Fig. 2: Diamond surface fabrication and images.

a Schematic of the reactive ion beam angled etching (RIBAE) fabrication process. (i) Etch mask is patterned onto the diamond sample surface. (ii) Top-down etch with the sample mounted perpendicular to the ion beam path on a rotating sample stage. (iii) Sample is tilted during etching to obtain the target angle α with respect to the direction of the ion beam, uniformly etching underneath the etch mask. (iv) Mask removal yields an array of 3-D nanostructures etched into the surface of diamond. b Optical image of the diamond mirror on a 4.2 mm × 4.2 mm diamond crystal. Each division on the ruler is 1 mm. Photo Credit: H. A. Atikian, Harvard. c SEM image of the diamond mirror taken at 60° from normal. d Zoomed SEM image of the mirror taken at 40° from normal.