VOLUME APPROXIMATIONS OF LASER PIT ABLATIONS

Radiometric dating estimates the age of rocks by comparing the concentration of a decaying radioactive isotope to the concentrations of the decay byproducts. Radiometric dating has been instrumental in the calculation of the Earth's age, the Moon's age, and the age of our solar system. Geochronologists in the School of Earth and Space Exploration at ASU use radiometric dating extensively in their research, and have very specific procedures, hardware, and software to perform the dating calculations. Researchers use lasers to drill small holes, or ablations, in rock faces, collect the masses of various isotopes using a mass spectrometer, and scan the pit with an interferometer, which records the z heights of the pit on an x-y grid. This scan is then processed by custom-made software to determine the volume of the pit, which then is used along with the isotope masses and known decay rates to determine the age of the rock. My research has been focused on improving this volume calculation through computational geometry methods of surface reconstruction. During the process, I created an web application that reads interferometer scans, reconstructs a surface from those scans with Poisson reconstruction, renders the surface in the browser, and calculates the volume of the pit based on parameters provided by the researcher. The scans are stored in a central cloud datastore for future analysis, allowing the researchers in the geochronology community to collaborate together on scans from various rocks in their individual labs. The result of the project has been a complete and functioning application that is accessible to any researcher and reproducible from any computer. The 3D representation of the scan data allows researchers to easily understand the topology of the pit ablation and determine early on whether the measurements of the interferometer are trustworthy for the particular ablation. The volume calculation by the new software also reduces the variability in the volume calculation, which hopefully indicates the process is removing noise from the scan data and performing volume calculations on a more realistic representation of the actual ablation. In the future, this research will be used as the groundwork for more robust testing and closer approximations through implementation of different reconstruction algorithms. As the project grows and becomes more usable, hopefully there will be adoption in the community and it will become a reproducible standard for geochronologists performing radiometric dating.