A variety of GaP lens arrays have been routinely produced (array dimensions up to 1.5×1.0 cm, 30×50 elements) with high yield, uniformly good finish, and low transmission loss for 0.8 μm<λ<2.5 μm. Microlenses up to 300 μm in diameter with f numbers as low as 0.7 have been fabricated by a new sealed ampoule mass‐transport technique. The mesa‐step spacing was increased from 10 to 15 μm, with mass‐transport smoothing time‐at‐temperature as short as 8 h, representing a transport‐rate 10–40 times higher than previously reported. By additional chemistry control, smoothing of 30 μm spacings has been demonstrated. Only small pieces of phosphorus are required (no phosphine or hydrogen), consequently little safety burden is incurred. Smoothing in the fused quartz ampoules is shown to be self‐terminated by wafer oxidation, which is sufficiently delayed by loose‐fitting aluminum oxide shielding. © 1995 American Institute of Physics.