Showing papers on "Night vision published in 1992"

Backlight for liquid crystal devices

Abstract: A backlight system for liquid crystal device display is equipped with a dual lighting system for day viewing and compatible with night vision systems. The day lighting system uses conventional fluorescent or incandescent lamps for full color display during daytime use. The night lighting system uses a light source which is either filtered to remove infrared and near infrared wavelengths or which is chosen from a class of sources which does not emit such wavelengths. The day lighting system is disabled while the night system is in use.

Night vision binoculars

Abstract: A night vision binocular assembly ( 10 ) capable of converting low light and infrared energy into a visible image. The night vision binocular assembly ( 10 ) includes at least one objective lens assembly ( 62 ), image intensifier tube ( 64 ), collimator lens assembly ( 66 ) and diopter cell assembly ( 68 ) encased in an easy to assembly waterproof housing ( 16 ). The objective lens assembly ( 62 ), image intensifier tube ( 64 ), collimator lens assembly ( 66 ) and diopter cell assembly ( 68 ) are all supported by a common base structure ( 80 ) within the housing ( 16 ). As a result, variations caused by thermal expansions and contractions are evenly distributed among the various optical elements, thereby preserving a predetermined optical relationship between those elements. Simple button controls ( 28, 30, 31 ) are used to operate and adjust the night vision binocular assembly ( 10 ). The button controls ( 28, 30, 31 ) are disposed on a common circuit board ( 38 ). An elastomeric structure ( 36 ) is disposed between the circuit board ( 38 ) and the interior of the binocular housing ( 16 ). The circuit board ( 38 ) is affixed to the interior of the binocular housing ( 16 ) in a manner that compresses the elastomeric structure ( 36 ) against the binocular housing ( 16 ) to provide a water tight seal. The elastomeric structure ( 36 ) has switch membranes or domed portions which extend through apertures ( 37 ) in the housing ( 16 ) creating both a fluid impermeable seal with the housing ( 16 ) and a means for the tactile engagement of the switches on the below lying circuit board ( 38 ).

Status of uncooled infrared imagers

Abstract: Brassboard infrared imagers containing focal plane arrays of more than 80,000 uncooled detectors sensitive to radiation in the 8- to 14-micrometer wavelength region have been fabricated and tested. These imagers, which have demonstrated noise-equivalent temperature difference (NETD) values of 0.10 degree(s)C, do not require cryogenic cooling or mechanical scanning. Two different types of detector, one ferroelectric and the other bolometric, are used for the focal plane arrays. Measurements of NETD, minimum resolvable temperature (MRT) and modulation transfer function (MTF) are reported. Uncooled sensor technology is being incorporated into prototype security sensors and weapon sights that can also be used as handheld surveillance devices.© (1992) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Night vision goggle compatible liquid crystal display device

Abstract: A full color, night vision goggle compatible, liquid crystal display device achieves uniform illumination and color integrity at wide viewing angles by creating collimated, uniform light in a backlight assembly before the light reaches an IR filter having a sharp cutoff between near IR and red, and thereafter diffusing the light which is emitted from the filter to create the desired wide viewing angle.

Color night vision camera system

Abstract: A camera system providing color night vision for use in reconnaissance, orhe like. The system includes a first lens, a mirror subassembly for splitting the lens image into three images, a filter subassembly for respectively filtering the three images through a red filter and a green filter and a blue filter first and second and third intensifiers having respective first and second and third camera units which view the three images and send three image signals in series to a display monitor where the color image is viewed.

Dual mounting assembly for night vision system

Abstract: A mounting assembly for a night vision system is provided which allows the night vision system to be easily and rapidly switched from one eye to the next. The night vision system has an optical portion, and a control housing affixed to the optical portion. The control housing has a first and a second mounting plate. The mounting assembly has a first and a second carriage, and each of the carriages are configured to receive a selected one of the mounting plates. The mounting assembly can then be secured to either a face mask worn by the operator, or a helmet worn by the operator. The position of the carriages can be adjusted to compensate for the inter-pupillary distance and elevation relative a normal line of sight of an operator's eyes. The carriages are carried by a threaded rod having two portions threaded in opposite directions, so that rotation of the knob moves the carriages either closer together or further apart, as desired. The carriages also pivot against a pivot rod to selectively alter the carriage's elevation.

Helmet-mounted night vision system and secondary imager

Abstract: A helmet-mounted night vision system that is compact, light in weight and ejection-safe. The system incorporates a night vision goggles apparatus for receiving incoming infrared and/or visible light from a viewed object and for converting the incoming light to an intensified visible light for presentation to an eye of a user, a visor mounted to a helmet to be worn by the user and adapted to be positioned in front of the night vision goggles apparatus, and connecting structure for connecting the visor to the night vision goggles apparatus for retaining the visor in position in front of the night vision goggles apparatus. By ensuring that the visor is safely retained in front of and substantially fully covers the goggles apparatus at all times, the system of the invention is rendered ejection-safe. The system also provides the user with numerous other structural and operational advantages.

Night vision weapon sight

Abstract: A night vision sight is provided for use with a weapon, which includes an objective lens and a non-inverting image intensifier tube disposed along an optical axis, providing an intensified target image. The sight is focused by direct movement of the image intensifier tube relative to the fixed position of the objective lens. A reticle projector is disposed orthogonal to the optical axis and provides a collimated reticle image, the reticle image providing an aiming point for the weapon. The reticle image is superimposed over the target image, which are reflected into an eyepiece of the sight. The eyepiece has an axis between the optical axis and a sight line passing through a pre-existing sight provided with the weapon. Adjustment of the apparent position of the reticle to compensate for azimuth and elevation is accomplished by moving the reticle projector about crossed cylindrical bearings.

Mounting device for night vision mount and goggle assembly

Abstract: Apparatus for detachably securing a night vision goggle mount to a protective helmet visor housing in which the heads of a pair of upper fasteners carried by the mount are adapted to be inserted through the head receiving portions of a pair of upper keyhole slots in a base plate on the housing against the action of a leaf spring on the plate. When the shanks of the fasteners are moved into the lower head-retaining portions of the upper slots, the upper fastener heads are held by ears on the leaf spring to lock the mount. A releasing element on the base plate is adapted to be actuated to flex the spring to a position at which the spring ears are clear of the upper fastener heads to permit the mount to be removed. Preferably, a pair of lower fasteners having heads and a pair of corresponding lower keyhole slots are provided to insure stability and alignment of the night vision goggle mount.

NVEOD FLIR92 Thermal Imaging Systems Performance Model.

Abstract: The Night Vision and Electro-Optics Directorate's FLIR92 model predicts minimum resolvable temperature difference (MRTD) and minimum detectable temperature difference (MDTD) for scanning and staring infrared sensors. FLIR92 retains unchanged for two- dimensional MRTD, and incorporates sampling effects and three-dimensional noise more thoroughly than the simple approximations used in the FLIR90 model. The FLIR92 MRTD predictions are shown to be valid for representative scanning and staring systems.© (1992) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Night vision goggles having enlarged field of view and interchangeable optics

Abstract: Night vision apparatus, particularly night vision goggles, having a wide field of view The apparatus includes an objective optical system having a selected field of view for collecting visible and/or infrared light from an object to be viewed and for providing an input image of the object; image intensifying and magnifying means for receiving the input image and for providing a visible, intensified and magnified output image of the input image, and an eyepiece optical system for receiving the visible, intensified and magnified output image and for presenting a visible intensified image of the object to an eye of a user at unity magnification The image intensifying and magnifying means preferably comprises an image intensifier tube having a fiber optic bundle beam expander therein The image intensifying and magnifying means permits the eyepiece optical system to have a longer focal length and, hence, to provide greater eye relief than would otherwise be possible The goggles of the present invention can be provided in both see-thru and non-see-thru configurations and can be constructed in modular form to provide for interchangeability of objective optical systems providing varying fields of view with eyepiece optical systems providing either see-thru or a non-see-thru capability

Method and device for improved IR detection with compensations for individual detector response

Abstract: An advanced infrared (IR) Sensor based on the present invention would add the following two elements to a basic staring IR sensor using a 2 dimensional array of detector elements to significantly enhance the detection sensitivity of the device. The added features are: (1) Additional optics or modification to the normal optics to scan the image over a small fraction of the array dimensions so that each point in the image is sampled by a number of different detector elements, and (2) signal processing to combine the multiple samples for each image point so as to exclude the effects of "dead", "weak" or excessively noisy detector elements and average out the element to element sensitivity variations and calibration/correction imperfections of the "normal" elements. The effect of this process would be to provide an output which contained no "dead" picture elements (pixels), with root-mean-square (RMS) spatial noise reduced by approximately a factor of the square root of the number of image samples averaged and with dramatic suppression of the extreme values in the output variation statistics. In addition, the performance improvements outlined above can be accomplished using detector arrays having a large number of bad elements which would normally make them unacceptable for use.

Process and device for improvement of night vision in vehicles

Abstract: Process for the improvement of night vision in vehicles consisting in illuminating the road and the objects therein by means of two long-range headlights (3, 4) emitting light rays of predetermined wavelength, and in sensing an image of the roadway illuminated by these rays by means of a viewing system, characterised in that the two headlights (3, 4) respectively illuminate in the close infrared and ultraviolet fields, in that the viewing is also carried out inside the spectral bands covering close infrared and ultraviolet, and in that the combined night image resulting from this double viewing is restored to the driver in or close to his normal driving field of view.

Polymer dispersed liquid crystal infrared light shutter

Abstract: We have developed a polymer dispersed liquid crystal (PDLC) device for operation in the midinfrared region of the electromagnetic spectrum. This device can be incorporated in thermal imaging systems that utilize pyroelectric vidicons for night vision applications. The infrared electro-optic properties of several PDLCs as a function of substrate, droplet size, film thickness, and applied ac voltage are examined using infrared spectroscopy, electro-optic and differential scattering measurements, and static video analysis.

Optical mixer for helmet visual display system

Abstract: An optical mixer for use in a helmet visual display system including a light intensifier tube for night vision and a cathode-ray tube for the display of a synthetic image The mixer includes a swinging glass plate with a spectrally reflective and angularly selective coating When the angle of the swinging glass plate is changed, the amount of light transmitted through the mixer is changed

Chalcogenide glass optical fibers

Abstract: Amorphous Materials (AMI) has served since 1977 as a source of high purity, optically homogeneous plates of selenium-based glasses used in passive IR (FLIR) night vision systems. Over the past three years, Amorphous Materials has used this chalcogenide glass technology and capability to develop a unique process to prepare optical fibers. The process is based on using 2 inch cores removed from a homogeneous plate and sealed in a chamber which can be heated so that fibers may be pulled from a small tube in the bottom. Methods for cladding and coating with thermal plastic using split dies have been developed. The method has been used to produce flexible, low attenuation fibers based on an As-Se-Te composition. High purity As2S3 glass has been used to produce fibers capable of transmitting substantial amounts of IR laser energy. Physical properties of both fibers are discussed.

Helmet mounted night vision apparatus and method of separation

Abstract: A helmet mounted night vision device for a pilot that is automatically propelled away from the pilot before the pilot ejects from an aircraft, thereby preventing injury to the pilot caused by the night vision device striking the ejecting pilot. In a preferred embodiment, the present invention night vision device is a binocular device, having a right optical assembly and a left optical assembly that are viewed by the right and left eyes of the pilot, respectively. The right and left optical assemblies are each attached to elongated arm members. Each of the arm members, supporting the optical assemblies, are pivotably coupled to a common mounting plate that is removably attachable to the helmet of the pilot. Prior to ejection, the left and right optical assemblies are joined in front of the eyes of the pilot, thereby forming the binocular device. Before the pilot ejects, the left and right arm members pivotably rotate in opposite directions and detach from the common mounting plate, thereby separately propelling the right and left optical assemblies away from the pilot.

Methods for Characterizing the Human Head for the Design of Helmets

Abstract: : For complex helmet systems that include optical displays and enhancements, as well as advanced sound attenuation, etc., the old methods for using anthropometry in design are inadequate. In this report, approaches for characterizing the human in the design process are described that provide, for the first time, shape and contour information. These methods have begun to revolutionize the helmet design process....Anthropometry, Helmets, Design.

Ivhs - smart vehicles, smart roads

Abstract: The various possibilities of intelligent vehicle highway systems (IVHS) are described, and IVHS AMERICA, a group which forms the focus of IVHS projects across the country is noted. The article describes IVHS projects across the country. TravTek is an IVHS demonstration Project in Orlando, Florida in which cars will be equipped with route selection guidance, traffic information, in-vehicle services and the ability to request emergency services. In a related technology, heat sensing infrared rays allow the outline of a person or car to be seen at night at distances of over 500 yards. Collision avoidance and warning systems, Near Obstacle Detection Systems, and heads-up displays are also described. It is noted that the first vehicle to be equipped with IVHS technology will be in mass transportation.

Study of field-of-view overlap for night vision applications

Abstract: The effect of increasing the field-of-view by partial overlap technique was studied experimentally for static and moving images. A number of factors such as binocular rivalry, suppression, image breakup resolution, and search time were investigated. The experimental results show that the binocular overlap area should be greater than 40% for the display to be comfortable to the eye. Image breakup effects were found to be predominant for static images but negligible for moving images. >

Pilot Errors Involving Head-Up Displays (HUDs), Helmet-Mounted Displays (HMDs), and Night Vision Goggles (NVGs)

Abstract: : Having become aware of difficulties with night vision and display equipment in helicopters and fixed-wing aircraft, IDA staff members collected pertinent literature, interviewed aircrews, aeromedical research people, and cockpit designers, and then carried out display simulations. They found serious safety problems associated with the newer techniques of displaying information to aircrews. At highly task-loaded moments, pilots are often stressed that they channelize attention and ignore indications of trouble. Thus, human-factors problems cancel the technological advances being introduced into modern aircraft cockpits. To help solve those problems, the investigators undertook to: appraise the reality and severity of shortcomings in display instrumentation and its use; arrange for specific laboratory research by the Army and the Air Force, followed by tests and demonstrations. They presented their findings and recommendations to the Air Staff and the Air Force Scientific Advisory Board, as well as the Army Deputy Under Secretary for Operations Research and the Commander of the Army Aviation Center and his aeromedical staff at Fort Rucker.

Standard night vision thermal modeling parameters

Abstract: The Night Vision ACQUIRE model predicts range performance when provided with parameters describing the atmosphere, a 2-D MRT curve which describes the sensor and three additional parameters. Two of the additional parameters (characteristic dimension and target- background contrast) describe the target. The third additional parameter, a cycle criterion (N50) relates to task difficulty. Characteristic dimension and target-background contrast are measured directly in the field. The third parameter N50 is empirically determined from the measured range performance associated with the task. The purpose of this communication is to define terms, protocols and where possible to give recommended values for parameters used with the ACQUIRE model. The methodology and recommended parameter values given here represent Night Vision's best estimates based on years of laboratory and field experience.© (1992) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Eyecup insert for night vision goggles

Abstract: An eyecup insert is provided which allows easy attachment and removal of an eyecup from an associated night vision goggle. The eyecup provides a light secure seal when pressed against the head of an operator of the goggle. A connecting end of the eyecup has annular channel which engages the insert. The insert is ring shaped with a central aperture having a plurality of detents protruding inwardly of the aperture. The operator can form a snap-fit connection between the eyecup and the goggle by forcing the aperture over a circular flange which surrounds an eyepiece of the goggle until the detents have snapped passed the flange. The eyecup can be removed by reversing the installation procedure.

Visual illusions and other effects with night vision devices

Abstract: To investigate the breadth of visual illusions experienced by aviators flying with night vision devices (NVDs), an open-ended questionnaire was distributed to the military helicopter community. Of the 242 returned questionnaires, there were 221 image intensification (I2) reports and 21 thermal imaging system reports. Most sensory events occurred at night, during low illumination, good weather, and over varied terrain. Contributing factors included inexperience, division of attention, and fatigue. Frequently reported illusions were misjudgments of drift, clearance, height above the terrain, and attitude. Also reported were illusions due to external lights and disturbed depth perception caused by differences in brightness between I2 tubes. Other respondents cited hardware problems and physiological effects. There were no obvious differences between the experiences of I2 users and FLIR (forward-looking infrared) users. Although incidence rates cannot be inferred from these data, the variety of aviator reports will be useful to all those connected with the human factors and safety of NVDs.© (1992) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Backlighting system for electro-optic displays

Abstract: There is described a way to provide night vision viewing compatibility of backlit electrooptic modulated light valve or LCD displays designed for daylight viewing. Liquid crystal displays (LCD) having only backlighting systems which provide a high brightness, good contrast, display under daylight conditions are inappropriate for use in dark, night time, conditions where viewing is desired utilizing electronic night vision equipment. There are described improvements to standard backlighting displays in which, through the utilization of arrays of low-level intensity light sources (37) such as secondary fluorescent light sources, miniature incandescent lamps or light emitting diodes, the lighting means (18) used in daylight vision can be turned off and the secondary low-level lighting sources (37) achieve a minimum intensity acceptable for night vision electronic viewing.

Binoculars with computer system

Abstract: The invention relates to an optical device (32) of the binoculars type, including, between the objective and eyepiece, a miniature screen, the image of which can be controlled by a computer (34) and an optical return device making it possible to superimpose the image of the screen on the image seen by the objective. The device furthermore includes, selectively or cumulatively, a variable light attenuator, a light intensifier (50) for night vision, and line-of-sight sensors for the optical device; the computer (34) may itself be furthermore connected, selectively or cumulatively, to a localising (cracking) receiver (37) of the "global positioning system" type and to a transmitter-receiver set (39). The device can be used to "inform" the scene seen in the binoculars with additional information about geographical positions, friendly and enemy positions, infrared images, etc.

Forensic uses of infrared video

Abstract: A comprehensive investigation of the commercial applicability of infrared technology has been conducted. While the main focus of these efforts has been evaluation of technology applicable to an infrared facial identification system, the availability of imaging and image processing equipment has made it possible to assess the use of infrared systems and analytical techniques for other applications. The investigation has included collection and analysis of indoor and outdoor infrared imagery for potential use in scene surveillance, target identification, vehicle identification and tracking, and structural inspection. In addition, studies of medical and quality control applications of infrared imagery have been conducted. As a result of these efforts several potential uses of infrared imagery in criminal investigations have been identified, including crime scene investigation, surveillance, vehicle identification, and pursuit of suspects. >

Infrared focal plane array crosstalk measurement

Abstract: Crosstalk between two neighboring elements in a focal plane array (FPA) occurs when signal incident on one element in the array is seen on another. This undesired effect can occur due to both the electrical and optical properties of the FPA. An effort is underway at the U.S. Army's Night Vision and Electro-Optics Directorate to develop a capability to measure crosstalk on both mid-wave infrared and long-wave infrared FPAs. A single detector in an array is illuminated using a laser source coupled with a beam expander, collimating lens, and focusing lens. The relative response of that detector to that of its neighboring detectors is measured to calculate crosstalk. The various components of the test station, the methodology for implementing the crosstalk measurement, and a model of the laser spot size are discussed.

Night vision module for a viewing and aiming system

Abstract: A night vision module is adaptable as an input stage on a daylight viewing and aiming device for constituting a system operational during night. It comprises an infra-red imaging unit and a unit for reproducing an image of the field of view of the imaging unit on a screen for display in the input field of the daylight device which has fixed reference marks. The image reproducing unit has a generator for inlaying, in the image of the field, a plurality of marks having a predetermined position with respect to the optical axis of the module, out of the central aiming zone. The inlaid marks are so located as to be centered with respect to the fixed reference marks when the module is harmonized. The module further comprises potentiometers enabling to control the location of the image on the screen and to center the inlaid marks with respect to the reference marks.