Analysis of a low-aberration holographic scanner

Low-aberration holographic scanners that eliminate the need tor lenses or mirrors promise to greatly reduce the cost of laser printers and image scanners. This paper describes how the spot profile of such a scanner can be predicted using the Fresnel-Kirchhoff diffraction integral, and the diffraction efficiency of the scanner can be predicted using Kogelnik's coupled-wave theory. Experimental results verity the accuracy of these design methods. For a prototype scanner used in a high-resolution He-Ne laser printer, the measured linearity error was under +/- 100 microm, and the spot size (half-intensity beamwidth) was under 60 microm for a span (scan width) of 280 mm.