  WL16 is a unique member of the embedded young stellar population in the
nearby rho Ophiuchi cloud core: its extended (900 AU diameter), high surface
brightness disk is visible only at mid-infrared wavelengths. We present
diffraction-limited (~ 0.3 arcsec) images, from 7.9 to 24.5 microns, of WL16
acquired at the Keck II telescope. We find the central star to be a 250 Lsun, 4
Msun, Herbig Ae star, seen through foreground material of the rho Oph cloud
core that provides an extinction of Av=31+/-1 magnitudes. WL16's disk is
detected through all nine observed passbands. We confirm, therefore, that the
emitting particles are composed of both polycyclic aromatic hydrocarbons (PAHs)
and very small (5--100 Angstroms) graphitic grains (VSGs). We confirm a
resolved (1.5" diameter) core component at 7.9 and 8.8 microns, due to emission
from positively charged PAHs. An enhancement in the emission at 12.5 microns at
the disk's edges is found for the first time, and signals the presence of
larger (>= 50-80 carbon atoms) PAHs and/or more hydrogenated PAHs than those
found in the bulk of the disk. We find a disk asymmetry, observed at all nine
mid-infrared wavelengths, at projected radii 1"-2.5" (corresponding to 125 AU
<= r <= 300 AU) from the central source.
