Optical elements of precise thickness profiles are desired for instruments such as coronagraphs [1], wavefront coding systems [2], and compact hyperspectral imagers [3,4]. Lack of subwavelength precision in the fabrication of these optical elements has required additional optical components, reducing the manufacturing yield and degrading performance. Here, we demonstrate a fabrication technique allowing for the control of surface fabrication errors of less than 1 nm and use this technique to fabricate a compact hyperspectral imager with the capability of high yield manufacturing.