Laurie Christian

• Josephson voltage standards
• dc voltage, current and resistance, including the Reference Step Methods for dc voltage and current scale buildup
• Mains power and related quantities measurement
• Cryogenics

• PhD, experimental physics, 1983

Laurie has spent 40 years working as a metrologist specialising in electrical measurements. He is responsible for the 10 V Josephson Voltage Standard, which is New Zealand’s standard of dc voltage. In 1997 he spent 10 months working with the team at the NIST, Boulder, Colorado laboratories who developed the Josephson array chip that is the heart of this standard. He has carried out research into developments of this technology that allow the synthesis of arbitrary low-frequency waveforms.
Laurie has been active in many areas of electrical metrology, including DC voltage, current and resistance. In 1999 Laurie developed the Reference Step Method for measuring dc voltage ratios for resistive dividers up to 1000 V and has since then applied it to calibrating both dc voltage sources and meters over the same range. Several NMIs are using this method for dc voltage scaling. In 2006 he applied the core principle of this method to create the Current Reference Step Method, which can be used to scale from a low current to a much higher current (hundreds of amperes).
Laurie has been a technical expert for many IANZ accredited electrical calibration laboratories and has peer-reviewed several NMIs in the Asia-Pacific region.

• Member of the New Zealand Institute of Physics
• Member of the Metrology Society of Australasia
• Formerly a member of the CCEM (Consultative Committee on Electricity and Magnetism)

• Early, M.D.*; Christian, L.A.*; Lawson, T.B.*. 2014. Building-up the DC voltage scale for sources and meters. CPEM Digest (Conference on Precision Electromagnetic Measurements). p.138-139.
• Early, M.D.*; Sira, M.; Andersson, B.-O.; Christian, L.A.*; Gunnarsson, O.; Rydler, K.-E.; Streit, J. 2013. A simple build-up method for the DC voltage scale of a source. IEEE transactions on instrumentation and measurement. Vol.62, no.6, article no.6399596, p.1600-1607.
• Christian, L.A.*. 2006. A new method for calibrating DC Current Transformers at high DC current. CPEM Digest (Conference on Precision Electromagnetic Measurements). p. 236-237.
• Marullo-Reedtz, G.; Cerri, R.; Blanc, I.; Gunnarsson, O.; Williams, J.; Raso, F.; Kim, K.-T.; Frenkel, R.B.; Xiuzeng, Z.; Katkov, A.S.; Dziuba, R.; Parker, M.; Wood, B.M.; Christian, L.A.*; Tarnow, E.; Mahajan, S.K.; Singh, A.; Sakamoto, Y. 2003. Comparison CCEM-K8 of DC voltage ratio: results. IEEE transactions on instrumentation and measurement. Vol.52 no.2, p.419-423.
• Christian, L.A.*; Chua, S.W.; Sim, T.Y. 2001. Measurement uncertainties arising from unpowered shipment of DC voltage references. IEEE transactions on instrumentation and measurement. Vol.50 no.2 (Apr.), p.259-262.
• Benz, S.P.; Christian, L.A.*; Burroughs, C.J. 2000. DC voltage synthesis using a pulse-quantized Josephson voltage source. CPEM Digest (Conference on Precision Electromagnetic Measurement). p.339-340.
• Christian, L.A.*. 2000. A new method for measuring ratios of DC voltages from 10V to 1100V. CPEM Digest (Conference on Precision Electromagnetic Measurements). p.665-666.
• Christian, L.A.*; Millar, K. 1999. A Josephson-array calculable- waveform generator. IEEE transactions on instrumentation and measurement. Vol.48 no.2, p.469 - 475
• Christian, L.A.*; McLeod, D.R.*. 1998. Microwave frequency sensitivity of Josephson array systems. CPEM Digest (Conference on Precision Electromagnetic Measurements). p.445.
• Reymann, D.; Kim, K.T.; Christian, L.A.*; Frenkel, R.B. 1996. Comparisons of the Josephson voltage standard of the BIPM with those of the KRISS, the MSL and the NML. Metrologia. Vol.33, p.75-79.