Abstract: A system and method for creating a three-dimensional image of an opaque object utilize frequency diverse coherent illumination in combination with an opacity constraint in performing three-dimensional phase retrieval and/or profile retrieval. An opaque object is one which exhibits only surface scattering and no volume scattering over volumes that extend beyond the desired range resolution. The system and method require only Fourier intensity information to create a three-dimensional image which avoids the difficulties associated with prior art systems and methods requiring phase information to produce similar images. Furthermore, the system and method of the present invention do not require imaging optics, precise alignment of optical components, or precise phase stability of the coherent illumination source.

Abstract: A night vision apparatus 10 includes a first focusing refracting lens 28 which focuses light rays 29 from distant scene 14 onto a light intensifier 30. The kinoform 40 or bifringent lens 78 are disposed in the light path to allow light rays 35 from near scene 18, 20, 22 and 24 to be focused onto light intensifier 30 to form a multi-focus night vision apparatus with increased depth of focus.

Abstract: A dual focal length ophthalmic lens is formed from a birefringent material with its fast and slow axes perpendicular to the user's visual axis. The dual focal property arises due to the differing indices of refraction of the birefringent material for light polarized parallel to the fast and slow axes. Light emanating from far objects having one polarization and light emanating from near objects having the opposite polarization are both focused onto the user's retina. Depending upon which object is being viewed, an in-focus and a blurred image appear simultaneously on the user's retina. The ability of the user's eye/brain system to distinguish between the two images provides bifocal action from a single lens. The invention may take the form of a spectacle, contact, or intraocular implant lens.