The invention relates to an energy filter image generator for filtering electrically charged particles. The composite sheet comprises a low-density, lightly bonded non-woven web that is stitch-bonded and bulked such that the stitch-bonding yarns are not visible to the naked eyes without the need of post-processing steps to hide the yarns. The meltblown fibers include first meltblown fibers formed using a polyolefin and second meltblown fibers formed using a polyester.