Showing papers on "Night vision published in 1974"

A Night Vision Pocketscope for Patients With Retinitis Pigmentosa: Design Considerations

Abstract: A Generation II night vision pocketscope has been shown to be effective in eliminating the symptom of night blindness in patients with retinitis pigmentosa. This pocketscope provides sufficient light amplification to allow cone function under scotopic conditions. Minimum pocketscope gain and minimum output screen luminance required for mobility by these patients under scotopic conditions are correlated with their cone threshold elevations above normal. Instrument gain and output screen luminance should be minimized to extend the period of usefulness of the instrument and to protect the patient against the possible harmful effects of excessive light exposure. The advantages of a wide-angle lens and infrared light-emitting diode, attached to the pocketscope, are considered.

Development and use of driving tests to evaluate headlamp beams

Abstract: Results of analyses of accident data to evaluate the contributory role of headlighting were inconclusive Reflectance values of various objects in the drivers field of view were measured Pilot studies were made to evaluate test targets, and the results were used to describe desirable characteristics of a test target for use in subsequent tests A series of headlighting field tests were carried out to develop a reliable field test method, evaluate variables affecting visibility provided by headlamps, and generate data for use in validating a mathematical model Driving tests were also used to evaluate glare effects of various beams to oncoming and preceding drivers Three types of targets were developed for the work; a simulated overhead sign, a simulated roadside sign and a general purpose target to simulate objects on or near the roadway The latter target could be placed to the right or left of the test vehicle or in the center of its lane of travel In addition, its reflectivity could be changed The following variables were investigated: the headlamp beam, lateral separation between vehicles, longitudinal separation between vehicles, target type, target reflectivity, target position relative to car path and target height All of the above variables were found to be significantly related to the distance at which the orientation of the target could be identified

Night vision testing method and apparatus

Abstract: A subject whose vision is to be tested wears a face mask having an eyepiece in which is mounted a light-emitting diode connected to means for varying the light intensity of the diode in a time ordered sequence. The level of light intensity is also numerically displayed to the operator of the device. The test subject is provided with means for selectively stopping and resetting the sequence of varying light intensities to an initial intensity and automatically repeating the cycle.

Utility of several clinical tests of color-defective vision in predicting daytime and nighttime performance with the aviation signal light gun.

Abstract: : Subjects of varying type and degree of color deficiency were tested on a battery of color tests, including the American Optical Company Plates (both 1940 and 1965 editions), the Dvorine Plates, the Farnsworth-Munsell 100-hue, the Farnsworth Lantern, the Farnsworth Panel D-15, the SAM Color Threshold Tester, the Titmus Vision Tester Color Plate, and an anomaloscope. Correlations with a daytime and nighttime practical test of the ability of subjects to discriminate aviation signal red, white, and green were obtained. The results indicate that color defective people can identify flashes from a signal light gun better at night than during the day. It was also found that the Farnsworth Lantern, the SAM Color Threshold Tester, the two sets of A O Plates, and the Dvorine Plates were among the best predictors of performance on the practical test; the Titmus Plate was the poorest predictor. (Author)

IERI. Losses in Nighttime Visibility Caused by Transient Adaptation

Abstract: Research on transient visual adaptation is concerned with the quick changes in sensitivity which the eye makes as it adjusts to variations in luminance levels. Investigations reported here provide a description of transient adaptation effects at luminance levels comparable to those found in nighttime highway lighting conditions. Findings indicate that for downward changes from a low luminance to an even lower one, smaller losses were observed than those found at higher luminance levels. Visibility loss breaks down at the lower limit of 0.002 to 0.02 fL (0.0069 to 0.069 cd/sq m). Individual differences in the amount of visibility loss for a given luminance change, whether upwards or downwards, were found to be large. Within the limits examined, the size of the target has no effect on the degree of visibility loss as measured by the interval between the beginning of the transition from one background to another and the onset of the test-letter presentation.

Effects of Secobarbital and D-Amphetamine on Tracking Performance during Angular Acceleration,

Abstract: Thirty young men wore randomly assigned in equal numbers to one of the following groups: placebo (lactose), secobarbital (100 mg), or tj-amphetamine (l0 mg). The drugs or placebo wore administered in capsules in a double- blind procedure following practice at a tracking task and baseline determinations of tracking performance levels in both static (stationary) and dynamic (angular acceleration) conditions. Tests wore scheduled 1, 2, and 4 hours after capsule ingestion; all tests were conducted inside a St:lle-Werner rotator and were in total darkness with the exception of the illuminated tracking display. With the rotator stationary, d-amphetamino subjects performed significantly better than controls during the 2-hour and 4-hour post-drug sessions; no other static differences among the groups wore significant. However, during angular acceleration, secobarbital subjects made significantly more tracking errors and had significantly more vestibular nystagmus than both the control and the d-amphetami...

Illuminated reticle projection system

Abstract: The illuminated reticle projection system includes a frame comprised of an annulus for mounting the frame about the objective lens assembly of a night vision device and a reticle projector for projecting a reticle image through the objective lens assembly for coincidence with the image focus at an image plane. The projector includes a light emitting diode which illuminates a reticle mask and projects a reticle image through a projection lens into the entrance pupil of the objective lens. The projector is carried by an elevation platform connected to an azimuth platform for pivotal movement in a vertical plane about a horizontal axis. The azimuth platform is, in turn, connected to the frame for pivotal movement in a horizontal plane about a vertical axis. Elevation and azimuth adjustment screw knobs are provided for adjusting the angular position of the elevation and azimuth platforms to effect angular displacement of the reticle projector about vertical and/or horizontal axes and hence vertical and/or horizontal displacement of the reticle image in the night vision equipment.

Eye Fixations Of Drivers In Night Driving With Three Headlamp Beams

Abstract: EYE FIXATIONS OF DRIVERS IN NIGHTDRIVING WITH THREE HEADLAMP BEAMSRudolf G Mortimer & Craig M JorgesonHighway Safety Research InstituteThe University of MichiganAnn Arbor, MichAbstractTwo drivers drove an automobileover a 15 mile two -lane course in thedaytime and at night using American andEuropean low beam headlamps and a midbeam The eye fixations of the driverswere measured, using a silicon diodeTV camera and light reflection fromthe cornea as the recording deviceComparisons between the eye fixationsused in daytime and at night, suggestedthat dwell time was longer when look-ing straight ahead at night than in thedaytime, and there was a reduction inthe proportion of the viewing timedevoted to the left lane at night thanin the day, when there was no oncomingvehicle Drivers looked at approach-ing vehicles in both day and night con-ditions with glance durations of inter-mediate length, which increased in fre-quency as the separation distancebetween the vehicles decreased Atnight preview distances were less thanin the dayThe characteristic shift of theeye fixations in the direction takenby the road was found in this study,in both day and night driving Atnight the eye fixations were influencedby the characteristics of the beampattern being used On left curvesthe American and European low beamsprovided eye fixations which mostclosely resembled those used in day-time, whereas on straight sections andparticularly on right curves the midbeam provided the most compatible dis-tribution of glances A revised com-posite mid beam, incorporating somecharacteristics of the European lowbeam was suggested as an improvedmeeting beam

Visual Acuity as a Function of Wavelength in Three Catarrhine Species

Abstract: The visual acuity criterion was used to determine the relative spectral luminous efficiency function at scotopic and photopic levels in the rhesus monkey, sooty mangabey, and olive baboon. The stimulus energy necessary to resolve gratings subtending 11.235 and 1.976 min of arc was determined at nine wavelengths. The coarser gratings had a visual acuity requirement of 0.089, which could be resolved at very dim luminance levels, while the finer gratings had an acuity requirement of 0.506, which could be resolved only at very high luminance levels. The relative luminous efficiency functions obtained with the coarse gratings were comparable for the three species except in the long wavelength region where the baboons were relatively less sensitive and the mangabeys relatively more sensitive than the rhesus. With the finer gratings, the major differences among species again were in the long wavelength region with the rhesus showing a pronounced relatively reduced sensitivity.

Studies in motor vehicle rear vision: ii, evaluation of innovations in passenger car and truck rear view systems

Abstract: Twelve innovative and one conventional passenger vehicle rear vision systems and three innovative truck rear vision systems were evaluated using driver information gathering behavior as the primary criterion measure. Systems were evaluated under actual on-the-road conditions, in freeway and city street environments, both day and night. In addition two ESV-mounted periscope systems were evaluated under simulated roadway conditions. Estimates of rear vision area criticality were derived using subjective judgment scaling techniques. Specific design factors, e.g., display location, multiple vantage points, minification are discussed.

Optical Systems For Direct Vievi Night Vision Devices

Abstract: Optical system designs specifically tailored for the high apertures required for direct view, passive, image intensifier, night vision systems began in the late fifties with a 14 inch focal length F/1.4 catadioptric objective. Three spherical corrector lenses were used in a flat field design for a 40mm image intensifier system. The principles developed proved quite successful, eventually leading to similar objectives used on most 40mm, 25mm, and 18mm format, first generation, night vision sighting telescopes. The principles are discussed and comparisons are made with several other high aperture catadioptric systems recently discussed in the literature. More compact second generation electrostatic and wafer type tubes opened new opportunities for light-weight system designs. The 18mm microchannel plate wafer tube in particular resulted in a number of new viewing systems, including nairs of 1X wide angle telescopes used as night vision goggles. The principles involved in these systems are described as well as the eyepiece performance and characteristics which are unusually important. For these eyepieces and in fact for all of the newer Magnifier eyepieces, Night Vision Laboratories has developed new methods of testing and criteria for specifications that require considerably better correction that had previously been required. The most recent development in the field of direct view night vision devices has been that of the Biocular eyepiece. The principles and characteristics of this rather successful innovation are discussed.

Full view of the road.

Abstract: THIS ARTICLE DISCUSSES THE EFFECTS OF REDUCING THE LIGHT INTENSITY AT NIGHT BY THE USE OF TINTED WINDSCREENS IN CARS. IT IS IMPORTANT THAT AS MUCH LIGHT REACHES THE RETINA AS POSSIBLE. IT IS ESTIMATED THAT 40% OF ACCIDENTS ARE DUE TO VISUAL IMPEDIMENTS. NIGHT VISION DIFFERS CONSIDERABLY FROM DAY VISION AND, ALTHOUGH THE USE OF TINTS MAY BE TOLERABLE DURING THE DAYTIME, AT NIGHT THEY SHOULD NOT BE USED. ANTIGLARE GLASSES FOR NIGHT USE CANNOT BE JUSTIFIED. TINTED VISORS, WORN BY MOTORCYCLISTS, CONSTITUTE AN UNNECESSARY HAZARD AT NIGHT. ALL TRANSPARENT SCREENS USED AT NIGHT SHOULD BE CLEAR AND SHOULD HAVE MAXIMUM TRANSMITTANCE OF LIGHT. ANY LIGHT FILTERING REQUIRED DURING DAYLIGHT SHOULD BE PROVIDED BY ACCESSORY BUT REMOVABLE MEANS.

Biological Individuality of Man

Abstract: : The report suggests that the concept of biological individuality is worthy of study as a means of identifying those persons who possess unique attributes or inadequacies for specific tasks or responsibilities. Many biological factors related to individual differences are known and can be quantified objectively and thus may permit the prediction of some performance capability of an individual. The background of work on biological individuality is reviewed, three examples are cited, and key investigators in these specific fields are identified. However, numerous other examples can be found to illustrate the effects of individual biological factors that impinge on human performance. The suggestions for future research emphasize the basic concerns for performance in a military environment that may reflect the expression of biological individuality.

Thresholds and resolution in human vision: a new approach to night vision testing

Abstract: Visual acuity dark adaptation in the fovea was studied in immediate temporal alternation with foveal threshold adaptation. This method avoids some of the inconsistencies of earlier work and produce...

Air-to-Ground Target Acquisition with Night Vision Devices

Abstract: Three hand-held image intensifiers were studied. Two of these were passive visual aids (Starlight Scope and Uniscope) and one was an active IR viewer (Find-R-Scope). These devices were evaluated in terms of number of targets (trucks, boats, village) recognized on a 1000:1 scale terrain model. Simulated air-to-ground views of 20 observers were provided as they circled the model at a simulated 520 MPH and 8500 ft slant range under a moon-light illumination level. Although all targets were visible through the devices when observers were shown when and where to look, almost no target recognition occurred when any of the aids were used in a search viewing-mode under the conditions of the study.

Image Evaluation Of Image Intensifiers

Abstract: Image Intensifiers are used to detect, recognize, and identify objects of, or in, radiation of low intensity. The type of radiation for which image intensification can be used, ranges from x-rays into the near infrared region. In this review, x-ray intensifiers will not be considered. A review of the various types of image inten-sifiers has been given recently (Ref 1).

A Technique For Effectively Measuring MTF Of Image Intensifiers At Low Output Levels

Abstract: A TECHNIQUE FOR EFFECTIVELY MEASURING MTF OF IMAGEINTENSIFIERS AT LOW OUTPUT LEVELSW. Travis WaltonSperry Rand Sensor GroupGainesville, FloridaAbstractA unique instrumentation tech-nique has been developed by industryand is in regular application at theNight Vision Laboratory to repeatablymeasure the modulation transfer func-tion of image intensifiers operatingat output light levels well below thatvisible. Two of the most severe prob-lems associated with such measurements,very poor signal -to -noise ratio anddifficulty of normalization, have beenovercome while maintaining an instru-ment that may be set up, adjusted, andoperated quickly by personnel with askill level comparable to that neededfor routine MTF measurements of lensesat high light levels.These advances were made possi-ble by the inclusion of a digitalsignal averager, a unique film pattern,and innovative electronic interfacingand analization circuitry. Both thefundamental instrumentation conceptand the details of how the practicalinstrument was realized are discussedin this paper.IntroductionOver the past several years themodulation transfer function techniquehas grown in popularity and usefulnessas knowledge of its application andinstrumentation have improved. Forlens work there are a number of useabletechniques that have been successfullyused in both special laboratory setupsand commercially available equipments.Once the basic techniques are mastered,repeatable measurements are usually

Laser Aiming Light.

Abstract: : The laser aiming light (LAL) for use with small arms was developed and field tested. The aiming light was designed with advanced state-of-the-art components consisting of a room temperature laser diode, low impedance laser diode mount, and microelectronic pulser. The LAL has an emission wavelength ranging from 820 to 850 nanometers for use with night vision goggles. The LAL housing is single structured, that is, 6.25 inches long, 0.78 inch diameter, with a 1.20-inch-diameter lens compartment; the LAL weighs 7.87 ounces. The LAL is powered by an 11.2-volt battery, and the average optical output power ranges from 50 to 350 microwatts. The aiming light has a boresight mechanism that interfaces with the rifle adapter. The LAL was field tested on the M-16 rifle in the single as well as rapid-fire mode and did not exhibit degradation. The laser aiming light is considered to be eye-safe. (Author)

The Diabetic Retinopathy Study-Reply

Abstract: Reply To the Editor. —The investigators in the Diabetic Retinopathy Study (DRS) appreciate Professor Phillips' interest in our study and we share his concern about observer and patient bias in any serious attempt at evaluating therapeutic efficacy. The existence of both of those biases has been demonstrated often, yet emphasized inadequately. Any clinical investigator who assumes, without efforts to verify, that these biases are not present may be seriously deceiving himself. The ideal defense against these biases, if it can be made to work, is a "double masked" (we prefer this term to "double-blind," particularly in ophthalmology) study in which neither the patient nor the observer knows how or whether the patient was treated. The inclusion of a sham procedure was considered for the DRS, but is neither ethically justifiable, because retrobulbar injection would be required for some patients, nor feasible, since diminution of peripheral field or night vision or

Reaction time as a measure of night vision ability

Abstract: The hypothesis tested was that the amount of increase in reaction time (RT) due to decreased light intensity could be used as a measure of the light sensitivity of S. The results supported this hypothesis. A considerable interindividual correlation between the threshold for light and the amount of increase in RT was obtained. The relation between RT and light intensity could be described by an equation that allowed prediction of the threshold from the amount of increase in RT.

A Flare Effectiveness Model.

Abstract: : A method is proposed to measure the effectiveness of different types of flares in terms of night vision performance. Eyeball, image intensifier, and image converter performance models have been developed at the Night Vision Laboratory and are the basic tools in this evaluation. Validation of the performance models was accomplished by conducting a terrain model test simulating the nocturnal use of pyrotechnics. Sample analyses utilizing the proposed measure of effectiveness are illustrated for alternative types of flare intensity configurations including the standard, increment, and Neopolitan flares. A description and performance predictions of the covert flare are included. (Author)

Some Zoological Studies with Image Intensifiers

Abstract: The homosapien, when placed in perspective with other mammals is a diurnal creature; that is, his primary activities are carried out during daylight hours. (Ref. 1) The fact that man is diurnal rather than nocturnal will not rattle the cages of our civilization, but when we look at ourselves relative to other mammals we find the homo sapien making up part of a 15% minority (Ref. 2) of animals. One need not refer to his slide rule to calculate the fact that 85% of all mammals are eithe r nocturnal or functional at night. (Ref. 3)© (1974) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.