  A compact cryogenic calibration target is presented that has a peak diffuse
reflectance, $R \le 0.003$, from $800-4,800\,{\rm cm}^{-1}$ $(12-2\,\mu$m).
Upon expanding the spectral range under consideration to $400-10,000\,{\rm
cm}^{-1}$ $(25-1\,\mu$m) the observed performance gracefully degrades to $R \le
0.02$ at the band edges. In the implementation described, a
high-thermal-conductivity metallic substrate is textured with a pyramidal
tiling and subsequently coated with a thin lossy dielectric coating that
enables high absorption and thermal uniformity across the target. The resulting
target assembly is lightweight, has a low-geometric profile, and has survived
repeated thermal cycling from room temperature to $\sim4\,$K. Basic design
considerations, governing equations, and test data for realizing the structure
described are provided. The optical properties of selected absorptive materials
-- Acktar Fractal Black, Aeroglaze Z306, and Stycast 2850 FT epoxy loaded with
stainless steel powder -- are characterized and presented.
