A Laser Could Offer a Peek Into the Insides of Our Muscles or Look Through Fire

I use lasers to see things that are hard to see and measure with the naked eye.

For instance, I developed a laser system that might be capable someday of assessing muscle health when a person flexes their arm. These lasers also help me see how an object changes during heat exposure when it is in a fire. 

It’s a pretty cool job!

Lasers Moving Science Forward 

Lasers have lots of interesting uses in our daily lives, including in science.

I mostly work with a specialized laser called a frequency comb. A frequency comb is a very bright light bulb that can be used to detect the presence or absence of a particular type of light.  

When a sample, which could be air, is exposed to the frequency comb light, certain frequencies, or parts of that light, interact with the sample. This process leaves a unique imprint on the frequency comb light that we can learn from. This interaction between light and matter is known as spectroscopy. We use the frequency comb to help us see things we couldn’t see with our eyes, such as invisible greenhouse gases. 

A more advanced version of this tool contains two combs. The second comb allows researchers to conduct dual-comb spectroscopy research. Essentially, the second comb helps to get more information about our sample efficiently and quickly. 

For example, using one frequency comb enables us to detect a greenhouse gas in the air. However, with two frequency combs, we can not only see that greenhouse gas but also know quickly and easily what type of gas it is. We can also measure many different types of gases very precisely at the same time. 

This is important because if we want to reduce greenhouse gases in our environment, we need to be able to measure them. Some companies are using this as a tool, among others, to measure their pollutants and comply with environmental regulations. 

I’m working on a new sampling technique to do dual-comb spectroscopy research more efficiently. Spectroscopy is used in all sorts of science, including chemistry, physics and astronomy. My goal is that one day, we can have a very versatile spectrometer instrument that smartly focuses to measure the most useful information for the project and also offers varied imaging options.

Laser Light in Our Bodies 

I am also researching how we can potentially use this comb laser technology to look inside our muscles. 

Your muscles contract when you move because of a filament called a sarcomere. Striped like a barber pole, sarcomeres are the microscopic workhorses behind every jump, skip and smile. 

Right now, if a doctor wants to see the inside of a human muscle, they must remove a sample during a procedure called a biopsy. 

However, using a technique I’m working on, it’s possible that in the future, a doctor could use frequency combs to look deep inside your muscles without cutting. 

This could benefit research for conditions such as strokes or muscular dystrophy. Also just imagine having a tool in the future that lets the surgeon illuminate your muscle (similar to an X-ray) and immediately know which parts of the muscle are healthy and which are not. They could do this simply by looking at which frequencies of light the muscle reflects (without hurting it).

The most challenging part of this work is figuring out how to get the light into the muscle and interpreting the measured signals. Such muscle signals look pretty different than the gas signals I used to analyze, so we still have many things we need to figure out before this is something your doctor can actually do for you. But with additional research (most of which would happen outside of NIST), maybe such an instrument can be available to doctors in the future. 

Seeing Through Fire

In another research project, we used a laser that can help us see through flames. 

For instance, consider a house engulfed in flames. How can firefighters determine from afar if the structure is still stable enough to allow for safe entry? 

Many buildings have central steel or aluminum beams called I-beams that are vital to keeping them standing. If a firefighter could see how such a beam joint is deforming, they could tell if the building is likely to fall down. But they often can’t see it through flames. That’s where our lasers come in. 

In safe, controlled fire research here at NIST, we pointed a laser through a fire at an I-beam and precisely measured how quickly it deformed. There aren’t many ways to measure something accurately through flames, but lasers have the potential to do this. 

We also (again, safely and with many controls in place) burned some vegetation and measured it with the laser. So, in the future, lasers could also be beneficial for studying how different types of trees burn in a wildfire. 

There is still much more research to be done before either of these tools will be in firefighters’ hands, but the development is promising and exciting. 

Lasering In on the Future of This Research 

When I first started at NIST 16 years ago, I wasn’t a “laser person” per se. At that time, I was studying and working with small samples of layered semiconductors that I was cooling to minus 265 degrees Celsius (or minus 445 Fahrenheit) — very cold!

While I occasionally used lasers to probe my samples, it wasn’t until I encountered frequency combs that I got truly hooked.

I first learned how to build my own frequency comb lasers. Since then, I have looked into many applications. I’ve used frequency combs for gas spectroscopy in the lab and studying greenhouse gases over cities. I’ve measured distances at very high precision, even through flames! 

I am sure that there are many more possibilities with frequency combs, which keeps the excitement in this work alive and boredom at bay. Whether seeing through fire or into the depths of your muscles, researchers are always “lasering in” on ways to improve our lives with this important science.