Experimental realization of an imaging system with an extended depth of field

Abstract

We describe the experimental realization of an all-optical imaging system with an extended depth of field (DOF). The core of the system is a phase mask consisting of 16 Fresnel lenses (FLs) that are spatially multiplexed and mutually exclusive. Because each FL, in tandem with the primary lens, is designed to produce a sharp image for a specific object plane location, jointly the FLs achieve a wide DOF. However, the resultant image exhibits reduced resolution. The acquired image, onto which we did not apply any postprocessing, clearly is sharper than that acquired with a clear-aperture imaging system with the same pupil size.

Nanophotonics for optical super resolution from an information theoretical perspective: a review

“…Other approaches include aperture apodization by absorptive mask [88][89][90][91][92] which extend the depth of focus but also result with reduced resolution and energetic throughput. Other approaches use diffractive optical phase elements such as multi focal lenses or spatially dense distributions that suffer from significant divergence of energy into regions that are not the regions of interest [93][94][95]. Other interesting techniques include tailoring the modulation transfer functions with high focal depth [96] and usage of logarithmic asphere lenses [97].…”

Extending the depth of field with chromatic aberration for dual-wavelength iris imaging

“…That is, the scene is divided into sections where each section is examined and restored independent of the other sections in the image. Multiple Fresnel lenses can mimic the effect of a phase mask, where each Fresnel lens in conjunction with the primary lens produces a sharp image at discrete locations along the optical axis [11]. The acquired image can produce a sharper image with a larger depth of field when compared with a clear-aperture lens of the same pupil size without the use of image post-processing.…”

Extending the Depth of Field in a Fixed Focus Lens Using Axial Colour

“…6 This method can produce a sharper image with a larger depth of field when compared with a clear-aperture lens of the same EDOF pupil size without the use of image post-processing. A combination of logarithmic aspheres together and postprocessing allows for a desired PSF to be generated.…”