Measuring the energy of one of the most powerful lasers in the USA: mission accomplished

Case study

Application: Research and development of lasers

Measurement type: Laser energy measurement, high energy levels measurement

Customer goals

A well-known research center for high-power lasers is actively developing a new laser that will be one of the most powerful lasers in the United States once it is finished.

The goal of their research is to advance fundamental physics. Of course, they are also highly motivated by making ground-breaking discoveries and adding notoriety to their research center by being the first to achieve specific scientific milestones.

To achieve their goal, they need to measure the energy of their laser at multiple points in the beam path to make sure every component is as efficient as possible. They need to create as much laser power as possible. All of these energy levels will need to be monitored for safety protocols as well as to add to their scientific papers.

These types of laser systems have very little downtime. They usually have a schedule that plans every experiment in advance and every scientist has a limited amount of time with the laser. These lasers can also make a limited number of shots in a day since they need time to recharge. If the peak power is not the correct one, the experiment they are making might fail. Then, it can take a while before they are able to try it again.

Challenges

How do you measure the one of most powerful lasers that exists around the world? That’s a big challenge, especially if this laser is still being built at the moment.

That’s the challenge the Gentec-EO’s R&D team was given. Not a simple task, but we have yet to find a single laser that is too powerful or too exotic for us to measure its energy.

Apart from the extremely high power level, there are many challenges with this measurement:

• The beam size can be quite large in the amplification stage (up to 160 mm).
• Power density is also extremely high at the target.
• They are measuring in the hundreds of Joules in the nanosecond range and the tens of Joules in the femtosecond range.
• Extremely high energy levels and extremely short pulses that aren’t suitable with damage thresholds of most laser energy detectors.

Gentec-EO’s solutions

Gentec-EO’s laser beam measurement experts sat down with the research center’s research scientists to identify the best solution that works for their laser specifications. Because the laser changes specifications a lot throughout the beam path, we helped the customer choose which detector was best suited for which location. Most of the detectors recommended were part of our standard offering except for the calorimeter we will discuss below.

QE pyroelectric laser energy detectors

Gentec-EO’s QE pyroelectric laser energy detectors were the best match for their laser system since the repetition rate is 10 Hz and most of the setup has beams small enough to fit in their apertures.

QE series

The energy detectors in the QE series are available with aperture sizes that range from 9x9 mm up to 95 mm Ø. Thus, accommodating the beam size at many points in its delivery path. Also, the largest model in this series can support up to 250 J of energy.

The customer really likes the MB absorber we use for our QE series since they have a broadband source with wavelengths that span 100 nm. This wavelength range coincides with a common transition in glass absorption. Our unique-in-the-market MB absorber is flat in this range which brings them a lot more accuracy in their measurements.

INTEGRA: Measurement on a PC interface

Many display solutions were a good choice for this customer application, but they really liked our INTEGRA solution. With it, they can literally plug their QE detectors into their computer with a USB cable. Then, they visualize the data with our free proprietary PC-Gentec-EO software on their computer.

INTEGRA

PC-Gentec-EO software

The software also allows them to do data logging and even export the data in spreadsheets for further analysis on their end. This kind of feature is a necessity for customers doing fundamental research.

Custom calorimeters for large beams

We also recommended Gentec-EO’s calorimeters for measurements at the amplification stage where the beam is really large. We can offer solutions up to 420 x 427 mm for energy measurements.    

Custom calorimeter

For large beams, high energies, and special applications that do not fit with the QE or UP series, Gentec-EO can build custom calorimeters to fit special requirements. In this application, it was clearly needed. We work with a wide range of materials from surface coatings to the most robust volume absorbers to provide the best solution for our customer’s specific applications. The glass chosen to absorb the energy of the laser is the best we could find on the market. This one is used with extremely high power density applications. The cable was also customized to fit their needed length. Finally, the calibration took into account their specific wavelength. The Gentec-EO team always makes sure that if you spend money on a high-energy calorimeter, it is well invested in the perfect detector for your application.

Results

The customer has been using our QE detectors for over 10 years now and enjoys their performance and durability, which contribute to keeping their development cost as low as possible. They are overall their favorite energy measurement products.

The development of groundbreaking technologies such as this one requires time and quality partnership. The first laser shot of this powerful laser is scheduled in a couple of months. Gentec-EO is proud to support research centers in their project.