Showing papers on "Night vision published in 1989"

Conditions and significance of night feeding in shorebirds and other water birds in a tropical lagoon

Abstract: -On a small bay of the Chacopata lagoon complex in northeastern Venezuela, we analyzed the temporal feeding activity patterns of shorebirds and other water birds, and we determined the factors or conditions related to these patterns. During daytime and nighttime observations, we measured the abundance of each species as well as environmental factors (time, wind velocity, cloudiness, tide level, presence of moonlight and bioluminescence). A night vision module (light intensifier) was used during nighttime observations. Samples x species matrices were summarized by reciprocal averaging (RA) analysis, and the information was related to environmental factors. Feeding activity patterns were related most significantly to time of day, i.e. daytime and nighttime. Some species like "egrets," the Whimbrel (Numenius phaeopus), and the Black-bellied Plover (Pluvialis squatarola) fed principally during daylight, but most other species (including a majority of shorebird species) fed more regularly and in higher numbers at night. Lesser and Greater yellowlegs (Tringa flavipes and T. melanoleuca, respectively) and Willets (Catoptrophorus semipalmatus) foraged with comparable frequency during the day and the night. Daytime and nighttime data were analyzed separately, and tide level best explained both the variations of nocturnal and diurnal abundance of foraging birds. Nocturnal feeding may be a natural habit in response to regularly limited feeding space and time mainly induced by tide. Received 4 January 1988, accepted 24

Miniature Refrigerators for Cryogenic Sensors and Cold Electronics

Abstract: A surprisingly wide diversity of sensors, instruments or devices used for military, civil, scientific and medical purposes require cooling to cryogenic temperatures. Some work better or faster at low temperatures, are more sensitive or more effective. For others cryogenic cooling is essential to utilize phenomena which exist at very low temperatures, sometimes a narrow or precise temperature range. The cooling capacities required range from fractions of a watt to as much as 10W at temperatures extending from a minimum of 1 K or less to those well above the limit of the cryogenic range (120 K). At present there is a concentration of interest for fractional watt cryocoolers at near liquid-nitrogen temperatures (80 K). These needs are currently filled by immersion in liquid or solid cryogens, miniature Linde-Hampson cryocoolers with Joule-Thomson expansion energized by compressed gas from storage bottles and miniature mechanical refrigerators. Following a long period of intensive development and evaluation of many different mechanical systems miniature Stirling engines appear to emerge as the system of choice. They are smaller, weigh less, are more efficient and can be made at a reasonable price. Early disappointment with limited life and high maintenance requirements have been alleviated as the technology matures, designs are stabilized and manufacturing and test techniques develop. The present large scale application for miniature cryocoolers in infrared night vision and missile guidance systems will probably remain and expand as ‘smart’ projectile and beam guided weapons are widely introduced. Other large scale applications are in prospect with the development of semi-conductor ‘cold electronics’ systems and the new high temperature superconducting devices.

Mounting means for use of ground system type goggles as aviators goggle

Abstract: A flip-up mounting bracket for use of a stripped down ground system type ht vision goggle on an aviators helmet. The frame and excess padding surrounding the ground system goggle is removed and the mounting bracket is substituted for the frame as a threadable mount for the ground system goggle. The bracket is rotatably connectable to standard aviators night vision imaging system (ANVIS) hardware on the helmet. The mounting bracket and goggles are rotatable about the hardware for stowing the ground system goggles up in the vertical flip-up position or down in the direct view of the pilot for use in night observation.

Vitamin supplementation and athletic performance.

Abstract: Vitamins serve primarily as regulators of metabolic functions, many of which are critical to exercise performance. Depending upon the nature of their sport, e.g., strength, speed, power, endurance, or fine motor control, athletes may use megadoses of various vitamins in attempts to increase specific metabolic processes important to improved performance. Surveys have indicated that most elite athletes do take vitamin supplements, often in dosages greater than 50-100 times the United States Recommended Dietary Allowances. The theoretical basis underlying the use of each vitamin depends upon its specific metabolic function in relation to sport. Vitamin A functions to maintain night vision; thiamin, riboflavin, niacin, and pantothenic acid are all involved in muscle cell energy metabolism; niacin may also block free fatty acid release; pyridoxine is involved in the synthesis of hemoglobin and other oxygen transfer protein; folic acid and vitamin B12 are integrally involved in red blood cell (RBC) development; vitamins C and E are antioxidants, possibly preventing the destruction of the red blood cell membrane during exercise; vitamin D may be involved in muscle cell energetics through its influence on calcium. These are but a few of the possible metabolic functions of vitamins which have been suggested to have ergogenic applications to sport. Research has shown that a vitamin deficiency impairs physical performance. If this deficiency is corrected, performance usually improves. In general, vitamin supplementation to an athlete on a well-balanced diet has not been shown to improve performance. However, additional research with certain vitamins appears to be warranted, such as with the vitamin B complex and fine motor control, and with vitamin E and endurance at high altitudes. Moreover, research with megadose supplementation may also be necessary.

Human Factors And Safety Considerations Of Night Vision Systems Flight

Abstract: Military aviation night vision systems greatly enhance the capability to operate during periods of low illumination. After flying with night vision devices, most aviators are apprehensive about returning to unaided night flight. Current night vision imaging devices allow aviators to fly during ambient light conditions which would be extremely dangerous, if not impossible, with unaided vision. However, the visual input afforded with these devices does not approach that experienced using the unencumbered, unaided eye during periods of daylight illumination. Many visual parameters, e,g., acuity, field-of-view, depth perception, etc., are compromised when night vision devices are used. The inherent characteristics of image intensification based sensors introduce new problems associated with the interpretation of visual information based on different spatial and spectral content from that of unaided vision. In addition, the mounting of these devices onto the helmet is accompanied by concerns of fatigue resulting from increased head supported weight and shift in center-of-gravity. All of these concerns have produced numerous human factors and safety issues relating to thb use of night vision systems. These issues are identified and discussed in terms of their possible effects on user performance and safety.

Helicopter flights with night-vision goggles: Human factors aspects

Abstract: Night-vision goggles (NVGs) and, in particular, the advanced, helmet-mounted Aviators Night-Vision-Imaging System (ANVIS) allows helicopter pilots to perform low-level flight at night. It consists of light intensifier tubes which amplify low-intensity ambient illumination (star and moon light) and an optical system which together produce a bright image of the scene. However, these NVGs do not turn night into day, and, while they may often provide significant advantages over unaided night flight, they may also result in visual fatigue, high workload, and safety hazards. These problems reflect both system limitations and human-factors issues. A brief description of the technical characteristics of NVGs and of human night-vision capabilities is followed by a description and analysis of specific perceptual problems which occur with the use of NVGs in flight. Some of the issues addressed include: limitations imposed by a restricted field of view; problems related to binocular rivalry; the consequences of inappropriate focusing of the eye; the effects of ambient illumination levels and of various types of terrain on image quality; difficulties in distance and slope estimation; effects of dazzling; and visual fatigue and superimposed symbology. These issues are described and analyzed in terms of their possible consequences on helicopter pilot performance. The additional influence of individual differences among pilots is emphasized. Thermal imaging systems (forward looking infrared (FLIR)) are described briefly and compared to light intensifier systems (NVGs). Many of the phenomena which are described are not readily understood. More research is required to better understand the human-factors problems created by the use of NVGs and other night-vision aids, to enhance system design, and to improve training methods and simulation techniques.

Panoramic periscope for two spectrum ranges

Abstract: The panoramic periscope has a panoramic head and a tube. In the panoramic head is mounted a viewing mirror movable in elevation and azimuth, upstream of which is arranged an at least bispectral front window. Various measuring or observation devices, for example a daylight and night vision device and a laser range-finder, are provided in the tube. Panoramic head and tube are connected to one another by an optically transmitting component such as a transparent cylinder or by webs. As a result, the visual beam path can be reflected out laterally by means of a spectrum divider, so that the latter can be arranged in the observation beam path immediately downstream of the viewing mirror in the upper tube portion. In addition to a compact design, this also makes possible a separate, better optimization of the optical systems for the daylight and night vision range.

Optical motion detector detecting visible and near infrared light

Abstract: An optical motion detector detects changes in scene lighting indicative ofotion and is also capable of detecting surveillance by active night vision devices using near-infrared light. The detector includes two photodetectors which each provide data to a signal processing network. One photodetector is sensitive to visible light; the other is sensitive to near-infrared light. Both signal processing networks are identical and include a sample-and-hold, a comparator network, and a pulse stretcher. The output of a photodetector is provided to the sample-and-hold and comparator network. The comparator network compares a voltage corresopnding to the instantaneously detected ambient lighting scene with a voltage corresponding to a reference lighting scene. The pulse stretcher receives the output of the comparator network and in turn provides an output to a logical processor. The logical processor compares the outputs of both signal processing networks and provides an output indicating surveillance with near-infrared light. The logical processor also indicates any perturbations in the intensities of incandescent and fluorescent light.

Helmet-mounted pilot night vision systems: Human factors issues

Abstract: Helmet-mounted displays of infrared imagery (forward-looking infrared (FLIR)) allow helicopter pilots to perform low level missions at night and in low visibility. However, pilots experience high visual and cognitive workload during these missions, and their performance capabilities may be reduced. Human factors problems inherent in existing systems stem from three primary sources: the nature of thermal imagery; the characteristics of specific FLIR systems; and the difficulty of using FLIR system for flying and/or visually acquiring and tracking objects in the environment. The pilot night vision system (PNVS) in the Apache AH-64 provides a monochrome, 30 by 40 deg helmet-mounted display of infrared imagery. Thermal imagery is inferior to television imagery in both resolution and contrast ratio. Gray shades represent temperatures differences rather than brightness variability, and images undergo significant changes over time. The limited field of view, displacement of the sensor from the pilot's eye position, and monocular presentation of a bright FLIR image (while the other eye remains dark-adapted) are all potential sources of disorientation, limitations in depth and distance estimation, sensations of apparent motion, and difficulties in target and obstacle detection. Insufficient information about human perceptual and performance limitations restrains the ability of human factors specialists to provide significantly improved specifications, training programs, or alternative designs. Additional research is required to determine the most critical problem areas and to propose solutions that consider the human as well as the development of technology.

Aviator's night vision system

Abstract: An aviator's night vision system (10) includes a small, compact, portable battery pack (68) separate from, and unattached to, a helmet (12), but comprising a container housing a battery (78) with a goggle assembly receptacle of the type that is mounted on the helmet. The goggle assembly receptacle of the portable battery pack housing includes engaging means (86 & 88), electrical contacts (90 & 92), and an orientation ridge (106) of the same type found on the helmet mounted receptacle (14). With this small portable battery pack, a goggle assembly can be removed from the helmet mounted goggle-assembly receptacle, snapped onto the portable battery pack receptacle, and thereafter used by hand for enhancing night vision.

Apparent limitations of head-up-displays and thermal imaging systems

Abstract: A simulated helicopter flight through a slalom course was presented on a Silicon Graphics IRIS 3130. The display represented the major visual characteristics of thermal images. Subjects were asked to maintain a designated altitude, while flying a slalom course between regularly spaced pylons. The presence of some of the high frequency details in the image improved subjects' ability to reach and maintain the correct altitude. A head-up-display helped in maintaining altitude, but impaired maneuvering around the poles. The results are interpreted in terms of the competition for visual resources between the HUD and the world view.

Low distortion focal plane platform

Abstract: An infrared detector assembly (12) of the type used in munitions and night vision systems having an improved focal plane platform (10). The focal plane platform (10) includes an end-cap (32) made from tungsten. Adhesively bonded to end-cap (32) is a ceramic mounting board (34). Ceramic mounting board (34) further comprises gold trace pattern (50) for conducting electrical signals generated by hybrid detector (26) to external control electronics. The improved focal plane platform (10) provides a relatively distortion free, thermally stable mounting platform upon which detector (26) is secured. Premature thermal fatigue failure of the hybrid detector is thereby inhibited.

Infrared detector focal plane

Abstract: An infrared detector assembly (12) of the type used in munitions and night vision systems having an improved focal plane platform (10) construction. In accordance with this invention, the thermally conductive focal plane platform (10) supports a detector array (26) and integrated readout chips (28). The focal plane platform (10) includes relatively thermally non-conductive inserts (38) disposed in cavities (36) positioned generally below each integrated read out chip (28). The inserts insulate the chips (28) during cryogenic cooling of detector array (26). Freeze-out of the chips (28) is thereby inhibited.

Distortion free dewar/coldfinger assembly

Abstract: An infrared detector assembly (10) of the type used in munitions and night vision systems having an improved coldfinger assembly (42). Such detector assemblies (10) include a tubular coldfinger (22) which is surrounded by a vacuum and an end-cap (28) mounted to the coldfinger tube (22) to define a cold end (24) which supports the infrared detector array (30) and related components. In accordance with this invention, the coldfinger tube (22) is a thin-walled titanium cylinder and the end-cap (28) is made of tungsten. The components are metallurgically bonded at the cold end (24) by an active brazing alloy deposited during vacuum furnace brazing. The titanium coldfinger (22) provides the necessary bending stiffness to support cold end components. The tungsten end-cap (28) provides a low distortion, thermally stable focal-plane. The metallurgical bond (46) provides for a hermetic seal which inhibits structural distortion during brazing, and during cyclical cooling of the detector assembly (10).

Fluoroborosilicate glass clad article and night vision device

Abstract: There are disclosed fluoroborosilicate glasses that are particularly adapted to being drawn with lead silicate core glasses to produce clad glass fibers useful in forming fiber optic bundles to be incorporated in night vision equipment. The cladding glass has a refractive index not over about 1.45 and a coefficient of thermal expansion not over about 120×10 -7 /°C. The clad fiber has a numerical aperture approximating or equal to one.

Analysis for mission reliability of a combat tank

Abstract: Mission reliability is the probability that a system will perform its specified mission. In a reliability sense, some subsystems or components are not required to operate perfectly for a certain mission, and sometimes it is not reasonable to assume that the states of all components are statistically independent. The purpose of this study is to set up mathematical models for the moving and firing mission reliabilities of a combat tank, taking into account these two problems. A discussion is presented of how the models can be used by the combat tank planner or the tank designer. >

Pupillary response: an index of visual threshold.

Abstract: The present study investigates the use of the afferent pupillary reflex as an objective index of a subject’s ability to detect a dim flash. The results support the general notion that the pupil responds to flashes near the absolute threshold for vision. In contrast to several previous studies, however, our results document that minute pupillary constrictions occur in response to small diameter (i.e., 3.5° and 1.2°) stimuli. These pupillary constrictions occur mostly on the trials when the subject also reported seeing the flash and little evidence of a response is found on the trials when the flashes were not detected. We infer that the sensitivity of the perceptual and pupillomotor pathways are very similar for the scotopic conditions tested.

Modeling Human Search And Target Acquisition Performance: II. Simulating Multiple Observers In Dynamic Scenarios

Abstract: The Center for Night Vision and Electro-Optics search model is extended to cover cases involving multiple observers under conditions with time-varying obscurants. We find that simulations with two levels of visibility conditions indicate that the persistence time of an obscurant and the correlation between observers are crucial parameters for determining the average time for first detection.

Driving after dark

Abstract: This article gives advice on how to avoid collisions while driving after dark. Two factors that account for the increased night time death and accident toll are poor visibility and poorly functioning drivers. Drivers should drive slow enough to stop within the area lighted by the headlights. Glare from oncoming headlights would be avoided by shifting the center of vision to the right margin of the road or to the lane markers. Wait 5 minutes before driving away from brightly lighted areas. Also, avoid fatigue and alcohol-impaired drivers. Ways of spotting alcohol impaired drivers are listed.

Remote Active Spectrometer

Abstract: The Remote Active Spectrometer is a compact, lightweight sensor designed to demonstrate remote detection of chemical vapors. A prototype model was developed by Hughes Aircraft Company for the U.S. Army's Center For Night Vision and Electro-Optics, and the Chemical Research Development and Engineering Center. The Remote Active Spectrometer is comprised of four, frequency agile, CO2 laser transmitters (each operating at a rate of 10 hertz), optics for transmission, pointing, reception, and calibration, and detectors and electronics for information processing and recording. To provide a visual record of the scene observed a TV Sensor is integrated with the system. In this paper the Remote Active spectrometer is described, and its performance in the field discussed.© (1989) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Dimming circuit for dual display aircraft instruments

Abstract: A dimming circuit (10) for use with an illuminated dual display (12) of an aircraft instrument is provided. A voltage divider (14) divides a variable supply voltage, V S , produces an input voltage, V IN , and applies V IN to one input of a switch (16). A threshold voltage circuit (15) receives the V S voltage and produces a reference voltage, V REF , and a lower magnitude supply voltage, V' S . A reference comparator (OA3) compares the V REF and V' S voltages and produces a threshold voltage, V T . The V T voltage is applied to a second input of the switch (16). A first comparator (OA1) in the switch (16) produces a low output voltage when the V T voltage exceeds the V IN voltage and causes a first lamp (L1) to brightly illuminate a first indicia (24). A second comparator (OA2) in the switch (16) produces a low output voltage when the V T voltage is less than the V IN voltage, which causes a second lamp (L2) to dimly illuminate a second indicia (26). The illuminated first indicia (24) provides daytime illumination of the dual display (12) and the illuminated second indicia (26) provides nighttime illumination. A night vision goggle compatible filter (22) makes the indicia (26) readable by crew members wearing night vision goggles. The voltage divider (14) and threshold voltage circuit (15) operate to ensure a substantial difference between the values of the V IN and V T voltages, and thus, provide precise switching between daytime and nighttime illumination of the instrument (12).

Pattern Recognition Using Photon-Limited Images

Abstract: The spatial coordinates of detected photoevents and the number of detected photoevents in a given area convey information about the classical irradiance of the input scene. In this paper the effectiveness of photon-counting techniques for image recognition is discussed. A correlation signal is obtained by cross correlating a photon-limited input scene with a classical intensity reference function stored in computer memory. Laboratory experiments involving matched filtering, rotation- and scale-invariant image recognition, and image classification are reported. For many images it is found that only a sparse sampling of the input is required to obtain accurate recognition decisions, and the digital processing of the data is extremely efficient. Using available photon-counting detection systems, the total time required to detect, process, and make a recognition decision is typically on the order of tens of milliseconds. This work has obvious applications in night vision, but it is also relevant to areas such as process control, radiological, and nuclear imaging, spectroscopy, robot vision, and vehicle guidance.

Army's FLIR/ATR Evolution Path

Abstract: Early Automatic Target Recognizer (ATR) systems have been plagued by inconsistency in frame to frame recognition performance and high false alarm rate. One major source of this variation has been traced to instabilities in the Foward Looking Infrared (FLIR) image. The application of classical segmentation algorithms to the unstable FLIR imagery results in the extraction of a "wobbing" silhouette. This paper explores the attributes of first generation FLIRs that contribute to image instability and artifacts. The value of performing higher samples per dwell in a next generation FLIR sensor is explored along with the benefits of equal sampling in X & Y directions. Image instability and degradation result from a number of different sensor or environment factors that include aliasing due to undersampling, a-c coupling effects, 1/f noise, interface scan effects, mechanical scanner jitter, sensor platform motion, and atmospheric scintillation. To circumvent the sensor effects, the Army CECOM Center for Night Vision & Electro-Optics (C2NVE0) is currently developing an new generation of FLIR sensor under the SAIRS program. In parallel to the sensor development, two next generation ATR system testbeds are being developed under the Multi-Function Target Acquisition Processor (MTAP) program to support the evaluation of next generation ATR technology. These testsbeds include extensive instrumentation and are completely reprogrammable to facilitate the rehosting and evaluation of new ATR techniques. Following the MTAP thrust is a miniaturization program, ALgorithm Adaptive & Diminished DImensioN (ALADDIN), to shrink the size, weight & power of the current ATR processors. This paper presents an overview of the SAIRS, MTAP and ALADDIN programs within the context of the Army's overall plan for FLIR/ATR technology evolution.

Attenuating the Luminous Output of the AN/PVS-5A Night Vision Goggles and Its Effects on Visual Acuity

Abstract: : Aviators in combat may be subjected to a variety of noxious light stimuli. Filters and other eye protective devices may be used to counter these threats. At night, filters may be used in conjunction with image intensification devices (e.g., night vision goggles) to provide useful low-light vision as well as protection from deleterious light sources (e.g., lasers, pyrotechnics, nuclear fireballs, etc.). Technologies may be combined in a single, integrated head gear unit. The present study was performed in order in consider the effects on visual acuity after reducing night vision goggle luminous output from 0-99 percent. A range of target contrasts and ambient illumination levels was investigated. AN/PVS-5A goggles were selected based upon their compatibility with current phosphor display technology and their current ubiquity within aviation units. Visual acuity was assayed behaviorally because of its critical importance in flying performance. The results of the study provide normative acuity data with goggles alone and document the effects on goggle visual acuity with reduce goggle luminances as might be produced by protective materials placed between the goggles and the eyes. Keywords: Light filters; Human factors engineering; Night vision devices.

Cockpit Lighting Compatibility With Image Intensification Night Imaging Systems: Issues And Answers

Abstract: Night imaging systems based on image intensification (I 2 ) tubes are a major factor in the night operation capability of U.S. Army rotary-wing aircraft. A major problem associated with the use of these systems is the detrimental effect caused by internal cockpit lighting. Instrument lamps, caution lamps, utility lights, and other light sources inside the cockpit activate the bright source protection control circuits of the intensification tubes, thereby reducing their sensitivity to external natural and artificial illumination. In 1986, a Tri-Service specification, MIL-L-85762, "Lighting, aircraft, interior, night vision imaging system compatible," was adopted to resolve the cockpit lighting problems. MIL-L-85762 defines the measurement instrumentation and techniques required to certify lighting components as "ANVIS compatible." The specification does not address compatibility problems associated with AN/PVS-5 usage. Ongoing efforts related to MIL-L-85762 include characterization of lighting incompatibilities in current U.S. Army aircraft, implementation of programs to modify the lighting in incompatible cockpits, and certification of proposed lighting components for future aircraft systems. Additional work has been done to provide "near compatible" solutions to lighting problems associated with the use of AN/PVS-5 systems.

Helmet-Mounted Displays For Helicopter Pilotage: Design Configuration Tradeoffs, Analyses, And Test

Abstract: Human engineering criteria applicable to the design of helmet mounted displays for use with night vision sensors, such as forward looking infra-red (FLIR) or low light level television (LLTV), are stated and reviewed. Systems requirements are presented which call for pilot operation at night that is as equivalent as practicable to flight under normal daytime visual rules. Requirements are developed that utilize head motion coupled to sensor movement to achieve the semblance of daytime pilotage while conducting operations at night under the cover of deep darkness. At the outset, salient factors are identified and prioritized which are applied to further design tradeoffs leading to helmet mounted visor displays. The prime design objectives being operational suitability, acceptability by the pilot community, reduced crew training requirements and minimal logistics support. In conclusion, alternate design configurations, computer analyses, operating experience, and pilot reaction are cited. Items to be addressed include: overall head supported weight, center-of-gravity, and other ergonomic factors affecting pilot acceptance: such as: comfort, eye-relief, total and instantaneous field of view, full or partial overlap of left-eye and right-eye fields of coverage, and head movement-to-sensor servo response. In addition, items of interest to the operating command: such as: training (ease or difficulty), maintenance of proficiency, and ease of viewing, will be discussed in light of data and operating experience from recently conducted flight trials. Finally, compatibility with nuclear biological and chemical (NBC) defense equipment and requirements, and laser eye protection will be discussed.

Effects of Broadbanded Eye Protection on Dark Adaptation

Abstract: The effects of visible broadband attenuating filters (sunglasses) on final dark adaptation thresholds were examined with the aid of LED spectral dark adaptation measurements. We found a differential effect governed by spectral composition of the test light source. Peripheral dark adaptation functions measured with long-wavelength light showed no significant sunglass effect whereas such functions measured with intermediate spectral light significantly decreased in final visual thresholds. No differential spectral effects were obtained in control subjects who were not provided with sunglasses. Explanations with regard to static as well as dynamic peripheral receptor tuning mechanisms are discussed.

XX 1610 The Super Second Generation Image Intensifier

Abstract: Many years of research in Philips laboratories have enabled the development of a second generation image intensifier, the XX 1610, with characteristics close to an image intensifier of the third generation. In this paper, we will describe the various technical characteristics which determine the excellent performance of the XX 1610, such as photocathode sensitivity, signal to noise ratio, modulation transfer function and mean time to failure. We have made a comparison between image intensifiers of the second and third generation and the XX 1610. It is shown that the XX 1610 nearly matches the performance of a third generation image intensifier in term of equipment performance. When economic factors are also taken into account, the XX 1610 can be considered as a very competitive image intensifier.

Compatibility of the aviation night vision imaging systems and the aging aviator.

Abstract: With the advent of the night vision goggle (NVG) mission requirements in the United States Army, the reserve components began training with the second generation (AN/PVS-5 & AN/PVS-5A) systems. These systems prohibit the wear of spectacles by the aviator. Certain modifications on some systems allowed for spectacle wear. However, there still exists a 5-h day filter training minimum in which the full NVG with facemask and cushion must be worn without spectacles. The NVG system corrects up to +2.00 diopters of hyperopia and up to -6.00 diopters of myopia, but only +/- 1.00 diopter of astigmatism. A survey of the reserve component (USAR and NG) aviators in the Southwest was conducted to establish the relative incompatibility of the NVG system among an aviator population older than the active component aviators. All medical record custodians received questionnaires and the flight surgeon followed up replies by telephone or on-site visits. We screened a total of 127 aviator records. The aviator's average age was 39.5 years; 65.3% had 20/20 vision and were emmetropes. Of those that wore spectacles, 82.4% had hyperopia or myopia correctable by the built-in optical adjustments contained in the NVG. The other 17.6%, who had vision that exceeded the correction factors built into the NVG, consisted of astigmats with greater than 2.00 diopters of cylinder. Nearly 20% of the aviators who wore corrective lenses exceeded the corrective limits of the goggles that they used. Further, pilots had no specific prescreening instruction. With the development of more sophisticated aviation optics. Three options exist: modify visual standards, allow contact lens wear, or design future systems to be compatible with spectacles.