Showing papers on "Night vision published in 1971"

Vision and driving: a report on research.

Abstract: INFORMATION ON VISION TEST PERFORMANCE AND PERSONAL AND DRIVING HABITS WAS OBTAINED FOR 17,769 CALIFORNIA DRIVERS AND WAS COMPARED WITH THEIR DRIVING RECORDS, I.E., ACCIDENTS AND CONVICTIONS FOR TRAFFIC CITATIONS. OF THE VISION TESTS EVALUATED, DYNAMIC VISUAL ACUITY IS BY FAR THE ONE MOST CLOSELY RELATED TO DRIVING RECORD, FOLLOWED BY STATIC VISUAL ACUITY, VISUAL FIELD, AND NIGHT VISION. THE RESULTS SHOW THAT MILEAGE, AGE, AND SEX ARE ALSO IMPORTANT FACTORS INFLUENCING DRIVING RECORD, AND THAT CONVICTION EXPERIENCE IS A MUCH MORE STABLE DRIVING RECORD VARIABLE THAN ACCIDENT EXPERIENCE. /AUTHOR/

Attacking Behavior of the Vampire Bat, Desmodus rotundus, Under Field Conditions in Mexico'

Abstract: The mode of attack by vampire bats, Desmodus rotundus (E. Geoffroy Saint Hilaire), on cattle in Mexico, under field conditions, was observed by means of night vision viewing 'scopes. The behavior reported includes the approach and landing of vampire bats on cattle; the reactions of cows to them; the apparent searching by bats for a suitable feeding site; interactions among vampires at a feeding site, suggesting a social hierarchy or the requisites of territoriality while feeding; the urination of bats while feeding; the drinking of water; the multiple feeding, where as many as four vampires were observed feeding at the same time from the same bite; the location of biting sites on the cow were the neck and flanks. The bats had no difficulty in launching themselves into flight after feeding. The foraging behavior of the vampire bat, Desmodus rotundus, under natural conditions in Mexico has been previously reported. However, little is known about the behavior of free-living vampire bats prior to foraging, when they actually approach and attack their prey. This paper describes the mode of attack of wild vampire bats on cattle and discusses its relation to the transmission of disease. These studies have been undertaken during the course of the Research on Paralytic Rabies Project conducted by the Food and Agriculture Organization (FAO) of the United Nations at the Instituto Nacional de Investigaciones Pe

Alcohol and Disorientation-Related Responses. III. Effects of Alcohol Ingestion on Tracking Performance during Angular Acceleration,

Abstract: : Most studies of the effects of alcohol on human performance involve static (absence of motion) situations. However, the addition of motion, involved in such activities as piloting an aircraft, might well produce impairments not usually obtained in static situations. The present study examined some of the effects of alcohol ingestion on visual tracking performance (eye-hand coordination) during angular acceleration. Following practice and base-line tests of tracking performance in both static (stationary) and dynamic (whole body angular acceleration) conditions, 10 subjects received orange juice which contained 2.0 ml of 100-proof vodka per kg of subject weight; another 10 drank orange juice with a few drops of rum extract added. Tests, conducted 1, 2, 4, 8, and 10 hours after drinking, were in total darkness with the exception of the visual display which was illuminated to recommended levels for cockpit instruments. Static tracking errors for Alcohol subjects were significantly higher than those of Control subjects only at the 4-hour session. However, Alcohol subjects made significantly more dynamic tracking errors than Controls during the 1-, 2-, and 4-hour sessions. These data suggest that eye-hand coordination may show little or no impairment following alcohol ingestion in static situations, yet may be seriously degraded during motion. (Author)

Review Lecture Electronic Aids to Night Vision

Abstract: The human eye is a very sensitive and versatile image detector, but has a number of physical limitations The most important of these at very low light levels is the restriction in sensitivity resulting from the statistical fluctuations in the numbers of detected photons It is shown how electronic image intensifies can provide a fundamental improvement in this situation by capturing a larger fraction of the available photons and using these more efficiently The important parameters of such instruments are discussed, together with the principles of operation of their most significant component: the image intensifier tube This is followed by a more detailed discussion of the possible performance of night vision equipments based on different types of tube, both for direct and remote viewing applications

Command guidance transmitter system

Abstract: A command guidance, ranging, and night vision system is provided which utilizes a single optical source. A gallium arsenide laser diode array generates pulses of optical energy in response to high frequency modulation by a transistor driver. The laser array is cryogenically cooled allowing diode array operation at high average power and enhancing the output wavelength. An image intensifier tube with a gating power source therefor is synchronized with the array output pulse, being gated on only when the reflected return signal is expected, sometime after the array output pulse is transmitted. The night vision intensifier tube is used in conjunction with the diode array by an operator to locate a target. When a target is located the gating capability of the night vision device is used to determine the range from the operator to the target.

Alcohol and Disorientation-Related Responses. IV. Effects of Different Alcohol Dosages and Display Illumination on Tracking Performance During Vestibular Stimulation,

Abstract: : A previous CAMI laboratory investigation showed that alcohol impairs the ability of men to suppress vestibular nystagmus while visually fixating on a cockpit instrument, thus degrading visual tracking performance (eye-hand coordination) during angular acceleration. Reduced display illumination, independently, has also been shown to degrade tracking performance during vestibular stimulation. The present study investigated the way in which low and moderate dosages of alcohol and two levels of instrument-display illumination combined to affect tracking performance (a) in a static (no motion) environment, and (b) in a dynamic (whole-body motion) environment. Mean blood alcohol levels as low as .027 per cent significantly decreased (P<.05) tracking performance during whole-body motion, yet caused little change in performance in a stationary environment. Impairment was much more pronounced with dim display lighting (0.1 ft-L) than with bright lighting (1.0 ft.-L). These results suggest that serious problems may be encountered by the pilot who drinks even lightly and who considers flying, especially at night. (Author)

Combined use of visible and near-IR imaging systems with far-IR detector system

Abstract: A light-weight, night vision system which combines a reflected-light, imag device with an audio-monitored, far infrared detection device (HANSAM) for detecting long wavelength infrared radiation from warm bodies. The imaging device may be a near-infrared image converter or a visible image intensifier such as a "starlight scope". The Hansam is attached to the imager so that the center of its field of view coincides with the center of the field of view of the imager.

Microchannel plate inverter image intensifiers

Abstract: The characteristics of microchannel plate/inverter image intensifiers (MCP/III) are described. This type of image tube is shown to be well suited to some night vision applications. The 25 mm MCP/III developed by the authors has a minimum magnification of 0.96, a maximum distortion of 5 percent, and a limiting resolution of 10 cycles/mm. Its luminance gain is about 105at input levels up to 2 × 10-3fc when an S20 photocathode and a P20 phosphor screen are employed. The operational life of a MCP/III is generally a few thousand hours. Accurate life data can be determined, for a given application, after the operating input light level value, the applied MCP potential, and the duty cycle are established. The unique bulb design allows the tube high voltage power supply to be placed around the tube envelope within a 50 mm diameter and reduces the total interelectrode capacitance of the gating/focus electrode to 7 pF.

Low-Light-Level Performance of Visual Systems

Abstract: : Visual systems for employment at low light levels are examined from two points of view: As extensions of the human visual system and As optical information acquisition and conversion systems. The first point of view is adopted to examine the general suitability and the limitations of reliance on the dark-adapted human eye alone, the dark-adapted human eye aided by binoculars, and the light-adapted human eye aided by photoelectronic imaging systems such as image intensifiers and low-light-level television. The second point of view is adopted to analyze the dependence of photoelectronic imaging system performance on system parameters.

Lighting, visibility and accidents

Abstract: THE FIRST PART OF THE REPORT CONSISTS OF A REVIEW OF THE STATE OF THE ART OF USING ARTIFICIAL LIGHTING ON ROADS AND VEHICLES WITH PARTICULAR REFERENCE TO THE SIMULTANEOUS USE OF THESE TWO TYPES OF LIGHTING. THE CHAPTER ON PUBLIC LIGHTING IS SUPPORTED BY AN ANNEX REVIEWING THE DATA AVAILABLE ON THE EFFECT OF PUBLIC LIGHTING ON ACCIDENTS. THE CHAPTER ON VEHICLE LIGHTING STRESSES THE IMPORTANCE OF STANDARDIZATION WITH REGARD TO HEADLIGHTS AND ALL FORMS OF VEHICLE MARKERS AND SIGNALLING LIGHTS. IT IS CONCLUDED THAT THERE IS INSUFFICIENT EVIDENCE AVAILABLE TO RECOMMEND SOLUTIONS TO THE MAJOR PROBLEMS. THE SECOND PART, OF THE REPORT CONTAINS THE DETAILS OF THE FOLLOWING EIGHT RECOMMENDED INTERNATIONAL COOPERATIVE PROGRAMS OF RESEARCH: (1) POLARIZED HEADLIGHTS, (2) USE OF VEHICLE FRONT LIGHTS ON LIGHTED ROADS, (3) VEHICLE MARKERS AND SIGNALLING LIGHTS, (4) SUPPLEMENTARY LIGHTING AT PEDESTRIAN CROSSINGS, (5) TRAFFIC PROBLEMS AT TWILIGHT, (6) IMPROVEMENTS IN RELATION TO CONVENTIONAL HEADLIGHTS, (7) EFFECT OF PUBLIC LIGHTING ON SAFETY AND TRAFFIC, AND (8) EFFECT OF ROAD SURFACE TEXTURE AND COLOR ON VISIBILITY AND SAFETY AT NIGHT. /AUTHOR/

Color Defective Vision and Day and Night Recognition of Aviation Color Signal Light Flashes

Abstract: : A previous study reported on the efficiency with which various tests of color defective vision can predict performance during daylight conditions on a practical test of ability to discriminate aviation signal red, white, and green. In the current study, subgroups of the subjects used in the previous investigation were tested with the signal light gun at night. Comparisons of the efficiency of each of seven tests of color defective vision in predicting performance under day and night conditions are reported.

Vehicle forward lighting performance and inspection requirements. final report

Abstract: THIS PROJECT WAS INSTITUTED TO STUDY MEANS OF IMPROVING SEEING DISTANCE IN NIGHT DRIVING. OBJECTIVES WERE TO DETERMINE HEADLAMP SYSTEMS PERFORMANCE REQUIREMENTS, DEVELOP PROCEDURES FOR COMPLIANCE TESTING AND FIELD INSPECTION, AND MAKE RECOMMENDATIONS FOR UPDATING FEDERAL MOTOR VEHICLE SAFETY STANDARD 108 COVERING VEHICLE LIGHTING. EXPERIMENTAL TESTING WAS CONDUCTED USING NEW AND PRESENT STANDARD HEADLIGHT SYSTEMS TO DETERMINE COMPARATIVE GLARE AND TARGET DETECTION DISTANCES. LAMPS USED IN SAID FIELD EVALUATION OF LIGHTING SYSTEMS WERE PHOTOMETERED USING CONTRACTOR-DEVELOPOED TECHNIQUES. A TOTAL OF EIGHT UNIQUE SYSTEMS WAS EVALUATED UNDER CONTROLLED CONDITIONS, AND GLARE TOLERANCE BY THE DRIVING PUBLIC WAS INVESTIGATED ON PUBLIC ROADS IN FIVE GEOGRAPHICAL AREAS OF THE CONTINENTAL UNITED STATES. FROM ANALYSIS AND FIELD TESTS, A THREE-BEAM SYSTEM WAS DEVELOPED AS A PROPOSED SHORT-RANGE IMPROVEMENT IN VEHICLE LIGHTING, AND, FOR LONG-RANGE IMPROVEMENT, A SYSTEM OF POLARIZED LIGHTING. THE NECESSITY FOR AND, SAFETY EFFECTIVENESS OF SPEED-SENSITIVE, VARIABLE-INTENSITY LIGHTING SYSTEMS WERE INVESTIGATED. COMMERCIALLY AVAILABLE VISUAL, MECHANICAL, AND PHOTOELECTRIC EQUIPMENT FOR AIM INSPECTION WAS USED AND EVALUATED, AND EFFECTS OF VEHICLE STRUCTURAL DETAILS, LOADING, AND OTHER FEATRUES ON AIM AND RETENTION OF AIM WERE INVESTIGATED. CONCLUSIONS AND RECOMMENDATIONS PERTAIN TO MOTOR VEHICLE STANDARD 108, COMPLIANCE TESTING, AND FURTHER STUDY. /AUTHOR/

Performance Synthesis (Electro-Optical Sensors)

Abstract: : This effort is a continuation of the Performance Synthesis Study (Electro-Optical Sensors) reported in Technical Report AFAL-TR-71-137, dated May 1971. Analytical models are developed for evaluating and predicting the performance of observers augmented by electro-optical sensors for laboratory test images such as rectangles and periodic bar patterns and for a limited number of real world objects. The models developed are improved, and modified to bring them into closer agreement with those models proposed by other investigators for the purpose of obtaining greater acceptance and making available a wider body of technical literature. In the models developed, a signal-to-noise ratio is associated with an image based on the image's irradiance and spatial dimensions. Through psychophysical experimentation, the observer's thresholds for discrimination of these images are determined. Methods of predicting the range capability of sensor-augmented observers are developed and applied to both range-gated active and passive low-light-level television systems. These models take into account properties of the scene, atmosphere and level of target discrimination. Also, pure image motion effects, observer effects due to motion, and sensor effects due to motion are analyzed. The general area of system specification is discussed.

A digital read-out day and night marine sextant

Abstract: The Naval Ordnance Laboratory has under development and feasibility study a new digital read-out marine sextant which can be operated in the day and during the night with light illumination as low as starlight. The traditional marine sextant, which has been essentially the same design since the 18th Century, has been altered completely retaining only the index mirror and horizon principle. Using a lightweight, rugged rectangular frame the index mirror upon the frame is turned by an accurate gear train that controls mechanical counter which reads in degrees, 0.1, 0.01, and 0.001 degrees. The optical or replacement night vision image intensification telescope is inserted coaxially into the frame. Dual knobs on each side of the index mirror housing allows the sextant to be operated equally well by a right-handed or left-handed observer. The new sextant will be easier to read, less prone to reading error, lighter in weight, better balanced than the traditional sextant, and it is expected to have an accuracy of 10 arc-seconds. The digital read-out capability of the new sextant may eventually lead to remote read-out of altitude and time and automatic computation of ship's position. A pilot model of the new sextant has been constructed for shore and sea evaluation.

The effect of vibration on visual acuity with electro-optical aids to night vision.

Abstract: Visual acuity at a level of illumination comparable to overcast starlight was measured at various frequencies and amplitudes of vibration chosen to be representative of conditions aboard various ships. Measures were made with electro-optical scopes of four-power and one-power, standard Navy 7×50 binoculars, four-power field glasses, and the naked eye. Decrements in acuity under vibration were largest for the four-power scope and least for the naked eye. The decrements were, in fact, directly related to the original acuity level determined for the specific optical systems with no vibration. Despite the loss, vision with the four-power electro-optical aid remained superior to that with any other system under all conditions. The importance of antivibration mounts is emphasized.

Low-Light-Level Devices: A Designers' Manual

Abstract: : The purpose of this report is to present in orderly fashion the key factors in the design, analysis, and characterization of low-light-level devices. The parameters of interest are those that have the greatest effect on the transfer of information from the scene before the lens of the television camera to the human looking at the picture tube. Part I examines specifications for low-light-level devices. Part 2 discusses criteria for image quality. Part 3 examines the human visual process and optical aids to that process under conditions of low illumination. Part 4 discusses the image intensifier as a device to aid vision at low light levels and lists the parameters of a variety of available image intensifiers. Part 5 introduces television camera tubes and develops the concepts leading to display signal-to-noise ratio, Rosell's signal- to-noise ratio at the display. It is this, the authors believe, that is the most powerful means of evaluating 'resolution,' a term usually used loosely and incorrectly. Part 6 compares camera tubes on the basis of lag and display signal-to-noise ratio and discusses adverse factors such as 'burning' and 'blooming.' Part 7 sums up with some brief comments on important tube parameters and their specification.

Antiglare safety rearview mirror for automotive vehicles

Abstract: In a day and night rearview mirror system for an automotive vehicle, whether an otherwise conventional inside or outside mirror or a periscope system, on a mirror over its horizontal extent and horizontally parallel to road as viewed in the image display, there is provided a middle band of reflectivity reduced to a degree that, for following headlights imaged to the driver in the band, the glare is diminished to a level which is not interfering to a safe driving night vision nor annoying to the driver; a sufficient width or vertical dimension of the band enabling the driver easily to bring imaged following headlights into, and with changing inter-vehicle spacing keep them within, the reduced reflectivity area by a slight head tilting.

Night vision and accident involvement

Abstract: This is a preliminary report of a research project on night vision, glare vision and glare recovery utilizing an automatic device, the ZEISS Recording-Nyctometer. A pilot group of 400 was tested. A questionnaire was administered and an abstract of their driving history obtained. It is planned to examine 10,000 individuals. The data indicate that night vision scores cannot be used to predict glare sensitivity scores and vice versa, that nyctometer test scores deteriorate with increasing age and that glare recovery scores are related to sex. Further, there is a connection between accident and conviction history and nyctometer test scores. It was also noted that many examinees overestimated their night vision and glare recovery. Last, no significant difference was found in the test scores of cigarette smokers and non-smokers.

Lens for night vision apparatus

Abstract: An objective for night vision apparatus with a positive curvature of field whose radius corresponds approximately to the focal distance and which has a ratio of lens aperture of up to about 1:1.1, preferably 1:1.3, and a field angle of about 50* for visible rays, which comprises a converging meniscus-shaped collective lens as the front lens, a first cemented diverging meniscus following the front lens which in turn is adjoined by a second diverging meniscus that is uncemented and consists of a single lens; the diaphragm space is enclosed between two meniscus lenses, while the second meniscus lens is adjoined by three collecting lenses which, in turn, are followed by two Smyth lenses.

Application of aspherics for weight reduction in selected catadioptric lenses

Abstract: : The history of modern wide-field, high-speed catadioptric lenses is reviewed. One system comprising only spherical curves and representative of the current art for low-light-level systems is evaluated and used as a baseline design in a weight-reduction study. Five aspheric designs are computed and evaluated. It is found that the use of aspherics will permit weight reduction only in certain instances, i.e., if one element of an all-spherical design can be eliminated or if a fundamentally different configuration that is possible only with aspherics is substituted for the all-spherical configuration. Of these possibilities, the elimination of an element is the best replacement for the baseline design. The case of a highly constrained, purely refractive triplet is studied in some detail. Four designs are computed-from the all-spherical case to the most complex polynomial aspheric.

Color defective vision and the recognition of aviation color signal light flashes.

Abstract: : Subjects of varying type and degree of color deficiency were tested on a battery of color tests, including the American Optical H-R-R plates, the Dvorine plates, the Color Threshold Tester, the Farnsworth-Munsell 100-hue, the Farnsworth Panel D-15, the Titmus Vision Tester Color Plats, and an anomaloscope examination. Correlations with a practical test of the ability of subjects to discriminate aviation signal red, white, and green were obtained. The results generally indicated that the Farnsworth Lantern was a superior predictor of performance on the practical test.

Closed-Cycle Refrigeration for an Airborne Illuminator

Abstract: The U.S. Army’s NVASS Night Vision System is a helicopter-mounted, direct-view, night-vision reconnaissance system. An infrared illuminator consisting of a closed-cycle cooler, diode array, vacuum chamber, vac-ion pump, and pulsing electronics is mounted on the nose of a helicopter to provide covert illumination on the target scene. Reflected energy is sensed by a range-gated image-intensifier tube through a viewer assembly which extends from the crew compartment below the helicopter. Also extending below the helicopter is a ruby laser which performs ranging and target-designation functions. A digital computer displays target coordinates in UTM format. The operator views a fixed field-of-view scene presented by the image-intensifier tube through a binocular eyepiece. He can control the system, including illuminator, viewer, and laser, to scan a full 360° in azimuth and 0 to 70° in elevation.

Retinitis pigmentosa and lymphocytic leukemia.

Abstract: THE OCULAR manifestations of retinitis pigmentosa and lymphocytic leukemia are each well documented in the ophthalmic literature. 1-6 Recently, a patient with the unique combination of both disorders was hospitalized at the National Institutes of Health (NIH). It is the purpose of this report to document this unusual combination of unrelated conditions. Report of a Case The patient (NIH 08-13-37), a white 53-year-old woman, was referred to the Solid Tumor Service, National Cancer Institute, in April 1969, with a four-month history of asymptomatic cervical lymph node enlargement. A node biopsy done elsewhere showed replacement of the tissue with abnormal small lymphocytes consistent with the diagnosis of well-differentiated lymphocytic lymphoma. This patient observed difficulty with night vision at age 20 years. The diagnosis of retinitis pigmentosa was first made at age 27 years. From age 20 years, the patient noticed deterioration in her ability to adapt in darkness and a constriction

Improved Search Techniques with Passive Night Vision Devices

Abstract: : The NIGHT OPERATIONS Program is concerned with problems in optimizing human performance in relation to night vision devices and related sensors. In the furtherance of this research, studies are being conducted with passive night vision devices. Passive night vision devices developed for the Army have greatly increased night observation and target acquisition capabilities. Effectiveness of these devices, however, is highly dependent upon how and under what conditions they are used. The present study sought to determine whether new search techniques and procedures could increase the effectiveness of soldiers using passive night vision devices. The subjects (54 operators) using the Starlight Scope (SS) or the Night Observation Device, Medium Range (NOD) were given specialized search training and their training performance was compared with another group previously tested under the same conditions but without special training on search method and pattern.

Visual Systems for Night Vision

Abstract: The formation and detection of images at low light levels depend on the quantum nature of light. For example, in human vision the eye collects a certain number of photons per second which emanate from an object in proportion to its radiance and area. An image is detected as a result of the absorption of photons by the retina of the eye. The number of photons absorbed by the elements of the retina per integration time of the eye varies with the brightness of the image elements, the rate being greater for bright elements and lesser for dark ones.

Effects of Search Area Size on Target Acquisition with Passive Night Vision Devices

Abstract: : The NIGHT OPERATIONS Program is concerned with optimizing human performance in relation to night vision devices and related sensors Specific aspects deal with determining performance effectiveness of sensor systems, factors which affect performance, and means of improving effectiveness The present study describes research involving the use of such devices in assessing the effectiveness of soldier performance during night operations The primary objective of the experiment was to investigate the effects of search area size on performance--as it interacts with a number of environmental, target, and human factors--and to determine the implications of findings for operational use, basis of issue; and search deployment, as well as for improvement of soldiers' effectiveness in using these devices