  Debris disks around main-sequence stars are believed to derive from
planetesimal populations that have accreted at early epochs and survived
possible planet formation processes. While debris disks must contain solids in
a broad range of sizes - from big planetesimals down to tiny dust grains -
debris disk observations are only sensitive to the dust end of the size
distribution. Collisional models of debris disks are needed to "climb up" the
ladder of the collisional cascade, from dust towards parent bodies,
representing the main mass reservoir of the disks. We have used our collisional
code to generate five disks around a sun-like star, assuming planetesimal belts
at 3, 10, 30, 100, and 200 AU with 10 times the Edgeworth-Kuiper-belt mass
density, and to evolve them for 10 Gyr. Along with an appropriate scaling rule,
this effectively yields a three-parametric set of reference disks (initial
mass, location of planetesimal belt, age). For all the disks, we have generated
spectral energy distributions (SEDs), assuming homogeneous spherical
astrosilicate dust grains. A comparison between generated and actually observed
SEDs yields estimates of planetesimal properties (location, total mass etc.).
As a test and a first application of this approach, we have selected five disks
around sun-like stars with well-known SEDs. In four cases, we have reproduced
the data with a linear combination of two disks from the grid (an "asteroid
belt" at 3 AU and an outer "Kuiper belt"); in one case a single, outer
component was sufficient. The outer components are compatible with "large
Kuiper belts" of 0.2-50 earth masses (in the bodies up to 100 km in size) with
radii of 100-200 AU.
