Showing papers on "Night vision published in 1982"

Night vision imaging system adapted for helmet mounting

Abstract: There is disclosed a night vision imaging system for mounting on a helmet. The helmet contains a visor having a slot into which is inserted a helmet mount assembly which can be vertically adjusted within the slot by means of a control mechanism including a rotatable knob. The mount assembly is an arcuate planar member conforming to the surface of the helmet and contains two "U" shaped receptacles for receiving two pivots located on a central fork support frame. The fork frame has two adjacent tines which are secured within two slots contained in a gear box. Coupled to the gear box are right and left carriage assemblies which interface with the gear box by means of a first threaded shaft to afford eye relief adjustment and a second rod assembly to afford tilt adjustment. Each carriage assembly is symmetrically positioned on the right and left sides of the gear box assembly and are coupled to a first and a second unity power image intensifier telescope housing containing an image intensifier tube. The carriage assembly is coupled to the tube housing to move in a horizontal plane for eye relief by contacting either a right or left knob coupled to the threaded shaft at right and left sides. The gear box, carriage assemblies, and intensifier housing as supported by the fork frame, can be "flipped-up" and away from the eyes of a user when the night vision system is not in use or can be "flipped-down" in front of the user's eyes when in use.

Distance Transform for Images Represented by Quadtrees

Abstract: The concept of distance used in binary array representations of images is adapted to a quadtree representation. The chessboard distance metric is shown to be particularly suitable for the quadtree. A chessboard distance transform for a quadtree is defined as the minimum distance in the plane from each BLACK node to the border of a WHiTE node. An algorithm is presented which computes this transform by only examining the BLACK node's adjacent and abutting neighbors and their progeny. However, unlike prior work with quadtrees, computation of the distance transform requires a capability of finding neighbors in the diagonal direction rather than merely in the horizontal and vertical directions. The algorithm's average execution time is proportional to the number of leaf nodes in the quadtree.

Night vision goggle system

Abstract: A night vision goggle system comprising a housing, an optical system accommodated therein and including a pair of eyepiece assemblies, with each assembly slidably mounted for interpupillary adjustment. The assemblies are respectively focusable. The optical system further includes an objective lens assembly, an image intensifier tube provided with concave-faced fiber optics, and a collimator lens assembly, all in axial alignment, and a splitter member. The objective, collimator and eyepiece assemblies feature prescription optics. The goggle system preferably is head mounted via a quick-release connection to a face mask provided with an adjustable strap assembly.

Night vision goggles

Abstract: An optical device suitable for attachment to headgear (13) such as a pilot's helmet, for use as a night vision goggle (11) wherein an image intensifier (19a or 19b) whereby radiation in the visible and/or near infra-red portions of the spectrum received from the scene to be viewed is converted to visible light is arranged so that its input (33a or 33b) and output (21a or 21b) faces are directed respectively away from and towards the scene to be viewed, light from the output face being reflected to the user's eyes by a viewing eyepiece (23a or 23b) which intercepts the user's line of sight, and the received radiation being directed onto the input face by an objective and ray-folding means (27a or 27b; 29a or 29b; 31a or 31b). A design of goggle which is lighter and has a smaller forward projection can be achieved in goggles using such optical devices.

Activity and time budget of Tufted Ducks on Swiss lakes during winter

Abstract: Since the invasion of Lake Neuchtel by Dreissena polymorpha in 1967, the wintering population of Tufted Duck Aythya fuligula has greatly increased. From 1975 to 1979 the author studied the activity and movements of these birds with a telescope and, at night, with a night vision scope, the complete daily activity of the ducks was determined. Feeding occurs mainly during the night, resting during the day. The same result was obtained on Lake Geneva, which is also colonized by D. polymorpha, and on the Niederried reservoir, not yet colonized. On Lake Neuchtel, the feeding area with the least disturbance was occupied first, and had, on the whole, the greatest number of wintering ducks. The movement of ducks towards the other feeding places was caused by night disturbance during the feeding. There were some similarities of behaviour between these and other species of wintering ducks, such as the diurnal resting and nocturnal feeding and the collective restlessness at dusk and dawn. Nocturnal feeding activity was not confirmed as being due to diurnal predation pressure.

Effects of Glare and Background Luminance on Visual Acuity and Contrast Sensitivity: Implications for Driver Night Vision Testing.

Abstract: The visual acuity and contrast sensitivity of two groups of 30 male and female drivers (aged 20-25, 40-45, and 60-65 years) were measured over a range of background luminances and in the presence of glare. Results showed that (1) visual acuity decreased significantly with both increasing age and decreasing background luminance, (2) threshold target luminance increased significantly with age, (3) glare had a multiplicative effect on theshold target luminance that was independent of age, and (4) there were high correlations between vision measures made at "high" and "low" background luminances and under glare. It is concluded that a "nightdriving" vision test could be successfully based upon measurement of visual acuity at low luminance. Whereas the rate at which drivers would fail such a test is dependent upon the acuity required and the definition of "low" luminance chosen, the failure rate would increase significantly with age; this would primarily affect the older portion of the driving population.

Head mounting apparatus

Abstract: Head mounting apparatus which can accommodate different head sizes and shapes comprises a substantially rigid member for supporting equipment, such as night vision equipment, to be used by the wearer, and a flexible member which can flex to adapt to the head of the wearer The rigid and flexible members are connected by pivotal means at pivot positions along spaced pivotal axes The flexible member has buttons for attachment of straps by which it is in use secured to the wearer's head The position of the rigid member relative to the flexible member may be adjustable by manual rotation of knobs

Optical arrangements for Head-up Displays and Night Vision Goggles

Abstract: An optical arrangement suitable for use in night vision goggles and head-up display units comprising an optical projector (19) which forms a real image of optical data (F) to be displayed and an eyepiece (21) comprising a body of light refractive material (55) with input and output surfaces (59 and 63) and a mirror surface (54) angularly mutually so disposed that rays emanating from the real image and entering the body (59) at its input surface (63) are refracted at the input surface (59), totally internally reflected at the output surface (63), reflected at the mirror surface (54) and finally transmitted through the output surface (63) for viewing by an observer. For night vision goggle use the projector provides an image of the forward scene and incorporates an image intensifier (33). Where the observer is required to have a direct view of the forward scene the mirror surface (54) is a partially light-transmissive, partially light reflective surface at the interface between the light refractive body (55) and a second body of light refractive material (57) having an input surface (67) parallel to the output surface (63) of the first-mentioned refractive body (55).

Nighttime Driving and Visual Degradation

Abstract: Recent developments which provide new insights into night driving accidents are reviewed. Selective Degradation: The mechanisms subserving steering are different from those underlying hazard recognition and these two modes of processing visual information are selectively impaired at night. Although it is possible to steer a vehicle as well at night as during the day, the ability to recognize and respond to infrequent hazards is seriously degraded. Night Myopia: Many individuals become nearsighted under reduced illumination. The finding that this is a normal consequence of the passive return of the accommodative system to an intermediate resting posdition has led to a procedure to ameliorate this effect. By determining the value of an individual's dark focus it is possible to provide a special night driving prescription which effectively eliminates night myopia.

Visual Improvements With Red-Tinted Glasses in a Patient With Cone Dystrophy

Abstract: • A patient with cone dystrophy empirically discovered that his vision improved when a red filter was placed in front of his eyes. The present study documents the conditions under which his visual acuity and field improved and shows that the patient's vision is mediated by the night vision photoreceptors, the rods. Increment threshold functions examined the benefits (and limitations) of red glasses to the patient's vision.

Pixel Classification Based on Gray Level and Local ``Busyness''

Abstract: An image can be segmented by classifying its pixels using local properties as features. Two intuitively useful properties are the gray level of the pixel and the ``busyness,'' or gray level fluctuation, measured in its neighborhood. Busyness values tend to be highly vari-able in busy regions; but great improvements in classification accuracy can be obtained by smoothing these values prior to classifying. An alternative possibility is to classify probabilistically and use relaxation to adjust the probabilities.

Effects of approach lighting and variation in visible runway length on perception of approach angle in simulated night landings

Abstract: Previous experiments in this laboratory have demonstrated illusions due to variations in both length and width of runways in nighttime "black hole" approaches. Even though approach lighting is not designed to provide vertical guidance, it is possible that cues from approach lights could interact with cues from runway lighting to reduce illusions due to variation in runway size. Two experiments were conducted to evaluate the effect of approach lighting on perception of approach angle in simulated night approaches. In the first experiment, 40 pilots made simulated visual approaches to a 150- by 6,000-ft runway (45.7-1829 m) with and without a 3,000-ft approach (914 m) light system (ALSF-2). Pilots controlled a moving runway model to produce a constant "normal" angle of approach over the distance range of 23,000 ft (7010 m) to 8,000 ft (2438 m) from threshold. In the second experiment, 24 pilots made simulated approaches to a 150- by 6,000-ft runway which was either fully visible or which had lights of the upwind half occluded. In addition, a 1,400-ft (427 m) abbreviated approach light system (SSALS) was used at three intensities. Decreasing the visible length of the runway by occulting lights of the far half increased mean generated approach angles from 2.2 degrees to 2.7 degrees in agreement with results of a previous experiment involving similar lengths of runways. Neither the presence of equal intensity approach lights nor uncomfortable glare from approach lights 20 times brighter than runway lights had an effect of practical significance on responses. These findings reinforce previous experimental demonstrations of the importance of runway size cues related to varying runway length, and also show that potential size cues provided by approach lights do not prevent illusions due to variations in runway size.

Modified Faceplate for AN/PVS-5 Night Vision Goggles.

Abstract: : Lack of peripheral vision while flying with the AN/PVS-5 night vision goggles (NVG) was a contributing factor in an aircraft accident. Because of this accident, a modified faceplate (MFP) for NVG was configured to allow pilots unaided lateral and lower vision. Twenty MFP NVG were worn during flight by 47 NVG qualified aviators for an average of 18 hours per aviator. The average recorded flight hours for each of the 20 MFG NVG was 43.5 hours. NVG aviators indicated that the MFP significantly enhanced intruder aircraft detection, inside-the-cockpit vision, and comfort. Spectacles can be worn with the MFP, and less fogging of the eyepieces occur. There were deficiencies reported during the study which were corrected with modifications to the mounting apparatus, thorough preflight briefings, and required familiarization flights. The proposed modification is being considered for adoption by the proper authorities. (Author)

Evaluation Of Image Intensifiers

Abstract: The performance of image intensifiers is rated according to their capability of detecting, recognizing, and identifying objects at low light levels The most important characteristics limiting these capabilities are noise and imaging parameters Noise parameters are normally expressed in signal-to-noise ratios, whereas imaging parameters are described by the modulation transfer function and veiling glare This paper will describe the methods used at the Night Vision Laboratory to determine these parameters and report typical results

Feature Analysis For Forward Looking Infrared (FLIR) Target Identification

Abstract: Feature analysis and classifier design toward real-time FLIR target identification are presented. After target candidates of military vehicles are segmented in a low resolution FLIR scenario, 1 a set of 17 features is extracted from these target areas in a single pass. These features consist of two optical intensity features, nine geometry features as well as six texture features. Five types of target candidates are examined in this study. They are tanks, APC's, jeeps, burning hulks, and other nontargets such as noise regions. A simple tree classifier is designed that is based on the manual interpretation of feature distribution among target categories at each nonterminal node of the tree classifier. The approach of feature extraction and classifier design has been applied to FLIR imagery provided by the U.S. Army Night Vision Laboratory and has shown promising results.

Epochal trace elements and evolution.

Abstract: The use of some trace elements by plants and animals during the evolutionary process has resulted in epochal changes. Noteworthy is the fact that plants (but not animals) needed boron in order to grow stems and roots as they left the seas and became anchored on land. Iodine is plentiful in sea water but rare on land. Therefore, the iodination of tyrosine provided an iodine transport mechanism which allowed for the metamorphosis and the development of warm bloodedness-a great evolutionary advantage. Zinc from clay was needed for the formation of the first primitive nucleic acids and, later, the presence of zinc in the retina provide the enhanced night vision of the nocturnal predators-a natural advantage. Hence, boron, iodine and zinc can be termed epochal trace elements. Inquiry should be directed towards the possible roles of other trace elements, which may have been epochal in evolution.

Detection potential of normal observers at visibility conditions prevailing in automobile night driving

Abstract: Laboratory measurements were carried out to determine the detection potential of 25 normal observers engaged in an automobile headlight research programme. An exposure duration was selected to represent search and detection functions of night driving tasks. Target sizes and luminance ranges were chosen to encompass visibility conditions prevailing in automobile night driving. An analytical expression was then derived to yield threshold luminance increments required by normal observers as a function of target size and background luminance.

Long lifetime, low intensity light source for use in nighttime viewing of equipment maps and other writings

Abstract: A long-lifetime light source with sufficiently low intensity to be used for reading a map or other writing at nighttime, while not obscuring the user's normal night vision. This light source includes a diode electrically connected in series with a small power source and a lens properly positioned to focus at least a portion of the light produced by the diode.

Improvements in or relating to head mounting apparatus

Abstract: Head mounting apparatus which can accommodate different head sizes and shapes comprises a substantially rigid member (1) for supporting equipment, such as night vision equipment, to be used by the wearer, and a flexible member (2) which can flex to adapt to the head of the wearer. The rigid and flexible members are connected by pivotal means at pivot positions (8,9) along spaced pivotal axes. The flexible member (2) has buttons (6) for attachment of straps by which it is in use secured to the wearer's head. The position of the rigid member (1) relative to the flexible member (2) is adjustable by manual rotation of knobs (19).

PAVE LOW III: interior lighting reconfiguration for night lighting and night vision goggle compatibility.

Abstract: The PAVE LOW III aircraft is a modified HH-53H helicopter that has a low altitude--below 30.48 m (100 ft)--night/day rescue mission. The desired night flying configuration is for the pilot to wear night vision goggles (NVGs) to fly the aircraft while the copilot, without NVGs, observes the video display and monitors the aircraft instruments. The problems of NVG incompatibility in the cockpit were successfully countered using several light control techniques. The light control modifications were evaluated on the ground in the PAVE LOW III helicopter at Kirtland AFB in April, 1980, by PAVE LOW instructor pilots. The evaluation results were extremely positive. Language: en

A formulation of the transient adaptation mechanisms of automobile night driving

Abstract: An analysis is presented to describe the state of adaptation of the fovea as a result of sudden luminance changes. Extensive use is made of data found in the literature that relate observer response to luminance changes in order to validate the formulation as well as to quantify some parameters associated with the derivation. Downward and upward transitions are treated in a similar manner. The results are intended for application in automobile headlight visibility studies concerned with calculating the state of adaptation of drivers exposed to transient levels of opposing glare.

Night Vision Electro-Optics technology transfer: A decade of activity

Abstract: The US Army’s Night Vision and Electro-Optics Laboratory, Fort Belvoir, Virginia, has for the past decade encouraged the transfer of its unique technology into the non-military community. Our scientists and engineers have developed a wide spectrum of devices that provide the military forces with such benefits as being able to “see” at night without being detected, the ability to accurately determine ranges and to designate targets. Although our objective has been to develop devices to enhance the combat effectiveness of the US Army, many of these night vision and electro-optical devices have a great potential for serving useful functions in the non-military community. Therefore, the technology behind these devices which are not classified may, as the need dictates, be transitioned into the private sector through technology transfer. It is the intent of this paper to provide an introduction to the nature of this technology and to illustrate by high-lighting selected spinoffs, the many uses of night vision and electro-optics which have been adapted by the non-military community.

Evolution Of Forward Looking Infrared

Abstract: The Vietnam War surfaced an important fact: The ability to see at night as effectively as during the day is indispensable. During the conflict, the Army fielded the first generation image-intensified tube systems. These systems added a new dimension to the tactics of land warfare. Taking the night away from the Vietcong was the goal during the late sixties and the early seventies, and it was attacked with ingenuity, enthusiasm, and a sub-stantial number of research and development contracts to U.S. industry.© (1982) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Visual perception in vertebrates depends on synergistic and antagonistic interactions of retinal receptors

Abstract: Publisher Summary This chapter examines the dependence of visual perception on synergistic and antagonistic interactions of retinal receptors in vertebrates. Visual perception is based on differential stimulation of adjacent retinal areas. The following are the three categories of differential stimulus conditions: (1) same spectral composition, different stimulus intensity, (2) different spectral composition, same stimulus intensity, and (3) different spectral composition, different stimulus intensity. Both the spectral composition and stimulus intensity are signaled to the central nervous system (CNS) via discrete pathways, that is, the color and luminance channels. Night vision is based solely on the synergistic action of rods that convey a signal to the CNS via the luminance channels. During day-vision, however, these channels are supplied by synergistically acting cones. In either case, excitatory or inhibitory effects are summed. Colour vision, however, is based on antagonism, that is, the summation of excitatory and inhibitory effects from different classes of cones. The chapter presents a study on the relative contribution of rods and cones to the spectral sensitivity in different vertebrate species. The following two following methods with reference to wild rabbits' vision were used in the study: (1) the spectral sensitivity of wild rabbits determined by ERG-null-detection and (2) the spectral sensitivity of wild rabbits determined using an increment threshold method Increment threshold experiments were carried out to investigate the nature of rabbits color vision. It was found that when background intensity was low, the spectral sensitivity was dominated by the excitatory input from the 498 system, whereas with high background intensity, the inhibitory input from the 523 system and the excitatory input from the 425 system were predominant.

Establishment Of System Design Requirements Of The DIVAD Visual Fire Control Optics

Abstract: The develornent of the specified optical system parameters is followed ^ron initial constraints, retire­ ments, and scenarios. The process includes consultina with the optical designers to keep the desion practical and performing analyses to define the system confiouration, such as apportioning apertures and spectral bands. Ihe fire control system consists of two. sightinq systems, a search sensor called the Squad Leader's Periscope and a tracking system with -integral laser range finder called the Gunner's Sight. Roth systems are stabilized and have a night vision capability.BackgroundThe DIVAD competition for a mobile armored gun system began in early 1978. By summer of 1930, both competitors had fielded two prototypes. Figure I is a nhoto of the winninrr Ford Aerospace system whlnh is now called the 40mm. DIVAD Gun. The sightline stabilization units were fabricated by F^CC; the laser ran^e- finder was sunnlied by ^ughes Aircraft by modification of an existing system design, and Koll^oraen Corporation designed and fabricated two new separate telescope configurations. All of -the subsystems were specified by FACC to meet the aeneralized reouirements of the contract specifications and scenario implica­ tions. Figure 2 shows the assembled gunsight consisting of a stabilized sight unit (SSU) , the telescope and components of the range finder. Other features include a niaht vision system., a set of projected cues, protection against battlefield lasers and automatic solar protection. A second subsystem used by the squad leader is a panoramic periscope. It is an independent surveillance and acquisition system. Due to its similiarity to the gunsight, it is omitted from further consideration.Figure 1. The 40mm DIVAD gun on the move Figure 2. The contnlete nunsiqht is comprised of the telescope, the laser rangefinder and the stabilized sicrhtIntroductionA brief look is taken at the specification process bv which desiqn reouirenents are formalized and trans­ mitted. This is followed by examples of specific design concerns relative to a visual fire control system. System models and trade studies are presented jcor these concerns.The specification processFigure 3 presents two (2) views that one night hold about the process of generating the design requirements of a system for the fabricator of the syste . In the simple view, the contract requirements ^low down via a specification to a fabricator. In the more complex view, contract reouirements are transformed into a form applicable to the needs of the fabricator. v*io r^ay actually possess the d'esicn knowledge. The system spec­ ifier, typically a systems engineer, identifies constraints, discovers or determines relevant relationships and interfaces, applies his suspicions from ^revious experience and performs the appropriate trade studies using existing or invented models to set the required system design parameters. He ^ust have some sense of the applicable physical laws and have a sense of what can be achieved, such as can a laser share the aperture or how does magnification effect various telescope parameters. After the preliminary specification is set,

Device for detecting hot spots in the dark and procedure for night vision using this device.

Abstract: The invention relates to a device for detecting hot spots in the dark This device includes: - an infrared-ray detector emitting a signal when the variation in amplitude of the light waves which it receives exceeds a certain threshold; - downstream of the detector, a device for amplifying and interpreting the signals emitted by the detector and - upstream of the detector, a focusing device at the focal point of which is placed a modulator intended to isolate the characteristic frequencies of the hot spots Application for the detection of the presence of objects, for example of vehicles, in the dark