Achim Leistner is an Australian optician of German origin. During his retirement, he was asked to join the

Avogadro project The scientific community examined several approaches to redefining the kilogram before deciding on a redefinition of the SI base units in November 2018. Each approach had advantages and disadvantages. Prior to the redefinition the kilogram, and s ...

to craft a

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sphere A sphere () is a geometrical object that is a three-dimensional analogue to a two-dimensional circle. A sphere is the set of points that are all at the same distance from a given point in three-dimensional space.. That given point is th ...

with high smoothness, as automated machining does not match his precision. In addition to precision instruments, Leistner uses his hands to feel for irregularities in the roundness of the sphere. The research team has called his extraordinary sense of touch "atomic feeling". As a result the sphere is the roundest man-made object ever manufactured in the world. If the sphere was scaled to the size of Earth, it would have a high point of only above "sea level".The sphere shown in the photographs has an out-of-roundness value (peak to valley on the radius) of . According to ACPO, they improved on that with an out-of-roundness of . On the diameter sphere, an out-of-roundness of (deviation of ± from the average) is a fractional roundness . Scaled to the size of Earth, this is equivalent to a maximum deviation from sea level of only . The roundness of that ACPO sphere is exceeded only by two of the four fused-quartz gyroscope rotors flown on Gravity ProbeB, which were manufactured in the late 1990s and given their final figure at th
W.W. Hansen Experimental Physics Lab
at Stanford University. Particularly, "Gyro 4" is recorded in the Guinness database of world records (their database, not in their book) as ''the'' world's roundest man-made object. According to a published report
221kB PDF, here
) and the GPB public affairs coordinator at Stanford University, of the four gyroscopes onboard the probe, Gyro4 has a maximum surface undulation from a perfect sphere of ± on the diameter sphere, which is a Scaled to the size of Earth, this is equivalent to a deviation the size of North America rising slowly up out of the sea (in molecular-layer terraces high), reaching a maximum elevation of ± in Nebraska, and then gradually sloping back down to sea level on the other side of the continent. Leistner holds certificates in precision optics,

geometrical optics Geometrical optics, or ray optics, is a model of optics that describes light propagation in terms of '' rays''. The ray in geometrical optics is an abstraction useful for approximating the paths along which light propagates under certain circumstan ...

, optical design drawing, and mathematics from Optic

Carl Zeiss Carl Zeiss (; 11 September 1816 – 3 December 1888) was a German scientific instrument maker, optician and businessman. In 1846 he founded his workshop, which is still in business as Carl Zeiss AG. Zeiss gathered a group of gifted practica ...

Jena Technical College. He has served as a member of the Australian Optical Society and on international conference working committees for

SPIE SPIE (formerly the Society of Photographic Instrumentation Engineers, later the Society of Photo-Optical Instrumentation Engineers) is an international not-for-profit professional society for optics and photonics technology, founded in 1955. It ...

and the

Optical Society of America Optica (formerly known as The Optical Society (OSA) and before that as the Optical Society of America) is a professional society of individuals and companies with an interest in optics and photonics. It publishes journals and organizes conference ...

.Stanford Who’s Who: Achim Leistner
Accessed June 11, 2013.

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Footnotes

{{DEFAULTSORT:Leistner, Achim Year of birth missing (living people) Place of birth missing (living people) 20th-century births 20th-century Australian physicists 21st-century Australian physicists German emigrants to Australia Living people Optical engineers Opticians

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References

Footnotes