  Analytical forms of the optical helicity and optical chirality of
monochromatic Laguerre-Gaussian optical vortex beams are derived up to second
order in the paraxial parameter $kw_0$. We show that input linearly polarised
optical vortices which possess no optical chirality, helicity or spin densities
can acquire them at the focal plane for values of a beam waist $w_0 \approx
\lambda$ via an OAM-SAM conversion which is manifest through longitudinal (with
respect to the direction of propagation) fields. We place the results into
context with respect to the intrinsic and extrinsic nature of SAM and OAM,
respectively; the continuity equation which relates the densities of helicity
and spin; and the newly coined term Kelvins chirality which describes the
extrinsic, geometrical chirality of structured laser beams. Finally we compare
our work (which agrees with previous studies) to the recent article K\"oksal,
et al. Optics Communications 490, 126907 (2021) which shows conflicting
results, highlighting the importance of including all relevant terms to a given
order in the paraxial parameter.
