Coming Up To Speed

Eric Rufe, U.S. Northeast Sales Manager, EDAX

“Dad, do you want to see someone cut an arrow in half with a sword?”

That is the sort of question I’ve come to expect from my 13-year old son. Lately, he and his friends watch a YouTube show where two intrepid scientists conduct all sorts of crazy experiments, record with a high-speed camera, and play the results back in slow motion. In this case, one guy shot an arrow at the other, who managed to cut it in half in mid-flight on his first attempt. In other videos, they burst water balloons and spin flaming steel wool to create cascades of sparks. All these experiments are recorded with a high-speed camera and played back in slow motion. It is really a lot of fun to watch. And, I noticed the camera they use is made by AMETEK!

I have been paying attention to AMETEK high-speed cameras lately, in a tangential way. Let me explain. I joined EDAX just over one year ago as Northeast Sales Manager. At EDAX, I handle the EDS, WDS, EBSD and µ-XRF products. Although I used some of these products as a student, that was a long time ago. During most of my career I worked with other types of microscopy techniques, and the EDAX technology has advanced dramatically during that time. For example, silicon drift detectors with thermoelectric cooling had replaced the SiLi detectors form my student days, which mean no more filling up a LN2 dewar (Figure 1). Joining EDAX meant that I had a lot to learn and I had to learn it quickly.

Very old stock photo of a scientist filling a LN2 dewar for the old SiLi detectors.

Figure 1. Very old stock photo of a scientist filling a LN2 dewar for the old SiLi detectors.

Fortunately, EDAX has a lot of resources to bring me up to speed. EDAX does a good job of presenting webinars on new techniques and recent developments. These are all archived on the EDAX website, along with videos of presentations recorded at different meetings and workshops. I counted 94 different presentations dating back to 2014 and quickly set to work watching and learning. EDAX also has a lot of literature available through the website: product brochures, data sheets, articles, presentations, and essential knowledge briefings. Somewhere over 120 pieces of literature.

One of the benefits of the Northeast territory is that the EDAX headquarters is in my territory, located in Mahwah, NJ. This proximity makes it easy for me to bring customers to Mahwah for demonstrations. As you enter the demonstration area in Mahwah, you are greeted by a group of signs showing all of the different companies within AMETEK’ s Materials Analysis Division (MAD) (Figure 2). EDAX is one of several companies in MAD, along with CAMECA, Amptek, SPECTRO, Forza Silicon and Vision Research. There is some cross-pollination among these different companies, and I like to tell the story that EDAX is part of a larger group of related technologies. So, I made it a point to also learn something about each of these different companies and set about examining their websites.

Canvas signs on the wall outside the demo labs in Mahwah, NJ showing some of the companies in the AMETEK Materials Analysis Division.

Figure 2. Canvas signs on the wall outside the demo labs in Mahwah, NJ showing some of the companies in the AMETEK Materials Analysis Division.

Now we come back to the high-speed cameras. One of the sister companies makes high-speed cameras for a variety of applications. They have many great slow motions videos on their web page, including ballistics tests, water droplets, flying insects, and an exploding strawberry (yes, an exploding strawberry).

Collaboration with this sister company resulted in the Velocity™ EBSD camera, with collection speeds up to 4,500 indexed points per second. This is the fastest EBSD camera available, and it has been fun to demonstrate the speed to customers. Large maps that may require an overnight run can now be completed in minutes. The first generation of the Velocity™ EBSD Systems was launched in June 2018 with speeds up to 3,000 fps. This release date was shortly before I joined EDAX. The faster Velocity֭™, the Velocity™ Super EBSD Systems, were launched in March 2019. Only 9 months later, the new Velocity™ has a 50% increase in speed (Figure 3).

EDAX Velocity™ Super EBSD Camera EBSD orientation map from an additively manufactured Inconel 718 collected at 4,500 indexed points per second at 25 nA beam current
Figure 3. EDAX Velocity™ Super EBSD Camera (left) and an EBSD orientation map from an additively manufactured Inconel 718 collected at 4,500 indexed points per second at 25 nA beam current (right).

There has been a rapid release of new and improved products since I joined, in addition to the developments in the Velocity™ camera. EDAX released a 160 mm2 EDS detector for TEM, the Elite T Ultra. APEX™ software development has continued, and now APEX™ is available on the Element, Octane Elect, and Octane Elite EDS Systems. We are on the verge of releasing APEX™ for EBSD as well. New EBSD software (OIM Matrix™) has been released, which includes dynamic pattern simulation and dictionary indexing. In November, we will host a webinar on EBSD using a Direct Electron Detector.

The challenge I have been facing over the past 12 months is that no matter how fast I read, and watch, and learn, it seems there is always something new. I am reminded of the Red Queen, in Through the Looking-Glass, explaining to Alice:

“Now, here, you see, it takes all the running you can do, to keep in the same place”.

Things That Change The Way We Use EDS

Dr. Shangshang Mu, Applications Engineer, EDAX

I got into the EDS world about 10 years ago, when I started my PhD study at Boston University. In my first project, I needed to quantify the elemental composition of my experimental samples. My advisor told me that ideally, we should use an electron microprobe and that the nearest one was at MIT, which is literally on the other side of the Charles River. But after we heard of the hourly fee and estimated the number of samples I would need to analyze, we started to plan an alternative. We found out that there was a field emission SEM equipped with an EDS detector in our own Photonics Center, just across the street and most importantly it was free of charge. At that time, I knew neither microprobe nor EDS and decided to give EDS a try first. Even if it did not work, I had nothing to lose except wasting some time. Graduate students have plenty of time to waste. So finally, I didn’t cross the beautiful Charles River but Commonwealth Avenue for the EDS.

As a result, I was introduced to the EDS world by the EDAX Apollo 40 SDD detector and EDAX was the only EDS manufacturer I knew as a beginner. It is such a good brand name standing for Energy Dispersive Analysis of X-rays so in the first couple of years I was under the impression that it was the term of this technique. For quantitative analysis, I used known standards that were close to my experimental samples in composition to standardize and got pretty good results fast and easy. In the subsequent projects, I collected a lot of EDS maps and the Apollo 40 never disappointed me. Since the EDS detector worked well for my PhD projects, I no longer considered other techniques. By the way, although I missed the opportunity to learn how to use the microprobe across the river due to the budget issue, my first full-time job in the states was to manage a much fancier microprobe acquired by a former user of the MIT’s microprobe. He received his PhD in geochemistry from MIT and I got most of my microprobe skills from him.

As an entry level EDAX user in graduate school, I had no way to imagine that I turned myself into an EDAX applications engineer and right now I am celebrating my one-year anniversary. After I joined EDAX, I got to know that the Apollo was the first generation SDD detector series of EDAX and our current EDS detectors have much better all-around performance. At the beginning of my second year with EDAX, I looked back into the EDS data I collected in graduate school and noticed that they were collected at a much slower amp time (the time the detector processes one X-ray count) compared to current ones and the EDS maps looked kind of noisy in comparison to my current perspective. Prompted by these findings, I wanted to initiate the discussion with how advancements in detector technology shaped the way we use EDS.

Apollo 40 SDD at Boston University
EDAX Octane Elite SDD in Draper, UT
Figure 1. The EDAX Apollo 40 SDD attached to the SEM I used at Boston University (left) and the EDAX Octane Elite SDD I am currently using (right).

 

I believe all EDS users have heard of this rule of thumb: keep the dead time between 20% and 40%, or something like this. At least I was taught to keep the percentage within this range and as far as I know a lot of EDS users are following this rule. This is a traditional perspective that came out in the past when detector amp times were much slower. The dead time is all about throughput and affected by the amp time. Historically, if the dead time is below 20%, it means the detector either doesn’t receive enough X-ray counts per second to ensure high data quality or the amp time is too fast to maintain an optimal detector resolution. On the other hand, if the dead time is over 40%, the Input Counts Per Second (ICPS) is too high to be handled optimally by the current amp time and may lead to excessive summed peaks. We can get the dead time back in the range by either decreasing the beam current to lower the count rate or choosing a faster amp time.

In the past, we usually did not consider the second option since it would sacrifice the detector resolution a lot for throughput. However, the current generation of EDAX EDS detectors is equipped with CMOS based pre-amplifiers that allow much faster amp times ranging from 0.12 μs to 7.68 μs, while keeping very good resolution and high throughput. For example, if I have the EDAX Octane Elite detector in my lab, I can run eight times faster by moving the amp time from the slowest 7.68 μs to the intermediate 0.96 μs, the resolution is only decreased by roughly 4 eV (from 124 eV to 128 eV). This intermediate amp time can handle at least 80% of the job, however under this condition it is hard to make the dead time go over 20% unless the detector is receiving over 100K ICPS. Even if I use the fastest amp time at 0.12 μs, the resolution is still below 150 eV, which is not a significant decrease in resolution if you know that the detector resolution for those equipped with traditional JFET pre-amplifiers is about 250 eV at this fastest amp time. Since resolution is no longer a limiting factor, feel free to open your aperture to increase the count rate and choose a faster amp time to lower the dead time. In return, you will get a higher throughput, which means more statistics and higher quality of data. Although we can go below 20% dead time to have a throughput improvement, it still makes sense to apply the 40% upper bound since the detector will not convert X-rays efficiently once the dead time is beyond this maximum percentage.

When do we want to hit hundreds of thousands of ICPS and take advantage of the fast amp time and high throughput brought by current EDS detectors? While I was using the Apollo 40 at Boston University to collect EDS maps, I stuck to 12.8 μs amp time believing the higher the detector resolution, the better the map quality. Now, I have realized that the major limitation to the quality of EDS maps is not the detector resolution but the limited statistics at the pixel level. Not to mention for our current detectors, the degradation in resolution when running fast is very little. The quality of peak deconvolution is primarily determined by the level of statistics, even when dealing with tricky peak overlaps.

I did a quick study on a piece of floor tile in my lab that contains both calcium phosphate and zirconium silicate, so P and Zr are in distinct phases. P K and Zr L peaks are heavily overlapped with only 29 eV of energy difference. I used the Octane Elite detector to do a quick five-minute net intensity map on this floor tile at 26 nA beam current and 0.96 μs amp time. This combination gave me 160K ICPS and 28% dead time. For the purpose of comparison, I used the slowest amp time at 7.68 μs to yield the highest detector resolution and recollected the maps for 6.5 minutes. To keep the dead time at 28% I had to lower the beam current to 3.2 nA to constrain the ICPS at 20K. Obviously, in the first run Zr and P were separated out nicely in the sharp images (Figure 2 left), as it built up eight times more statistics than the second run in roughly the same amount of time. In the second run at the highest detector resolution, the separation was not quite as good (Figure 2 right). As we can see, the images are kind of pixelated and the coral pixels are mixed within the green in the overlay, so the slightly better detector resolution did not help at all. If I were able to know this trick as a rookie, I would be able to get higher quality maps in the same amount of time or get the same quality of maps faster.

Net intensity maps of P/Zr overlay and P collected at 0.96 μs amp time (left) and 7.68 μs amp time (right) for roughly 5 minutes.
Figure 2. Net intensity maps of P/Zr overlay and P collected at 0.96 μs amp time (left) and 7.68 μs amp time (right) for roughly 5 minutes.

From my point of view, the advancements in detector technology, the experience we gain, or a combination of the two change the way we use EDS.

Texture on the Greens

Matt Nowell, EBSD Product Manager, EDAX

For better or worse, I am a golfer. The story of how I became a golfer helps explain my love for EBSD, and evolution as a material scientist. While I was at the University of Utah trying to decide on a major, I enjoyed fishing. Here in Utah, we have lovely access to many rivers, streams, and lakes with great fishing potential. When I started investigating Materials Science and Engineering as a degree, I thought it would be interesting to learn about the graphite used in fishing rods, and how the different processes used improved the performance of the rods. With this interest, I enrolled in the Materials Science department. Fortunately (for the fish I like to think), two things happened that changed my recreational and professional focus.

Tate Nowell catching a Utah trout

My son catching a nice Utah trout.

First, I enrolled in Organic Chemistry. Memorizing different molecules was not something that I excelled at. This dampened my enthusiasm for all things polymer-based, like composite fishing rods. Second, I was hired to work in the Electron Microscopy lab for the Materials Science department. This gave me lots of direct exposure to SEM, TEM, EDS, and even XRD instruments. It also helped to build a strong appreciation for sample preparation, but that’s the topic for another blog. All these things pushed me in the direction of materials characterization, and when I graduated, it led me to TSL, EDAX, and EBSD.

How does all this relate to golf? Soon after I started working, I played a round of golf with some friends. I had played a few casual rounds over the years, but nothing serious. Looking back, I consider myself lucky because the parking lot for the EM characterization facility was also the parking lot for the University golf course, and if I had been bitten by the golf bug at that point, things might have occurred differently. After this round, which I greatly enjoyed, I went to the local golf store thinking about different golf clubs. I found a set where the shafts of the club were manufactured by the same company that made my favorite fishing rod. This seemed like a sign to me, so I bought the clubs and jumped right into becoming a golfer.

It was great timing. EBSD scans were slow. To collect a 20,000-point scan, which was our typical target at the time, took 5-6 hours. It was easy to fit in 9 holes during some of these scans. Today, with our new Velocity™ cameras, it takes about 5 seconds to collect this data. Sometimes there is barely enough time to hit a practice putt down the hall in the lab. Many of us in the office enjoyed playing together. We even commissioned an annual tournament called the Burrito Open, where we combined golf with Mexican food. If you examine the picture of the 2008 tournament closely, you may notice it is an International event, with participants from Europe (Rene de Kloe) and Japan (Suzuki-san).

2008 Burrito Open

2008 Burrito Open

This tournament also allowed us to indulge and combine golf with work a little bit. The first trophy was constructed from an old port cover we no longer needed. The second trophy was of course a crystal trophy. As you might imagine, there was some discussion over what crystal structure would be most appropriate.

Burrito Open Trophies

Burrito Open Trophies

There is plenty of time to think during a round of golf, and one of the things I’ve thought about is how the club heads are produced. When thinking about this, we are considering either woods (or more accurately metal woods) or irons. Irons are typically either cast or forged. Forged clubs are generally positioned for the better players, but what caught my eye is that some manufacturers started marketing the idea of microstructure and the role of grains in the material. One brand even pushes what they call Grain Flow Forged.

Grain Flow Forged Iron

Grain flow forged iron

Of course, just like the fishing rods, the processing of the club affects the properties. The key link is that the processing changes the microstructure, and the microstructure defines the properties. With that in mind, it’s a fun experiment to compare the microstructure of cast clubs versus forged clubs. Stuart Wright and I first did this experiment about 20 years ago for a conference on Materials in Sports, but given the increases in capability, it would be fun to reevaluate.

I sectioned and prepared EBSD samples from both forged and cast irons. These were both made with an unknown steel alloy and prepared with my standard metallographic preparation approach. Enough coarse-grained polishing was used to remove plating from the club surface. The resulting Image Quality + Orientation Maps (IPF relative to the surface normal direction) are shown below. These were collected from the face of the golf club. I prepared cross-sections for further analysis. I was a little surprised by both microstructures. The cast iron had a dual-component microstructure, with both generally equiaxed grains and needle shaped grain constituents. It looks a lot like a dual phase Ferrite-Martensite microstructure, but with martensite being tricky to directly identify with EBSD relative to ferrite, I indexed both regions with a BCC Ferrite material file. The local misorientations were higher in the needle shaped regions, and there were also some austenitic grains present in these regions. The forged iron microstructure has a bimodal grain size distribution, with larger equiaxed grains decorated and intermixed with smaller equiaxed grains. A second scan was collected at higher magnification and with a finer step size to better resolve these fine grains.

IQ and IPF ND Orientation Map from cast golf club

IQ and IPF ND Orientation Map from cast golf club

IQ and IPF ND Orientation Map from forged golf club

IQ and IPF ND Orientation Map from forged golf club

Higher magnification IQ and IPF ND Orientation Map from forged golf club

Higher magnification IQ and IPF ND Orientation Map from forged golf club

As expected, the microstructures of the forged and cast clubs are different. As a Materials Scientist and EBSD guy, I tend to think forging is a more interesting materials processing option. In this case though, both casting and forging have produced interesting microstructures that could use further investigation. I once bought a set of forged clubs, and it was with this set I made my only hole-in-one. I’m pretty sure there is a direct correlation, and when I buy my next set, I’ll continue my experimentations.

Celebrating Nearly 60 Years of Materials Analysis Expertise with EDAX

Arjun Dalvi, Regional Sales Manager – Southeast Asia and India, EDAX

During a recent trip to Bangkok, Thailand I visited a customer and was very happy to see that two EDAX DX-95 units were installed at his location. The units are a piece of history because EDAX hasn’t sold liquid nitrogen cooled detectors or systems anywhere in the world in quite some time.

When I asked the customer when this system was installed, he said it was installed more than 30 years ago, at a time when I was still in elementary school! EDAX was one of the first companies to produce liquid nitrogen cooled detectors for microanalysis.

EDAX DX-95 EDAX SiLi Detector
EDAX DX-95 (left) and SiLi detector (right) used over 30 years ago.

Since its origin in 1962, EDAX has provided customers with reliable, accurate microanalysis systems. The company has benefitted from its stellar reputation, as well as its, name recognition. The name EDAX almost has a generic trademark, because many people throughout the world refer to their Energy Dispersive Spectroscopy (EDS) systems as “EDAX” systems.

EDAX, a big name in microanalysis and microscopy, has a vast history in research and development of new technology and product improvements. The company has been a part of the AMETEK corporation since 2011. Since joining the well-respected organization of AMETEK, EDAX has been able to pursue new developments in the fields of EDS, EBSD and WDS analysis. After AMETEK acquired a company that produced silicon nitride windows, EDAX gained a great advantage by having an inhouse supplier for its new SDD window. This was a big revolution for EDAX’s EDS products. Now, EDAX is the only manufacturer that has a unique silicon nitride window with vacuum encapsulation technology. EDAX has become one of the top manufacturers of EBSD systems, providing solutions to various applications in the fields of microstructure and formation and deformation of new materials. The new CMOS-based Velocity™ EBSD Camera is the fastest EBSD camera on the market for high-speed EBSD mapping. In India, we have many users that have EBSD systems and are doing research in the fields of steel and metals.

Today, EDAX has a complete range of products with all the latest developments and inhouse raw materials needed to help us maintain quality and add to our customers’ confidence in our products.

I feel EDAX will come up with new developments for years to come. Maybe 30 years or more down the road, we will see the Element, Octane Elect, Octane Elite or Orbis at one of our customers sites, much like the DX-95, which is still in use today.

Intersections

Dr. Stuart Wright, Senior Scientist EBSD, EDAX

The city has recently started burying a pipe down the middle of one of the roads into my neighborhood. There were already a couple of troublesome intersections on this road. The construction has led to several accidents in the past couple of weeks at these intersections and I am sure there are more to come.

A question from a reviewer on a paper I am co-authoring got me thinking about the impact of intersections of bands in EBSD patterns on the Hough transform. The intersections are termed ‘zone axes’ or ‘poles’ and a pattern is typically composed of some strong ones where several high intensity bands intersect as well as weak ones where perhaps only two bands intersect.

To get an idea of the impact of the intersections on the Hough transform, I have created an idealized pattern. The intensity of the bands in the idealized pattern is derived from the peaks heights from the Hough transform applied to an experimental pattern. For a little fun, I have created a second pattern by blacking out the bands in the original idealized pattern, leaving behind only the intersections. I created a third pattern by blacking out the intersections and leaving behind only the bands. I have input these three patterns into the Hough transform. As I expected, you can see the strong sinusoidal curves from the pattern with only the intersections. However, you can also see peaks, where these sinusoidal curves intersect and these correspond (for the most part) to the bands in the pattern.

In the figure, the middle row of images are the raw Hough Transforms and the bottom row of images are the Hough Transforms after applying the butterfly mask. It is interesting to note how much the Hough peaks differ between the three patterns. It is clear that the intersections contribute positively to finding some of the weaker bands. This is a function not only of the band intensity but also the number of zone axes along the length of the band in the pattern.

Eventually the construction on my local road will be done and hopefully we will have fewer accidents. But clearly, intersections are more than just a necessary evil 😊

Is It Worth The Salt?

Felix Reinauer, Applications Specialist, EDAX

When you are in Sweden at Scandem 2019 it is the perfect time to order SOS as an appetizer or for dinner. It is made of smör, ost and sill (butter, cheese and herring) served together with potatoes. Sometimes the potatoes need a little bit of improvement in taste. It is very easy to take the salt mostly located on all tables and salt them. Doing that I thought about how easy it is to do this today and what am I really pouring on my potatoes?

Salt was very important in the past. In ancient times salt was so important that the government of Egypt and other countries setup salt taxes. Around 4000 years ago in China and during the Bronze age in Europe, people started to preserve food using brine. The Romains had soldiers guarding and securing the transportation of salt. Salt was as expensive as gold. Sal is the Latin word for salt and the soldiers used to get their salare. Today you still get a salary. Later ‘Streets of Salt’ were settled to guarantee safe transportation all over the country. As a result, cities along these roads got wealthy. Even cities, like Munich, were founded to make money with the salt tax. Salt even destroyed empires and caused big crises. Venice fought with Genoa over spices in the middle ages. In the 19th century soldiers were sent out to conquer a big mountain of salt of an Inconceivable value, lying along the Missouri River. We all know the history of India´s independence. Mohandas Gandhi organized a salt protest to demonstrate against the British salt tax. The importance of the word salt is also implemented in our languages, “Worth the salt”, “Salz in der Suppe” or “Mettre son grain de sel”.

The two principle ways of getting salt are from underground belts and from the sea. It can be extracted from underground either by mining or by using solution mining. Sea salt is produced in small pools which were filled up during high tide and water evaporates under sunny weather conditions. Two kinds of salt mining are done. Directly digging the salt out of the mountain, then dissolving it to clean it. Or hot water is directly used to dissolve the salt and then the brine is pumped up.

Buying salt today is no longer that expensive, dangerous or difficult. But now a new problem arises. I´m talking about salt for consumption, which usually means NaCl in nice white crystals. So, are there any advantages to using different kind of salts? If we believe advertisements or gourmets, it is important, where the salt we use came from and how it was produced. Today the most time-consuming issue is the selection of the kind of salt you want in the supermarket!

For my analysis I chose three kinds of salts from three different areas. The first question was, are the differences big enough to detect them using EDS or will the differences be related to minor trace elements which can only be seen in WDS. It was a surprise for me that the differences are that huge. I had a look at several crystals from one sample. Shown as examples are the typical analysis of the different compounds and elements for that provenance.

First looking at the mined salt. I selected a kind of salt from the oldest salt company in Germany established over 400 years ago. One kind from Switzerland manufactured in the middle of the Alpes and one from the Kalahari, to be as far away as possible from the others. The salt from Switzerland is the purest salt only containing NaCl with some minor traces. The German salt contains a bigger amount of potassium and the Kalahari salt a bigger amount of sulfur and oxygen (Figure 2.).

Figure 2.

Secondly, I was interested in the salt coming from the sea. I selected two types of salt from French coasts one from the Atlantic Ocean in Brittany and another one from the Mediterranean Sea. The third one came from the German coast at the Baltic Sea. The first interesting impression is that all the sea salt contains many more elements. The Mediterranean salt contains the smallest amount of trace elements. The salt from the Atlantic Ocean and the Baltic sea contains, besides the main NaCl, phases containing Ca, K, S, Mg and O. A difference in the two is the amount of Ca containing compounds (Figure 3.).

Figure 3.

Finally, I was interested in some uncommon types of salt. In magazines and television, experts often publish recipes with special types supposedly offering a special taste, or advertising offers remarkable new kinds of healthy salt. So, I was looking for three kinds which seem to be unusable. I found two, a red and a black colored, Hawaiian salt. The spectrum of the red salt shows nicely that Fe containing minerals cause the red color. Even titanium can be found and a bigger amount of Al, Si and O. The black salt contains mainly the same elements. Instead of Fe the high amount of C causes the black color. A designer salt is the Pyramid finger salt, which is placed on top of the meat to make it look nicer. Beside the shape, the only specialty is the higher amount of Ca, S and O (Figure 4).

Figure 4.

It was really interesting that salt is not even salt. As the shape of the crystals varies, so they differ in composition. In principle it is NaCl but contain more or less different kinds of compounds or even coal to color it. There are elements found in different amounts related to the type of salt and area it came from. These different salts are located in a few very small areas in and on the crystals.
And finally, I pour salt onto my potatoes and think, ok it is NaCl.

 

Hats Off/On to Dictionary Indexing

Dr. Stuart Wright, Senior Scientist EBSD, EDAX

Recently I gave a webinar on dynamic pattern simulation. The use of a dynamic diffraction model [1, 2] allows EBSD patterns to be simulated quite well. One topic I introduced in that presentation was that of dictionary indexing [3]. You may have seen presentations on this indexing approach at some of the microscopy and/or materials science conferences. In this approach, patterns are simulated for a set of orientations covering all of orientation space. Then, an experimental pattern is tested against all of the simulated patterns to find the one that provides the best match with the experimental pattern. This approach does particularly well for noisy patterns.

I’ve been working on implementing some of these ideas into OIM Analysis™ to make dictionary indexing more streamlined for datasets collected using EDAX data collection software – i.e. OIM DC or TEAM™. It has been a learning experience and there is still more to learn.

As I dug into dictionary indexing, I recalled our first efforts to automate EBSD indexing. Our first attempt was a template matching approach [4]. The first step in this approach was to use a “Mexican Hat” filter. This was done to emphasize the zone axes in the patterns. This processed pattern was then compared against a dictionary of “simulated” patterns. The simulated patterns were simple – a white pixel (or set of pixels) for the major zone axes in the pattern and everything else was colored black. In this procedure the orientation sampling for the dictionary was done in Euler space.
It seemed natural to go this route at the time, because we were using David Dingley’s manual on-line indexing software which focused on the zone axes. In David’s software, an operator clicked on a zone axis and identified the <uvw> associated with the zone axis. Two zone axes needed to be identified and then the user had to choose between a set of possible solutions. (Note – it was a long time ago and I think I remember the process correctly. The EBSD system was installed on an SEM located in the botany department at BYU. Our time slot for using the instrument was between 2:00-4:00am so my memory is understandably fuzzy!)

One interesting thing of note in those early dictionary indexing experiments was that the maximum step size in the sampling grid of Euler space that would result in successful indexing was found to be 2.5°, quite similar to the maximum target misorientation for modern dictionary indexing. Of course, this crude sampling approach may have led to the lack of robustness in this early attempt at dictionary indexing. The paper proposed that the technique could be improved by weighting the zone axes by the sum of the structure factors of the bands intersecting at the zone axes.
However, we never followed up on this idea as we abandoned the template matching approach and moved to the Burn’s algorithm coupled with the triplet voting scheme [5] which produced more reliable results. Using this approach, we were able to get our first set of fully automated scans. We presented the results at an MS&T symposium (Microscale Texture of Materials Symposium, Cincinnati, Ohio, October 1991) where Niels Krieger-Lassen also presented his work on band detection using the Hough transform [6]. After the conference, we hurried back to the lab to try out Niels’ approach for the band detection part of the indexing process [7].
Modern dictionary indexing applies an adaptive histogram filter to the experimental patterns (at left in the figure below) and the dictionary patterns (at right) prior to performing the normalized inner dot-product used to compare patterns. The filtered patterns are nearly binary and seeing these triggered my memory of our early dictionary work as they reminded me of the nearly binary “Sombrero” filtered patterns– Olé!
We may not have come back full circle but progress clearly goes in steps and some bear an uncanny resemblance to previous ones. I doff my hat to the great work that has gone into the development of dynamic pattern simulation and its applications.

[1] A. Winkelmann, C. Trager-Cowan, F. Sweeney, A. P. Day, P. Parbrook (2007) “Many-Beam Dynamical Simulation of Electron Backscatter Diffraction Patterns” Ultramicroscopy 107: 414-421.
[2] P. G. Callahan, M. De Graef (2013) “Dynamical Electron Backscatter Diffraction Patterns. Part I: Pattern Simulations” Microscopy and Microanalysis 19: 1255-1265.
[3] S.I. Wright, B. L. Adams, J.-Z. Zhao (1991). “Automated determination of lattice orientation from electron backscattered Kikuchi diffraction patterns” Textures and Microstructures 13: 2-3.
[4] Y.H. Chen, S. U. Park, D. Wei, G. Newstadt, M.A. Jackson, J.P. Simmons, M. De Graef, A.O. Hero (2015) “A dictionary approach to electron backscatter diffraction indexing” Microscopy and Microanalysis 21: 739-752.
[5] S.I. Wright, B. L. Adams (1992) “Automatic-analysis of electron backscatter diffraction patterns” Metallurgical Transactions A 23: 759-767.
[6] N.C. Krieger Lassen, D. Juul Jensen, K. Conradsen (1992) “Image processing procedures for analysis of electron back scattering patterns” Scanning Microscopy 6: 115-121.
[7] K. Kunze, S. I. Wright, B. L. Adams, D. J. Dingley (1993) “Advances in Automatic EBSP Single Orientation Measurements.” Textures and Microstructures 20: 41-54.

A Cog’s Case for Corporate Utopia

David Durham, Regional Sales Manager, EDAX

Not too long ago I went to my optometrist to get an eye exam for some replacement glasses. My last pair had been stolen after my car was broken into in broad daylight during lunch at a restaurant in the Bay Area. (What the thief planned on doing with my prescription glasses is still a mystery to me.)

Figure 1: The old phoropter* (top) and the new phoropter** (bottom).

It had been at least a couple years since my last examination, but I was prepared to be guided through all the typical tests, culminating with that “giant-machine-with-multiple-lenses” pressed into my face to help the optometrist determine the prescription that would best correct the errors in my vision. I’d later learn that this machine is called a phoro-optometer, or more commonly a “phoropter.” And, contrary to my previous experiences with this instrument, it was now a super-sleek, slimmed down, digital version of the machine, using a computer controlled digital refraction system to cycle through the refraction options instead of using stacks of physical lenses that had to be manually cycled by the optometrist.

It was much smaller, quieter, faster, and easier than the version with which I was familiar. I was thoroughly impressed. But I was even more impressed when the instrument was pulled away and I saw the Ametek logo emblazoned on the side of it.

I couldn’t help but reflexively blurt out “Hey I work there!” to which the optometrist looked up from my file and began curiously interrogating me about my history in the eye care industry. Sadly, he quickly lost interest after I explained that I worked in a different division of Ametek that manufactures EDS, EBSD, and WDS systems.

After my exam, for some reason I felt a bit intimidated about not knowing more about Ametek’s business units outside of the EDAX niche to which I belong. I knew Ametek was a huge corporation, steadily growing larger over the decades — mainly by acquisition of smaller companies – but I’d never really grasped the sheer size and breadth of everything Ametek does. This wasn’t the first time I’ve been in this type of situation. Prior to joining EDAX/Ametek I worked for another scientific instrumentation corporation, slightly smaller than Ametek but still a similar type of behemoth with a wide range of companies making products that service comparable industries and applications. Even at that corporation my knowledge of the business outside of my business unit’s portfolio was very limited. These places are just so big!

Working at large corporations like these can, at times, be a little bit discouraging if you think of yourself as just a single cog in a machine with thousands of moving parts. Giant corporations certainly seem to have a bad reputation these days and I’ll admit I’ve experienced my fair share of corporation-induced angst over the years. Working within a large bureaucracy can make completing the smallest internal tasks overwhelming. Being in a smaller company that is acquired – I’ve been through two acquisitions — can be disruptive to business and cause a lot of anxiety.

But is there a good side to these mega-corporations? I think so.

I can find some important benefits that could be argued to outweigh the negative aspects, not just to the cogs like myself but also to the markets that they serve. Whether or not these apply to other more prominent mega-corporations is debatable, but I think they seem to be reasonable positive characteristics, at least from my experience in the scientific instrumentation field.

Having the brand name recognition has always been an advantage. Customers (and their procurement departments) are typically more willing to do business with companies that have a long history of manufacturing products. Being in business for multiple decades with a proven track record of having the resources to reliably deliver products to the market and consistently service its user-base generates heaps of reassurance for customers that a younger or smaller company just can’t provide. It works similarly for vendors as well – it turns out that people are always more willing to sell you stuff if they’re confident that your company will pay for it.

Being in a large corporation also offers a huge advantage in the ability to research and develop new technology and product improvements. This can come by brute force – having deeper pockets to invest more money into R&D – or even by utilizing the synergy between individual companies under the corporation’s umbrella. EDAX is a great example of this in a couple ways. Ametek’s purchase of a new business unit in 2014 facilitated the development of EDAX’s groundbreaking Octane Elite and Octane Elect EDS systems, allowing for speed and sensitivity that had never been achieved before in any other EDS system. Collaboration between EDAX and another sister company within the Materials Analysis Division of Ametek, ushered in the release of EDAX’s new Velocity™ highspeed CMOS EBSD camera, by far the fastest EBSD system available. Realization of these two milestones of innovation would have been significantly delayed without the help of Ametek’s resources.

Figure 2: The Octane Elite (left) and the Velocity™ Super (right), two of EDAX’s products that were developed, in part, with the help of other business units inside Ametek.

But what I think tends to be the best part is that, as long as a company is meeting its targets and things are humming along nicely, corporations – at least the good ones, in my opinion — are usually happy to just let the business unit do its own thing. Having an “if it ain’t broke don’t fix it” mentality is the ideal way to keep the key talent happy and keep the business growing and making money. It also makes it possible to retain some semblance of the original company culture that contributed to its success in the first place. This is the holy grail for us cogs – being able to keep that small business feel while also being able to take advantage of all the big business benefits at the same time. Again, EDAX is a good example of this, with many of EDAX’s employees being legacy staff hired on long before the EDAX acquisition. This tells me Ametek must be doing something right.

So, I guess it’s debatable. While we may be willingly marching our grandchildren into a dystopia where three or four companies own all the businesses in the world, there are some undeniable advantages that working for a big company brings as well. And I take some comfort in the fact there are some very intelligent and innovative people behind the curtains, trying to do good things to make their customers happy and generally improve the lives of everyone in the world. We may or may not see all the things like the better phoropters out there, but our lives are almost certainly benefited by them whether we realize it or not.

* Photo from https://en.wikipedia.org/wiki/Phoropter
** Photo from http://www.reichert.com/

Saying What You Mean and Meaning What You Say!

Shawn Wallace, Applications Engineer, EDAX

A recent conversation on a list serv discussed sloppiness in the use of words and how it can cause confusion. This made me consider that in the world of microanalysis, we are not immune. We are probably sloppiest with two particular words. They are resolution and phase.

Let us start with how we use the word phase and how phases are commonly defined in microanalysis. In Energy Dispersive Spectroscopy (EDS), we use phase for everything, for example, phase mapping, phase library. In Electron Backscatter Diffraction (EBSD), the usage is a little more straightforward.

So, what is a phase? Well to me, a geologist, a phase has both a distinct chemistry and a distinct crystal structure. Why does this matter to a geologist? Two different minerals with the same chemistry, but with different structures, can behave in very different ways and this gives me useful information about each of them.
The classic example for geologists is the Al2SIO5 system (figure 1). It has three members, Kyanite, Sillimanite, and Andalusite. They each have the same chemistry but different structures. The structure of each is controlled by the pressure and temperature at which the mineral equilibrated. Simple chemistry tells me nothing. I need the structure to tease out that information.

Figure 1. Phase Diagram of the Al2SiO5 system in geological conditions. Different minerals form at different pressures and temperatures, letting geologists know how deep and/or the temperature at which the parent rock formed.**

EDS users use the term phase much more loosely. A phase is something that is chemically distinct. Our phase maps look at a spectrum pixel by pixel and see how they compare. In the end, the software goes through the entire map and groups each pixel with like pixels. The phase library does chi squared fits to compare the spectrum to the library (figure 2).

Figure 2. Our Spectrum Library Match uses as Chi-squared fit to determine the best possible matches. This phase is based on compositional data, not compositional and structural data.

While the definition of phase is relatively straight forward, the meaning of resolution gets a little murkier. If you asked someone what the EDS resolution is, you may get different answers depending on who you ask. The main way we use the term resolution when talking about EDS is spectral resolution. This defines how tight the peaks in a spectrum are (figure 3).

Figure 3. Comparison of EDS vs. WDS spectral resolution. WDS has much higher resolution (tighter peaks) than EDS, but fewer counts and more set-up are required.

The other main use of resolution, in EDS is the spatial resolution of the EDS signal itself (figure 4). There are many factors which determine this, but the main ones are the accelerating voltage and sample characteristics. This resolution can go from nanometers to microns.

Figure 4. Distribution of the electron energy deposited in an aluminum sample (top row) and a gold sample (bottom row) at 15 kV (left column) and 5 kV (right column). Note the dramatic difference in penetration given by the right hand side scale bar.

The final use of resolution for EDS is mapping resolution. This is by far the easiest to understand. It is just the step size of the beam while you are mapping.

Luckily for us, the easiest way to find out what people mean when they use the terms resolution or phase, is just to ask. Of course, the way to avoid any confusion is to be as precise as possible with your choice of words. I resolve to do my part and communicate as clearly as I can!

** Source: Wikipedia

A New Light on Leonardo

Sue Arnell, Marcom Manager, EDAX

I recently spent 10 days’ vacation back in the UK, but my visit “home” turned into somewhat of a busman’s holiday when I visited the current exhibition at the Queen’s Gallery in London: LEONARDO DA VINCI: A LIFE IN DRAWING. While all the drawings were very interesting, one particular poster particularly caught my eye.

Figure 1: Poster showing the use of X-ray Fluorescence (XRF) analysis on one of the drawings in the exhibition.

It may be hard to see in this small image, but the drawing in the bottom left corner of the poster showed two horses’ heads, while the rest of the sheet showed very indistinct lines. When viewed under ultraviolet light, however, it is clear that there were an additional two horses depicted on the same page.

Figure 2: Drawing of horses seen under ultraviolet light

A video on the exhibit site shows a similar result with a second page:

Figure 3: Hand study seen in daylight

Figure 4: Hand study seen under ultraviolet light

According to the poster, researchers* at the Diamond Light Source at Harwell in Oxfordshire used X-ray fluorescence, which is non-destructive and would not therefore harm the priceless drawing, to explain the phenomenon in the first drawing of the horses. Scanning a small part of the drawing to analyze individual metalpoint lines, they were able to extract the spectrum in Figure 5.

Figure 5: the results of XRF analysis on the drawing showing the presence of copper (Cu) and Zinc (Zn) in the almost invisible lines and almost no silver (Ag).

The conclusion was that Leonardo must have used a metalpoint based on a Cu/Zn alloy and that these metals have reacted over time to produce salts and render the lines almost invisible in daylight. However, under ultraviolet light, the full impact of the original drawings is still visible.

When I shared this analysis back in the EDAX office in Mahwah, NJ, Dr. Patrick Camus (Director of Engineering) had a few additional (more scientific) observations.

  • XRF may be useful in determining the fading mechanism by looking for elements associated with environmental factors such as Cl, (from possible contact with human fingertips), or S in the atmosphere from burning coal over the centuries. It may be related to exposure to sunlight as well.
  • The use of ultraviolet light as an incoming beam has a similar reaction but slightly different with the material as the x-rays producing emissions at much smaller energy level. This process is called photoluminescence. The incoming beam excites valence electrons across an energy gap in the material to a higher energy level which during relaxation to the base energy releases a photon. The energy of these photons is typically 1-10 eV or much less than x-ray detectors can sense. Interestingly, this excitation does not occur in conductors/metals, thus proving more evidence of the picture material being a band-gap or insulating material like a salt.
  • This example shows that a single technique does not always provide a complete picture of the structure or composition of a sample, but the use of multiple techniques can provide information greater than the sum of the individual contributions.

From my point of view, I have been trying to explain, promote and market the EDAX products and analysis techniques for over eight years now, so it was very interesting to see the value of some of ‘our’ applications in a real-world situation.

* Dr. Konstantin Ignatyev, Dr. Giannantonio, Dr. Stephen Parry