Abstract: Head-mounted displays (100) are disclosed which include a frame (107), an image display system (110) supported by the frame (107), and a Fresnel lens system (115) supported by the frame (107). The HMD (100) can employ a reflective optical surface, e.g., a free-space, ultra-wide angle, reflective optical surface (a FS/UWA/RO surface) (120), supported by the frame (107), with the Fresnel lens system (115) being located between the image display system (110) and the reflective optical surface (120). The Fresnel lens system (115) can include at least one curved Fresnel lens element (820). Fresnel lens elements (30) for use in HMDs are also disclosed which have facets (31) separated by edges (32) which lie along radial lines (33) which during use of the HMD pass through a center of rotation (34) of a nominal user's eye (35) or through the center of the eye's lens (36) or are normal to the surface of the eye's cornea.

Abstract: Head-mounted displays (100) are disclosed which include a frame (107), an image display system (110) supported by the frame (107), and a Fresnel lens system (115) supported by the frame (107). The HMD (100) can employ a reflective optical surface, e.g., a free-space, ultra-wide angle, reflective optical surface (a FS/UWA/RO surface) (120), supported by the frame (107), with the Fresnel lens system (115) being located between the image display system (110) and the reflective optical surface (120). The Fresnel lens system (115) can include at least one curved Fresnel lens element (820). Fresnel lens elements (30) for use in HMDs are also disclosed which have facets (31) separated by edges (32) which lie along radial lines (33) which during use of the HMD pass through a center of rotation (34) of a nominal user's eye (35) or through the center of the eye's lens (36) or are normal to the surface of the eye's cornea.

Abstract: Computer-based methods and associated computer systems are disclosed for designing free space reflective optical surfaces (13) for use in head-mounted displays (HMDs). The reflective optical surface (13) produces a virtual image of a display surface (11) for viewing by a user's eye (15). The method includes using one or more computers to: (i) represent the display surface (11) by display objects (25); (ii) represent the free space reflective optical surface (13) by surface elements (23); and (iii) iteratively calculate spatial locations, normals, and radii of curvature for the surface elements (23) which will cause a virtual image of each display object (25) to be displayed to a nominal user's eye (15) in a desired direction of gaze of the eye (15).

Abstract: Head-mounted displays (100) are disclosed which include a frame (107), an image display system (110) supported by the frame (107), and a reflective surface, e.g., a free-space, ultra-wide angle, reflective optical surface (a FS/UWA/RO surface) (120), supported by the frame (107). In certain embodiments, the reflective surface (120) produces spatially-separated virtual images that are angularly separated by at least 100, 150, or 200 degrees. Methods and apparatus for designing reflective optical surfaces, including FS/UWA/RO surfaces, for use in head-mounted displays (100) are also disclosed.

Abstract: Head-mounted displays (100) are disclosed which include a frame (107), an image display system (110) supported by the frame (107), and a reflective surface, e.g., a free-space, ultra-wide angle, reflective optical surface (a FS/UWA/RO surface) (120), supported by the frame (107). In certain embodiments, the reflective surface (120) produces spatially-separated virtual images that are angularly separated by at least 100, 150, or 200 degrees. Methods and apparatus for designing reflective optical surfaces, including FS/UWA/RO surfaces, for use in head-mounted displays (100) are also disclosed.

Abstract: Head-mounted displays (100) are disclosed which include a frame (107), an image display system (110) supported by the frame (107), and a Fresnel lens system (115) supported by the frame (107). The HMD (100) can employ a reflective optical surface, e.g., a free-space, ultra-wide angle, reflective optical surface (a FS/UWA/RO surface) (120), supported by the frame (107), with the Fresnel lens system (115) being located between the image display system (110) and the reflective optical surface (120). The Fresnel lens system (115) can include at least one curved Fresnel lens element (820). Fresnel lens elements (30) for use in HMDs are also disclosed which have facets (31) separated by edges (32) which lie along radial lines (33) which during use of the HMD pass through a center of rotation (34) of a nominal user's eye (35) or through the center of the eye's lens (36) or are normal to the surface of the eye's cornea.

Abstract: Computer-based methods and associated computer systems are disclosed for designing free space reflective optical surfaces (13) for use in head-mounted displays (HMDs). The reflective optical surface (13) produces a virtual image of a display surface (11) for viewing by a user's eye (15). The method includes using one or more computers to: (i) represent the display surface (11) by display objects (25); (ii) represent the free space reflective optical surface (13) by surface elements (23); and (iii) iteratively calculate spatial locations, normals, and radii of curvature for the surface elements (23) which will cause a virtual image of each display object (25) to be displayed to a nominal user's eye (15) in a desired direction of gaze of the eye (15).

Abstract: An apparatus combining an optical sensor and a bomb impact assessment system, and corresponding method for facilitating bomb impact assessment, comprising means for receiving an optical signal, means for splitting off a portion of the optical signal from a primary optical path to form a secondary optical path, a lens in the secondary optical path, the lens comprising a plurality of facets generating a plurality of tertiary optical paths, means for combining signals from the primary and one or more of the tertiary optical paths, means for detecting the combined signals, and means for projecting onto a focal plane array bomb impact assessment data comprising detected signals from one or more of the tertiary optical paths.

Abstract: Refractive optical systems having first and second lens systems are transmissive to infrared radiation. The first lens system includes one of BaF2 and CaF2. An exemplary second lens system includes an optical material selected from at least spinel, MgF2, and aluminum oxynitride. Such exemplary refractive optical systems provide correction of chromatic aberration in multiple wavelength bands.

Abstract: A method of selecting optical materials for an optical system having a first lens system and a second lens system to provide correction of chromatic aberration in multiple wavelength bands comprises representing a first expression related to chromatic aberration of the optical system in a first wavelength band as a function of Abbe numbers of the first and second optical materials in first and third wavelength bands, representing a second expression related to chromatic aberration of the optical system in the second wavelength band as a function of Abbe numbers of the first and second optical materials in the second and third wavelength bands, comparing pairs of values calculated from the first and second expressions for potential combinations of first and second optical materials, and making a choice for the first and second optical materials based upon the comparison.

Abstract: In a method for boresighting an infrared search and track sensor to an inertial reference frame provided by a boresight module, a collimated image of a reticle pattern of the boresight module is projected. The projected image is scanned with the sensor to obtain a scanned image. Rotation of the scanned image due to boresight module roll and distortion of the scanned image due to sensor roll are isolated. Distortion of the scanned image due to sensor roll is removed. An arrangement in an infrared search and track sensor is also disclosed.

Abstract: In a forward looking infrared (FLIR) sensor, a scanning mirror views an external scene, and the infrared energy from the scanning mirror is directed along an optical path to a solid state detector. In the optical path there is a three-position mirror which is driven by an actuator to three predetermined positions. The FLIR sensor also includes two thermal reference sources which are disposed on either side of the optical path and viewable by the three-position mirror. When in a neutral position the three-position mirror reflects the infrared energy from the external scene onto the detector. When the three-position mirror is moved away from the neutral position to two different predetermined positions, the three-position mirror views each of the thermal reference sources and reflects the thermal energy of the thermal reference sources onto the detector in order to provide two reference irradiance levels for the FLIR sensor.

Abstract: A viewfinder system for a through-the-lens viewing camera which includes a focusing screen, a field lens, a prism, and an eyepiece is disclosed where the field lens is positionable in accordance with the position of the exit pupil of the objective lens and the eyepiece is positioned in accordance with the position of the field lens. Negative optical power is introduced between the field lens and the prism, and the prism design substantially reduces the size of the prism without sacrificing viewfinder brightness.