Persistence, Precision… and a PhD for Seasoned Metrologist
Innovative research on a refractometer that could reliably correct air distortions in laser-based distance measurements secured Dr Oelof Kruger, a metrologist at the National Metrology Institute of South Africa (NMISA), his PhD.
Building on research undertaken for his Master’s degree in Physics, which he received summa cum laude from UKZN in 2017, he measured the refractive index of air to tackle a subtle but crucial problem in precision measurement, namely, the difficulties with the transition from vacuum to air in traditional refractometers used to measure the refractive index of air.
Precise refractive index measurements are essential for high-accuracy dimensional metrology, and the refractometer Kruger developed, using permanent vacuum chambers, provides a reliable, stable, low-maintenance, and user-friendly method to correct for this distortion.
It bridges the gap between real-world air-based measurements and the ideal vacuum-based International System of Units (SI) standards, boosting accuracy in science, industry and technology, and simplifying processes that traditionally used weather station-based methods.
This topic directly supported his work at NMISA, where laser-based distance measurement systems require accurate refractive index values to correct the velocity of light in air. Aligning his research to his organisation’s mission helped Kruger advance his own academic goals and contribute to the enhancement of NMISA’s capabilities in delivering more accurate distance measurements.
‘Improving this measurement has a direct impact on the accuracy of our dimensional metrology services,’ said Kruger.
Achieving a PhD more than three decades into his career is especially meaningful for Kruger, giving him added credibility when applying for or managing large research contracts as well as enhancing his contributions to scientific leadership roles. It also equips him to co-supervise and mentor up-and-coming postgraduate students and early career researchers in metrology, contributing to the future of the field.
Maintaining motivation to complete his studies late in his career was a challenge for Kruger, particularly after the passing of his father, who also completed his PhD later in life and was a major inspiration for Kruger. Realising that completing his PhD was for his own personal and professional fulfilment, and with the moral and academic support from his supervisor, Professor Naven Chetty, Kruger persevered.
A key paper that formed the basis of Kruger’s research was published in the prestigious Nature journal. He is now preparing additional publications covering the second phase of his research.
Kruger thanked his family for their understanding as he spent time away from them to work on his PhD, NMISA for providing funding and a conducive environment for the completion of his research, and Chetty for his guidance, encouragement, support, and belief in the project that were all instrumental in helping bring it to completion.
Words: Christine Cuénod
Photograph: Sethu Dlamini
