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Showing papers on "Night vision published in 1994"


Patent
09 Jun 1994
TL;DR: In this article, a motor vehicle is equipped with an infrared camera for viewing roadway conditions in terms of a thermal image, and outputs a video signal to a head up display (HUD) which projects the camera view to the operator via the windshield or other combiner to display a virtual image in the operator's field of view.
Abstract: A motor vehicle is equipped with an infrared camera for viewing roadway conditions in terms of a thermal image, and outputs a video signal to a head up display (HUD) which projects the camera view to the operator via the windshield or other combiner to display a virtual image in the operator's field of view. The HUD is configured to magnify the image to the same size as the visual or real scene, and compensates for camera and windshield distortion. The virtual image is presented above or below the real scene or may be superimposed on the real scene. A video processor allows selection of only the warmest objects for display.

237 citations


Patent
09 Sep 1994
TL;DR: In this paper, a flip-up helmet mount for a night vision goggle includes a plurality of nested movable brackets (18, 72, 100), the first bracket is secured to a user's helmet and the second bracket pivots relative to the first to provide flipup motion for the goggle (12), and the third bracket (100) is pivotal to provide a tilt angle adjustment for the night vision viewer (140).
Abstract: A flip-up helmet mount (16) for a night vision goggle (12) includes a plurality of nested movable brackets (18, 72, 100), the first bracket (18) is secured to a user's helmet (14). The second bracket (72) pivots relative to the first to provide flip-up motion for the goggle (12), and the third bracket (100) is pivotal on the second bracket (72) to provide a tilt angle adjustment for the night vision viewer (140). In order to both save battery power, and prevent the user from inadvertently revealing his position, the support structure includes a magnetic flux switch that maintains the viewer (140) on only when the viewer (140) is in its use position.

89 citations


Journal ArticleDOI
TL;DR: Halos after PRK were found to be significantly larger than those in emmetropes and myopes corrected with spectacles, and the halos were diminished by using either artificial pupils or negative lens over-correction.
Abstract: A series of 85 patients with myopia, up to -600D, was treated by photorefractive keratectomy (PRK), using a 5 mm diameter ablation zone At six months, 38 patients (45%) reported slight disturbances of night vision, nine (11%) of whom had significant problems Perturbations of night vision after PRK are seen as starbursts and halos around lights Corneal haze produces the starbursts, which are usually transient In contrast, halos are myopic blur circles and may be persistent Using a computer program, halos after PRK were found to be significantly larger than those in emmetropes and myopes corrected with spectacles (p < 001) The halos were diminished by using either artificial pupils or negative lens over-correction In patients with identical bilateral PRK corrections, except for the ablation zone size, the magnitude of the halo was less with 5 mm than 4 mm zones (p < 001) Patients treated with 5 mm reported fewer problems attributable to halo than with the 4 mm ablation diameters (p < 001) Halos and pupil diameters were measured in nine patients with significant impairment of night vision haze Those with starbursts had small hyperopic shifts, minimal halos and high haze and light scatter measurements, whilst patients with halos had large hyperopic shifts, little haze and large pupil diameters Patients with persistent halo problems benefited from either negative lens over-correction or miotics at night

78 citations


Journal ArticleDOI
TL;DR: The women treated with 200 mg fenretinide daily showed a relatively high incidence of mild-to-moderate alterations of dark-adaptometry as measured with the Goldmann-Weekers adaptometer, and the reversibility of alterations in night vision is an open question.
Abstract: BACKGROUND: Fenretinide, a synthetic derivative of retinoic acid, is under study in clinical trials for the prevention of breast, skin basal cell, bladder, and oral cancer in patients at risk. Although fenretinide is well tolerated even after prolonged use, it does lower plasma retinol levels and thus may affect night vision. PURPOSE: The purpose of this study was to measure changes in dark adaptation resulting from fenretinide administration, to compare the measured results with the patient's subjective perception, to define the association with plasma retinol levels, to assess the reversibility of alterations in night vision, and to assess the effects of fenretinide on the surface of the eye. METHODS: The study involved 65 women who had been operated on for stage I breast cancer. Of the study group, 34 received 200 mg daily of fenretinide for a median of 32 months, while 31 control subjects did not. Dark adaptation was studied with the Goldmann-Weekers adaptometer and with a subjective questionnaire. Plasma retinol levels were measured at each test of dark adaptation. Effects of fenretinide on the ocular surface were evaluated through conjunctival impression cytology. RESULTS: Of the patients on fenretinide, eight (23.5%) showed mild and nine (26.5%) showed moderate alterations of measured dark adaptability, compared with just two controls (6.5%) with mild alterations (cumulative odds ratio = 15.4; P = .0008). A significant inverse correlation exists between the final sensitivity threshold of dark-adaptometry and plasma retinol levels, with mild alterations arising below 16 micrograms/dL and moderate alterations below 10 micrograms/dL. Abnormal rod function improved significantly after 7 days and normalized 1 month after use of fenretinide was stopped or vitamin A supplementation was begun, while the conventional 3-day drug suspension, or drug half dose, did not allow sufficient recovery. Alterations of conjunctival cytology were slightly higher in patients receiving fenretinide, but no clinical disorders of the ocular surface were observed. CONCLUSIONS: The women treated with 200 mg fenretinide daily showed a relatively high incidence of mild-to-moderate alterations of dark-adaptometry as measured with the Goldmann-Weekers adaptometer. However, the real-life implication of the measurements is an open question, for the questionnaire shows that 50% of the patients with altered dark adaptometry were asymptomatic.

75 citations


Journal ArticleDOI
01 Jan 1994-Eye
TL;DR: Patients with starburst effects in the early postoperative period noticed an improvement with time as their corneal haze gradually improved, and all patients should be informed pre-operatively of the possible consequences of disturbances in night vision.
Abstract: Eighty-four patients with up to -6.00 dioptres of myopia underwent photorefractive keratectomy (PRK), using 5.00 mm ablation zones. Three months post-operatively 38 (45%) complained of disturbances in night vision, compared with 21 (25%) pre-operatively. In the majority, these disturbances were regarded as negligible. However, 9 (11%) reported significant problems, defined as an inability to drive safely at night with the treated eye. At 12 months, 32 patients (38%) complained of impaired night vision, 4 (5%) of whom had significant problems. A series of measurements were performed to investigate the origins of these disturbances, especially in patients reporting significant problems. Visual impairment from forward scattered light was investigated using a computerised technique. Back scattered light was measured with a charge coupled device-camera system and a computer program was used to assess the degree of halation around a bright light source on a high-resolution monitor. Pupillary diameters were measured by infrared television pupillometry. At 6 months, those reporting a starburst effect around lights at night had small hyperopic shifts, minimal halos and high forward and back light scatter measurements. Patients who reported halo phenomena had large hyperopic shifts, little light scatter and large pupillary diameters. Of the 4 patients who reported significant disturbances at 12 months, all had persistent halo problems. Those with starburst effects in the early post-operative period noticed an improvement with time as their corneal haze gradually improved. Perturbations of night vision after PRK manifest as starbursts and halos around lights.(ABSTRACT TRUNCATED AT 250 WORDS)

74 citations


Patent
24 Oct 1994
TL;DR: In this paper, the grey level transformation rule is stored in a look-up table, which contains at least two different laws applying to distinct groups of pixels, and pixel selection is performed by the microcontroller.
Abstract: The method involves using a camera (20) with a matrix array of e.g. 256 x 256 CCD image sensors (21) which deliver an analogue video signal (23) contg. pixel grey levels for digitisation (24). A microcontroller (26) operates on the image stored in memory (54) using a data bus (55) for the grey level signals and an address bus (56) for the pixel row and column numbers (43, 42). A grey level transformation rule is stored in a look-up table (52) which contains at least two different laws applying to distinct groups of pixels. Selection (50) is performed by the microcontroller.

64 citations


Patent
05 Jan 1994
TL;DR: In this article, a backlit liquid crystal display device having improved nighttime operational characteristics includes a fluorescent lamp (300) for daytime operation and a separate light source (398) for nighttime operation which emits a low-intensity light.
Abstract: A backlit liquid crystal display device having improved nighttime operational characteristics includes a fluorescent lamp (300) for daytime operation and a separate light source (398) for nighttime operation which emits a low-intensity light. Preferably, the nighttime light source (398) is an electroluminescent panel which also acts as a daytime reflector of light. An integral image-splitting and collimating lens (302) is provided to increase the uniformity of the light emitted and to provide wide angle viewability. A sharp cut-off IR filter may also be included in the device to provide NVIS-B night vision goggle compatibility.

63 citations


Patent
15 Aug 1994
TL;DR: In this paper, a modular night vision device is presented where either one or two night vision monocular assemblies can be joined to a common mount to selectively create either a monocular night vision apparatus or a binocular night-vision apparatus.
Abstract: A modular night vision device wherein either one or two night vision monocular assemblies can be joined to a common mount to selectively create either a monocular night vision apparatus or a binocular night vision apparatus. Electrical contacts are present on the night vision monocular assemblies that couple to the common mount. The electronic controls and power source needed to operate the night vision monocular assemblies are contained within the common mount. Accordingly, the night vision monocular assemblies automatically become disabled when detached from the common mount. The common mount provides interpupillary and distance-to-eye adjustments for the night vision monocular assemblies. Additionally, the common mount enables the night vision monocular assemblies to be flipped up to a stowed position out of the field of view of the person utilizing the night vision device.

50 citations


Patent
17 Feb 1994
TL;DR: In this paper, the locking element of a night vision assembly is passed into the aperture of a pilot's helmet, where a locking element is engaged and retained by a collet, and current is passed through the wire surrounding the collet until the structural integrity of the wire fails.
Abstract: A quick release coupling apparatus and method used to connect and quickly disengage a night vision assembly from a pilot's helmet. The quick release coupling apparatus includes a locking element disposed on a pilot's helmet. An aperture is disposed on the night vision assembly to be attached to the pilot's helmet. The locking element of the pilot's helmet is passed into the aperture of the night vision assembly wherein the locking element is engaged and retained by a collet. The collet is biased against the locking element by a wire that is wrapped around the collet. As such, the collet engages the locking element and prevents the locking element from being withdrawn out of the night vision assembly, thereby firmly joining the night vision assembly to the pilot's helmet. Springs or similar repelling elements are disposed between the night vision assembly and the pilot's helmet. The springs act to bias the night vision assembly and pilot's helmet away from each other but the bias is checked by the presence of the locking element in the collet. To quickly separate the night vision assembly from the pilot's helmet, current is passed through the wire surrounding the collet until the structural integrity of the wire fails. With the wire broken, the collet is not biased against the locking element and the locking element no longer counter acts the force of the springs. Consequently, the springs quickly separate the night vision assembly from the pilot's helmet and propel the night vision assembly away from the pilot's helmet.

48 citations


Journal ArticleDOI
TL;DR: A wide variety of clinical expression of the disorder even within a family with the same mutation, its late onset, slow progression, and cone degeneration clearly suggest that some other factors or genes in addition to rhodopsin are responsible for the phenotypic expression ofThe disorder.
Abstract: Retinitis pigmentosa comprises a group of clinically variable and genetically heterogeneous inherited disorders of the retina. It is estimated that approximately 1.5 million people throughout the world are affected by this disease. It is a slowly progressive disorder and causes loss of night vision and peripheral visual field in adolescence. It can be inherited through an autosomal dominant, recessive, or X-linked mode; the autosomal dominant form is considered to be the mildest form. Molecular genetic studies on the autosomal dominant disorder have shown that, in some families, genes encoding the rhodopsin and peripherin/RDS map very close to the disease loci identified previously by the systematic linkage analyses. These results, together with the observation that a recessive nonsense mutation in the Drosophila opsin gene causes photoreceptor degeneration, prompted an extensive search for the alterations in the human rhodopsin and peripherin/RDS genes in families with autosomal dominant retinitis pigmentosa. As a result, several distinct rhodopsin and peripherin/RDS mutations have been found in approximately 30% of all autosomal dominant cases. A wide variety of clinical expression of the disorder even within a family with the same mutation, its late onset, slow progression, and cone degeneration clearly suggest that some other factors or genes in addition to rhodopsin are responsible for the phenotypic expression of the disorder. In this article, an attempt is made to highlight some of these recent developments and to correlate the various mutations and the phenotypes.

45 citations


Journal ArticleDOI
Dan-E Nilsson1, A. I. Ro1
TL;DR: Tory considerations suggest that, in the night eye, the peripheral retinula cells are involved in neural pooling in the lamina, with asymmetric pooling fields matching the visual fields of the rhabdomeres, which provides high sensitivity for nocturnal vision.
Abstract: Observations of the infrared deep pseudopupil, optical determinations of the corneal nodal point, and histological methods were used to relate the visual fields of individual rhabdomeres to the array of ommatidial optical axes in four insects with open rhabdoms: the tenebrionid beetle Zophobas morio, the earwig Forficula auricularia, the crane fly Tipula pruinosa, and the backswimmer Notonecta glauca.

Journal ArticleDOI
TL;DR: In this paper, the authors present a survey of IR detectors operating from mid IR wavelengths to very long wavelength IR detectors for a variety of ground based and space based applications such as night vision, early warning systems, navigation, flight control systems, weather monitoring, and astronomy.
Abstract: Infrared detectors operating from mid IR wavelengths to very long wavelength IR are of great interest for a variety of ground based and space based applications such as night vision, early warning systems, navigation, flight control systems, weather monitoring, and astronomy.

Journal ArticleDOI
TL;DR: In 95 eyes, uncorrected visual acuity improved and best-corrected acuity remained unchanged, and in eyes with myopia of more than -3.0 diopters, the postoperative refraction was within -1.0 D of attempted correction.
Abstract: We made a comprehensive study of 97 eyes that received photorefractive keratectomy (PRK) for myopia and followed them for one year. In 95 eyes, uncorrected visual acuity improved and best-corrected acuity remained unchanged. In eyes with myopia of more than -3.0 diopters (D), the postoperative refraction was within -1.0 D of attempted correction. Predictability decreased with higher myopia. We also examined the changes of both epithelium and endothelium with the specular microscope and found no significant changes after photorefractive keratectomy. Videokeratography showed an average of inferior decentration in most eyes by 0.51 mm +/- 0.31 (n = 60); only one clinical problem was noted--one eye experienced monocular diplopia for seven months. Pachometry showed a small percentage had corneal thinning--the amount depended on the degree of myopia. A rise in intraocular pressure over 21 mm Hg was observed in 8.9% of eyes but it was controlled without surgery. Haze was observed in most eyes, but faded gradually without significant problems. Reduced contrast sensitivity in night vision was noted and some patients experienced glare. Day vision contrast sensitivity was related to corneal haze.

Journal Article
TL;DR: The results show that patients aged over 55 years with a higher percentage of adipose tissue had higher plasma concentrations of 4-MPR, which turned out to be the major determinant of the retinol decrease.
Abstract: Administration of the synthetic retinoid Fenretinide lowers circulating retinol and may thus affect night vision. We have recently shown that plasma retinol levels below 100 ng/ml are associated with moderate alterations of the dark adaptometry test. To identify which patients are more likely to experience a decrease of plasma retinol under this threshold, we measured plasma levels of retinol, Fenretinide, and its metabolite 4-MPR in a cohort of 28 women receiving Fenretinide at the daily dose of 200 mg and studied their relationship with clinical characteristics such as age, menstrual status, body mass index, and time on treatment. Our results show that patients aged over 55 years with a higher percentage of adipose tissue had higher plasma concentrations of 4-MPR, which turned out to be the major determinant of the retinol decrease. This subgroup may thus deserve careful ophthalmological surveillance.

Patent
07 Dec 1994
TL;DR: In this paper, an active night vision system capable of viewing a target over long distances utilizes laser illumination in eye-safe, invisible wavelength regions of about 1.52 - 1.76 νm or about 2.03 - 2.34
Abstract: An active night vision system capable of viewing a target over long distances utilizes laser illumination in eye-safe, invisible wavelength regions of about 1.52 - 1.76 νm or about 2.03 νm - 2.34 νm for illuminating a target; and electronically receives, intensifies and displays or stores the reflected image.

Patent
24 Jan 1994
TL;DR: A night vision visor system that is compact, light in weight, and ejection-safe, and which provides the user with an unobstructed peripheral field of view and other structural and operational advantages is described in this paper.
Abstract: A night vision visor system that is compact, light in weight, and ejection-safe, and which provides the user with an unobstructed peripheral field of view and other structural and operational advantages. The night vision visor system includes a visor adapted to be mounted to a helmet to be worn by a user and to be positioned substantially in front of the user's face, and a night vision imaging apparatus mounted to the visor for receiving incoming visible and/or infrared light from an object, for converting the incoming light to an intensified visible light, and for presenting the intensified visible light to an eye of the user. The night vision imaging apparatus includes first and second night vision imaging devices mounted in openings in the visor and movable with the visor between a down position in front of the user's face when is use and a raised position away from the user's face when not in use.

Patent
22 Mar 1994
TL;DR: In this paper, a substantially rigid mounting plate is used to align the optical axis of a night vision device with the orientation of a camera, even if these optical axes normally do not align.
Abstract: An apparatus and associated method of joining a night vision device to a camera device to record images during night time or low light conditions. The present invention includes a substantially rigid mounting plate that connects to the bottom surfaces of both the night vision device and the camera device, whereby the objective lens assembly of the camera device is held in optical alignment with the ocular lens assembly of the night vision device. As a result, the night vision device and camera device are joined together both physically and optically, while each is also independently supported by the mounting plate. The mounting plate is configured to compensate for size differentials between the night vision device and the camera device. Accordingly, the mounting plate aligns the optical axis of the night vision device with the optical axis of the camera device even if these optical axes normally do not align. An adaptor is used to physically join the ocular lens assembly of the night vision device to the objective lens assembly of the camera device. The adaptor physically engages both the night vision device proximate the ocular lens assembly and the camera device proximate the objective lens assembly. The adaptor includes a stabilizing element that attaches to the mounting plate, thereby providing additional support to both the camera device and the night vision device.

Patent
18 Jul 1994
TL;DR: In this paper, a color liquid crystal display backlight system for daytime and nighttime use is described, where the NVIS compatible nighttime source is positioned to be out of sight of a user and produces an appropriately filtered, substantially collimated beam which diffusively reflects from the inside walls and base of the display housing before it illuminates the display surface.
Abstract: The disclosure is directed to a color liquid crystal display backlight system for daytime and nighttime use. Night vision imaging system retirements are met so that light emissions from the 630 nm to 930 nm range are substantially reduced or eliminated. Separate daytime and nighttime light sources are utilized. The NVIS compatible nighttime source is positioned to be out of sight of a user and produces an appropriately filtered, substantially collimated beam which diffusively reflects from the inside walls and base of the display housing before it illuminates the display surface. Intensities of both daytime and nighttime light sources can be controlled.

Journal ArticleDOI
TL;DR: A series of 84 eyes with up to -6.00 diopters (D) of myopia were treated by photorefractive keratectomy (PRK) using a 5.00 mm ablation zone, and there were 32 patients with minor disturbances of night vision, 4 with significant problems at 12 months.
Abstract: A series of 84 eyes with up to -6.00 diopters (D) of myopia were treated by photorefractive keratectomy (PRK) using a 5.00 mm ablation zone. Three months postoperatively, 43 eyes (51%) complained of disturbed night vision, compared to 12 (14%) preoperatively. Ten (12%) had significant problems, ie, interference with driving at night. At 12 months, there were 32 patients (38%) with minor disturbances of night vision, 4 (5%) with significant problems.

Patent
30 Mar 1994
TL;DR: In this article, the reticle pattern is formed on a clear, flexible substrate that is able to conform the curvature of the output surface, and an adhesive is coated on the flexible substrate.
Abstract: Reticle apparatus that is affixed to the output surface of an image intensifier tube fiber optic element in a night vision goggle system. One embodiment provides for an illuminated reticle pattern. The reticle pattern is etched into a glass substrate which is then filled by a light reflective material. At least one light emitting diode (LED) is positioned adjacent to the edge of the substrate. Light from the LED is then received by the edge of the substrate which then illuminates the reticle pattern. An alternate embodiment provides for a reticle pattern that is affixed to an output surface of a fiber optic element wherein the output surface is curved. The reticle pattern is formed on a clear, flexible substrate that is able to conform the curvature of the output surface. The substrate is affixed to curved output surface by an adhesive that is coated on the flexible substrate.

Patent
05 May 1994
TL;DR: In this article, a fiber optic rod is used to transfer the focused incoming light without any use of an image intensifier tube, which is also color filtered with a color filter.
Abstract: Night vision goggles that is internally modified such as to provide a reatic simulator without activation of any night vision enhancement and includes a depth perception loss. An assembly is positioned after the objective assembly on the same optical axis for the transfer of the focused incoming light, which light is also color filtered. A fiber optic rod achieves the transfer of the focused incoming light without any use of an image intensifier tube.

01 Jan 1994
TL;DR: Two systems developed to enhance visibility during night-time driving were tested: the Volvo ultraviolet light system and the Jaguar night vision system, which have a positive effect on the visibility of pedestrians and on road design elements.
Abstract: The overall goal with the EDDIT programme is to find out whether different ATT systems can enhance personal security and extend safe driving among elderly drivers. Two systems developed to enhance visibility during night-time driving were tested: the Volvo ultraviolet light system and the Jaguar night vision system. Both systems have a positive effect on the visibility of pedestrians and on road design elements. It appears likely that using these systems would give older drivers more confidence when driving at night and should improve both their own safety and that of other vulnerable road users such as pedestrians. (A) For the covering abstract see IRRD 868006.

Proceedings ArticleDOI
07 Aug 1994
TL;DR: Uncooled infrared focal plane arrays have been developed which employ four detection mechanisms: resistive bolometric, pyroelectric, ferroelectric bolometric and thermoelectric as mentioned in this paper. They find application in thermal imaging systems for night vision.
Abstract: Uncooled infrared focal plane arrays have been developed which employ four detection mechanisms: resistive bolometric, pyroelectric, ferroelectric bolometric and thermoelectric. They find application in thermal imaging systems for night vision. Each of the four mechanisms is described. Figures of merit are defined. The fundamental limits to the performance of thermal detectors are presented. The state-of-the-art of the four types of thermal detectors is described and the role of uncooled focal plane arrays in thermal imaging systems is discussed.

Journal ArticleDOI
TL;DR: Some of the basic psychophysics relevant to amplified night vision devices are examined, indicating that display luminance and geometrical artifacts degrade detection performance only slightly, whereas contrast and visual interference have a substantial degrading effect.
Abstract: In this article we examine some of the basic psychophysics relevant to amplified night vision devices. These devices produce images that are substantially different from ordinary visual scenes. Distortions in contrast and luminance and the introduction of visual interference and geometrical artifacts contribute to unusual viewing conditions. We carried out experiments to determine the effect of these parameters of the image on a highly controlled visual target detection task simulated on a computer graphics system that closely models a night vision device. Our results indicate that display luminance and geometrical artifacts degrade detection performance only slightly, whereas contrast and visual interference have a substantial degrading effect.

Journal ArticleDOI
TL;DR: Data is reported on roost characteristics, population patterns and seasonal cycle of P. t.
Abstract: -Limited information is available on the use of summer roosts by Virginia big-eared bats (Plecotus townsendii virginianus) or on the timing of the summer reproductive cycle for this subspecies. We measured internal temperatures and structural characteristics of roosts, and used emergence counts with night vision equipment and mist netting to monitor P. t. virginianus at three maternity roosts and one bachelor roost in Kentucky, during 1990, 1991 and 1992. Structural characteristics of roosts varied. All colonies selected limestone caves except one that used a sandstone rock shelter. There were no differences in internal temperatures between the rock shelter roost and a cave roost in summer 1991. Timing of establishment of maternity colonies varied among roosts. Roost abandonment (switching) occurred with maternity colonies in caves. Females at the rock shelter roost were pregnant on 10 May and lactating on 17 June 1991; young were volant on 5 August. Bimodal activity patterns were observed at maternity roosts, except during lactation when activity of bats at roost openings persisted throughout the night. Population patterns at the bachelor roost were consistent across years. Low numbers in the bachelor roost in mid-August coincided with the descent of testes and the onset of mating activity. INTRODUCTION The Virginia big-eared bat (Plecotus townsendii virginianus) is one of two eastern subspecies of Townsend's big-eared bat (P. townsendii) listed as endangered by the U.S. Fish and Wildlife Service, because of its restricted distribution and the paucity of data on location and use of summer roosts (Bagley, 1984). The only studies of a P. t. virginianus maternity colony have reported data on activity patterns and food habits in Virginia (Dalton, 1983; Dalton et al., 1986). For the Kentucky population of P. t. virginianus, only sporadic population estimates exist for summer colonies (J. MacGregor, pers. comm.). Plecotus townsendii virginianus are vulnerable to human disturbance at summer maternity roosts (Barbour and Davis, 1969; Harvey, 1975; Bagley, 1984). This has hindered attempts to collect data on summer colonies of this subspecies; consequently, no information exists on its reproductive cycle. In this paper we report data on roost characteristics, population patterns and seasonal cycle of P. t. virginianus maternity and bachelor colonies in Kentucky. STUDY AREA AND METHODS This study was conducted in Lee County, Kentucky, within the Stanton Ranger District of Daniel Boone National Forest. Lee County is approximately 80% forested (Newton et al., 1974) and has a climate characterized by warm and humid summers and moderately cold winters. Average maximum and minimum temperatures are 34 C in August and -18 C in January (Newton et al., 1974). Average monthly precipitation is 9 cm (Newton et al., 1974). July and October are the wettest and driest months, respectively. The only known population of Plecotus townsendii virginianus in Kentucky hibernates in Present address: Cape Canaveral National Seashore, 308 Julia St., Titusville, Florida 32796

Journal ArticleDOI
D. C. Donderi1
TL;DR: Daytime percentage detection was positively correlated with low-contrast visual acuity and negatively correlated with error scores on Dvorine pseudoisochromatic plates and the Farnsworth color test, and there was no relationship between either acuity or color vision and life raft detection using night vision goggles.
Abstract: Visual acuity and color vision were tested during a search and rescue exercise at sea. Fifty-seven watchkeepers searched for orange and yellow life rafts during daylight and for lighted and unlighted life rafts at night with night vision goggles. There were 588 individual watches of one hour each. Measures of wind, waves, and weather were used as covariates. Daytime percentage detection was positively correlated with low-contrast visual acuity and negatively correlated with error scores on Dvorine pseudoisochromatic plates and the Farnsworth color test. Performance was better during the first half-hour of the watch. Efficiency calculations show that color vision selective screening at one standard deviation above the mean would increase daylight search performance by 10% and that one standard deviation visual acuity selection screening would increase performance by 12%. There was no relationship between either acuity or color vision and life raft detection using night vision goggles.

Journal ArticleDOI
TL;DR: In this paper, the spectral reflectance distributions of natural surfaces were used to guide color selection for scene components in a CATS EYE-based simulator for scene color selection, where the reflectance data permit, relative luminances have also been computed for simulation of landscapes viewed through night vision devices.
Abstract: : This report supplies chromaticity coordinates and relative luminances of certain natural surfaces for which spectral reflectance distributions are presently available. Modelers of geographical databases for simulator displays may use this information to guide color selection for scene components. Where the reflectance data permit, relative luminances have also been computed for simulation of landscapes viewed through night vision devices. ANVIS, Luminance, Scene color, CATS EYE, Natural landscapes, Spectral reflectance, Chromaticity, Night vision simulation, Tristimulus values.

Journal Article
TL;DR: Sixteen U.S. Army aviators, who were given training on focus adjustment technique with aviator night vision goggles, showed an improvement in visual acuity with focus adjustment compared to a fixed infinity focus control.
Abstract: : Sixteen U.S. Army aviators, who were given training on focus adjustment technique with aviator night vision goggles (NVG), showed an improvement in visual acuity with focus adjustment compared to a fixed infinity focus control. The long-term effect of focus adjustment on vision was not measured; however, adjustment accuracy was found to be generally within acceptable limits based on computer modeling and available physiologic data. Fixed focus eyepieces that are set to a low minus power may partially compensate for instrument myopia, but they may not optimize visual acuity to the extent that adjustable focus eyepieces do. Eyepiece adjustment proficiency with present night vision devices can be improved through training that emphasizes focusing to the least possible minus dioptric power. Future night vision displays can minimize focus misadjustment by providing a tactile zero marking, a limited dioptric adjustment range, and a focusing knob capable of finer adjustment than is available with current NVGs.

Patent
21 Jul 1994
TL;DR: In this article, a very small mirror is used to reflect symbology from the source to the viewing device while minimizing the interference of the reception of light from the dimly lit scene by the viewing devices.
Abstract: Apparatus and method for introducing superimposed symbology from a CRT into a dimly lit scene being viewed through a viewing device by utilizing a very small mirror to reflect symbology from the source to the viewing device while minimizing the interference of the reception of light from the dimly lit scene by the viewing device, reducing the light from the source to a level consistent with that from the dimly lit scene and decreasing the aperture from the source so that the symbology remains in focus over a large depth of focus.

ReportDOI
TL;DR: The purpose of this study was to identify the display luminances which produce a transient reduction in vision when switching from a higher luminance (i.e., FLIR) to a lower luminance(s), and to avoid large changes in display luminance which could transiently impair visual resolution and performance.
Abstract: Helmet-mounted displays under development for rotary- and fixed-wing aircraft will allow the user to switch electronically between forward-looking infrared (FLIR) and night vision goggle (NVG) sensors. These sensor transitions potentially involve large changes in display luminance which could transiently impair visual resolution and performance. The purpose of this study was to identify the display luminances which produce a transient reduction in vision when switching from a higher luminance (i.e., FLIR) to a lower luminance (i.e., NVG) display. A letter recognition task was used to assess the effect of luminance adaptation on visual resolution in five subjects. A significant reduction in letter recognition was observed in the first second after switching from simulated FLIR to simulated NVG's when the FLIR luminance was > or = 10 fL. By varying letter size, contrast, and exposure time, the magnitude and duration of visual loss after switching from a bright (49.2 fL) FLIR display were determined. The visual loss lasted up to 4 s, and included a 2x reduction in visual acuity, and a 3x reduction in contrast sensitivity. Large differences in sensor display luminance should be avoided to maintain high levels of visual performance and aviation safety. Design features or training may be necessary to achieve a proper balance between FLIR and NVG luminances which optimize performance and safety without sacrificing the quality of the sensor image.