Showing papers on "Night vision published in 1984"

Vitamin A and retinoids in health and disease.

Abstract: NIGHT blindness was recognized as a disease entity in ancient Egypt. Moreover, literature dating from ancient times to the early 20th century contains comments that appear to indicate recognition of the existence of a dietary substance necessary for night vision. In 1913 McCollum and Davis1 reported that an essential lipid-soluble substance in certain foods promoted growth in rats. They later called this substance "Fat Soluble A," to distinguish it from essential water-soluble nutrients ("Water Soluble B"). Further studies by a number of investigators showed that "Fat Soluble A" (later named vitamin A) not only maintained growth but was capable of . . .

Night vision viewing systems

Abstract: A helmet mounted night vision viewing system comprising a goggle arrangement supported from above the face aperture of the helmet, the goggle comprising two independent viewing arrangements, one for each eye of a wearer of the helmet, each viewing arrangement comprising an optical projector (11, 13, 15) arranged to project an intensified image of a scene ahead of the helmet wearer downwardly to an eyepiece (17) in the form of a body of refractive material (20) in front of the wearer's eye wherein light from the optical projector is reflected at an aft surface (23), towards a curved reflective surface (25) from which the light is reflected back towards the aft surface for transmission therethrough to the wearer's eye. The optical projectors each comprise an objective lens (11), image intensifier (13) and roof prism (17), the intensifier being positioned between the objective and prism so as to allow the eyepiece to be relatively small and close to the wearer's eye in the interest of lightness and compactness, thus rendering the system suitable for use in high performance aircraft.

Dual field of view sensor

Abstract: A dual field of view sensor, particularly adapted for use as a forward-looking infrared night vision detector, includes a single detector (24) for receiving a light signal and developing an output electrical signal therefrom. A rotating polygon scanner (16) having a plurality of reflective facet (14) thereon receives light (12, 34) from two separate optical systems (10, 32) and directs the light onto the facets (14) of the scanner (16) at positions offset by one-half the facet angle such that the light beams alternately strike a facet and the juncture between two facets. The reflected light is then directed through a beam splitter 40 onto the detector in an alternating, interleaved sweeping motion. The beam splitter permits only one at a time of the light (12, 34) from entering the detector. In one embodiment, both optical systems include a steerable dual field of view telescope. In a second embodiment, a transparent display (60) such as an LCD panel, impresses a data image on one light beam (52) and the signals developed from that and another light beam are combined to drive a display. In a third embodiment, the two light beams represent the input to a stereoscopic viewing system, and the separate signals developed therefrom are used to drive a pair of small helmet-mounted displays for individual viewing by the wearer's left and right eyes to provide stereoscopic night vision viewing.

Night vision instrument with electronic image converter

Abstract: A night vision instrument with an electronic image converter, comprising for example an image intensifier tube or a similar device. This night vision instrument (FIG. 3) may be located beside an ordinary telescope, sight, TV-camera or similar device (6) so that this same device may be used during night time. The combined system (FIG. 3) thus arranged is very compact, with the center of gravity close to the user during handheld operation. The lightgathering objective lens consists moreover of only one mirror (1) and the image emerging on the screen (3) of the electronic image converter is facing the corresponding object being viewed. The image on the screen (3) is finally collimated so that it may pass into the entrance aperture of some other instrument (6) in parallel, and this image transfer is accomplished with three reflections or less and without any intermediate real image.

Latch for mounting a goggle system to a face mask

Abstract: An improved latch to mount a night vision goggle system to a face mask is disclosed. The latch comprises a part secured to the face mask and parts secured to the goggle system. Specifically, it includes a tongue, which angularly adjustably is secured to the face mask. In one embodiment, the goggle system is provided with a receiver, a switch to render the system operational mounted adjacent the receiver and means mounted in operative association with the receiver both releasably to secure the goggle system to the face mask via the tongue and also to actuate the switch. In a second embodiment, the goggle system is provided with a receiver and a leaf spring releasably to secure the goggle system to the face mask via the tongue.

Infrared receiver having a cooled radiation detector

Abstract: An infrared receiver having an infrared radiation detector cooled by means of a cold-gas engine, the thermal contact between a cooling surface of the cold-gas engine and the radiation detector being obtained by an elastic thermally conducting bridge. The cylindrical bridge is comprised of a plurality of turns of a metal strip. Due to the presence of the bridge, a good thermal conduction and further a compensation for differences in thermal expansion coefficients of the materials used are obtained. The infrared receiver is particularly suitable for night vision apparatus.

A review of vision physiology.

Abstract: As one of the most important aspects of aviation physiology, vision is a virtual sine qua non of the aviation field A basic understanding of vision is vitally important in the field of aviation medicine Following is a summary of some aspects of visual physiology, including visual acuity, night vision, dark adaptation, and acceleration effects on vision

Alarm monitoring device

Abstract: An alarm monitoring system which simultaneously provides a bright alarm light and audible alarm upon the occurrence of an abnormal condition in a function being monitored The alarm light is reduced to a dim illumination upon acknowledging of the alarm condition by the operator and the audible alarm is also deactivated The dimmed alarm indication reduces detrimental effect of night vision while maintaining notice of an abnormal condition Upon acknowledging the alarm condition, an electro-mechanical relay having two normally closed contacts and one normally opened contact is energized to redirect current flow to the alarm indicator lamp through a resistor and cause the dimmed illumination of the indicator lamp A plurality of alarm indicator circuits are connected in parallel and have diodes connected in the circuitry to prevent electrical feedback in the system from causing false alarm indications in the corresponding alarm circuits A test switch is provided which allows trouble shooting of the apparatus while the system is in normal use or out of use

Driver characteristics impacting highway design and operations

Abstract: Highway design standards should be reviewed periodically and modified as necessary to reflect changing highway conditions and findings from research on driver behavior. Recently, smaller and lighter vehicles have become prevalent on the road. Also, a larger proportion of women and older persons are driving. Female drivers now comprise approximately 50 percent of licensed drivers, and because women generally are shorter than men, the change in the composite eye height distribution may affect highway design standards. The percentage of drivers 60 years and older has increased during the past 40 years from 5 to over 15 percent. Because older drivers, tend to react more slowly than younger drivers, requirements for sight distance at intersections and railroad crossings may have to be increased. Older drivers also tend to have poor night vision, implying a need for increased night luminance of overhead guide signs. This article discusses the findings and recommendations of a Federal Highway Administration (FHWA) study to analyze the driver components of highway design standards.

Eye shield for a viewing device

Abstract: An eye shield or eyepiece for a viewing device, especially for a day and night vision sighting device for aiming a weapon essentially comprises a headrest and first and second mounting frames. These components form an assembly for mounting on the housing of a viewing device. For the practical manipulation and adaptation of the headrest to the form of the head of the observer, two hinge-like articulations are provided in mutually spaced relationship on the external face of a forehead rest of the headrest. A relatively low pressure force against the inner face of the forehead rest deforms and correspondingly adapts the elastomeric or flexible plastic headrest. In order to actuate, for instance, a laser distance measuring device mounted in the viewing device, the assembly formed by the headrest and first and second mounting frame components is articulated to the housing of the viewing device, and an actuating or switching member mounted on the second mounting frame can be brought into engagement with an enabling switch.

Comparative Visual Performance with ANVIS (Aviator's Night Vision Imaging System) and AN/PVS-5A Night Vision Goggles under Starlight Conditions

Abstract: : Experimental testing of 10 subjects wearing the AN/PVS-5A (II GEN) night vision goggles (NVG) and ANVIS (III GEN) NVG was conducted under field conditions of ambient starlight illumination (approx. 10-5 mL). The parameters measured were: 1) binocular visual acuity (BVA), 2) stereopsis (depth perception), and 3) a subjective forced choice test. Results showed that BVA was 20/124 and 20/86 for the II and III GEN NVG, respectively. This difference was statistically as well as clinically significant. The stereopsis test results were inconclusive and variable because of the limited sample size and relative inexperience of the subjects in using NVG. Neither BVA nor stereopsis with the NVG was found to be related to standard baseline measures of these parameters in the clinic. Even though the ANVIS has better gain, resolution and sensitivity, 6 out of 10 subjects preferred the AN/PVS-5A for viewing the subjective test. This seemingly paradoxical finding was surmised to be a result of the presence or lack of scene contrast due to the differential sensitivities in the II and III GEN photocathode tubes.

Simulator investigations of side-stick controller/stability and control augmentation systems for night nap-of-earth flight

Abstract: Several night nap-of-the-earth mission tasks were evaluated using a helmet-mounted display which provided a limited field-of-view image with superimposed flight control symbology. A wide range of stability and control augmentation designs was investigated. Variations in controller force-deflection characteristics and the number of axes controlled through an integrated side-stick controller were studied. In general, a small displacement controller is preferred over a stiffstick controller particularly for maneuvering flight. Higher levels of stability augmentation were required for IMC tasks to provide handling qualities comparable to those achieved for the same tasks conducted under simulated visual flight conditions. Previously announced in STAR as N82-23216

Long Life Microchannel Plate (L 2 MCP tm )

Abstract: The Long Life Microchannel Plate is a new version of the microchannel plate. The glass structure is specially formulated for high temperature processing. It offers superior electrical characteristics. Its features are: 1. Longevity - substantially greater electrical stability of the strip current and gain. 2. Superior dark noise to that of the standard microchannel plate. 3. Can be recycled more than the standard microchannel plate. 4. Can be vacuum baked at higher temperatures for optimum tube outgassing and better performance. In-house MCP electrical life test has shown that in three separate experimental cycles, Long Life Microchannel Plates are substantially more stable than our standard microchannel plates. The U. S. Army's Night Vision Laboratories have evaluated two tubes with L2 MCPs. The results were: superior MCP electron gain, better strip current and dark noise than a tube which was built with a standard microchannel plate.© (1984) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The effects of acceleration forces on night vision.

Abstract: The effects of Gy and Gz acceleration forces on cone-type mesopic vision threshold values are examined. An experiment has been conducted on the Dynamic Environment Simulator, a three-axis human centrifuge, to reproduce an acceleration environment in a simulated night-flight combat situation. Acceleration environments studied were levels of +1 Gz, + 1Gy, +1.4 Gz, +2 Gz, +3 Gz, and +2 Gy in combination with +1 Gz. A visual task was performed which determined 20/50 visual acuity illumination threshold values. Physiological parameters recorded were arterial oxygen saturation (SaO2) by ear oximetry, heart rate, and visual acuity threshold values. There were 10 male subjects, all members of the United States Air Force. Their ages ranged from 25-39 years (mean +/- S.D., 29.1 +/- 4.3). Results were zero means obtained by self-pairing with +1 Gz controls. Analysis was done by self-pairing, two-tailed t test. Results showed no significant shift in luminance threshold values at +1 Gy or +1.4 Gz, and significant increases in luminance thresholds at the 0.01 level for +2 Gz, +3 Gz, and +2 Gy in combination with +1 Gz.

Some thoughts on the implementation of pilot night vision devices for helicopters

Abstract: Night vision enhancement devices greatly expand the range and quality of services by extending night operational capabilities. Evolving military tactical concepts for helicopters survivability and battlefield effectiveness necessitate nap-of-the-earth (NOE) flying under both day and night conditions. From a pilot workload standpoint, flying a helicopter NOE in day VFR conditions with minimum clearance between rotors and obstacles is quite demanding. Doing the same job at night is several times more difficult. There are two general categories of night vision devices in operation in helicopter aviation: the Night Vision Goggles (NVG) and forward looking infrared (FLIR) system. The capabilities and limitations of those two devices are discussed.

The Relative Effectiveness of Red and White Light for Subsequent Dark-Adaptation

Abstract: : The literature concerning the effectiveness of red and white light for permitting subsequent dark-adaptation is reviewed. Although red light is clearly superior to white, its advantage decreases as intensity decreases, and at levels of ambient light found in submarine compartments, its superiority over white is probably not of practical significance in most situations. Considering the disadvantages of red light, it is concluded that low level white light is preferable to red light as general night-time ambient illumination.

Performance Modelling Of Image Intensified Night Vision Goggles

Abstract: A unified computer model of image intensified sighting systems based on signal to noise performance modelling but incorporating the eyes varying properties as a function of luminance has been developed at the Royal Signals and Radar Establishment. This model has been shown to fit field data collected on military systems and has been in extensive use over the last 18 months at RSRE and within British Industry. This paper considers the validation of the model for image intensified night vision goggles and, by this example, the range of validity of the model will be illustrated.© (1984) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Effect of Extreme Peripheral Light on Dark Adaptation

Abstract: : The effects of dark adaptation of light leaking around the edges of a spectacle frame worn under ambient light levels of 0.4 and 15 foot-Lamberts for 0.5 to 5 minutes were measured. Younger observers were virtually unaffected by light leaks in ambient illumination of 0.4 fL. However, after 5 minutes in ambient illumination of 15 fL, they required about 45 seconds to recover complete dark adaptation, and observers over the age of 40 required nearly three minutes. Originator-supplied keywords include: Night vision and Effect of peripheral vision on dark adaptation.

Scotopic Threshold of the Human Retina during Dynamic Physical Effort

Abstract: The scotopic threshold of 7 subjects was measured with a 1° circular white light located 15° below fixation during 45 min at rest followed by 10 min of running on an exercise treadmill. The slope of t

Characterization of the Photoreceptor Population of the Retina of the Bushbaby.

Abstract: : This project was undertaken to determine the characteristics of the photoreceptor population in the retina of the bushbaby (Galago crassicaudatus), as a contribution to assessment of this nocturnal primate retina as a potential model for human scotopic, or night, vision. In particular, detection of cone (photopic) photoreceptors and, if detected, estimates of their frequency were primary objectives. Retinas of eight Galago were examined by light and/or electron microscopy. Presence of cones was considered established if photoreceptors meeting four traditional structural criteria could be found and if one or more of the 'cone-specific' procedures could be shown to selectively label photoreceptors. Structures meeting two of the four anatomical criteria were identified. These were pedicle-type synaptic endings and cone-like nuclei. These are not sufficient conditions to prove presence of cones. None of the cone-specific procedures selectively labelled any photoreceptors in the Galago retinas, although all clearly selectively labelled cones in the retinas of the control species. The evidence from this study does not support the presence of cones in the Galago retina. These results indicate that the Galago retina offers significant potential as a model scotopic system.

Surveillance and night vision

Abstract: Of all the complex hardware used in the Falklands conflict, probably the most successful and reliable was the new generation of infra-red night-vision equipment. This article reviews the latest `24-hour? fighting aids