Abstract: This invention relates to coded aperture imaging apparatus and methods. In one aspect a coded aperture imager has at least one detector array and a reconfigurable coded aperture mask means. A reconfigurable coded aperture mask means can display various coded aperture masks to provide imaging across different fields of view and/or with different resolution without requiring any moving parts or bulky optical components. More than one detector array can be used to provide large area imaging without requiring seamless tiling and this represents another aspect of the invention. The present invention also relates to the use of coded aperture imaging in the visible, ultraviolet or infrared wavebands. The use of coded aperture imaging for imaging through a curved optical element is taught as the image decoding can automatically remove any aberrations introduced by the curved element.

Abstract: A method of generating a Computer Generated Hologram (CGH) using the diffraction specific algorithm allows a curved wavefront to be produced from a single hogel, rather than the planar waves of the prior art. This allows a wavefront from a singel hogel to generate a point in the image volume. An imaginary wavefront is transmitted from each point in the image volume and sampled at a plurality of points over the hogel. These samples are used to produce a set of complex Fourier coefficients that can be used to approximate the original waveform.

Abstract: A method of generating a Computer Generated Hologram (CGH) using the diffraction specific algorithm allows a curved wavefront to be produced from a single hogel, rather than the planar waves of the prior art. This allows a wavefront from a singel hogel to generate a point in the image volume. An imaginary wavefron is transmitted from each point in the image volume and sampled at a plurality of points over the hogel. These samples are used to produce a set of complex Fourier coefficients that can be used to approximate the original waveform.

Abstract: A procedure for displaying Diffraction Specific (DS) Computer Generated Holograms (CGH) includes the provision of a novel diffraction table (DT) modified so as to store a complete decoded fringe for each point capable of being projected into the image volume. When generating a DS CGH the diffraction table is produced that holds data relating to the image to be projected. The prior art stores in this diffraction table a set of hogel vectors that are used to select a set of basis fringes relating to each point to be displayed on the CGH. This means that each basis fringe corresponding to a particular hogel vector must be accumulated together with all the others before a complete fringe is produced. The pre-computation of the fringes as per the current invention singificantly reduces the online processing requirements of producing an image, as the new DT can be produced offline with no knowledge of the image to be displayed.

Abstract: Apparatus which allows selection and generation of a variety of hologrammatic optical wavefronts. A device, which comprises a substrate layer of varying thickness and an electro optic layer, with a voltage dependent refractive index mismatch between the two, is used to modulate transmitted light, thus generating a hologrammatic wavefront. Said modulation can be changed by variation of an applied voltage and this changes the wavefront which is generated. The range of wavefronts which can be generated is defined by the distribution of substrate layer thicknesses across the device.