Showing papers on "Night vision published in 1978"

Training aid for use with night vision apparatus

Abstract: A filter arrangement is described which is incorporated with a night vision device. The filter arrangement consists of a variable density polaroid filter array and a blue-green filter all contained in a common housing and directed along a given optical path. The filter arrangement serves to control the amount of light directed to an input port of a night vision device such as a pair of goggles. In this manner, a user can be trained to employ the night vision device under direct supervision in daylight conditions and by variation of the polarizing plates is enabled to simulate nighttime conditions.

The role of drivers' vision in road safety:

Abstract: The literature on relationships between drivers' vision and their driving performance is reviewed. Certain vision tests, particularly those which use moving targets, are weakly associated with measures such as accident frequency and rate; their practical value in terms of road safety is very limited. Some visual abilities, such as extent of visual field, are unassociated with driving performance in general but may be relevant to specific types of accident; any association for tests of night vision remains open to question. Methodological problems are considered and possible reasons why associations are not stronger are discussed. Development of a new rapid test of contrast sensitivity function is mentioned together with some current and future research plans.

Perceived orientation of a runway model in nonpilots during simulated night approaches to landing.

Abstract: : Illusions due to reduced visual cues at night have long been cited as contributing to the dangerous tendency of pilots to fly too low during night landing approaches. The cue of motion parallax (a difference in rate of apparent movement of objects in the visual field) is frequently suggested as contributing to visual judgments of glide path but has not been systematically studied in relation to the night approach problem. Thus, the present experiment examined the effect of varying levels of motion parallax from both radial and vertical motion on perception of the orientation of a runway relative to the ground.

Advances in Microchannel Plate Technology and Applications

Abstract: Microchannel plates are widely used today in military night vision devices. Their successful application has prompted widespread interest in many laboratories and in the industry for use in diagnostic tools. Of particular interest are the applications as: (a) an electro-optical ion detector to enhance the sensitivity of a mass spectrometer for clinical environment and chemical analysis, (b) an electron collimator for subpicosecond x-ray and visible streak camera tubes, and (c) particle detectors in spaceborne instrumentation. Many of these applications required the development of strip multichannel arrays (SMCA) ranging in active area from 1 mm x 15 mm up to 1 mm x 360 mm. Also described herein is the state of the art of high resolution and increased detection efficiency multichannel arrays.

Vertical Structure in Atmospheric Fog and Haze and its Effects on IR Extinction.

Abstract: : Vertical structure of the size distribution and number concentration of particulates in atmospheric fog and haze near Grafenwoehr, West Germany, was measured with a balloon-borne light-scattering aerosol counter for periods spanning parts of 8 days in February 1976. The work was part of a US Army field exercise conducted for the purpose of determining the effect of atmospheric constituents on various night vision systems. For haze (approximately 5 km visibility) conditions, little vertical variation is seen; but for low visibility (1 km) fog conditions, significant vertical increases in concentration of droplets with radii larger than 4 micrometers are seen over the first 150 m altitude. Liquid water content values for haze and fog range from 0.0001 to 0.45 g/cu m. Extinction calculated from the particle size distributions shows an approximate 1/lamba wavelength dependence for haze conditions, but nearly neutral (wavelength independent) extinction for heavy fog. A correlation exists between calculated particulate extinction and calculated liquid water content, independent of particle size distribution, for the fogs and hazes studied.

Lenses with distortion

Abstract: An objective lens particularly for use in a low light level or night vision system designed to introduce a controlled amount of barrel distortion at the edges of its field of view to permit use with a flat input faced imaging tube.

Comparison of the visual perception of a runway model in pilots and nonpilots during simulated night landing approaches.

Abstract: : At night, reduced visual cues may promote illusions and a dangerous tendency for pilots to fly low during approaches to landing. Relative motion parallax (a difference in rate of apparent movement of objects in the visual field), a cue that can contribute to visual judgments of glide path angle, was studied for its effect on the nighttime approach problem in two experiments. Neither flying experience nor a visual frame of reference enhanced sensitivity to relative motion parallax. However, errors in horizontal adjustments were smaller in pilots, indicating that flying experience enhances other cues in the runway image. Direct judgments of approach angle magnitude indicated overestimation by an approximate factor of 2. These findings give further evidence of large visual illusions in the nighttime situation and indicate that the ineffectiveness of relative motion parallax may be an important part of the night approach problem.

Spectral response of the human eye

Abstract: A thermal activation energy of 1.5 eV for the activation of rhodopsin is needed to reduce the rate of thermal activations below the rate of optical activation at the luminance of the absolute threshold. The thermal energy of 1.5 eV is not inconsistent with the optical threshold energy of about 1.8 eV.

Infrared HgCdTe photovoltaic detectors by planar technology

Abstract: Following years of intensive research and development (1) , (2) , (3) , (4), HgCdTe photovoltaic detectors (photodiodes) have found definite acceptance for infrared detection for commercial and military applications. Many infrared imaging and detection systems operating in the 8 to 12 µm wavelength region and developed during the past few years have almost exclusively incorporated this detector type. A number of infrared systems, particularly in the imaging area, will soon experience an increased development effort to respond to the various needs, in particular, for military night vision. The need for large-scale fabrication can, therefore, be foreseen in the years ahead. In order to be cost-efficient, production must lean toward integrated circuit fabrication techniques. It is, therefore, proper to consider planar technology. From among the two basic detection modes (photovoltaic and photoconductive), only the former responds to these requirements.

Night vision system comprising a light source and image intensifier powered in alteration

Abstract: A night vision system for use in an environment having at least one observer using artificial light means (lamp lit instruments, torch, etc.) and at least one observer using a light intensifying direct vision device has a power supply which supplies pulses of power to the artificial light device and which switches off the light intensifying direct vision device in synchronism with the pulses.

Influence of Surface Defects on the Glare Characteristics of a Night Vision System with Refractive Optics

Abstract: In order to prepare the optical specifications for night vision systems a study of their glare characteristics is required. Such systems use lenses of very high aperture and, as the information content of the signal is lower than in the daylight equivalent, the glare characteristics are particularly important. This is a study of a particular night vision system that incorporates a channel intensifier tube, 18 mm in diameter, and a refracting objective. The object of the investigation was to study the glare characteristics of the optics, the tube and the complete system and to evaluate the glare due to surface defects on the optical components. For the instrument studied, an important source of glare was found to be the distributed defects on the optical surfaces (scatter and surface reflectivity), but localized defects (sleeks and scratches) could, under some circumstances, produce streaks of light superimposed on the substantial background glare. There was also an apparent design fault which led to a sev...

Visual performance assessment through clear and sunscreen-treated windows

Abstract: : Reflective sunscreen filters are frequently bonded to vehicle windows to reduce interior heat and brightness. The present study was conducted to investigate the optical properties of and visual preformance through clear and sunscreen-treated glass panels that served as windows in an observation booth. Five combinations of external and internal brightness levels were used. Light transmission values through the clear, gold, silver, and bronze panels were 92, 20, 18, and 8 percent, respectively. Visual performance tests were conducted at 6 m (20 ft) on 12 subjects with normal visual acuity and color vision. Two tasks were conducted under brightness levels on the external display and in the subject's booth, respectively, of 1:1, 5:1, 50:1, 5:5, and 50:5 fL. Visual acuity using Landolt C figures and scores on a contour identification task were minimally impaired for any luminance ratio when the clear (control) panel was used. With the sunscreen panels, scores on both tests decreased as a function of target brightness and panel density. With one external/internal luminance ratio(5:1), identification of signal light colors was generally impaired while viewing through sunscreen materials. Decreases were particularly evident for green and red lights presented at intermediate and low intensity levels. (Author)

HEL Participation in the Plan for Assisting in the Definition of Army Helicopter Electro-Optical Symbology: An Interim Report.

Abstract: : This is an interim report on progress made thus far toward optimization of symbology for electro-optical flight displays in Army aircraft The Army aviation community adopted a plan in late 1977 aimed at determining standardization requirements and optimal symbology formats At this time, a literature review, a task analysis and trade-off analysis have been completed while a time-line analysis, information conflict identification, an analysis of flight modes and evaluation criteria development are all in progress This report provides a summary of the program tasks listed above as well as a review of concurrent efforts toward defining symbology for the pilot night vision system in the Advanced Attack Helicopter (Author)

ESA SYMPOSIUM: Night Vision Equipment for Studying Nocturnal Behavior of Insects

Abstract: Many of the technologies that have been and are being developed by research organizations for offensive and defensive purposes against human aggression have great potential for use in the biological sciences. Possible adaptations of these technologies by the scientific community for applications of civilian usage that enhance rather than destroy human lives and property are plentiful. Thus, today we have available to us a technology, night vision goggles (NVG), that greatly extends a basically weak human sense—night vision. This equipment offers the biological sciences a tool for studying the nocturnal behavior of animals. As entomologists, we are probably more interested in the nocturnal behavior of insects which is one of the weakest areas of knowledge in the insect world.

Liquid crystal image intensifier tube - has liquid crystal spectral filter and colour display driven in synchronism to enhance night vision

Abstract: The appts. comprises an image intensifying tube provided with a liquid crystal spectral fitter at the input end w.r.t. the direction of propagation of light. On the image side is a colour display device. Electric signals applied in synchronism to the fitter and the display, vary in sequence the transmission spectrum and display colour. The appts. allows a spectral analysis of the colour of an object and the restoration of its colour without requiring any movement. It improves the visibility of objects esp. for night vision.

Where We are Going in the Biological Sciences

Abstract: The information presented in the previous papers describes the development of night vision equipment and current application to problems in agriculture and forestry. Such equipment has so far been utilized to only a limited extent in agriculture and forestry, but it will probably be much more used in the next several years.

A laser optometer for varied illuminance

Abstract: The first prototype of a moveable laser optometer is described together with some preliminary test results. A second version of the apparatus is also described, the aim of which is to measure and investigate dusk and night myopia. (TRRL)

Aerospace and military: Voyager begins planets rendezvous; improved night vision for the foot soldier

Abstract: Electronics, and particularly solid-state circuitry, have provided the springboard from which military and aerospace systems, large and small, have been advancing on a broad front. Examples are cited.

Night Vision Equipment: Uses in Forestry

Abstract: In 1973, Congress appropriated special funds to the Forest Service to investigate new potential techniques which would help alleviate the severe wildland fire threat that exists nationwide. One such project initiated was designated “Helicopter Night Operations.” Several other agencies participated in this investigation; the Los Angeles Fire Department (LACFD), California Department of Forestry, Bureau of Land Management, Oregon Department of Forestry, Aerospace Corporation, U. S. Army, and U. S. Air Force. The exploratory capability was achieved through the use of image intensification devices and thermal imaging systems installed on a UH-1M helicopter loaned by the U. S. Army's Night Vision Laboratory.

Night Vision Equipment Developments: Where We've been, Where We are Today, and Where We're Going

Abstract: Although research and development in the advancement of night vision technologies has been in progress since the early stages of World War II, it was not until the early 1960's that the Army launched an extensive effort to develop equipment that would enable the individual soldier to move and fight at night with efficiencies equaling his present daylight capabilities. Since that time the mission of the U. S. Army's Electronics Research and Development Command's Night Vision and Electro-Optics Laboratories (NV&EOL) has expanded to include night vision not only for the individual soldier but all armored vehicles, Army aircraft, and anti-armor missile systems. Further adaptation of this militarily developed technology is being made at an astounding rate to aid other scientists in carrying out their diverse research experiments.

A Rapid Screening Device for Infrared Luminescence Examination of Questioned Documents

Abstract: The use of the Star-tron Night Vision System in the examination of alterations, over-writing and obliterations on questioned documents was compared with conventional infrared luminescence photographic techniques. The Star-tron was found to provide the basis for a rapid and effective visual means of screening documents.

An appreciation on system limitations for observation by electro-optical devices

Abstract: The intention is to analyse the possibilities of detection, recognition and identification of objects at various ranges utilizing the visible and the infrared regions of the electromagnetic spectrum in the passive mode. The analysis reveals as to in what manner a category in instrumentation can be brought about which could complement the Radar.Certain parameters have been introduced to permit comparison between different types of instrumentation in order to arrive at the system limitations. Efforts at IRDE, Dehra Dun in these areas have been broadly discussed in comparison with other such devices from foreign countries, where so possible.

Night vision goggles and in-flight evaluation of the inside/outside refocusing problems in a uh-1h helicopter

Abstract: Rotary wing aircraft are being tactically flown closer and closer to the ground in an effort to take maximum advantage of concealment and protection afforded by trees, man-made structures and terrain features. In recent years, night vision goggles have been used to aid the pilot in his/her flight duties. It has been noted, however, that visual transition from the outside environment into the cockpit (and vice versa) requires manual refocusing of the goggles. This requires the pilot to remove his hand from one or the other of the controls, thus compromising safe flight. In this study, eight U.S. Army aviators hovered an instrumented Army JUH-1H helicopter ten feet above the ground at night under four visual conditions using the unaided eye (normal night vision) and three configurations of the AN/PVS-5 night vision goggles (NVG). The NVG configurations included: (1) 40° field-of-view piano tubes focused at infinity; (2) a bifocal arrangement in which the bottom 14% of the field was focused at approximately 22 inches; and (3) a bifocal arrangement with the bottom 24% focused at 22 inches. Aircraft status and control position monitors were scanned at a rate of 20 times per second and recorded on a seven-track magnetic tape via the helicopter in-flight monitoring system (HIMS). Subsequent review and analysis of these data indicate no significant difference between configurations in terms of control movements. In terms of aircraft status variables, radio measured altitude indicated a large variability under the 40° piano NVG. However, hover behavior stabilized significantly in the bifocal condition. Subjective pilot responses supported these observations. Language: en