Department of Electrical and Computer Engineering
Spring 2014 Seminar Series
Seminar Title: Carbon Nanotubes for Laser Radiometry
Time: 3:00-4:00 PM, Friday, Jan 31, 2014
Location: ECE 101 Lankford Lab
Speaker:
John H. Lehman
National Institute of Standards and Technology
Boulder, Colorado
Abstract:
Since the 19th Century the world has sought a better thermal detector for radiometry. When we think of making a
better thermal detector we consider improving the intrinsic properties of the detector element, but we also seek to
increase the efficiency of converting photons to heat. That is, we also want to make the detector as black as
possible. Carbon nanotube (CNT) bearing films and composites present new opportunities for our next generation
of standards for laser power and energy measurements. I will address the interaction of light and CNTs and
compare CNTs to other carbon and nano-fractal materials. I will introduce examples of black coatings prepared at
NIST and elsewhere such as CNT bearing films, vertically aligned CNTs, and composites consisting of polymerderived silicon carbon nitride and CNTs. Measurement results such as spectral responsivity, reflectance and laserinduced damage from practical devices such as our picowatt radiometer, kilowatt radiometer, pyroelectric
detectors, thermopile detectors and bolometer will be presented.
Speaker Bio:
Dr. John Lehman received his PhD in applied Physics from University of Kent in Canterbury, England in 2003. He is
currently the Project Leader for NIST Laser Radiometry, which provides the US and much of the world with laser
power meter calibrations. The project generates approximately 10 % of NIST’s calibration income. The group seeks
to develop sources and detectors for absolute radiometry ranging from single photons to 100 kW, and ranging in
wavelength from ultraviolet to far infrared. Dr. Lehman is particularly interested in the optical characteristics and
low-temperature electrical properties of carbon nanotubes and exploiting radiation pressure for a variety of
detector applications. He has 4 patents and three provisional patents pending and over 50 peer-reviewed
publications. His current ‘bestseller’ is titled “Evaluating the Characteristics of Multiwall Carbon Nanotubes,”
averaging more than one hundred downloads per week. In addition to NIST, he has worked for the United States
Air Force and Peace Corps, Morocco. He is the past president of the Colorado State Science Fair, Inc. From the
Institute of Physics (IoP, UK), he received the Quantum Electronics and Photonics Ph.D. prize for his dissertation
titled “Freestanding and domain-engineered LiTaO3 and LiNbO3 pyroelectric detectors.” His most recent award is an
Alexander von Humboldt Foundation Research Fellowship to be undertaken at Physikalisch-Technische
Bundesanstalt (PTB) in Berlin, Germany beginning in 2014.