Using Handheld LIBS for Positive Material Identification

If you’re a metal maniac like me, I’m assuming you know about XRF and what a staple it is in Positive Material Identification (and if not, here’s a handy article about that).

But there is another method that is perfectly capable of doing many PMI testing applications for metal identification, and it is, without doubt, a super cost-effective option.

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Unfortunately, there is a surprising amount of misinformation and confusion around this technology. Plus, there’s training needed and things you have to watch out for.

So I thought it would be a good idea to dig in and cover everything that’s important to know about LIBS (specifically, handheld LIBS).

The obvious question to start with is:

What is handheld LIBS? Handheld LIBS (AKA, Laser-Induced Breakdown Spectroscopy) is the use of a laser rather than a spark or radiation to create light signature emissions that a detector and analyzer can use to determine the chemistry of a metal and identify it using a grade library.

In this article, we’re going to explore

• How LIBS works
• Why use it?
• The cost of owning a handheld LIBS
• Mistakes to avoid
• The brands that make LIBS

Let’s get started!

Psst: This post is based on a podcast with co-host Chris Carolan. To hear this episode (and more like it), subscribe to The Manufacturing Show on Apple Podcasts, Spotify, or wherever you listen to podcasts.

How does LIBS work?

LIBS stands for laser-induced breakdown spectroscopy. It’s actually in the same family as OES (Optical Emission Spectroscopy). It just uses a laser instead of a spark.

How it works:

1. It burns and vaporizes the metal with a laser
2. This makes the elements in the material give off a light signature
3. The detector sees those light signatures 
4. The analyzer determines the chemistry and makeup of the metal
5. It matches the percentages, chemistry, and composition against a grade library

This is how it’s able to tell you whether you’ve got stainless steel 316, aluminum 6061, aluminum 6063, Vibranium (just kidding; it doesn’t know Vibranium, but #WakandaForever).

How long has LIBS been available?

Handheld LIBS has only been around for 7 or 8 years, but the technology itself is actually about fifty years old.

It's been limited to laboratory benchtop instruments, but new technological advances have made it possible to miniaturize the laser while keeping the performance high.

This is what makes it possible to use in a handheld format: the handheld LIBS you see today.

“Today, LIBS is a perfectly capable tool to do a lot of the things XRF can’t do in a handheld format."

Chris Carolan

Sad plot twist: a combination of factors like over-promising and lack of training has led to distrust in the technology when handheld LIBS first came out.

Why use LIBS?

Let me tell you some of the pros and cons of using handheld LIBS to give you an understanding of why you might consider using it instead of a handheld XRF.

Cost of using LIBS

Buying an analyzer will run you between $20,000 and $40,000. The reason for the wide range is that there is a group of LIBS analyzers that can test for carbon and sometimes even non-metals.

Those are closer to $40,000. The other group that does not analyze carbon will run in the $20,000 to $30,000 range.

Beyond the purchase price, the cost of maintenance and ownership is very minimal compared to handheld XRF and OES. 

What you have to spend money on:

• Maybe repairs or maintenance — but it’s less expensive and less likely.
• Swabs to clean the window of the analyzers on a regular basis.

When you consider the lifetime cost of the instrument, these analyzers are likely the most cost-efficient in the industry.

Common mistakes to watch out for

Without proper training or understanding, people can make mistakes with handheld LIBS. These mistakes have led to misconceptions about the performance and viability of LIBS versus handheld XRF.

It all comes down to sample preparation:

On the one hand, you’ve got handheld XRF:

• Very forgiving
• You can have some surface contamination
• The prep doesn’t have to be perfect 
• You don’t have to have perfect contact with the metal in order to get a result

On the other hand, with LIBS:

• You need perfect contact 
• A clean surface on the base metal is needed
• No rust or corrosion
• No dirty surface
• No coatings

All of this will get in the way.

“With LIBS it’s very important to have a clean surface and to get perfect contact.”

Chris Carolan

If you try to use it like a handheld XRF, you’ll probably produce faulty results because surface contaminants will have a bigger impact.

Sadly, a lack of training and understanding has led to these common mistakes. However, here are two extra tips to know so you can be a master at LIBS:

1. Be extra sure to have good contact in hard to reach places and rounded samples.
2. Be careful not to move small parts.

Should you buy a specific brand?

These are the current suppliers of LIBS instruments:

• SciAps
• Thermo Niton
• Hitachi
• Bruker
• Rigaku (only LIBS brand without handheld XRF)

Unlike handheld XRF, there's not really a market leader for handheld LIBS yet. This is mostly due to its relative newness in the field.

LIBS takeaways

Props for taking the time. You are now a Jedi when it comes to LIBS vs the other PMI methods!

Here are a few points I hope you got from this article:

• LIBS is the fastest and safest PMI technology available
• Proper LIBS training is crucial for positive results
• It's not XRF; it’s its own technology 
• If you train for it then you can reap the benefits of the faster and safer method
• LIBS has the lowest cost of ownership 

Now, go forth and master your metals!

For more information on positive material identification or LIBS, subscribe to The Manufacturing Show on Apple Podcasts, Spotify, or wherever you listen to podcasts.