Abstract

Free-space optics offers a means of exploiting the large bandwidths of optical signals and the high densities of optical imaging.^[1] Many of the free-space optical computing and switching systems proposed and constructed thus far have relied on conventional imaging using bulk lenses, as in Fig. 1(a).^[2] These solutions must provide large space bandwidth products (SBWP) since they offer high resolution over the entire image field. Less than one tenth of the device array area is commonly used for optical I/O, due to fabrication^[3] or cross talk issues.^[4] The percentage of the total area occupied by the optical I/O windows will decline as the amount of functionality per pixel is increased (e.g. "smart pixels").^[1] If the number of optical I/Os remains large, then the object and image fields provided by the lenses must grow. The requirement of high resolution across larger fields will continue to increase the cost and complexity of conventional optical solutions. Additionally, the increased field angles of the beams propagating between the lenses may introduce unwanted polarization effects at the polarization beam splitters and retarders. Since the large SBWP of the bulk lenses is not being fully utilized, it seems reasonable to investigate means by which the required high resolution (<10 μm) could be supplied only at the optical I/O windows. One means of doing this is to provide a separate optical relay system for each I/O, as shown in Fig. 1(b).

© 1991 Optical Society of America