The Government Laboratory (GL), Hong
Kong Council for Testing and Certification (HKCTC), Open University of Hong
Kong (OUHK) and Standards and Calibration Laboratory of Innovation and
Technology Commission (SCL) jointly organized the Metrology Symposium 2020 on 10th
Jan 2020. The theme is “The
International System of Units – Fundamentally Better”. Hong Kong Society for Quality (HKSQ) was one
of supporting organizations. On May 20, 2019, the World Metrology Day (WMD)
2019, the International System of Units (SI) was revised so that all the seven
base units, namely, the second, the metre, the kilogram, the ampere, the
kelvin, the mole and the candela, were defined based on seven defining
constants related to the fundamental laws of nature. Before the seminar, I met many
friends in testing and certification industry and we took a photo for memory.
Ir. Brenda Lam and I took a photo first.
I also took a photo with Dr. Dr.
Eric Sze and Mr. Raymond Leung.
I met Mr. CM Tsui again and took
a photo for memory.
Dr. Steven Yang, Ms. Brenda Lam
and I were all gradated in CityU (EE, AP & BCH/AP/SEEM).
I am honor to meet Dr. Alex CK
Tse (Programme Director, Directorate Office, OUHK).
Gilson HK Lab team (Nic, Sally
& Ben) also joined this metrology symposium.
In the beginning, Prof. Yuk-Shan
Wong (President, OUHK) gave welcoming address. He said he serviced as Chairman
of Consumer Council for many years in which metrology is important in
measurement. It is not only focused on
Quality but Quantity is also critical.
Finally, he expected metrology as foundation of science in Testing and
Certification which could be a new economic development engine.
Then all speakers and guests took
a group photo.
The first and keynote speaker was
Mr. CM Tsui (Head of Laboratory, Standards and Calibration Laboratory) and his
topic entitled “A 35-year History of Setting up Primary Standards of Physical
Measurements for Hong Kong”. Firstly, Mr.
Tsui reviewed the history of metrological infrastructure development since Mr.
Gordon Bell (Director Royal Observatory) suggested to maintain and certify
standards of measurement in 1977. In
that time, the Governor of Hong Kong appointed the Advisory Committee on
Diversification (ACD) to study the ways to facilitate diversification of
industry and the report issued in 1979.
Then Mr. Tsui told us that HKG
Standards and Calibration Laboratory (SCL) was established in 1984. He
introduced their time and frequency standard and the first HP5061A caesium beam
frequency standard was acquired in 1983.
At that time LORAN-C timing receiver was used to synchronize the HP5061A
to UTC(USNO) by receiving the LORAN-C signal from Gesashi, Okinawa, Japan. He also briefed the history of traceability
for time synchronization such as 1989 using GPS Receivers, 2007 using
Multi-Channel GPS Receivers and 2017 using Multi-Frequency GPS Receivers.
Finally, Mr. Tsui introduced that their Mass Laboratory and Length Laboratory were established in 1986. SCL acquired the International Prototype Kilogram (IPK) Copy No.75 for Hong Kong from BIPM in 1990. He said SCL is lucky to order IPK in the Third Periodic Verification (PV) that 1st PV from 1899 to 1911, 2nd PV from 1939 to 1953 and 3rd PV from 1988 to 1992. In future, SCL planned to replace with silicon sphere as the reference standard mass for Hong Kong.
Ms. Brenda HS Lam (Senior
Electronic Engineer, Standards and Calibration Laboratory) was the second
speaker and her topic named “The Story of the Candela, the Eye and the
Cryogenic Radiometer”. She firstly
briefed the candle light in which the highest temperature zone is about upto
2000K.
And then Ms. Brenda Lam compared
the different of radiometry and photometry.
In Photometry, visual response of eye was mentioned and it found that
human eye is more sensitive in sun light (at 555nm) rather than at night (at
507nm).
Therefore, we would use CIE 1931 in sunlight. The following equation showed how luminosity function transferred from radiometric quantity. The peak value of luminous efficacy for photopic vision, Km, occurs at a wavelength of 555nm and has the value 683.002 lm/W (max).
Finally, she introduced SCL
primary cryogenic radiometer system in which included laser stabilization
system and cryogenic radiometer for alignment use.
Dr. Kelly WY Chan (Chemist,
Government Laboratory) was the third speaker and her presentation topic was “Mole:
The Fundamental of Metrology in Chemistry and Biology”. In the beginning, Dr. Chan briefed the
history of the Mole since John Dalton developed the “Atomic Theory” in 1808.
Avogadro said that the same volumes of all gases contain the same number of
molecules in 1811 and Wilhelm Ostwald introduced the concept of the “mole” in
1902.
Dr. Kelly Chan stated mole
definition which was SI base unit that measure amount of substance. One mole contained
a defined number of elementary entities (atoms/molecules) that is Avogadro
constant (NA) about 6.22 x10^23 mol-1. Then she mentioned
that one mole of grapefruit would have approximately the same volume as the
Earth!
After that Dr. Chan said metrology in Chemistry and Biology focused on the study of comparability and traceability of those measurements to ensure the reliability results. The following diagram demonstrated how analytical measurement could be traceable to SI unit (unbroken chain) for comparison of their results.
Lastly, she explained the
calibration hierarchy for protein which needed to decompose to small unit as
amino acid which could be traceable to SI unit.
The fourth speaker was Dr. Steven
SL Yang (Acting Senior Electronics Engineer, Standards and Calibration
Laboratory) and his presentation title named “Let’s Count Elementary Charges”. Firstly, he explained how to count elementary
charges. It was using conventional
current (from +ve to -ve) or flow of electron (from -ve to +ve).
In 1860s, people determined the
mass of the silver before and after to indicate the current passed through it. (1A
generate ~ 1.118g silver per second or per coulomb). Another old method was oil drop experiment in
1909. Recently, SI definition of
electric current that the ampere (A) is the SI unit and defined by taking the
fixed numerical value of the elementary charge e to be 1.602 176 634 x10-19
when expressed in the unit C, which is equal to A s, where the second is
defined in terms of △VCs. (A = C/s)
The Quantum Metrological Triangle
was introduced for practical realization of ampere that included Voltage,
frequency and Current. He explained
Single electron transport (SET) had technical limitations and larger relative
uncertainties but it offered unique and elegant approaches to realizing SI
units.
Finally, Dr. Steven Yang showed
SCL equipment for practical realization the ampere. At the end, he asked us how much capacity of
portable power bank and give three equal amount but different unit answers that
10,000mAh = 36,000C = 2.246 943 266 805 87 x1023e.
During the tea break, there were
some research posters demonstration.
Poster for Transition from the IPK to a fundamental constant h.
Another poster showed the story of the candela.
The fifth speaker was Dr. Terry
HW Lai (Electronics Engineer, Standards and Calibration Laboratory) and his
topic entitled “From Ancient to Modern, the Development of Time Measurement
Using Optics”. Dr. Lai briefed the history
of timekeeping development in Ancient to now.
Since sunrise and sunset is
periodical that is suitable for time measurement using Sundials in
ancient. In Hong Kong, there were some
place established Sundials and the most famous one was in HKUST. And then
Crystal Oscillator developed for digital timekeeping based on the piezoelectric
material to generate an electrical signal with a precise frequency (Typically
32,768 Hz per second).
And then Dr. Lai briefed the
atomic time since 1960 that an atomic standard of time, based on a transition
between two energy levels of an atom or molecule, could be realized and reproduced
much more accurately. Caesium 133 atom
was chosed in 1967.
Lastly, Dr. Lai showed the comparison
between optical clock and Caesium Fountain Atomic clock. He concluded optical clocks had potential to
realize the second in the future.
The sixth speaker was Dr. Eric TP
Sze (Associate Professor, OUHK) and his presentation was “Reference Materials –
Considerations to Maintain Metrological Traceability”. Dr. Sze briefed the metrological traceability
that related to a reference through a documented unbroken chain of
calibrations, each contributing to the measurement uncertainty.
In order to give student experience
the important of traceability, he ordered the Standard Reference Material 2582
powdered paint (nominal 200mg/kg Lead) for student use. It costs HK$6000 per 20g!
At the end, Dr. Eric Sze briefed the
main steps in producing and maintaining CRM based on PD ISO Guide 35:2017 and
explained how to assure the homogeneity and stability of this CRM.
Mr. Raymond Leung (Electrical and Mechanical Engineer, SCL) was the last speaker and his topic entitled “Optical Clocks and the Future of the Second”. In the beginning, Mr. Leung briefed the history of International Mass Prototype, The Grand K (1889-2019).
Then he briefed the new
definition of kg by taking the fixed numerical value of the Planck constant h
to be 6.606 070 15 x10-34 when expressed in the unit Js, which is
equal to kgm2s-1, where the metre and the second are
defined in terms of c and △VCs. And then
practical realization for the definition of the kilogram were discussed.
After that Mr. Leung used Kibble balance calculation to derive the relationship of the Planck constant and the mass.
Lastly, Mr. Raymond Leung briefed
how to use X-ray-crystal-density method (XRCD) and the single crystal of
silicon sphere (high chemical purity and no dislocations) for practical
realization for the definition of the kilogram.
He told us that the Silicon Sphere cost 1 million Euro!
Q&A Session:
I questioned that we studied mole
in Chemistry under university BSc level but we all used ppm working in
laboratory; and why let student use very expensive CRM. Dr. Kelly Chan said it related to chemical
reaction but both units were related to each other that ppm could be mg/l in
which was able to calculate back to mole again.
Dr. Sze said it could let student more understand the traceability and
experience on how to handle CRM.
Reference:
OUHK – http://www.ouhk.edu.hk/
Metrology
Symposium 2019 (The New SI for a Smarter World) - https://qualityalchemist.blogspot.com/2019/01/metrology-symposium-2019-new-si-for.html
The WMD,
the WAD and the WSD Forum 2018 - https://qualityalchemist.blogspot.com/2018/07/the-wmd-wad-and-wsd-forum-2018.html
Metrology
Symposium 2017 (Redefinition of the SI Unit) - https://qualityalchemist.blogspot.com/2017/10/metrology-symposium-2017-redefinition.html
The WMD,
the WAD and the WSD Forum 2017 - https://qualityalchemist.blogspot.hk/2017/06/the-wmd-wad-and-wsd-forum-2017.html#more
Seminar
on the WMD, the WAD and the WSD 2016 (flyer) - http://www.itc.gov.hk/en/quality/hkas/images/Photos/World_Accreditation_Day/WAD_2016_flyer.pdf
Seminar
Celebrating the WMD, the WAD and the WSD 2015 - https://qualityalchemist.blogspot.hk/2015/05/seminar-celebrating-wmd-wad-and-wsd-2015.html
Seminar
Celebrating the WMD, the WAD and the WSD 2014 - http://qualityalchemist.blogspot.hk/2014/05/seminar-celebrating-wmd-wad-and-wsd-2014.html
World
Metrology Day 2013 Seminar - http://qualityalchemist.blogspot.hk/2013/05/world-metrology-day-2013-seminar.html
World
Metrology Day 2012 Seminar - http://qualityalchemist.blogspot.hk/2012/05/world-metrology-day-2012-seminar.html
World
Accreditation Day 2012 Seminar - http://qualityalchemist.blogspot.hk/2012/06/world-accreditation-day-2012-seminar.html
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