Two methods for increasing the depth of focus of imaging systems

In this paper we describe two approaches for extending the depth of field in incoherent imaging system. The first one, a hybrid opto-digital incoherent imaging system, relies on an optical setup whereby the image is deliberately distorted, followed by a digital restoration stage. The second, an all-optical incoherent imaging system is based on a spatially code multiplexed multiple Fresnel lens mask, positioned in the lens aperture. Both provide a relatively high optical throughput and small contrast reduction, for an extremely wide range of misfocus positions. For both cases, design considerations for an extended depth of field will be described. It is important to mention that both approaches are able to provide results in real time, thus enabling their usage in practical systems; yet the all-optical system presents a remarkable simplification.