Conventional lenses are based on refraction, while a Fresnel binary lens operates by diffraction. Fresnel lenses offer the ability to perform unique beam manipulation and frequency-dependant focusing. The linearly frequency-dependent focal length of a Fresnel lens allows tomographic imaging of a target using multiple frequencies. Objects at various locations along the beam propagation path are uniquely imaged on the same imaging plane using a Fresnel lens with different frequencies of the imaging beam. This procedure allows the reconstruction of an object's tomographic contrast image by assembling the frequency-dependent images, provides a new tomographic imaging modality [1].
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