# Ovality

In telecommunications and fiber optics, ovality or noncircularity is the degree of deviation from perfect circularity of the cross section of the core or cladding of the fiber.

The cross-sections of the core and cladding are assumed to a first approximation to be elliptical. Quantitatively, the ovality of either the core or cladding is expressed as ${\displaystyle {\frac {2(a-b)}{a+b}}}$, where a is the length of the major axis and b is the length of the minor axis. The dimensionless quantity so obtained may be multiplied by 100 to express ovality as a percentage. Alternatively, ovality of the core or cladding may be specified by a tolerance field consisting of two concentric circles, within which the cross section boundaries must lie.

In measurements, ovality is the amount of out-of-roundness of a hole or cylindrical part in the typical form of an oval.

## In chemistry

In computational chemistry, especially in QSAR[1] studies, ovality[2] refers to, a measure of how the shape of a molecule approaches a sphere (at one extreme) or a cigar shape (at the other). Ovality is described by a ratio of volume to area:

${\displaystyle O={\frac {A}{4\pi ({\frac {3V}{4\pi }})^{\frac {2}{3}}}}}$

where:

O = Ovality
A = Area
V = Volume

The ovality of the He atom is 1.0 and that of HC24H (12 triple bonds) is ~1.7.

## References

1. ^ Leach, Andrew R. (2001). Molecular modelling: principles and applications. Englewood Cliffs, N.J: Prentice Hall. ISBN 0-582-38210-6.
2. ^ Hehre, Warren J.; William Sean Ohlinger (2008). Spartan'10 Tutorial and User's Guide. Irvine, CA: Wavefunction, Inc. ISBN 1-890661-41-4.