Author: kvan637 (page 2 of 8)

Our new paper on laser ultrasonics on rocks under in situ conditions

Today, research led by Jonathan Simpson, and co-authored by Kasper van Wijk and Ludmila Adam and Caitlin Smith, was published in Reviews of Scientific Instrumentation. The four of us are very proud of this paper, as it has taken us many years leading up to the moment where we can do rock physics under in situ conditions in our pressure vessel with optical windows. Many labs will claim “unique” experimental capabilities, but this particular setup is truly the first one like it in the world. We look forward to tackling new geophysical problems that require estimation of the elastic properties of samples under pressure and temperature control.

Jonathan wins poster award at the 2019 APOS meeting

This past week, members of the PAL participated in the 2019 APOS meeting. Jami presented her work on photoacoustic imaging through bone, and Kasper gave an overview talk on how we use waves of different length scales for applications in rocks, ice, fruit and others. Jonathan presented a poster on laboratory measurements of Alpine Fault rock properties under in situ conditions, and was awarded the student prize from the Australian Optical Society. Congratulations, Jonathan!

Group photo at the conference dinner of the APOS meeting in Auckland, 2019. FLTR: Sam Hitchman, Jonathan Simpson, Laura Cobus, Jami Shepherd and Kasper van Wijk.

“Timberrr!” – A new new laser ultrasonic way to estimate the physical properties of wood

Wave Motion just published our latest research on estimating the physical properties of wood. Our method, based on laser-generated and laser-detected ultrasonic  waves, has major advantages over current techniques, as you can read here. This work started as part of Sam’s PhD thesis, and has since been picked up by Jonathan and Kasper. Maybe one day, laser ultrasonic scanning will displace the standard bending test in the woodmill, as a fast and noncontacting alternative to the grading process!



postdoctoral fellowship opening

In the physical acoustics lab, we remotely sense photoacoustic and ultrasonic wavefields with optical techniques. Most of these techniques result in point measurements of the wavefield, which tell us about the physical properties of rocks, fruit, ice, timber and the human body. Point detection of the wavefield is useful, but certain applications require instant recording of the wavefield at more than a single point. A new postdoctoral researcher position opened up to develop line- or areal detection of these wavefields. Methods will include line detection with Gas Coupled Laser Detection and areal wavefield detection with Speckle Pattern Interferometry.

For more information, contact Kasper van Wijk or Jami Shepherd


Our PALs at the GSNZ meeting

At last week’s annual meeting of the Geological Society of New Zealand, the PALs (and our friends from the PORO lab) had quite the showing! Icing on beautiful presentations by all were two prizes for runner-up student presentations. James Clarke presented his work on laboratory analogues of volcano-seismic signals, and Jonathan Simpson reported on the setup he built for laser ultrasound under pressure to explore anisotropy and fracturing in Alpine Fault Rocks. To top the awards off, Shreya Jagdish Kanakiya won the Jim Ansell award, “awarded by the Committee of the Geoscience Society of New Zealand (Inc.) to the applicant whose subsequent career, in the opinion of the Committee, is the most likely to advance geophysics in New Zealand.” No pressure, Shreya!

Caitlin Smith

Hi, I am Caitlin, and I am a summer research student using ambient seismic noise to monitor the Auckland Volcanic Field.

I am a third-year undergraduate majoring in Physics and Chemistry,  but I am particularly interested in how these fields can help us understand the processes that created and shaped the planet we live on.

Over the summer I hope to use the python package MSNoise to process and analyse Auckland’s seismic station data.  From this data, a Green’s function or impulse response can be obtained and, over time, determine changes in seismic wave speed between stations.  I hope to investigate the sources of these changes, with some possible leads being:

  • Changes in the source of the seismic noise(ocean waves)
  • Precipitation altering the groundwater/water table level
  • Changes in the material properties of the earth between stations (magmatic intrusision= imminent volcanic eruption?)

As my research progresses I intend to post my findings on the PAL blog, so stay tuned!



Jami Johnson Shepherd (is back)!

After a postdoctoral fellowship at Sorbonne Université, Laboratoire d’Imagerie Biomédicale in Paris, France, Jami has returned as a DWC postdoctoral fellow in the Physical Acoustics Lab. We thank the Dodd Walls Centre for their support and are thrilled that she’s back to lead our research in medical imaging. On a personal note: Jami is from here on called “Jami Johnson Shepherd”, which means we also congratulate her and her new husband Sam!

Apple Seismology is Big in Japan

Dr. Sam Hitchman

Barring some minor thesis corrections, Sam Hitchman has now fulfilled all the requirements towards his PhD degree! Today’s oral defence of his work was highly impressive to witness. We are all very proud of Sam and congratulate him on a thesis full of exciting developments in laser ultrasound. Sam has built laser detectors for ultrasound, and successfully used them in some very exciting applications in deciphering the physical properties of rocks, fruit, and timber. Well done, Sam!

Jonathan wins another prize

At this year’s annual meeting of the Dodd Walls Centre, Jonathan Simpson won a prize for his presentation on the first laser ultrasonic measurements on rocks under high pressure. For his MSc research, Jonathan has built an arduino-driven servo system to rotate rocks inside our pressure vessel with optical windows. We congratulate Jonathan (again!) for the success of his hard work!