Abstract: An external pupil lens system (200) with an entrance pupil distance at least three times that of the effective focal length. The lens system is comprised of several conventional lenses and a diffractive optical element (DOE) for secondary chromatic aberration correction. In the illustrative embodiment, the system includes an entrance pupil (50), followed by a lens group (52) containing two refractive elements for primary color correction. Next along the optical axis is lens group (54), which contains two refractive elements for astigmatism and higher order coma correction, followed by lens group (60), which contains one refractive element (62) and one DOE (64) for secondary color correction.

Abstract: A collimating optical device utilizes a reflective beamsplitter in the form of a linear polarizing beamsplitter to achieve a wide field of view. One form of the wide-angle collimating optical device includes, in order from an image source, a first absorptive linear polarizer; a first quarter-wave plate; an optical doublet including a plano-concave singlet, a plano-convex singlet whose convex surface has the same curvature as the curvature of the concave surface, and a first reflective beamsplitter joining the concave surface of the plano-concave singlet to the convex surface of the plano-convex singlet; a second quarter-wave plate; and a second reflective beamsplitter. One of the reflective beamsplitters is a linear polarizing beamsplitter, most preferably a wire grid polarizer.

Abstract: An external pupil lens system (200) with an entrance pupil distance at least three times that of the effective focal length. The lens system is comprised of several conventional lenses and a diffractive optical element (DOE) for secondary chromatic aberration correction. In the illustrative embodiment, the system includes an entrance pupil (50), followed by a lens group (52) containing two refractive elements for primary color correction. Next along the optical axis is lens group (54), which contains two refractive elements for astigmatism and higher order coma correction, followed by lens group (60), which contains one refractive element (62) and one DOE (64) for secondary color correction.

Abstract: A display device for a display wavelength range includes an image source, a relay group made of optical elements transparent to the display wavelength range, and a reflective combiner in facing relation to the relay group. The relay group includes a glass optical wedge, a glass lens, and a group of plastic lenses including a diffractive optical element. The group of plastic lenses is positioned between the glass optical wedge and the glass lens. The relay group has the optical wedge having a front face in facing relation to the image source, and a back face; an aspheric lens module having a front face in facing relation to the back face of the optical wedge, and a back face; and an aspheric lens having a front face in facing relation to the back face of the aspheric lens module, a back face, and an optical axis. The aspheric lens module is tilted and decentered with respect to the optical axis of the aspheric lens.

Abstract: A display device for a display wavelength range includes an image source, a relay group made of optical elements transparent to the display wavelength range, and a reflective combiner in facing relation to the relay group. The relay group includes a glass optical wedge, a glass lens, and a group of plastic lenses including a diffractive optical element. The group of plastic lenses is positioned between the glass optical wedge and the glass lens. The relay group has the optical wedge having a front face in facing relation to the image source, and a back face; an aspheric lens module having a front face in facing relation to the back face of the optical wedge, and a back face; and an aspheric lens having a front face in facing relation to the back face of the aspheric lens module, a back face, and an optical axis. The aspheric lens module is tilted and decentered with respect to the optical axis of the aspheric lens.

Abstract: A situation awareness viewing device, typically in the form of a head-mounted display device, includes a polarizing beam splitter made of a cube of a material transparent to light and having an index of refraction greater than 1, and a wire grid polarizer lying within the cube on a cube-diagonal plane extending between two diagonally opposed edges of the cube. The polarizing beam splitter has a first optical axis extending from a first face of the cube toward an opposing second face of the cube and lying at an angle of 45 degrees to the cube-diagonal plane, and a second optical axis extending from a third face of the cube toward an opposing fourth face of the cube and lying at an angle of 45 degrees to the cube-diagonal plane, the second optical axis being perpendicular to the first optical axis.

Abstract: A biocular display system (19) for generating a virtual image (30) of a visible display (20). A diffractive binary optical element (22) is used to create the virtual image (30). The binary optical element (22) contains magnifying power to increase the size of the virtual image (30). Also, the binary optical element (22) contains prismatic power to displace the virtual image (30) away from the display (20). Multiple displays (40), (42) may be viewed by employing a binary optical element (34) having multiple diffractive orders.

Abstract: An abrasive article is provided which comprises a substrate having a surface bearing and abrasive layer and an opposite surface having a layer of pressure sensitive adhesive and a protective liner covering the layer of pressure sensitive adhesive. The liner includes a lift flap secured thereto which does not extend beyond the perimeter of the liner and has a free portion accessible to finger grip.

Abstract: The present disclosure is directed to an apparatus which can be installed for opening and closing fluid flow production from a formation penetrated by a cased well borehole and connected therewith through perforations. The production tubing string is installed with a moveable sleeve having a closed and open position. The moveable sleeve defines a controllable pathway into the production tubing string. In conjunction with that, there is an internal receptacle formed in the production tubing string to enable landing of a sonde there at. The sonde connects firmly at the receptacle. Similarly, the moveable sleeve in the production tubing string has a receptacle it in which enables unique landing of a latching mechanism, the latching mechanism extending along the axis of the production tubing string at the urging of a motor in said sonde. The motor operates an elongate extendible member to move the sleeve from the closed to the open position and back.

Abstract: A fluid flow velocity measuring device is shown. In the preferred and illustrated embodiment, an elongate body receives a removable spinner cartridge assembly. The assembly is formed of an elongate sleeve surrounding a rotating shaft supported by bearing assemblies at opposite ends of the shaft. The shaft supports a spinner. Particular sizes of spinners are calibrated to a particular flow velocity ranges and density of material. The insert is held in position by a compressed spring behind the insert so that fluid flow is directed from an inlet port in the tool adjacent a petal basket, along an axial passage in the tool, and through the spinner and out through an outlet port.

Abstract: A barrier for separating the passenger compartment of a vehicle from the compartment occupied by the vehicle operator. This barrier is comprised of a stiffly flexible, firm but not hard, frame made of a material such as polyvinyl chloride tubing, the size of the frame being expandable to allow for press fit installation. The frame is traversed by flexible bands which perform the barrier function.

Abstract: An optical heterodyne receiver comprises a system of reflectors forming a folded Gregorian configuration for collecting a signal beam, and an optical detector located at the focus of the system. The reflectors comprise a paraboloidal primary reflector and an ellipsoidal secondary reflector facing each other on an optical axis with the focus of the secondary reflector coinciding with the focus of the primary reflector. An auxiliary laser generates a local oscillator beam that is combined with the signal beam after the signal beam emerges from the exit pupil (which is also the aperture stop) of the system, and the resultant is impinged on the detector. A pair of image motion compensators is located as close to the exit pupil as possible for aligning off-axis inputs to the detector. The compensators also ensure that off-axis as well as on-axis inputs are substantially coaxial with the local oscillator beam, thereby maximizing signal detector efficiency.