Showing papers on "Night vision published in 1995"

Color night vision: fusion of intensified visible and thermal IR imagery

Abstract: We introduce an apparatus and methodology to support realtime color imaging for night operations. Registered imagery obtained in the visible through near IR band is combined with thermal IR imagery using principles of biological color vision. The visible imagery is obtained using a Gen III image intensifier tube optically coupled to a conventional CCD, while the thermal IR imagery is obtained using an uncooled thermal imaging array, the two fields of view being matched and imaged through a dichroic beam splitter. Remarkably realistic color renderings of night scenes are obtained, and examples are given in the paper. We also describe a compact integrated version of our system in the form of a color night vision device, in which the intensifier tube is replaced by a high resolution low-light sensitive CCD. Example CCD imagery obtained under starlight conditions is also shown. The system described here has the potential to support safe and efficient night flight, ground, sea and search & rescue operations, as well as night surveillance.

Far-IR transparency and dynamic infrared signature control with novel conducting polymer systems

Abstract: Materials which possess transparency, coupled with active controllability of this transparency in the infrared (IR), are today an increasingly important requirement, for varied applications. These applications include windows for IR sensors, IR-region flat panel displays used in camouflage as well as in communication and sight through night-vision goggles, coatings with dynamically controllable IR-emissivity, and thermal conservation coatings. Among stringent requirements for these applications are large dynamic ranges (color contrast), 'multi-color' or broad-band characteristics, extended cyclability, long memory retention, matrix addressability, small area fabricability, low power consumption, and environmental stability. Among materials possessing the requirements for variation of IR signature, conducting polymers (CPs) appear to be the only materials with dynamic, actively controllable signature and acceptable dynamic range. Conventional CPs such as poly(alkyl thiophene), poly(pyrrole) or poly(aniline) show very limited dynamic range, especially in the far-IR, while also showing poor transparency. We have developed a number of novel CP systems ('system' implying the CP, the selected dopant, the synthesis method, and the electrolyte) with very wide dynamic range (up to 90% in both important IR regions, 3 - 5 (mu) and 8 - 12 (mu) ), high cyclability (to 10 5 cycles with less than 10% optical degradation), nearly indefinite optical memory retention, matrix addressability of multi-pixel displays, very wide operating temperature and excellent environmental stability, low charge capacity, and processability into areas from less than 1 mm 2 to more than 100 cm 2 . The criteria used to design and arrive at these CP systems, together with representative IR signature data, are presented in this paper.

Spectral distribution emulation

Abstract: A test arrangement for assessing the spectral energy distribution-determined response of a night vision device or other electro-optical apparatus. The test arrangement provides a library of spectral energy-distributed test signals or input scenes which may be selected to represent for example typical or extreme conditions expected during field use of the tested night vision device. The test signals originate in an array of energy transducer devices such as light emitting diode elements with each such light emitting diode element proving a limited wavelength component of the wide band composite optical signal received at the input port of the night vision device. Each component signal is arranged to be controlled electrically in presence or absence and also controlled electrically in radiance or intensity according to the needs of the scene being presented; such control is provided by a manual controller or by a programmed digital computer or by other controlling apparatus such as a programmed logic array. The composite test signal may include both infrared and visible components. In addition to control of the composite test signal, other aspects of the performed test such as test scene data storage may also be accomplished in the controller or computer. The disclosed apparatus is especially suited to performance verification of night vision systems in a laboratory environment prior to field use of similar systems. Military and non-military uses are contemplated.

Night vision system for motor vehicles

Abstract: A motor vehicle (10) is equipped with an infrared camera (12) for viewing roadway conditions in terms of a thermal image, and outputs a video signal to a head up display (HUD) (18) which projects the camera view to the driver (24) via the windshield (22) or other combiner to display a virtual image (23) in the driver's field of view. The HUD (18) is configured to magnify the image to the same size as the visual or real scene, and compensates for camera (12) and windshield (22) distortion. The virtual image is presented above or below the real scene or may be superimposed on the real scene. A video processor (14) allows selection of only the warmest objects for display.

Synthetic-color night vision

Abstract: A synthetic color arrangement for a night vision inclusive surveillance system and its display is disclosed. The system partitions an input scene video signal into spectrally segregated scene components which are provided with separate processing as video signals and then recombined into a composite but now multiple color inclusive output representation of the input scene. The system in effect shifts input spectral components to a different part of the electromagnetic spectrum, the visible range of the spectrum, where operator controllable new spectral wavelength values are assigned to each different input scene spectral wavelength. Use of charge coupled device video camera elements, a video signal mixer apparatus, input wavelengths within both the visible and infrared spectral regions and signal processing according to the NTSC standards are also included. Military and non military uses of the apparatus are contemplated.

Modular binocular electronic imaging system

Abstract: A portable, electronic imaging system (100) includes a compact housing (102) extending across and beyond the eyes of the user, a wide field of view binocular viewfinder imaging subsystem (104) operating on an image produced by an electronic display subsystem (104) located within the housing, speakers (106) integrally mounted with the housing, an internal, interactive electronic control subsystem (108) to control the functions of the system, and an external input/output interface (110) to facilitate connection with a plurality of optional external devices and/or modules. The housing may further provide for modular mounting and removal of a plurality of optional system modules such as the electronic camera (120), a video tape record and playback device and battery (122), the electronic display (118), a night vision camera, a television tuner, a video game electronic system, a head orientation and position tracking device, or a means for mounting the system on the user's head.

Night vision monocular with balanced optics

Abstract: A night vision device that uses low cost optics in a balanced arrangement that corrects for distortions created by the low cost optics. The night vision device is a monocular assembly that uses a Gen II or a Gen III image intensifier tube. An objective lens assembly, containing a plurality of low cost lenses, is positioned in front of the image intensifier tube so that the objective lens assembly directs low intensity light onto the input surface of the image intensifier tube. A collimator assembly is positioned proximate the output surface of the image intensifier tube, wherein the collimator assembly collimates the visible image produced by the image intensifier tube. The collimator assembly is comprised of lenses that are identical in shape, size and material to the lenses found within the objective lens assembly. However, the lenses in the collimator assembly are arranged in reverse, as a mirror image of the lenses in the objective lens assembly. As a consequence, the lenses in the collimator assembly optically balance the lenses in the objective lens assembly correcting for any distortion, magnification or reduction created by the lenses in the objective lens assembly. This enables lower cost lenses to be used in the objective lens assembly, thereby reducing the cost of the entire night vision device. Furthermore, by using the same lenses on both sides of the image intensifier tube, the number of different optical parts is reduced as is the cost of manufacture.

Multipurpose night vision monocular

Abstract: The present invention is a multifunctional night vision monocular that is adapted for use by a soldier as a hand-held spotting scope, a helmet mounted scope, a head mounted scope, and a weapon mounted scope depending upon circumstances and the needs of the soldier. The night vision monocular is a self-contained unit capable of carrying its own power source. A universal mount on the bottom of the night vision monocular enables either a helmet mounting adaptor or a weapon sight mount to be quickly added to the monocular. The night vision monocular contains a GEN III image intensifier tube positioned between an objective lens assembly and an eyepiece lens assembly. The housing of the night vision monocular opens in a plane perpendicular to the optical axis, thereby enabling easy access to the various optical elements for repairs, maintenance and replacement. A reduced number of wire leads are used within the night vision monocular thereby reducing manufacturing costs and improving reliability. The image intensifier tube is directly coupled to a circuit board that provides power to the image intensifier tube. As such, the image intensifier tube can be replaced without cutting leads or soldering.

Cell biology and metabolic activity of photoreceptor cells: light-evoked and circadian regulation

Abstract: Retinal photoreceptor cells are specialized sensory neurons that convert light energy into electrical and neurochemical signals for transmission to other neurons. The two main photoreceptor subtypes, rods and cones, function over several log units of light intensity to provide information about luminance, contrast, movement, and color in the visual environment. Rod photoreceptor cells are more sensitive to light than cones, and are the predominant photoreceptor mediating scotopic or night vision. Cones respond to higher, photopic intensities of light, and mediate color vision. Rods and cones hyperpolarize in response to absorption of photons, with a consequent decrease in neurotransmitter release.

Patient satisfaction following photorefractive keratectomy for myopia

Abstract: This study was conducted to evaluate the subjective response of patients who underwent photorefractive keratectomy (PRK) for myopia with the Summit Technology UV 200 LA excimer laser (Summit Technology, Inc., Waltham, Mass.) (3.5 to 5.0 mm diameter ablation zone) 36 months previously. One-hundred thirteen patients with preoperative myopia between -1.50 diopters (D) and -6.50 D with an ablation diameter of 3.5 mm to 5.0 mm answered a questionnaire at the 36-month examination. Sixty-two percent of patients had both eyes treated. Halo problems were experienced always by 34% of patients in the group, 26% sometimes, and 40% never. Permanent night vision problems were experienced by 40%; 30% reported them sometimes and 30% reported no problems at all. Sixty percent never needed to use glasses after treatment, 30% sometimes did, and 10% always wore glasses. Seventy percent of patients thought the results were very good; the remaining 30% experienced different degrees of halo and night vision problems.

Low cost night vision camera

Abstract: A low cost infrared camera (1) for night vision. The camera (1) is disposed within a housing (2) having an infrared transmissive window (6) disposed at an input aperture (5) thereof. A compact optical arrangement (10) is disposed within the housing (2) to focus energy from the window (5) onto a focal plane array (20). A chopper disk (19) is positioned between the reflective optical arrangement (10) and the focal plane array (20) to establish a reference level for the array (20) and to facilitate a sequential readout thereof. A signal processing circuit (100) is included for processing the output of the array (20) for display on a standard video screen. Thus, the problems with uncooled detectors are overcome by use of a fast optical system in combination with an uncooled detector. The fast optical system provides a high signal level to the uncooled detector, thereby compensating for losses in collection of thermal radiation. Reflective optical systems can be manufactured inexpensively from plastic or aluminum and reduce the need for expensive infrared materials commonly used in military systems. The combination of the fast optics and uncooled detector provides a truly low cost thermal camera for night vision.

Magnification lens coupling device for a night vision assembly

Abstract: A coupling device and associated method for coupling an unassociated afocal optical assembly to a night vision apparatus in order to alter the optical power normally associated with the night vision. The coupling device includes two separate adapter rings that threadably connect to each other. The first adaptor ring is sized and shaped to threadably engage the night vision apparatus proximate the objective lens of the night vision apparatus. The second adaptor ring is sized and shaped to screw onto the output end of the afocal optical assembly. Accordingly, when the first adaptor ring is joined to the second adaptor ring, the output end of the afocal optical assembly is optically aligned with the objective lens of the night vision apparatus. Consequently, the afocal optical assembly enhances the optical power associated with the night vision apparatus.

The electronic motorist

Abstract: The shortcomings of the human driver are getting help from emerging technologies in the guise of navigation systems, engine immobilizers, night vision assistance, automated collision alert, air bag systems, low tyre pressure warning system, and fuzzy logic. The author describes these technologies. In particular the author describes some of the LCD display navigation systems, and intelligent transportation systems, including vehicle location, of which navigation is a component. >

Target acquisition modeling for contrast-limited imaging: effects of atmospheric blur and image restoration

Abstract: The incorporation of atmospheric aerosol and turbulence effects into visible, near-infrared, and thermalinfrared target acquisition modeling is considered. We show how the target acquisition probabilities and, conversely, the ranges at which objects can be detected are changed by the inclusion of atmospheric effects. It is assumed that images are contrast limited rather than noise limited, as is indeed the case with most visible, near-infrared, and thermal infrared sensors. For short focal lengths with low angular magnification, atmospheric effects on target acquisition are negligible. However, for longer focal lengths with large angular magnification, resolution is limited by the atmosphere, and this has a strong adverse effect on target acquisition probabilities, times, and ranges. The considerable improvement possible with image correction for atmospheric blur automatically in a fraction of a second is significant for contrast-limited imaging and is also discussed. Knowledge of the atmospheric modulation transfer function is essential to good system design and is also useful in image restoration for any type of target or object. Finally, a new target-transferfunction model is suggested that considers the overall image-spectrum target received by the human visual system rather than only the main harmonic detail as in the Johnson chart model. [ J. Johnson , in Proceedings of Seminar on Direct-Viewing Electro-Optical Aids to Night Vision ( IDA, Alexandria, Va., 1966), p. 177.]

Night vision monocular

Abstract: A night vision monocular that includes an objective lens subassembly for receiving low intensity and/or infrared light. The objective lens subassembly focuses the light onto an image intensifier tube that converts the light into a visible image. The visible image passes through a collimator subassembly that collimates the visible image. Finally, the collimated image is viewed through an eyepiece subassembly. The objective lens subassembly, image intensifier tube, collimator subassembly and eyepiece subassembly are each separately manufactured subassemblies that are encased in subhousings and are ready to be assembled into a larger optical device. The housing of the present invention night vision monocular is a two piece structure, having a first half and an opposite second half. Partitions extend inwardly from a plurality of locations on both halves of the housing. The partitions are contoured and positioned to abut against and retain the various subassemblies within the night vision device. At least two partitions from each half of the housing abut against and support the objective lens subassembly, the image intensifier tube, the collimator subassembly and the eyepiece subassembly. The partitions within the housing are the only elements of positioning and optically aligning the various subassemblies. Consequently, no adhesive or mechanical fasteners are needed to retain components within the housing. The housing itself need not be precision machined, consequently, a night vision device is provided that is easy to manufacture and is well suited for a low-cost mass-production manufacturing environment.

Abnormal night vision with isotretinoin therapy for acne.

Abstract: SIR, we would like to report a case of a 19-year-old trainee RAF navigator who developed abnormal night vision during isotretinoin therapy, given in a dose of 70 mg daily for acne vulgaris. He developed the common side-effects of dry skin and cheilitis, but after 3 weeks of treatment he complained of blurred vision, photophobia and decreased night vision. His visual acuities were reduced to 6/18 in the right eye and 6/12 in the left eye. Refraction showed 1-5 dioptres of myopia in both eyes but appropriate correction of this produced 6/4 vision in both eyes. Blepharoconjunctivitis was noted bilaterally but otherwise ocular examination was unremarkable, and in particular both fundi and optic discs were normal. There was no family history or ophthalmic evidence of retinitis pigmentosa. Isotretinoin therapy was withdrawn immediately and the decreased night vision was investigated using electrophysiology. Visual evoked potentials (VEP) were normal but the scotopic electro-retinogram (ERG) and the electro-oculogram (EOG) were abnormal, suggesting poor retinal function in dark adapted conditions. At 2 weeks followup his unaided vision had returned to normal with no significant refractive error. However, at 3 months follow-up the patient still complained of poor night vision and the ERG and EOG showed little recovery in retinal function. At the last follow-up appointment, 9 months after withdrawal of isotretinoin, the patient subjectively felt that his night vision was still poor.

Dynamic uses of image intensifiers

Abstract: Nowadays the applications of image intensifiers are no longer limited to night vision but include a wide variety of industrial and scientific applications. For the latter applications the image intensifiers are nearly always coupled to CCD cameras. The dynamic use of the ICCDs requires the availability of a variety of configurations. We review the possibilities with ICCDs and discuss the influence on the performance of a large number of options.

Effect of field-of-view restriction on rotocraft pilot workload and performance: preliminary results

Abstract: The Aeroflightdynamics Directorate of the US Army's Aviation Research, Development and Engineering Center initiated a study to determine the effects of limiting a rotorcraft pilot's field-of-view (FOV) on performance and workload. Pilot FOV was restricted to simulate current and next generation helmet mounted display FOVs used in night vision systems. A helmet visor was constructed for this test to restrict the horizontal peripheral limits of the square shaped FOV to values of 100, 80, 60, 40, and 20 degrees. The vertical limits and overlap were held constant to 40 degrees (except for the 20 degree FOV). Six pilots executed a series of prescribed low altitude maneuvers with an instrumented NAH-IS (Cobra) rotorcraft at the Crows Landing Airfield located in California. The aircraft flight path was measured with a laser tracker. On board data was recorded, as well as pilot handling quality ratings and visual cue ratings. This test is not yet complete, but some preliminary observations and results are provided. It was observed that reducing FOV increased the difficulty of controlling the aircraft and altered head movement. Reducing FOV also diminished the pilots' situational awareness. The reduction in situational awareness affected the ability of the pilots to provide an accurate report of their own flying performance, and the ability to observe warning indicators inside the cockpit.

Night Vision Monocular with unistructural optical bed

Abstract: A night vision device having an image intensifier tube, collimator lenses and at least one aspheric ocular lens are retained within a unistructurally formed optical bed. The optical bed is essentially a tubular structure having a large receptacle at one end to receive the image intensifier tube. The tubular structure is configured so that the various collimator lenses can be stacked within the tubular structure in a highly precise yet labor and cost efficient manner. A housing is provided that conforms to the shape of the electro-optical subassembly. The housing has a substantially similar ocular end structure and objective end structure. An objective lens assembly and ocular lens assembly are retained by the housing. Both the objective lens assembly and the ocular lens assembly contain at least one lens held with a commonly shaped lens casing. Since the lens casings for both the ocular lens assembly and the objective lens assembly are substantially the same and the object and objective ends of the housing are substantially the same, a common focusing assembly can be used on both the objective end and the ocular end of the housing. The use of identical parts in both the objective and the ocular of the night vision device, as well as the use of the optical bed provides for a night vision device that is low cost to manufacture and easy to assemble.

Infra-red headlamp to aid night vision in motor vehicle

Abstract: The night vision system has multiple electroluminescent infra-red diodes (6) as the light source. The electroluminescent diodes operate with bandwidths between 800nm and 900nm. A cover (9) over the diodes has the inside face shaped with individual curved segments, one in front of each diode, to concentrate the infra-red light from each electroluminescent diode. The diodes are standard diodes of 5mm diameter. The diodes can be formed on a single substrate, providing an array of diodes on a single substrate. A CCD camera is fitted to the vehicle to gather the scene illuminated by the array of diodes. The camera has a filter with its pass band corresponding to the wavelength of the diodes. The diodes and the camera can operate in synchronised impulse mode.

Composite infrared windows using silicon and plastic

Abstract: Low-cost composite infrared windows that are transparent to long wave infrared radiation (8-12 microns) that provide sufficient strength and impact resistance for automotive-type environments, and the like. The windows may be used with night vision systems for automobiles, surveillance imaging systems, and other applications requiring low cost, long wave infrared windows. In one embodiment, the composite infrared window is a sandwich comprised of a polyethylene plastic film bonded with an acrylic adhesive to a relatively thin (0.015-0.040 inch) silicon substrate. The thin silicon substrate is mechanically stiff and low cost, and transmits in the 8-12 micron bandpass. The thin (0.001-0.007 inch) plastic film provides an exterior particle impact absorbing layer sufficient to enable the use of the window in automotive applications. In another embodiment, the infrared window is a dual pane, long wave infrared transmitting window comprising a thin, antireflection coated, silicon window and a plain or reinforced, embossed, plastic window that may be mounted in a frame.

Drivers’ vision, age, and gender as factors in twilight road fatalities

Abstract: Data from the U.S. Fatal Accident Reporting System (1980-1993) were examined to test the hypothesis that age-related changes of vision are associated with increased involvement in fatal accidents under low illumination. A quasi-experimental analysis of 626,893 cases investigated the effects of light condition, driver age, and driver gender for two categories of fatal accidents, pedestrian/pedalcycle vs. all others combined. The investigation focused on monthly variations in the distribution of accidents occurring under three light conditions: 1) twilight zones, in which natural illumination varied on a monthly basis with the annual solar cycle; 2) daylight control; and 3) nighttime control. The present findings provide a new evidence that age-related changes in basic visual processes, which cause gradual deterioration of night vision, contribute to increasing involvement in fatal accidents, particularly with pedestrians and pedalcyclists, in low illumination.

Human Factors Issues Surrounding an Automotive Vision Enhancement System

Abstract: Although night vision systems have been used extensively for a wide variety of military applications, only recently have such systems been considered for automotive applications. This paper provides a technological primer for an automotive application of a vision enhancement system (or VES), and reviews the human factors literature, general human factors issues, and accident data relevant to such a system. The automotive VES consists of two primary components, an infrared sensor and a display. VES information can be displayed to the driver in a contact analog fashion on a head-up display, or in a non-contact analog fashion on either a head-down or head-up display. The primary potential benefit of a VES is to improve the driver's ability to see critical driving events (e.g., pedestrians, bicyclists, roadway direction) under nighttime driving conditions.

Localization of a novel X-linked congenital stationary night blindness locus: close linkage to the RP3 type retinitis pigmentosa gene region

Abstract: X-linked congenital stationary night blindness (CSNBX) is a non-progressive retinal disorder characterized by decreased visual acuity and loss of night vision. CSNBX is clinically heterogeneous with respect to the involvement of retinal rods and/or cones in the disease. In this study, we localize a new locus for CSNBX to Xp21.1, thus providing evidence that CSNBX is also genetically heterogeneous. A clear correlation between different genotypes and phenotypes cannot be found yet. The new CSNBX gene described here is closely linked to the X-linked retinitis pigmentosa type 3 gene region, which supports the hypothesis that there may be a functional relationship between congenital stationary night blindness and retinitis pigmentosa

Flight Behavior of Corn Earworm (Lepidoptera: Noctuidae) Moths Under Low Wind Speed Conditions

Abstract: Studies were conducted to develop technologies to observe movement behavior, within range of visual observation (≤100 m above ground level), of newly emerged Helicoverpa zea (Boddie) adults and to describe the flight behavior of moths from 6 age or previous activity categories. Moths were released and tracked using a 4-wheel all terrain vehicle, night vision equipment, and auxiliary infrared lighting. Movement, flight behavior, and weather parameters were recorded as moths moved from the take-off site. Observations at Lane, OK, during 1988 indicated that moths tracked on the night after emergence were observable longer than other moth categories. Moths released 1 and 2 nights after emergence were lost primarily because of altitude (> 100 m above ground level). Shortly after take-off, moths exhibited spiral flight up to a mean altitude of ≍50 m, and female moths ascended at a sharper angle and faster than males. Subsequently, the angle and rate of ascent decreased and relatively straight, more oriented flight was assumed. Differences in means of observed moth and calculated moth velocity indicated moths were heading crosswise or even into the wind to counter drift (crabbing) during flight. The moths crabbed positively (mean = 8l.8 ± 18.4) to east-northeast winds on 1 night and negatively (mean = −134.2 ± 19.1) to east-southeast winds on another night to obtain a preferred direction to the west. Plots of crab angles with respect to wind speeds suggest that orientation of the moths became increasingly upwind with increasing wind speed. Changes in crab angles with respect to wind speed indicated that there was less variation among crab angles as wind speed increased.

Transmission mode photocathode with multilayer active layer for night vision and method

Abstract: An improved photocathode and image intensifier tube are disclosed along with a method for making both the tube and photocathode. The disclosed photocathode and image intensifier tube have an active layer comprising two or more sublayers. The first sublayer has a first concentration of a group III-V semiconductor compound while the second sublayer has a second concentration of the group III-V semiconductor compound. The multilayer active layer is coupled to a window layer.

Design of an objective for night-vision applications using axial GRIN materials

Abstract: An F/1.27 objective lens suitable for night vision applications employing lanthanum axial gradient-index (GRIN) materials is described. Although two GRIN elements were used, the number of elements was not substantially reduced relative to that of conventional homogeneous systems with equivalent performance. Tolerances and fabrication issues are discussed.

The ergonomic and safety implications of in-car ATT devices-evidence from field trials with elderly drivers

Abstract: The DRIVE II project EDDIT (Elderly and Disabled Drivers' Information Telematics) has evaluated a number of in-vehicle telematic systems in terms of their potential value in extending the safe driving life of the elderly. Although the terms of reference of the project focus on the benefits and safety implications for what appears to be a particularly vulnerable group-the over-65s- EDDIT's experimental work has provided valuable insights into ergonomic issues that concern all users, and has highlighted both the usefulness and usability of different types of man-machine interface. Among the devices tested have been two reversing aids (one dashboard-mounted, the other located behind the driver), three types of route guidance system and a head-up night vision enhancement system. Unlike other in-vehicle innovations, such as mobile telephones and music systems, the systems studied within EDDIT add another element to the driving task, leading potentially to an increase in the driver's visual and mental workload, and many of them require the user to switch his/her visual attention from the road scene ahead. The possible safety implications of using such devices are therefore very important, particularly in the case of elderly people, whose capacity to cope with the various mental and cognitive demands of driving may in any case be almost saturated. This paper discusses these issues in the light of the results of EDDIT'S field trials.