work in progress so check back on our website for periodic improvements zThe code is copyright 2000 to the authors. Feel free to use it and modify it as you wish. If you use it in a publication a citation or an acknowledgement would be welcome zGo forth and magnify…….

4. Setting up SCION or NIH Image zBefore using SMART you must set up SCION or NIH Image zGo to the Options menu and click on Preferences zEdit the “Undo &Clipboard Buffer Size” to at least 2000k, ideally 4000k, then click OK. Unless this is done this macro may not work properly and may even fail completely zGo to File and Exit the Image program. This saves the preference setting to disc zThen restart Image

5. Loading SMART z Go to the Special menu and click on “Load Macros” z Navigate your way to the folder where you stored SMART and click Open in the dialog box z HINT - it is a good idea to store SMART in the MACRO folder of Image

6. Ready to go zIf you click on the Special menu item again then the drop down menu will now show the new options that are offered by the SMART macro zClicking on any of these new entries in the menu will start that function

7. Automeasure resolution zStep1 - Load the micro- graph you wish to analyze (using the File menu). Note NIH and SCION image can use almost any standard image file format. The number of pixels in the image is not important. zGo to the SPECIAL menu and select an ROI (128 up to 512). Position the ROI by clicking and dragging.

8. Automeasure Resolution zGo to SPECIAL menu and click the first option - AutoMeasure Resolution. zA dialog box appears and asks for the width of image - this is is width of the field of view of the entire image in microns zA second dialog box asks for the total number of pixels across the width of the image. zEnter the data and click OK Total image width (microns) Calculate width from the scale marker

9. The FFT display zAfter some processing the screen now shows the FFT zHint - if the dialog box covers the FFT drag it out of the way, but don’t click OK until you are ready zThe program has attempted to separate the signal from the noise. In many cases the guess that is made is good but you can adjust the result to your own needs...

10. The threshold toolbar z Click on the Threshold tool z Then put the cursor in the LUT window and drag the cursor up and down to change the threshold level z Too low a value of the threshold will reveal the noise in the background, too high a value may cut off some of the signal and give a pessimistic result z When satisfied click OK Threshold tool LUT window Threshold too low

11. Resolution result zThe info box now shows the computed resolution (in nm) and the eccentricity of the FFT. This is a measure of the stigmatic error in the beam. Ideally the value should be zero, anything below about 0.1 is good.

12. Mode 2 - Autocorrelation zLoad the image then go to the Special menu and select your ROI zNOTE - the ROI must be smaller than your image or else the macro will fail. For example with a 640x480 image you must use a 256x256 or 128x128 ROI zWhen the ROI is set then go to the Special menu again and select the AutoCorrelation mode

13. Autocorrelation - step 2 z After you answer the questions about image width and pixel number the program will display the 2-D AutoCorrelation plot as shown z The macro measures the Full Width Half Maximum of the correlation peak z The FWHM width is the spatial resolution. The Peak to Background ratio estimates the signal/noise ratio peak background

14. Mode 3 - Two Image Analysis zThis part of SMART uses two images to give an accurate measure of resolution and drift zThe two images should be recorded one directly after the other. Do not adjust the stage, focus, gun etc.. zLoad the two images then go to the SPECIAL menu select and position the ROI on the top image. The ROI must be smaller than the image size Image 1 Image 2

15. Mode 3 - step 2 z After you calibrate the image size as usual the Macro copies the image in the ROI from image 1, puts the same ROI on image 2 but shifted horizontally by 16 pixels, copies that image area, then forms a composite image from these two fragments. The 2-D power spectrum is then calculated and displayed 2-D power spectrum from composite image

16. Resolution analysis zOnly detail present on a pixel by pixel basis in both images appears modulated by the fringes in the FFT. Noise is unmodulated and so is readily distinguished from image detail zTo measure the resolution move the mouse around the perimeter of the fringes. The image resolution is read off in the INFO box zBecause of drift resolution will not be the same in all directions...

17. Measuring Drift zThe fringes should be vertical because the images are offset horizontally by 16 pixels  If drift or instability occurs the fringes rotate through some angle  from the horizontal zThe direction of the drift is as shown on the sketch zD -the magnitude of the drift is  fringes  Drift vector where offset = 16 * pixel spacing

18. Note that……. zThe resolution result given by this mode averages over the time interval required to record both images and so is a good test of real world resolution. zThis routine has failed to work on some computers, apparently because of screen driver problems with the SWITCH command. If the macro fails to work for you, load both images as usual, position the ROI on image 1, then manually put the ROI in position on image 2 as well, then run the Two Image routine. The resolution value will be correct although the drift estimate may be in error zOn small monitor screens, or when using big images, the INFO box may sometimes be hidden. Try and move it to a convenient corner of the screen before starting an analysis.