Abstract: A viewfinder having an optical axis and comprising a negative lens component including a lens element having a first diffractive surface which introduces a phase modification .phi.(r) into a light wavefront passing through this diffractive surface and a positive lens component receiving phase modified light from the negative power lens component.

Abstract: An improved Bragg grating for an optical waveguide comprising a core and a cladding. The grating includes refractive index perturbations formed within the waveguide. It has a bandwidth in reflection having a full width at half-maximum greater than 12 nm, a total intrinsic optical loss less than 0.2 dB, and a total peak optical extinction, measured in transmission, greater than 20 dB.

Abstract: An optical transmissive component (1) is described, which component has an entrance surface (4) and an exit surface (5) for optical radiation (20), in which one of the surfaces (4; 5) is provided with an anti-reflection grating (10; 15). By providing a second surface, (5; 4) with a second anti-reflection grating and by ensuring that the grating strips (11) of the first grating (10) extend essentially perpendicularly to those (16) of the second grating (15) in corresponding areas of the first and the second surface (4; 5), it is prevented that the component is birefringent.

Abstract: A dispersive optical element called a "grism" (50) which has characteristics of both a prism (56) and a grating (62). The grism (50) consists of a prism (56) with a grating (62) disposed adjacent to one surface of the prism (56). Light passing through the grism (50) is dispersed by both the prism (56) and the grating (62). The grating (62) may be attached to either the first or second surface of the prism (56) or may be simply adjacent to the prism (56). The grism (50) has dispersive characteristics such as resolving power that can be optimized in a very flexible manner by choice of both the grating (62) and prism (56) characteristics. For example, the grating (62) may be used to amplify the angular spread introduced by a prism (56). Also different diffractive orders of the grating (62) may be used simultaneously. The result is a device with a very flexible and improved dynamic range of its resolving power, which is particularly useful in applications such as spectrometers.

Abstract: A single fold optical magnifier including a plurality of optical elements having an aspheric field flattening light inlet with a light outlet directed at an angle to the inlet and a reflecting surface positioned to direct light from the inlet to the outlet. The optical elements define a light path from the inlet to the outlet with a total average optical length of approximately 15 to 35 millimeters. At least one aspheric surface and one diffractive optical element are positioned in the light path to provide aberration correction, and the optical elements are constructed to angularly magnify images by at least a power of ten.

Abstract: A method for forming a grating in a photosensitive medium such as a photosensitive optical fiber. The method comprises impinging a pair of interfering, actinic beams onto the medium, and during the impinging step, advancing the illuminated portion of the interference pattern relative to the medium. The advancement is carried out without changing the phase, or registration, of the interference pattern. According to one embodiment of the invention, a grating having a spatially dependent period is produced by varying the wavelength or the intersection angle of the actinic beams during the advancement. According to a second embodiment of the invention, a grating having a spatially dependent refractive index perturbation is produced by varying the dose of actinic radiation received by the medium during the advancement.

Abstract: An objective lens system comprising at least one diffractive optical element, having a high magnification and a large numerical aperture, and capable of favorably correcting aberrations, in particular, longitudinal chromatic aberration and lateral chromatic aberration.

Abstract: Diffractive lenses having gradial zones (62, 70, 78, 90, 98, 106, 114) are formed by separately, sequentially spin casting and polymerizing successive radial zones of the lens to produce optical phase differences of 2.pi. between adjacent gradial zones. Diffractive lenses may be molded in plano-plano(60), plano-concave (68) and plano-convex (76) geometries and also may be combined with conventional plano-plano (84), convex-convex (92), plano-concave (100) and plano-convex (108) refractive lenses.

Abstract: A distributed Bragg grating of uniform pitch is created in a length of unstrained optical fibre which is then secured in an arcuate path to a flexible plate so as to be displaced from the neutral surface of bending of that plate. Changing the curvature of the plate imparts axial strain in the fibre which is arranged to be non-uniform as the result of the path of the fibre being arcuate. This non-uniform strain has the effect of converting the uniform grating into a chirped grating, such as may for instance be used as a dispersion equaliser.

Abstract: Diffractive lenses having gradial zones (62, 70, 78, 90, 98, 106, 114) are formed by separately, sequentially spin casting and polymerizing successive radial zones of the lens to produce optical phase differences of 2.pi. between adjacent gradial zones. Diffractive lenses may be molded in plano-plano (60), plano-concave (68) and planoconvex (76) geometries and also may be combined with conventional plano-plano (84), convex-convex (92), plano-concave (100) and plano-convex (108) refractive lenses.

Abstract: A scan angle doubling system using a rotating cylindrical drum with reflective binary diffractive optical element facets, a cylindrical mirror, and a lens to increase the scanning angle available from a rotating mirror polygon of a given size. The properties of the passive components are such that the output light beam from the reflective binary diffractive optical element facets of the rotating cylindrical drum is collimated and normal to the rotating cylindrical drum. The cylindrical drum, cylindrical mirror, and lens are arranged such that the rotating cylindrical drum and the cylindrical mirror are opposed to each other and separated by a distance greater than the sum of the radius of curvature of the cylindrical mirror plus the focal length of the lens, and the lens is interposed between the rotating cylindrical drum and the cylindrical mirror so that the center of the radius of curvature of the cylindrical mirror and the focal point of the lens means are coincident.

Abstract: A modified diffraction grating having a predetermined amount of astigmatic power correction is substituted for the plane diffraction grating in an Ebert type spectrograph having a single concave collimating and focusing mirror for directing a light beam onto the surface of the modified diffraction grating. The surface of the modified diffraction grating is curved to introduce the proper amount of astigmatic power correction to converge the sagittal focus and the tangential focus of the diffracted beam to produce a stigmatic image. The modified diffraction grating may have a pure cylindrical surface or a toroidal surface. Another embodiment replaces the plane grating in a two mirror Czerny-Turner type of instrument with a modified grating according to this invention to reduce or eliminate astigmatism in that type of instrument as well.

Abstract: In a wavelength division multiplexer suitable for integrated optical systems, to multiplex a succession of waves ranked according to their wavelength two diffraction gratings are formed at the edges of a common guide area. One focuses odd ranked waves onto a first entry of an output guide. The other focuses even ranked waves onto a second entry of the same output guide.

Abstract: A method for forming a grating in a photosensitive medium such as a photosensitive optical fiber. The method comprises impinging a pair of interfering, actinic beams onto the medium, and during the impinging step, advancing the illuminated portion of the interference pattern relative to the medium. The advancement is carded out without changing the phase, or registration, of the interference pattern. According to one embodiment of the invention, a grating having a spatially dependent period is produced by varying the wavelength or the intersection angle of the actinic beams during the advancement. According to a second embodiment of the invention, a grating having a spatially dependent refractive index perturbation is produced by varying the dose of actinic radiation received by the medium during the advancement.

Abstract: The invention involves a method for making Bragg gratings in glass optical fibers, or other glass optical waveguides, which is relatively insensitive to perturbations in the actinic light used for processing. This method is suitable for mass production and lends itself well to the manufacturing environment. The invention method involves first providing an optical phase grating. An interference pattern is generated by impinging a single light beam on the grating. The optical waveguide to be processed is exposed to this interference pattern, leading to the formation of a Bragg grating in the waveguide.

Abstract: The present invention involves a corrective optical lens construction and process for its manufacture. The lens construction consists of a glass lens having a corrective layer consisting of a blazed grating of annuli whose angles are formed to correct aberrations in the glass lens. In a first embodiment, the corrective layer is formed on one convex surface of the lens. In a second embodiment, the corrective layer is formed on a second convex surface of the lens. Embodiments also describe alternative lens shapes and corrective layer construction. A method of manufacturing the lens is also disclosed in which the resin corrective layer is molded to the glass lens.

Abstract: A method of correcting or alleviating presbyopia in humans comprising (a) fitting a first contact lens to a first eye, and (b) fitting a second contact lens to the other eye. Each of the lenses has a first power provided by the shape, curvature and material of the lens to provide a refractive corrected image and a second power provided by diffractive means to provide a second corrected image, the second power being additive to (or subtracted from) the first power. The lenses are fitted so that one has a refractive near image optical power and the other has a refractive distance image optical power, and the diffractive means of the lenses are arranged so that the amount of the light directed into the near image by one lens is substantially greater than that directed into the far image by that lens, and the amount of light directed into the far image by the other lens is substantially greater than that directed into the near image by that other lens.

Abstract: A diffractive mirror has a plurality of diffractive zones at least one of which has an optical step having a height equal to j.lambda./2 and at least one of which has an optical step having a height equal to k.lambda./2 where .lambda. is a design wavelength of the mirror and j and k are unequal nonzero integers. Alternatively stated at least one of the optical steps induces a relative phase shift of 2j.pi. at the image point between two light rays emerging from a point source at the object point and striking the lens immediately on opposite sides of the step and at least one of the steps induces a relative phase shift of 2k.pi. at the image point between two light rays emerging from a point source at the object point and striking the lens immediately on opposite sides of that step.

Abstract: A phase grating optical low-pass filter having wavelength selectivity consisting of a plurality of layers which are the same in refractive index at a certain wavelength and different from one another in refractive index dispersion, and has a configuration for generating a phase difference at a boundary of the layers.

Abstract: A lens according to the invention has diffractive power and two primary foci, where one focus is associated with the first diffractive order and one with the second diffractive order.

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: In one embodiment, a three-element biocular eyepiece system 40 having a first optical element 42 with at least one diffractive surface 44, a second optical element 48 having a refracting convex surface 50 and a refracting concave surface b 52 is provided. A third optical element 54 having a refracting convex surface 56 and a refracting convex surface 58 is also employed. In another embodiment, a four-element biocular system 60 is disclosed as having an optical element 62 having a refracting concave surface 64 and a refracting convex surface 66, a refractive-diffractive hybrid optical element 68 having a diffractive surface 70 and a refracting convex surface 72, an optical element 74 having a refracting convex surface 76 and a refracting concave surface 78, and an optical element 80 having a refracting concave surface 82 and a refracting convex surface 84. The diffractive surfaces 44 and 70 have a kinoform profile 102 a-d or approximated kinoform profiles 112a-d and 122a-d.

Abstract: The invention is directed to a mirror for changing the geometric shape of a light beam. A two-dimensional intensity distribution substantially independent of the mode structure can be generated by mounting a grating in the optical beam path of the laser beam. The intensity distribution is constant in one direction and, in a direction perpendicular thereto, the intensity can have any preselectable intensity distribution.

Abstract: An ophthalmic lens exhibiting diffractive power has a plurality of diffractive zones and smooth surfaces. The zones are arranged such that R.sub.0.sup.2 does not equal R.sub.1.sup.2 -R.sub.0.sup.2 where R.sub.0 is the radius of the central zone and R.sub.1 is the radius of the first annular zone.

Abstract: A multifocal ophthalmic lens has diffractive power produced by a plurality of concentric zones. The zones have radii that meet the conditionR.sub.0.sup.2 is not equal to R.sub.1.sup.2 -R.sub.0.sup.2where R.sub.0 is the radius of the central zone and R.sub.1 is the radius of the first annular zone.

Abstract: A diffractive contact lens in relief includes a smoothing layer (50) of optically transparent material having a smooth outside surface (51) and placed over the optical surface (16) in relief so as to immerse the relief.

Abstract: An artificial eye lens such as a contact lens or intra-ocular lens corrects astigmatism by two sets of substantially linear parallel zones arranged to diffract light predominantly into one order at one orientation, the spacing of the zones diminishing on either side of the linear axis. In addition circular diffraction zones may be provided to give both spherical and cylindrical power for astigmatism correction.

Abstract: An arrangement for forming an extended length light redirecting embedded grating in an elongated solid material optical waveguide includes a source that directs a coherent light beam of a frequency in the ultraviolet range in a primary path transversely toward the waveguide. A section of a diffraction grating extends through the primary path at a spacing from the waveguide, and the diffraction grating has a dimension normal to the primary path that exceeds the corresponding dimension of the primary path. Relative movement is effectuated between the waveguide and diffraction grating in unison, and the primary path, so that the light beam is diffracted at the diffraction grating into two mutually frequency shifted partial light beams propagating in diverging secondary paths.