Showing papers on "Night vision published in 1997"

Computer Vision and Image Processing: A Practical Approach Using CVIPTools

Abstract: I. COMPUTER VISION AND IMAGE PROCESSING FUNDAMENTALS. 1. Introduction to Computer Vision and Image Processing. Overview: Computer Imaging. Computer Vision. Image Processing. Computer Imaging Systems. The CVIPtools Software. Human Visual Perception. Image Representation. Digital Image File Formats. References. 2. Image Analysis. Introduction. Preprocessing. Edge/Line Detection. Segmentation. Discrete Transforms. Feature Extraction and Analysis. References. 3. Image Restoration. Introduction. Noise. Noise Removal Using Spatial Filters. Frequency Domain Filters. Geometric Transforms. References. 4. Image Enhancement. Introduction. Gray-Scale Modification. Image Sharpening. Image Smoothing. References. 5. Image Compression. Introduction. Lossless Compression Methods. Lossy Compression Methods. References. II. CVIPtools. 6. Using CVIPtools. Introduction and Overview. The Graphical User Interface. Examples. 7. CVIPtools Applications. Introduction. Automatic Skin Tumor Border Identification. Helicopter Image Enhancement and Analysis. Wavelet/Vector Quantization Compression. Image Segmentation Using a Deformable Template Algorithm. Visual Acuity/Night Vision Simulation. 8. Programming with CVIPtools. Introduction to CVIPlab. CVIP Laboratory Exercises. The CVIPtcl and CVIPwish Shells. 9. CVIPtools Library Functions. Introduction. Arithmetic and Logic Library_libarithlogic. Band Image Library_libband. Color Image Library_libcolor. Compression Library_libcompress. Conversion Library_libconverter. Display Library_libdisplay. Feature Extraction Library_libfeature. Geometry Library_libgeometry. Histogram Library_libhisto. Image Library_libimage. Data Mapping Library_libmap. Morphological Library_libmorph. Noise Library_libnoise. Segmentation Library_libsegment. Spatial Filter Library_libspatialfilter. Transform Library_libtransform. III. APPENDICES. A. The CVIPtools CD-ROM. B. Setting Up and Updating Your CVIPtools Environment. Getting CVIPtools software updates. To get via the WWW. C. CVIPtools Functions. Toolkit Libraries. Toolbox Libraries. D. CVIPtcl Command List and Corresponding CVIPtools Functions. E. CVIPtcl Function Usage Notes. F. CVIP Resources. Index.

The costs of becoming nocturnal: feeding efficiency in relation to light intensity in juvenile Atlantic Salmon

Abstract: 1. Most animals are active by day or by night, but not both; juvenile salmonids are unusual in that they switch from being predominantly diurnal for most of the year to being nocturnal in winter. They are visual foragers, and adaptations for high visual acuity at daytime light intensities are generally incompatible with sensitive night vision. Here we test whether juvenile Atlantic Salmon Salmo salar are able to maintain their efficiency of prey capture when switching between diurnal and nocturnal foraging. 2. By testing the ability of the fish to acquire drifting food items under a range of manipulated light intensities, we show that the foraging efficiency of juvenile salmon is high at light intensities down to those equivalent to dawn or dusk, but drops markedly at lower levels of illumination: even under the best night condition (full moon and clear sky), the feeding efficiency is only 35% of their diurnal efficiency, and fish will usually be feeding at less than 10% (whenever the moon is not full, skies are overcast or when in the shade of bankside trees). Fish were unable to feed on drifting prey when in complete darkness. 3. The ability of juvenile salmon to detect prey under different light intensities is similar to that of other planktivorous or drift-feeding species of fish; they thus appear to have no special adaptations for nocturnal foraging. 4. While winter drift abundance is slightly higher by night than by day, the difference is not enough to compensate for the loss in foraging efficiency. We suggest that juvenile salmon can nonetheless switch to nocturnal foraging in winter because their food requirements are low, many individuals adopting a strategy in which intake is suppressed to the minimum that ensures survival.

Part task investigation of multispectral image fusion using gray scale and synthetic color night vision sensor imagery for helicopter pilotage

Abstract: Today, night vision sensor and display systems used in the pilotage or navigation of military helicopters are either long wave IR thermal sensors (8 - 12 microns) or image intensified, visible and near IR (0.6 - 0.9 microns), sensors. The sensor imagery is displayed using a monochrome phosphor on a Cathode Ray Tube or night vision goggle. Currently, there is no fielded capability to combine the best attributes of the emissive radiation sensed by the thermal sensor and the reflected radiation sensed by the image intensified sensor into a single fused image. However, recent advances in signal processing have permitted the real time image fusion and display of multispectral sensors in either monochrome or synthetic chromatic form. The merits of such signal processing is explored. A part task simulation using a desktop computer, video playback unit, and a biocular head mounted display was conducted. Response time and accuracy measures of test subject responses to visual perception tasks were taken. Subjective ratings were collected to determine levels of pilot acceptance. In general, fusion based formats resulted in better subject performance. The benefits of integrating synthetic color to fused imagery, however, is dependent on the color algorithm used, the visual task performed, and scene content.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Helmet mount for night vision goggle

Abstract: A flip-up helmet mount for a night vision device is disclosed. The flip-up helmet mount includes a position adjustment assembly for adjusting the position of the night vision device between a use and a stowed position, a tilt adjustment assembly for adjusting the tilt angle of the night vision device relative to a user's eyes, and a focal adjustment assembly for adjusting the focus or location of the night vision device relative to the user's eyes. The assemblies provided for position, tilt, and focus adjustment all permit one-handed adjustment of these features of the flip-up helmet mount. Additionally, the flip-up helmet mount includes an improved automatic shutdown assembly that provides reliable shutdown of the night vision device when not in the use position.

Fabrication of semiconducting YBaCuO surface-micromachined bolometer arrays

Abstract: Thermal infrared detectors require thermal isolation to permit the infrared-sensitive material to integrate the incident photon energy and thereby obtain high responsivity and detectivity. This paper describes the fabrication of semiconducting YBaCuO microbolometer arrays into thermal isolation structures by employing Si surface-micromachining techniques. An isotropic HF:HNO/sub 3/ etch was used to remove the underlying Si substrate from the front-side of the wafer and suspend SiO/sub 2/ membranes into 1/spl times/10 pixel-array structures. The infrared-sensitive material, YBaCuO, was subsequently deposited onto the thermal isolation structures and patterned to form the detector arrays. The high-temperature coefficient of resistance and low noise of semiconducting YBaCuO at room temperature is attractive for uncooled infrared detection. The fabrication process was conducted entirely at room temperature. In this manner, infrared detectors are fabricated in a process that is compatible with CMOS technology to allow for the integration with on-chip signal processing circuitry. The end result is low-cost infrared-detector arrays for night vision in a variety of applications including transportation and security. Preliminary results show a temperature coefficient of resistance above 3%, voltage responsivity close to 10/sup 4/ V/W, and detectivity over 10/sup 7/ cm/spl middot/Hz/sup 1/2//W at a bias current of 0.79 /spl mu/A.

Far/near infrared adapted pyramid-based fusion for automotive night vision

Abstract: We discuss the fusion of far infrared (FIR) and near infrared (NIR) image data for an improved automotive night vision device. The two wavebands have differing characteristics when using cameras sensitive to these wavelengths in the automotive environment. It is the aim of our work to fuse the information from these two sensor types to optimize the benefits of both wavebands. The choice of NIR radiation for an automotive night vision system with active illumination has been determined by one automotive manufacturer as the most suitable waveband for a single sensor night vision device. FIR radiation was chosen as a second waveband for fusion because sensors operating at these wavelengths detect passive radiation from objects at temperatures of approximately 300 K. Therefore, in principle, it should be possible to image to the horizon on a dry and humidity free night, and to provide clear images of hot bodies such as pedestrians and vehicles in use. We have chosen pyramid based techniques to fuse the two image types as they allow maximum flexibility, are relatively simple, and computationally efficient. We have adapted pyramid methods to suit our requirements. We demonstrate improved fusion for our particular application.

High myopia anterior chamber lens with anti-glare mask

Abstract: A two-piece anterior chamber artificial intraocular lens (1) for treating high myopia conditions by implantation in an eye after extracapsular removal of the natural eye lens, is disclosed The lens includes a lens body or optic (2), and a separate ring shaped tension frame (12) therefor, containing light masking means for inhibiting light rays directed toward the outer edge portions of the lens body from being scattered thereby toward the retina after the assembled lens has been inserted into the eye The lens body or optic (2) is generally smaller than the diameter of a pupil dilated for night vision, and is surrounded by a snugly fitting annular opaque or semi-opaque ring or frame (12) having a C-shaped cross section (12'), and a peripherally extending fin (12') of the same material The fin (12') is preferably formed of flexible material which is bent during insertion to allow insertion of the two-piece assembly through a minimal size corneal incision The lens (1) is also provided with position fixation means, such as haptic (3, 4), which are integrally formed with the lens body (2), and extend outward in the generally horizontal plane of the lens body for seating the lens in the eye The ring shaped frame (12) is preferably mated with the lens during manufacturing

NVG-compatible AMLCD backlight having a ridged prismatic TIR with an embedded diffuser doped with an IR absorbing dye

Abstract: An improved night vision goggle (NVG) compatible backlight for a liquid crystal display (LCD) and active matrix liquid crystal display (AMLCD) and other types of backlit displays is disclosed. The backlight includes a ridged prismatic TIR with an embedded diffuser layer doped with an infrared (IR) absorbing dye (57), a ridged prismatic TIR without diffuser layer (59) an infrared rejecting filter layer (63), and either a holographic diffuser layer or a lenticular lens array layer (65), or a fresnel wedge layer (67).

Effects of sleep deprivation with reference to military operations.

Abstract: This review discusses the need for sleep, effects of sleep deprivation on behaviour and performance in the military, and sleep management recommendations to optimise combat effectiveness. Most people, regardless of sex or race, prefer 7 to 8 hours of sleep each night. Sleeping during the day is less recuperative. Continuous sleep is more effective than multiple short naps-even when the total hours for naps is more. Ten to 20 minute naps are useful when continuous sleep is not possible. Sleep inertia is the 5 to 30 minute period of sluggishness after awakening and important military tasks should be avoided. Previously, continuous work episodes (CWEs) duration was restricted by limited night vision, unreliable equipment and reduced endurance of military personnel. With improved technology, CWEs are now restricted primarily by endurance which is affected by sleep deprivation. This was one of the experiences noted in recent conflicts (e.g. Desert Storm) by personnel in the air force, army and navy. Since there will be changes in operational requirements, several work-rest-sleep plans must be prepared. Sleeping the preferred 7 to 8 hours per 24 hours the week before an operation may help prepare for optimal performance. Personnel should be familiarised with conditions under which they may sleep. During combat, sleep management should ideally avoid situations where all personnel are exhausted at the same time. As sleep debt accumulates, a person's mood, motivation, attention, alertness, short-term memory, ability to complete routines, task performance (errors of omission more than errors of commission) and physical performance will become more negatively affected. Counter measures must then be taken (e.g. time for sleep or naps, changing routines or rotating jobs). Drugs like caffeine and amphetamine can help personnel stay awake. However, they may also keep them awake when they need to sleep- and on awakening, they could suffer from "hang-overs" and are less efficient. Sleep lost need not be replaced hour-for-hour. Therefore, after operations, personnel need continuous sleep for only 10 to 12 hours as longer sleep increases sleep inertia and delays getting back to normal schedules.

Optical design comparison of 60° eyepieces: one with a diffractive surface and one with aspherics

Abstract: An optical design comparison is made between two 60° field-of-view long-eye-relief eyepieces used for viewing a flat image-intensifier P-43 phosphor screen output. One eyepiece contains both spherical glass elements and plastic aspheric elements. The other eyepiece consists of spherical glass elements and a diffractive surface. Both optical designs were optimized by use of identical system constraints for size and weight. The eyepiece containing the diffractive surface provided an improved modulation transfer function performance and has been fabricated and tested. The fabricated lens characteristics and modulation transfer function performance closely matched the design expectations.

Characterization of small metallic objects and nonmetallic antipersonnel mines

Abstract: A metallic mine detector is one of the most effective pieces of equipment for detection of mines. Their main drawback is their extremely rate of up to 100 percent, but it can also produce a high false alarm rate in many environments. The high false alarm rate reduces the usefulness of the metal detector in the field. In order to keep a high detection rate with fewer false alarms, object/mine characterization or identification must be used. Several techniques have been implemented to reduce the false alarm rate of metal detectors. They are size discrimination, target imaging, and target signatures such as dipole moment characterization. These techniques are applied for large metallic objects/mines. P.V. Czipott and D.A. Waldron each used separate techniques to characterize smaller metallic objects and some anti-personnel mines, in work supported by US Army CECOM, Night Vision and Electronic Sensors Directorate. Dr. Czipott characterized objects/mines by measuring the frequency dependence of magnetic fields caused by electric currents induced in the target. The frequency responses were measured by using a fixture incorporating a solenoid excitation coil, a receiving coil wound as a gradiometer, and a HP 4195A network/spectrum analyzer. Ms. Waldron characterized small objects with different conductivities and orientations by measuring their phase differences using a search head with one transmitter and four receiver coils and a phase-lock analyzer. We believe that target discrimination and identification are the keys to reduce false alarm rates of metallic mine detectors. Thus, we continue to analyze and characterize small metallic targets/mines using a variety of methods.

Optically enhance day/night liquid crystal display backlight with TIR lens and both light sources on same side of waveguide

Abstract: Light emitting devices are combined with non-imaging optical elements to create a backlighting system for liquid-crystal displays (LCDs). A pair of optically isolated sub-systems, or sections a night vision imaging system (NVIS) (14) and a daylight system (12) are combined to provide optimum display legibility in ambient illuminations ranging from bright sunlight to total darkness. The sub-systems utilize non-imaging optics based upon total internal reflection (TIR) and light reflection, both coupled to a light emitting source, such as fluorescent tubes (34) and other linearly shaped light sources. Light reflectors (32) are shaped to concentrate light onto non-imaging optics lens (30) so as to compensate for non-linear characteristics of the TIR lenses.

Concepts for search and detection model improvements

Abstract: Recently the standard Night Vision search and detection thermal models have been challenged with the need to address scenarios which are quite different than those for which the models were originally intended. For example, there is a need to address the characteristics of the target and background in much more detail than was previously required. This paper will discuss and illustrate a selection of new concepts and formulations being considered by the Night Vision and Electronic Sensors Directorate for incorporation in improved search and detection thermal models. Included are new proposed formulations for the mean time for detection for both field-of-view and field-of-regard search and new concepts and formulas for thermal contrast signatures of targets and clutter characterization of backgrounds. Each new concept will be individually explained in detail with mathematical formulations and imagery examples. These formulations are then combined to illustrate how they can form new model metrics which can be used to predict both the static and dynamic probability of detection. The new candidate model formulations will be matched against available measured data to show the potential improvement in predictive capability offered.

Helmet with night vision system and optic capable of being substituted for day vision

Abstract: The invention concerns a helmet comprising a night vision system (6, 7). an image generator (2), a combining glass (8) for combining the light rays derived from the night vision system and the light rays derived from the image generator, and a fixed optic (3) downstream of the combining glass. The night vision system and combining glass assembly (6, 7, 8) is removable, and a substitute optic can be inserted, for day vision, in place of the assembly (6, 7, 8). The substitute optic has the same optical characteristics as the combining glass (8) but it has a transmission coefficient higher than that of the combining glass. The substitute optic is optimised for day vision. The combining glass is optimised for night vision: The invention is applicable to the helmets of pilots of armed helicopters or armed aircraft.

Effects of in-flight field-of-view restriction on rotorcraft pilot head movement

Abstract: The work reported in this paper examines the effect of restricting visual field-of-view (FOV) on rotorcraft pilot head movement. To simulate the FOVs of current and future helmet mounted displays (HMDs) used for night vision pilotage, a FOV restrictor was attached to the helmets of the test subject pilots. The restrictor limited horizontal FOV to 100, 80, 60, 40, and 20 degrees. Ten test subject pilots executed a set of low altitude flight maneuvers in an instrumented NAH-1S helicopter at the NASA Crows' Landing Airfield Head movement was measured with an IR head tracker for those pilots who flew in the rear seat and by a video camera for those who flew in the front seat. Test data indicated that pilots responded to restriction sin horizontal FOV by changing their pattern of head movement, both in azimuth and elevation. These compensation strategies change as FOV decreases and vary from pilot to pilot. Test results reported in this paper, in conjunction with referenced data outlining FOV effects on flight performance, handling qualities, and visual cue ratings, give visionic system designers and users predictive information on pilot workload and performance.

Performance history of AN/PVS-5 and ANVIS image intensification systems in U.S. Army aviation

Abstract: In 1973, the Development of the Army adopted night vision devices for use in aviation. Known as the AN/PVS-5 night vision goggle (NVG), these devices, which are based on the principle of image intensification (I2), have become the mainstay for the aviator's capability to operate during periods of low illumination, i.e., at night. In the 2 years that have followed, a number of engineering the advancements have improved greatly the performance of these devices. The current version, using third generation I2 technology, is known as the Aviator's Night Vision Imaging Systems (ANVIS). The performances histories of NVGs and ANVIS are presented with an emphasis on visual and biodynamic issues which have, and do, affect aviator mission effectiveness and safety.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Navigation system for a marine vessel in low light conditions

Abstract: An aid for marine navigation includes a low-light video camera mounted within a weather-proof enclosure on a vantage point of a marine vessel for improved night vision. A conventional video camera is also mounted with the low-light video camera for daytime viewing. Video signals from the cameras are automatically selected depending on light conditions for transmission to a cabin of the vessel. Motors rotate the housing in a horizontal plane and in a vertical plane for enabling remote-controlled aiming of the cameras from the helm of the marine vessel. Sensors provide information on azimuth and elevation of the cameras for overlaying the video signal transmitted from the camera housing with this information for display with the video image on a monitor near the helm. Information on longitude and latitude, as well as vessel velocity and direction, from a global satellite positioning system receiver is also displayed. The overlayed video signal is RF modulated on to a predetermined channel for distribution to television receivers in other locations on the vessel.

Method and apparatus for illuminating retroreflective and other objects

Abstract: An apparatus for viewing a retroreflective object positions a light source proximate a human eye, by affixing it to, for example, a pair of goggles. The light source emits light outward in substantially the direction of view of the human eye. Upon striking a retroreflective object, the light is strongly reflected back to the human eye, producing a unique visual effect. The apparatus may be used in toy form to simulate a night vision scope. Various combinations of colored light sources, optical color filters interposed between the human eye and the retroreflector, and colored retroreflectors may be used to enhance the visual effect and increase the play variations available. The light source may switch on and/or off automatically, or may flash. Electronic light sensing means may provide a visible and/or audible alert when a retroreflective object is in view.

Electronic imaging aids for night driving: low-light CCD, uncooled thermal IR, and color-fused visible/LWIR

Abstract: MIT Lincoln Laboratory is developing new electronic night vision technologies for defense applications which can be adapted for civilian applications such as night driving aids. These technologies include (1) low-light CCD imagers capable of operating under starlight illumination conditions at video rates, (2) realtime processing of wide dynamic range imagery (visible and IR) to enhance contrast and adaptively compress dynamic range, and (3) realtime fusion of low-light visible and thermal IR imagery to provide color display of the night scene to the operator in order to enhance situational awareness. This paper compares imagery collected during night driving including: low-light CCD visible imagery, intensified-CCD visible imagery, uncooled long-wave IR imagery, cryogenically cooled mid-wave IR imagery, and visible/IR dual-band imagery fused for gray and color display.

Infrared imaging with ferroelectrics

Abstract: Texas Instruments continues to push the limits of its hybrid ferroelectric uncooled focal plane array (UFPA) technology to improve performance and producibility. Emphasizing standard silicon wafer processing techniques, TI has developed a state of the art manufacturing facility which routinely produces significant volumes of high quality, low cost infrared detector assemblies. These arrays are being delivered as part of a variety of thermal imaging products to serve both military and commercial applications. Future improvements in device performance and cost will open the door to a new realm of imaging applications.

Observation or sighting system

Abstract: An observation or sighting system for vehicles is disclosed. The system comprises an optical unit (9) for a visible-range observation and/or detection channel, and sensors (7, 12) for night vision and/or angle error measurement and/or range finding and/or target designation. The optical unit and the sensors (9; 7, 12) are pivotably mounted about at least one axis relative to the vehicle, and the system further comprises detection and/or observation means (10, 14, 15, 16) operating in the EHF range and including transmission and reception means (14, 15, 16) that are adjacent to the optical unit (9) and the sensors (7, 12) and pivotable about at least one axis with said optical unit (9).

Clip-on power source for an aviator's night vision imaging system

Abstract: A clip-on power source for powering an ANVIS binocular. The power source has an electrical interface that enables the power source to be detachably coupled to the ANVIS binocular. The interface also enables the power source to pivot relative to the binocular from a first position to a second position to power-on and power-off the ANVIS binocular.

Ablatement designed for dark adaptability

Abstract: A system and method for performing a reshaping of a cornea of an eye for improved vision is presented. The system comprises a first appartus for determining dark adapted pupil size of an eye and a second apparatus for reshaping a cornea of the eye in an area approximately equal to the dark adapted pupil size as determined by the first apparatus. The method of the present invention involves dilating the pupil of an eye to its dark adapted size, determining the diameter of the dilated pupil, and ablating the cornea of the eye to match the dilated pupil size. The advantage to using such a system and method when reshaping a cornea of an eye is reduced halo effect or improved night vision.

Real-time adaptive thermal reference control for night vision systems

Abstract: A system for normalizing an infrared detector has two control loops, each of which includes a thermal source and a command system. Each command system controls the temperature of the associated thermal source. Each command system includes an error signal source for providing an error signal indicative of the difference between a commanded temperature for the thermal source and an actual temperature at the thermal source, and includes a compensator coupled between the error signal source and the thermal source. Each compensator includes a first inverse compensation circuit responsive to the error signal for providing an output, a bandwidth maximizing compensation circuit responsive to the output of the first inverse compensation circuit, and a second inverse compensation circuit responsive to an output of the bandwidth maximizing compensation circuit. The thermal source is responsive to the output of the second inverse compensation circuit.

Low profile night vision goggle having a fiber optic element

Abstract: A night vision goggle system having an objective lens for viewing an image scene, an image intensifier tube for amplifying a received image scene, an eyepiece lens for presenting the amplified image scene produced at the output of the image intensifier tube to a user's eye, and a fiber-optic element for folding an optical path between the image intensifier tube and one of the eyepiece lens and the objective lens thereby minimizing the length and weight of the system.

Study of the refractive index of microscopic glass beads by light-refraction analysis.

Abstract: The refractive index of submillimeter glass beads has been measured by means of a novel, to our knowledge, procedure with reference liquids that does not require close index matching and therefore avoids the use of toxic compounds for high-index glasses (i.e., n ≥ 1.8). The method is based on the analysis of the light refracted by a monolayer of beads in comparison with ray-tracing simulations. For the three different types of glass beads investigated a satisfactory fit is achieved by the assumption of a radial variation of the refractive index inside the beads. This is ascribed to the tensile and compressive stresses originating inside the beads during rapid solidification of the glass.