Showing papers on "Night vision published in 1993"

Practical Applications of Infrared Thermal Sensing and Imaging Equipment

Abstract: Part 1 Basics and Instrument Overview: Basics of Noncontact Thermal Measurements Matching the Instrument to the Application Instruments Overview Using IR Sensing and Imaging Instruments. Part 2 Instrument Applications: Introduction to Applications Plant Condition Monitoring Buildings and Infrastructure Materials Testing Product and Process Monitoring and Control Night Vision, Security and Surveillance Appendix A - Commercial Instrument Performance Characteristics Appendix B - List of Manufacturers Appendix C - Generic Emmisivities of Materials.

Dominant Retinitis Pigmentosa Associated With Two Rhodopsin Gene Mutations: Leu-40-Arg and an Insertion Disrupting the 5′-Splice Junction of Exon 5

Abstract: Objective: To determine the phenotypes of two families in which retinitis pigmentosa cosegregates with a rhodopsin ( RHO ) gene mutation: a leucine-to-arginine change at codon 40 (Leu-40-Arg) in one family, and a 150-base pair insertion that disrupts the RHO 5′-splice junction of exon 5 in another. Patients: Three affected members of each family. Results: The Leu-40-Arg mutation was associated with the onset of night blindness in the first decade of life. By the fourth decade, severe retinal functional loss was evident on dark-adapted static threshold perimetry, and electroretinographic responses were absent or barely detectable. In contrast, the RHO 150-base pair insertion was associated with the later onset of mild night vision difficulties; in two individuals, mild night vision difficulties were first noticed in the second decade while a third, a 25-year-old woman, was asymptomatic. Dark-adapted static threshold perimetry of this latter individual revealed a "regional" or class 2 pattern of retinal functional loss associated with equal loss of rod and cone electroretinographic responses. Conclusion: The RHO Leu-40-Arg mutation causes symptomatic retinal dysfunction by the end of the first decade while the insertion disrupting the 5′-splice junction of RHO exon 5 causes later onset "regional" or class 2 retinal dysfunction.

Individual beacon identification system

Abstract: A compact beacon-detector type IFF system to be carried by individual soldiers. The system consists of a beacon and a special purpose detector. The beacon is a small, light-weight, battery powered device that is worn on the soldier's web gear. The detector consists of a small flashlight-like device that can be hand held or mounted on a weapon, similar to a rifle scope. The beacon's signal is not visible to those using existing night vision equipment nor is it otherwise exploitable by a potential adversary. The system achieves its covertness through the selection of the optical wavelength used by the beacon. Further signature reduction is achieved through the use of a Low Probability of Intercept ("LPI") spread spectrum waveform as the beacon output. This waveform utilizes a spreading code to encode the beacon output signal. Even if an enemy has a sensor capable of detecting the proper optical wavelength, it would not be able to detect or emulate the beacon's signal without prior knowledge of the specific spreading code used. The detector of the present invention is designed to despread the beacon output waveform, allowing the signal to be detected. This spread/despread code can be changed as frequently as required, so that capture of the beacon or detector would not be a serious risk to compromising the system.

Flip-up mount for night vision system

Abstract: A flip-up mount is provided for a night vision system. The mount comprises a carriage (22) which is configured to engage a coupling device (18) provided on the night vision system and secure the system in place. A pivotal armature (30) is attached to the carriage and extends from a pivot axis. The armature pivots between a first operational position enabling an operator to use the system, and a second stowed position. An anchor (76, 78) secures the pivot point to a helmet worn by the operator of the system. The pivot point further comprises a brace (70) having an axle shaft (62), a sleeve (42) integral to the armature and rotatable about the shaft, and a spring biased locking member (56) securing the sleeve in a selected one of the first and the second positions. A supplemental chin strap (140) is provided.

The Infrared & Electro-Optical Systems Handbook. Passive Ellectro-Optical Systems, Volume 5,

Abstract: : The Infrared and Electro-Optical Systems Handbook is a joint product of the Infrared Information Analysis Center (IRIA) and the International Society for Optical Engineering (SPIE). Sponsored by the Defense Technical Information Center (DTIC), this work is an outgrowth of its predecessor, The Infrared Handbook, published in 1978. The circulation of nearly 20,000 copies is adequate testimony to its wide acceptance in the electro-optics and infrared communities. The Infrared Handbook was itself preceded by The Handbook of Military Infrared Technology. Since its original inception, new topics and technologies have emerged for which little or no reference material exists. This work is intended to update and complement the current Infrared Handbook by revision, addition of new materials, and reformatting to increase its utility. Of necessity, some material from the current book was reproduced as is, having been adjudged as being current and adequate. The 45 chapters represent most subject areas of current activity in the military, aerospace, and civilian communities and contain material that has rarely appeared so extensively in the open literature. Because the contents are in part derivatives of advanced military technology, it seemed reasonable to categorize those chapters dealing with systems in analogy to the specialty groups comprising the annual Infrared Information Symposia (IRIS), a Department of Defense (DoD) sponsored forum administered by the Infrared Information Analysis Center of the Environmental Research Institute of Michigan (ERIM); thus, the presence of chapters on active, passive, and countermeasure systems. It is organized into eight volumes. Volume 6, edited by Clifton Fox of the Night Vision and Electronic Sensors Directorate, treats active systems and includes mostly new material on laser radar, laser rangefinders, millimeter-wave systems, and fiber optic systems.

Night vision goggle mount

Abstract: A helmet mount (10) for night vision goggles (12) is disclosed that is formed with a rear clamp (24), front clamp (16), a strap (20) disposed between the front and rear clamps (16, 24), and a goggle mounting structure (14). The goggle mounting structure (14) secures the night vision goggles (12) to the helmet mount (10) and allows the goggles (12) to be placed in a stowed position when not in use and a line-of-sight position when a used. Additionally, the goggle mounting structure (14) has power activator (58, 60, 62, 64) that automatically deactivates the power when the goggles are not in use and activates the power when the goggles are in use. The helmet mount (10) has adapters (80, 86) that allow the mount to be used with various types of night vision goggles.

Multi-focal contact lens

Abstract: A tool for forming a soft contact lens having an optical zone formed with a center spherical surface and surrounding aspheric surfaces is disclosed. The tool includes a lens holder having a perfectly centered rearwardly extending cylindrical portion received in a collet of a lens cutting lathe and a transverse front end wall defining a front end opening receiving the lens blank body projecting forwardly through the opening. The lens blank is formed with a mounting flange seated against a rear facing step in the transverse end wall. The lens body is retained in the holder with an insert threadedly received in the holder. A set screw received in the insert applies pressure to the lens blank rear surface to deform the front concave surface which has been previously cut and polished to a spherical surface. The deformed front concave surface is re-cut into spherical shape in at least preselected portions of the front surface so that, upon release of squeezing pressure, the preselected portions of the front surface are aspheric to define portions of the optical zone having continuously variable optical powers. The center of the optical zone preferably remains spherical for improved night vision.

Helmet mounting for night vision assembly

Abstract: The present invention is a mounting assembly for mounting a night vision apparatus onto a standard army issue helmet. The present invention includes a support member for retaining the night vision apparatus and a clamping assembly used to join the support member to the helmet. The clamping assembly is removably attachable to a standard army issue helmet above the eyes of the wearer. The support member is pivotably connected to the clamping assembly in a manner that enables the support member to be pivotably rotated about the clamping assembly between an operational position and a stowed position. At the operational position, the support member retains the night vision apparatus in front of the eyes of the wearer. At the stowed position, the night vision apparatus is "flipped up" to a position above the field of view of the wearer, where the night vision apparatus can be retained until again needed. A moveable magnet and an associated reed switch serves to deactivate the night vision device in the stowed position and enable activation of the night vision device in the operational position.

Night vision goggle headgear mount

Abstract: A headgear mount (10) for night vision goggles (12) is disclosed. The headgear mount (10) is formed with a goggle mounting structure (14) secured to a mounting block (16). Mounting block (16) is secured to frame (22) that is secured to the front portion of the user's cranium by straps (28, 32, 38, 52, 54). Goggle mounting structure (14) allows the goggles (12) to rotate between a line-of-sight position when in use and a stowed position when not in use. A magnet means formed by two magnet positioners (72, 74) and two magnets (74, 76) adjust the power switch of goggles (12) so that the goggles (12) receive power in the line-of-sight position and do not receive power when in the stowed position. Headgear mount (10) has adapters (98, 104) that allow headgear mount (10) to be used with various types of night vision goggles.

Head-mounted flip-up night vision device with automatic turn-off upon flip-up

Abstract: A night vision device (12) with improved user safety includes a head gear support structure (16) which suspends a night vision viewer (32) relative to the head and eyes of the user. The head gear includes a flip up mount (26) allowing the user to flip the night vision viewer (32) up and out of the user's line of sight for an unobstructed natural view of the environment. In order both to save battery power, and to prevent the user from inadvertently revealing his position by forgetting to turn off the night vision viewer before flipping it up, the support structure (16) includes a magnetic flux source (1021) cooperable with a magnetically-responsive switch (401) of the night vision viewer to maintain the viewer turned on only when the viewer (32) is in its use position. When the viewer is flipped toward its upward position, the switch of the viewer is carried out of magnetic association with the flux source (1021) so that the viewer shuts off. Because the viewer remains mounted on the flip up mount during these series of events allowing the user an unobstructed view of the environment, the viewer is immediately available to be flipped downwardly to its use position back into operative association at its switch with the flux source, and to be turned on again for night vision viewing.

Universal adapter for night vision system

Abstract: An adapter (70) is provided for enabling the use of night vision goggles (50) having a plug-type mounting connector (58) and a spring biased latch (62), with a head mounting assembly having a plate-type receiving carriage (28). The adapter (70) comprises a housing having a plug-type receptacle which is configured to receive the plug-type mounting connector (58) and a bar capable of engaging the latch (62). The adapter (70) also comprises a mounting plate which is integrally formed to the housing and configured to engage the plate-type receiving carriage (28). The plug-type mounting connector (58) is secured within the plug-type receptacle by an engagement between the latch (62) and the bar. The plug-type mounting connector (58) is capable of selective disengagement from the plug-type receptacle by manual manipulation of the latch (62).

Portable monocular night vision apparatus

Abstract: A monocular night vision apparatus employing an infrared energy spectrum source of illumination and a camera lens and night vision image intensifier combined receiver apparatus into a small hand-held portable package that is both low in cost and reliable in nature is described The night vision transmitter apparatus includes a laser diode energy source that is coupled to an aperture controlled and focus controlled optical system and driven by an electronic closed-loop feedback energization circuit which employs self-contained battery sources of energy Multiple operating modes and operating intensities of the light source are provided through a plurality of signal inputs to the closed feedback loop of the laser diode energy source Disturbance of the closed feedback loop by reflected energy within the optical transmitter apparatus is precluded by the use of feedback prevention optical alignment in the transmitter's optical system

Night vision goggle aided flight simulation system and method

Abstract: A night vision goggle aided flight simulation system and technique allows an flight simulator operator wearing night vision goggles to view an approximate simulation of night vision goggle aided flight. A processor generates at least one look-up table of brightness values utilizing database sources including any selected options. A scene generation computer will then generate the scene image with the contrast based on values provided by the look-up table. An image display system displays the scene at light levels with sufficient dynamic range so that approximate simulation of night vision goggle aided flight is achieved. A neutral density filter can be placed over a CRT display if the CRT display as the display system cannot produce sufficient dynamic range.

Helmet visor adaptor assembly

Abstract: A visor adaptor assembly for use in conjunction with an aviator's helmet pted for supporting a helmet sighting system and night vision enhancement device. A support with vertical slot is adaptable to be mounted on a helmet and further includes a connector partially projecting through the slot with a connector extension coupled to the connector. A visor extension is connected to the connector which is coupled to an aviator's visor and a position adjustment nut is releasably coupled to the connector extension. Manual adjustment of the nut along the vertical slot adjusts the aviator's visor vertically within the support.

Spatial Contrast Sensitivity through Aviator's Night Vision Imaging System

Abstract: Visual acuity is often used to assess vision through image intensifying devices such as night vision goggles (NVG's). Fewer attempts have been made to measure contrast sensitivity through NVG's. Such information would be useful to better understand contrast processing through NVG's under various stimulus conditions. In this study, computer-generated letter charts were used to measure contrast sensitivity through third generation NVG's for a range of letter sizes. The red phosphor of a standard color monitor proved to be an effective stimulus for third generation devices. Different night sky conditions were simulated over a 3 log unit range. The results illustrate the profile of contrast sensitivity through third generation NVG's over a range of night sky conditions. Comparison of measurements through NVG's to measurements obtained without the device but at the same luminance and color distinguish between effects of luminance and noise on contrast sensitivity.

Influence of truck driver eye position on effectiveness of retroreflective traffic signs

Abstract: This study evaluated the relative amount of light reaching drivers of different types of vehicles by using survey data collected in 1989 by the Transport and Road Research Laboratory (TRRL) in England. The TRRL data included driver eye heights and headlamp mounting heights for 445 vehicles. This analysis considered three sign locations on a straight roadway: left shoulder, center, and right shoulder. Two viewing distances were included: 152 m (500 feet) (typical of a sign-legibility distance), and 305 m (1000 feet) (typical of a sign-detection distance). The analysis considered both the differential amount of illumination impinging on the signs from headlamps of trucks and cars, as well as the differential amount of the light reflected from the signs in the direction of truck drivers and car drivers. Results imply that the increased eye height of truck drivers could have a major effect on the legibility of retroreflective traffic signs, but only a modest effect on their detection.

Pocket laser communicator and illuminator

Abstract: A method of providing near simultaneous night vision and communication including directing a narrow voice modulated IR laser beam at a distant receiver/demodulator during communication periods, causing the IR laser beam to diverge substantially during scene viewing periods, other than the data communication periods, for illuminating a darkened scene which includes the laser beam receiver, and viewing the darkened scene with an IR viewing device

Consumer night vision viewing apparatus

Abstract: A night vision goggle device is fabricated for consumer use. The device employs interpupillary and diopter adjustments for each eye of the user. The combined adjustment mechanism incorporates manually operable control knobs located on the housing and one knob for each of the eye pieces. Each control knob is capable of moving both in a forward and rear mode and in a transverse mode. The knob can provide diopter focus adjustment for a front to back motion and for lateral movement or transverse movement the control provides for interpupillary adjustment. The movement of the knob and the removal of pressure or force from the knob enables the optical assemblies to be locked in position by a friction fit.

All terrain ground collision avoidance and maneuvering terrain following for automated low level night attack

Abstract: The development of an all-terrain ground collision avoidance system (GCAS) in conjunction with a maneuvering terrain-following (TF) system is discussed. Both systems use a digital terrain database. These systems are presented concurrently because of their complementary mission role. The unprecedented pilot interaction available with the automatic systems provides a means to improve combat survivability significantly. The pilot is able to execute high rate turns, evasive maneuvers, and inverted ridge crossings while following the terrain contour. Safety is maintained in day, night and weather by the GCAS. The combination of these systems with an automated attack system, automatic target handoff system, night vision system, and a route planner to provide a lethal night attack capability is examined. Piloted simulation and preliminary flight test results are presented. >

Backlight for a liquid crystal display

Abstract: A backlight system for a liquid crystal device display is equipped with a dual lighting system for day viewing and compatible with night vision systems. The day lighting system uses conventional fluorescent or incandescent lamps (42) for full color display during daytime use. The night lighting system uses a light source (50) which is either filtered to remove infrared and near infrared wavelengths or which is chosen from a class of sources which does not emit such wavelengths. The night lighting source (50) is situated adjacent the edge of a transparent block (46) which directs light to the liquid crystal display (60). The day lighting source (42) may be situated at the edge of the block (46) or behind it. The day lighting system is disabled while the night system is in use.

Programmable airdrop infrared decoy

Abstract: A battery powered self-contained source of infrared or other optical spectrum emission is disclosed. The emission source is provided with airdrop and other dispersal arrangements and is disposed in the form of an enclosed spherical or other housing which includes adjustment ports, adjusting tools, and tether cord attachment devices. The optical emission output of the disclosed source is adjustable as to flash duration and between-flash delay. In decoy device use the source is intended for multiple source deployments in a combat zone where the device output is collectively construable as a multiplicity of human originated emission events of random infrared energy pulses and is thereby capable of deceiving a night vision apparatus equipped enemy. Other uses of the invention including terrain marking and personnel location identification are also disclosed.

Night vision device with improved image stability

Abstract: An ANVIS 6 type of binocular night vision device includes a pair of night vision monocular scopes which adjustably depend from a support frame in front of a user's eyes. The support frame includes an interpupillary distance adjustment mechanism which allows placement of the monocular scopes to better achieve binocular vision with depth perception. The image quality of binocular vision afforded by the device is improved and made more durable by providing the monocular scope mounts with a dirt-shedding dry threaded engagement with their respective interpupillary adjustment shafts, as well as providing a laterally extended threaded engagement of these mounts with the adjustment shafts. As a result, wobble of the monocular scope mounts relative to the frame is significantly reduced, and wear of the component parts which over time contributes to increased wobble is also reduced.

Standard NETD test procedure for FLIR systems with video outputs

Abstract: The noise equivalent temperature difference (NETD) of forward looking infrared (FLIR) systems is a widely used performance parameter that characterizes the sensitivity of thermal imaging sensors. Although this parameter has been used for many years, there has always been some confusion and misunderstanding about how to measure it. Differences in opinion on how this measurement should be made can cause substantial variations in reported values of NETD measurements. It is the intent of this paper to clearly describe the measurement technique used at Night Vision and Electronic Sensors Directorate (NVESD).

Point Probe Decision Trees for Geometric Concept Classes

Abstract: A fundamental problem in model-based computer vision is that of identifying to which of a given set of concept classes of geometric models an observed model belongs. Considering a “probe” to be an oracle that tells whether or not the observed model is present at a given point in an image, we study the problem of computing efficient strategies (“decision trees”) for probing an image, with the goal to minimize the number of probes necessary (in the worst case) to determine in which class the observed model belongs. We prove a hardness result and give strategies that obtain decision trees whose height is within a log factor of optimal.

Excimer laser keratectomy for the correction of myopia

Abstract: We present the preliminary refractive and visual results in 46 sighted eyes that had undergone excimer photorefractive keratectomy. Although our sample size was small and the follow-up relatively limited (3-6 months), a few important conclusions were drawn. The visual and refractive results compare quite favorably to the preliminary results with radial keratotomy. Thirty-four of 46 patients (74%) were within 1 D of emmetropia; and 45 (98%) were within 2 D at the end of the follow-up period. Forty-four patients (96%) achieved at least 20/40 vision, with more than half achieving 20/20 or better. We encountered no significant vision threatening complications. Twenty of 46 patients (43%) complained of night vision disturbances, but symptoms improved in all patients by 6 months. The majority of patients developed trace epithelial haze; however, corneal haze did not produce reductions in visual acuity. Though the preliminary results of our study of the safety and efficacy of excimer photorefractive keratectomy are promising, further study of long-term vision stability and corneal clarity is clearly needed.

Night vision compatible color correction system

Abstract: An apparatus for achieving an active matrix liquid crystal display flat panel that optically eliminates bluish or purplish background luminance and fluorescence of the liquid crystal materials. Two polarized layers are placed in a crossed configuration one behind and one in front of an active glass thin film transistor (TFT) layer to block a majority of any background luminance. Two layers of tinted glass are further placed one behind and one in front of the active glass TFT layer to block any remaining background luminance which has leaked through the polarizing layers.

Vernier acuity through night vision goggles.

Abstract: : Night vision goggles (NVG) are being used increasingly in military and civilian environments. Despite the use of these devices, relatively few tests exist to assess visual performance through NVGs. Hyperacuity tasks may provide a sensitive index of performance through night vision devices. In this study, grating vernier acuity was measured through NVGs. As reported previously, a power law relation was observed between vernier acuity and stimulus contrast. Comparison of vernier acuity with and without NVGs indicated that performance is limited by the contrast transfer of the device. Vernier acuity measurements can be used to assess the quality of vision and quantity of contrast transferred through night vision devices. Night vision goggles, Image intensifiers, Vernier acuity, Contrast sensitivity.

Night vision device

Abstract: A binocular night vision device includes a pair of night vision monocular scopes which adjustably depend from a support frame in front of a user's eyes. The support frame includes an interpupillary distance adjustment mechanism which allows non symmetrical placement of the monocular scopes to better achieve binocular vision with depth perception. Also, the adjustment mechanism allows adaptive duplicative use of identically the same component parts of the device on both the left and right sides of the support frame so that the number of different parts required for the device is reduced.

Night vision goggles resolution performance at low contrast levels

Abstract: NVG (Night Vision Goggle) resolution performance data is usually given as measured against high contrast, black and white, targets. When NVGs are used as night vision aids for visual night flight, the scene viewed by the pilot is in most cases dominated by low contrast. Therefore, NVG performance at low contrast levels is more relevant to the piloting task than NVG resolution at high contrast levels. A set of resolution targets with different contrast levels was designed and ground tests performed at various light levels outdoors at night. The results showed a marked loss of resolution at lower contrast levels. The presentation will describe the test method, give the results and discuss how the results may be explained. A method for using the test results as the basis for correlating piloting performance to light levels will be presented.