Fabrication of diffractive optics with binary masks requires multiple photolithographic processes to produce efficient, continuous profile elements (kinoforms). Alignment or etching errors at any stage of fabrication decrease the efficiency of the element. We developed two accessible procedures that minimize fabrication complexity, component turnaround time, and cost. The first technique [Appl. Opt. 34, 7507–7517 (1995)] uses gray-scale masks produced by commercial slide-imager systems. Here, we report on an alternative technique for producing gray-scale masks by spatial filtering of halftone screens. Using the photoreduced gray-scale patterns as lithographic masks, we fabricated diffractive-optic blazed gratings and lens arrays in both photoresist and quartz. First-order efficiencies as high as 70% are reported. Also, the strengths and limitations of this technique are compared with the previously reported slide-imager method as well as other fabrication methods.
© 1995 Optical Society of America
Original Manuscript: May 15, 1995
Revised Manuscript: July 5, 1995
Published: November 10, 1995
Donald C. O’Shea and Willie S. Rockward, "Gray-scale masks for diffractive-optics fabrication: II. Spatially filtered halftone screens," Appl. Opt. 34, 7518-7526 (1995)