Showing papers on "Night vision published in 1979"

Argyria: clinical implications of exposure to silver nitrate and silver oxide.

Abstract: This article reports the clinical findings in a work force of 30 individuals who were exposed to silver nitrate and silver oxide Six individuals had argyria and 20 had argyrosis (deposition of silver in the eye) Measurements of blood silver levels were included as part of the examination The results of this examination generally support the benign nature of argyria, although the question of silver causing a decrement in kidney function and night vision is not settled Periodic slit lamp examinations as well as monitoring of silver air concentrations are necessary to assure that engineering controls are actually limiting worker exposure to silver

Increased incidence of abnormal nasal cilia in patients with retinitis pigmentosa.

Abstract: RETINITIS PIGMENTOSA (RP) is the name given to a group of inherited eye disorders of unknown aetiology, whose symptoms are loss of night vision and constriction of the field of vision. The conditions are progressive and eventually in some cases blindness occurs1. Although there are certain syndromes which include RP, for example, the Laurence–Moon–Biedl1, or Cockayne's syndrome2, in most cases the disease is considered to be localised to the eye. However, a high incidence of deafness has always been associated with RP1,4 and Massof and Finkle-stein (personal communication) have found that at least 15% of their cases have inner ear deafness not associated with pres-byacusis or acoustic trauma. As the outer limbs of photorecep-tors are modified cilia3 and the sensory epithelium of the inner ear is derived from ciliated epithelium, we wondered whether RP might be associated with a more general defect of ciliated structures. Accordingly we examined samples of nasal mucosa from 11 patients with RP and report here an increased incidence of cilia with abnormal axonemal microtubular structures, and also of compound cilia. Although our patient sample was small, it was heterogeneous and our findings may therefore apply to patients of different genetic type. If, as seems plausible, the ciliary abnormalities are related to the disease process in the eye, nasal mucosa would offer an accessible source of human material for the study of basic pathological processes in photoreceptors.

Non-Diabetic Retinal Abnormalities in Chronic Pancreatitis

Abstract: To determine whether retinal abnormalities occur in patients with chronic pancreatitis, ophthalmoscopic and retinal-function evaluation was performed in 28 patients with chronic pancreatitis and 19 healthy subjects. The final threshold of dark adaptation was significantly increased 40 per cent (P<0.001) in patients with pancreatitis, whether or not they had steatorrhea. Patients with steatorrhea had a significant decrease of about 42 per cent (P<0.001) in the b-wave of the electroretinogram, a measure of both rod and cone function. Seven of the 28 patients complained of difficulty with night vision; six of these seven had morphologic lesions on ophthalmoscopic examination, confirmed by fluorescein angiography. No correlation was found between any of the retinal abnormalities and the serum vitamin A or zinc levels or glucose tolerance. Non-diabetic retinal lesions and retinal-function abnormalities are common in patients with chronic pancreatitis, even in the absence of steatorrhea. (N Engl J Med ...

Home Office Police Scientific Development Branch

Abstract: The overall objective of the Home Office Police Scientific Development Branch is the improvement in operational efficiency of the British police forces, by the study and planning of new methods and the development of special-purpose equipment. Scientific staff work closely with senior police officers on a wide variety of subjects. For example, systems research projects include studies of command and control, traffic resource allocation, and major incident record handling, while other groups carry out research on fingerprints and on facial recognition. Equipment work encompasses assessment and development of an extremely wide range of hardware, and four examples are described, namely remote observation, night vision, location of hidden objects, and intruder detection.

Optical system for night-vision glasses

Abstract: An optical system for night-vision glasses having a long focal length and a large image angle including an objective having a structural length less than 1.6f and an aperture ratio larger than 1.2, with the objective having a high distortion and an image angle of about 50°. An image amplifier is provided for receiving an image from the objective and for providing an amplified image output with a viewing optic being provided for receiving the amplified image output and for compensating for the distortion of the objective to provide a substantially distortion-free image to a viewer.

Pilot performance during simulated approaches and landings made with various computer-generated visual glidepath indicators.

Abstract: Two simulator experiments were conducted to quantify the effectiveness, in terms of pilot performance, of four different visual glidepath indicator systems (the 2-bar VASI, 3-bar VASI, T-VASIS, and PAPI) in the severely reduced nighttime visual environment often referred to as the "black hole." Performance in Experiment I was best with the T-VASIS and decreased with the 3-bar BASI, PAPI, and 2-bar VASI, in that order; but differences between the T-VASIS, 3-bar VASI, and Papi were not statistically significant. Approaches flown withou the ground-vased glidepath indicators tended to be low and extremely variable. Observing behavior was compared in approaches with the T-VASIS and 2-bar VASI. Observing response frequency increased as distance from runway threshold decreased and was significantly higher with the T-VASIS. Differences in performanange provided by a given system and to the rate of observing the indicator during approaches.

The Physiological Optics of a Nocturnal Semi-Aquatic Spider, Dolomedes aquaticus (Pisauridae)

Abstract: The optics of the posterior eyes of the amphibious spider, Dolomedes aquaticus, are described. The lenses have strongly-curved spherical front and rear surfaces, and therefore, a fairly high light capturing ability - they have F-numbers of 0.9 - yet, the large amount of spherical aberration predicted by their shape is mostly corrected. The receptive segments of the receptors are arranged in rows, each row separated by pigmented glial cells, but within a row, rhabdomeres from neigh­ bouring cells are contiguous so that coupling between cells from the same row seems a possible way of increasing absolute sensitivity for night vision. When the spider submerges, an air-layer is held over the comeal surfaces - as with a diver’s face mask - so that light is focused on to the receptive layer of the retina under water as well as above. These features are considered as adaptations for the nocturnal and semi-aquatic habits of the spider.

Armoured turret for tank - carries sub-turret with small calibre gun and all round day or night vision

Abstract: The armoured turret (11) has a field of view and aim less than 360 deg. for the main gun (13). A small subturret (17) rotates on this turret and has a high fire rate small calibre weapon (20). This rotates on the turret and has 360 deg. field of view. Part, at least, of this can give night vision. The subturret has several periscopes around it. One has the line of sight of the small calibre weapon, fixed to it. This can give day or night vision, using light intensification helped by a laser.

Accommodation in Untextured Stimulus Fields.

Abstract: : Recent research employing the laser optometer has shown that accommodation is notably inaccurate with reduced illumination, textural cue removal, or small aperture viewing. These situational ametropias are most plausibly and parsimoniously explained as a passive return to an intermediate resting position for accommodation, operationally defined as the dark focus. Although, for any individual, large correlations exist among these ametropias, statistically reliable differences occur among them as well. A series of experiments show that a portion of the differences may be due to chromatic aberration. The dark focus is the major determinant of the accommodative response; under steady-state conditions the response is a compromise between stimulus and dark focus distances. Spatial characteristics of the stimuli also appear to be important factors in determining this compromise distance of accommodation. (Author)

Effects of pseudoephedrine and triprolidine on visual performance.

Abstract: The effects of q.i.d. administration of 60 mg pseudoephedrine (Sudafed) tablets or pseudoephedrine-triprolidine (Actifed) tablets after 5 d of medication were measured on tests of night vision, color perception, stereopsis, and reaction time. Neither drug appeared to impair performance.

Flexible leaf contact system for night vision optical instruments

Abstract: Disclosed is an electrical contact system for a night vision optical instrument having a cylindrical housing body intermediate an objective lens and an ocular. An intensifier tube is carried within the body for relative movement therebetween whereby the objective lens carried by the body and the intensifier tube are longitudinally adjustable relative to one another. Electrical leaf contacts, one of which is electrically connected to a battery carried by the housing body, are carried by and extend into the path of movement of the intensifier tube. The distal ends of the leaf contacts are maintained in electrical contact with electrical terminals on the end face of the intensifier tube throughout the range of relative movement between the intensifier tube and housing body.

Runway image shape as a cue for judgment of approach angle.

Abstract: : One cue for visual judgment of glidepath angle has been referred to as form ratio. Form ratio is defined as the ratio of vertical height of the runway to width of the far end in the runway retinal image. The ability of pilots to judge form ratios was compared with the ability to judge approach angles in the nighttime 'black hole' situation in two experiments. In one experiment, 16 pilots observed a stationary model of a lighted airport runway under nighttime conditions at different simulated approach angles from a simulated distance of 8,000 ft from threshold. Pilots made verbal judgments of approach angle using the categories 'low,' 'high,' and 'OK,' and on half the trials also estimated form ratios. In the second experiment, 20 pilots made observations both in a similar static condition at simulated distances of 8,000 ft and 26,000 ft from threshold, and in a dynamic condition in which they controlled the model to produce (i) specified values of form ratio (1.0, 2.0, and 3.0) or (ii) a 3 deg approach angle, as the model approached them between 8,000 and 26,000 ft. The simulated approach speed was 125 knots. Responses in both static and dynamic conditions indicated a general tendency to over-estimate form ratios and approach angles less than 3 deg. Intersubject and intrasubject variability of form ratio and approach angle responses were comparable.

Night armor training in simulated darkness.

Abstract: : To reduce problems with safety, logistics, and evaluate feedback inherent in training at night, the Army Research Institute (ARI) has developed experimental light-attenuating devices (LADs), which simulate visual conditions of night during the day. Single-density or bidensity lenses can be fitted to various existing facemasks and used to conduct certain simulated night-training operations during the day, with little reduction in effectiveness.

Development Of Low-Cost Military Night Vision Goggles For Individual Use

Abstract: The historical background, of U.S. Army individual night vision, goggles is briefly traced and the current status is summarized, leading to the conclusion that a dramatic reduction in unit cost is essential for maximum military utilization of such devices. System. requirements are outlined for low cost night vision goggles. A. current development program is described in which low cost is achieved by use of one image intensifier tube, by extensive use of injection molded aspheric plastic optical elements and by molded Plastic mechanical components. System concepts and design. considerations are presented.

Direct Measure Of Cathode-Ray Tube (CRT) Image Quality

Abstract: This paper describes a direct measuring technique for determining the image quality ofraster - scanned cathode -ray tube (CRT) displays. This technique is based on the ModulationTransfer Function (MTF) theory and human visual psychophysical data. The rationale for thetechnique is discussed from a theoretical as well as functional viewpoint. The instrumenta-tion necessary to obtain these measures in manual and automatic modes is discussed. Dataobtained using this measurement technique are analyzed and compared with the theoreticalperformance of the displays. The image quality of new CRT displays procured for the U.S.Army's Advanced Attack Helicopter is being specified and tested using this direct measuringtechnique.IntroductionAdvances in electronic display technology have not yet changed the primacy of the CRT inthe area of video information displays. Yet, a comprehensive basis for specifying televi-sion display image quality which relates to human operator performance parameters has notevolved even though numerous studies have investigated various facets of this specificationproblem during the past thirty years.This specification problem is directly related to the lack of standardization in displayperformance metrics. Currently, no universally acceptable technique exists for analyzingtelevision display system quality. Each manufacturer establishes his own test, measurement,and evaluation procedures.The lack of standardization in measurement techniques makes it virtually impossible toestablish comprehensive performance specifications. Presumably, television display manufac-turers publish specifications so prospective buyers can evaluate this data before selectinga particular unit for their needs. But, it is difficult to find a common denominator sothat one can compare units built by various manufacturers on the basis of performance.Many techniques were tried during the late 1960's and early 1970's to measure the imagequality of the miniature CRT's. In the mid 1970's a new technique was developed at theAerospace Medical Research Laboratory (AMRL), Wright- Patterson Air Force Base./ The U.S.Army Aeromedical Research Laboratory, Fort Rucker, Alabama, U.S. Army Night Vision and Elec-tro- Optics Laboratory, Fort Belvoir, Virginia, and Honeywell, Inc., have continued to useand refine the techniques developed at AMRL. The evolved procedures and caveats for apply-ing the measuring technique to miniature as well as panel- mounted CRT displays are presentedin detail. BackgroundThe resolution of optical elements has been measured for years by means of two- dimension-al bar patterns with various spacings and angular arrangements. The optical element underinvestigation forms an image of the bar pattern, and the observer subjectively determinesthe limiting resolution from the smallest set of bars he can resolve. With this type oftest, it is possible to determine only a subjective maximum resolution. This resolutionmeasure provides information about only a single spatial frequency. How the display oper-ates at other spatial frequencies is not determined. Also, there is too much variabilityin this method of measurement for it to be used as a basis for setting specifications.

Night Vision Performance in Detection and Identification of Moving Targets after Glare

Abstract: : The purpose of this work is to evaluate night vision performance after photo-stress to allow development of optimum strategies for detection and resolution of moving targets under these environmental conditions. Contrast thresholds for detection and resolution were determined at scotopic light levels for static and moving targets of different sizes. The sensitivity for detection is highest for moving targets while the sensitivity for resolution is highest for static targets. Glare recovery measurements for detection and resolution were also performed at scotopic background levels for the same target parameters used in the thresholds measures without glare. Glare recovery is linearly related to target contrast for both resolution and detection over the range of contrasts used. The results indicate that performance on the glare recovery task cannot be predicted on the basis of contrast threshold alone. The results also show that one can predict glare recovery for either detection or resolution of different size targets, moving at different velocities on the basis of a single glare recovery measurement for a specific size and velocity using either detection or resolution as the criterion.

The Supply Of Germanium For Future World Demands

Abstract: The supply of germanium has been of major concern to industry who utilize it in numerousapplications. One application, Electro- Optics Viewing Systems, use the unique opticalproperties of germanium to operate within a given spectral range. Similarly, germanium isused in such semiconductor devices as radiation detectors, light emitting diodes, and solar cells. The oxide of germanium is used in the textile industries of Europe and Asia as acatalyst. For these commodities, there is a predictable increase in demand for both non-military and military use in the 1980's. The impact of this increase in demand is evalu-ated and compared with its supply.IntroductionThe US Army's Night Vision and Electro- Optics Laboratory of the U.S.A. and Roskill Infor-mation Services in the U.K. have recently carried out independent surveys on the futuresupplies of germanium.(l,2,3) Both surveys showed that an increased demand for germaniumis predicted for the U.S.A., Europe, U.K., U.S.S.R., and Asia. This growth will be due tothe increased use of germanium in optics for infrared surveillance devices. These findingsindicate the possibility of creating an unprecedented demand for germanium. This paperwill briefly describe the supply and demand for germanium then proceed to illustrate theimpact that the increasing utilization of infrared devices may have upon the supply ofoptical grade germanium.Germanium does not occur as a native element, but is found in low concentrations incertain metallic ores and minerals. There are only a limited number of mines throughoutthe world which have ores or minerals with a high enough concentration of germanium to makeit commercially extractable. The ores from these mines are shipped to smelters where theimportant base metals, zinc, lead, and copper are separated. A smelter is an establishmentwhere ores are treated to separate crude metallic products. Germanium and other byproductsare found in the fume and residue resulting from the smelter process and are collected andstored in "dumps" at the smelter site. Independent producers of germanium can purchasethese residue "byproduct dumps" from smelting companies throughout the world. Table 1summarizes the world's germanium refiners with their respective smelter and mine sources.Table 1. Composite of the World's Germanium Producers,Zinc Smelters and Mine Sources

Intelligent Tracking Techniques - A Progress Report

Abstract: Under contract to the Army's Night Vision and Electro-Optics Laboratory, Westinghouse has been investigating the design, test, and implementation of a set of algorithms to perform intelligent target tracking and intelligent target homing on FLIR and TV imagery. The focus is a system of algorithms which can quantitively identify a target and its present background, but can acknowledge the approach of a new background in the target's path, characterize this new region, and intelligently predict the target's signature before it enters a new domain. The operating environment for the system is a high clutter background associated with ground targets. Three types of obscurations are considered: (1) the target enters a background very similar in gray scale to it, (2) the target passes behind an obscuration such that some identifiable portion is always visible, and (3) where the target passes behind a thin screen of obscuration and portions of the target can be seen on each frame but portions vary from frame to frame. The system may be viewed as a target cuer operating in conjunction with a target signature predictor and high speed frame to frame registration. The review describes some of the work performed in the first 6 months of a 19-month program.

Visual Problems and Night Landing Guidance of the CH-47 (Chinook) Helicopter.

Abstract: : Visual ergonomics problems in the Chinook helicopter were investigated in a study following an earlier, broader ergonomics study by ARL Cybernetics Group. Important visual problems do occur in the Chinook and solutions or further studies are suggested as appropriate. Brief trials of tactical night landing devices were observed, and these are discussed in the light of previous DSTO participation in the development of visual landing guidance systems. Improvements to the devices currently in use are necessary to improve operational effectiveness and flight safety. (Author).

Development of Light-Attenuating Devices (LADs) to Simulate Night Visibility during Daylight

Abstract: : To circumvent safety, evaluation, and logistics problems in nighttime training, ARI has developed light-attenuating devices (LADs) to simulate night visual conditions and allow daytime training. Both single-density and bidensity lenses have been developed for a variety of facemasks. This report documents ARI's role in developing and fabricating LADs and discusses potential applications for training. Using LADs to simulate night visibility for night training and testing may be more advantageous than actual night training for several reasons. First, safety: With single-density LADs, someone with full vision can monitor trainees' performance. Second, performance evaluation: Instructors working in daylight can better observe and evaluate trainees' performance. Third, convenience: Daylight is a more convenient time for many qualifications tests.

Advanced Bandwidth Compression Schemes

Abstract: Bandwidth compression schemes have found useful application in preventing the jamming of transmitted information. Such data reduction methods are particularly needed in the case of RPV imagery transmission. The Night Vision & Electro-Optics Laboratory has initiated funding of separate studies to access the feasibility of obtaining 1000 to 1 and 10,000 to 1 compression ratios. The achievement of such ratios necessitates a considerable degree of local intelligence in which specially selected scene information only, is transmitted. The 1000 to 1 concept involves sending with fidelity, just such information that is deemed to be of probable value to the RPV mission. In the case of 10,000 to 1 ratio the image is segmented, classified and only coordinates and image descriptors are transmitted.© (1979) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Delineation as Road Signing: A Study of Visual Cues on Rural Roads at Night

Abstract: Formal delineation schemes on rural roads need to supply several types of information to the driver under night conditions. He needs longer-term delineation information or reasonable preview in order to plan ahead on approach to curves. The experiment reported explored the effect of various delineation schemes, road contour, distance to the curve, and the curve direction of turn under two reaction time instructional conditions. The results demonstrated that road-side post delineation provides effective information of this type, while no benefit was found from edgelining. Right-hand curves were responded to faster and were more easily detected than left-handers.* Several interesting interactions were found between the factors studied.

Technical Evaluation Report on the Guidance and Control of Helicopters and V/STOL Aircraft at Night and in Poor Visibility.

Abstract: : The GCP Symposium was held in The Hague, The Netherlands, 9-12 October 1978 The Programme as presented at the symposium is appended to this report The complete compilation of papers has been published as Conference Proceedings CP-258 The technical evaluation for each session has been done partly by the session chairmen and edited by the programme chairman The evaluation includes most of the comments and recommendations which were received from the particpants in the symposium (Author)

Programmable Multifunction Processor

Abstract: A new two -dimensional DEFT sensor (for Direct Electronic Fourier Transform) for multi-processing will be described. Operating at a center frequency of 100 MHz, it is capable ofresolving 1800 unique spatial Fourier image components in a random access mode. As aFourier transformer it can identify vector spatial fre,uencies, their amplitude and phase.By suitable change of input functions, the device can be operated as a spatial rasterscanner, Hadamard transformer, matrix multiplier, or convolver.The device achieves this flexibility by virtue of producing the spatial integral of theproduct of two electronic signals with an optical signal. 1. IntroductionWe have succeeded recently in fabricating monolithic direct electronic Fourier transform(DEFT) imaging sensors. We here present the results of tests conducted with those devices.We also present Fourier space raster scan data previously not reported. In previous publi-cations [1,2,3,4,5] we have reported data taken with devices having an externally mountedsampling mask [6].A DEFT device is an electronic image sensor. The output of the device is a sinusoidalelectrical current. The amplitude of the current is proportional to the amplitude of theFourier transform components of the two -dimensional image, and the phase of the current isproportional to the phase of the Fourier transform components of the image.The device has three input ports; two electronic, one optical; and one electronic output.The optical input is usually considered stationary, while the electronic signals used toexcite the surface waves are time -varying.Such devices have considerable flexibility. By appropriate choice of the inputs, a largeclass of signal and optical processing functions can be performed. We shall describe aprototype system, currently used to raster scan the two -dimensional spatial Fourier trans-form of the optical intensity. It could be expanded to provide direct video scanning, Had -amard transformation, etc.As a signal processing device, it can be operated to obtain generalized matrix innerproducts of digital signals.Recently, an alternative structure also capable of two- dimensional processing has beendescribed [7]. It is based on a Si diode -array separated -medium surface -wave convoler, andhas been used to line scan images.One embodiment of the device is showy, in Fig. 1. The image sensor consists of a layeredCdS film deposited on a z -cut LiNbO3 substrate. The metal contacts, consisting of an Al /Infilm sandwich in the form of an interdigital pattern, are deposited onto the CdS film.This pattern permits the collection of the total photocurrent over the area of the CdS film.Indium is used as the contact material. It is our experience that In makes ohmic contactto CdS and aluminum provides better longitudinal conduction. Two interdigital transducers,each parallel to one of two orthogonal edges of the square sensor, are used for the genera-tion of surface acoustic waves. The sensor area is overlayed by a thin polymer insulatingfilm after the contacts are fabricated. An array of aluminum film squares deposited on thepolymer film form a monolithic shadow mask. This shadow mask provides the sampling of theimage in the x- direction. The image is sampled in the y- direction by the interdigital con-tact pattern.Previous devices had an externally mounted shadow mask [3,5]. Since the mask was spacedabout 50 um from the device, imaging with a lens was difficult. The light rays incident atan angle other than 90" to the plane of the device would undercut the shadow mask.The present monolithic device eliminates this difficulty, as well as providing a strongermechanical unit.Research leading to this paper supported by U.S. Army Night Vision and ElectroopticsLaboratory, Ft. Belvoir, VA.Work supported in part by U.S. Army Engineer Topographic Laboratories, Ft. Belvoir, VA.

Helicopter pilot performance and workload as a function of night vision symbologies

Abstract: In the near future, military helicopter pilots will be required to fly night time nap-of-theearth (NOE) missions using helmet-mounted displays of their flight environment. These displays will be composed of an infrared video representation of the outside world and flight control information, in a symbology format, superimposed on the visual scene. The piloting task under such conditions must be classed as extremely demanding in terms of performance requirements, safety, and workload. A study was undertaken to investigate several human factors questions of man-machine integration mediated through such displays and symbologies. A full six-degree-of-freedom motion simulation of an advanced U.S. Army helicopter flying a night NOE scenario was conducted. The dynamic visual scene was obtained from a video picture of a terrain board and three-candidate computer generated flight control symbologies were video-mixed with the scene. Six experienced helicopter pilots were employed as subjects and trained to fly a scenario incorporating multiple precision hover maneuvers which varied in difficulty and task loading.

A human performance/workload evaluation of the AN/PVS-5 biofocal night vision goggle

Abstract: Eight experienced U.S. Army aviators performed various maneuvers in an instrumented helicopter to test the relative usability of two bifocal-configured night vision goggles. Both configurations were statistically better than the unmodified arrangement when looking at a pilot's ability to fly a standard traffic pattern and to hold a precise altitude at night. The subjective data, supported by comparative flight performances with the two bifocals, further suggested that a 24% bifocal version was more desirable than a 14% configuration. The inference is that the reduced inside field of view presented by the 14% bifocal interferes with a pilot's ability to readily locate instruments once he has directed his attention inside the cockpit.