Red interior lighting used to preserve dark-adaptation needs to be replaced in military applications by blue/green lighting which is not detectable by 3rd-generation image intensifiers. This study investigated the influence of blue/green as compared to red and white light of equal photopic intensity on subsequent visual acuity , contrast sensitivity and dark-adaptation. Male subjects (n = 90) were assigned to one of 15 treatment conditions (n = 6) as determined by the colour (blue/green, red or white) and intensity (0.1; 0.4; 1.6; 6.4 and 25.6 cd/m²) of the pre-adaptation stimuli. A modified Goldmann/Weekers adaptometer was used to present the preadaptation stimuli, test stimuli and record visual (luminance) thresholds of each subject. Blue/green lighting had the same affect on visual (photopic) acuity and contrast sensitivity as white and red lighting. Blue/green affected visual (absolute) threshold at the start and during the process of dark-adaptation in the same manner as white but not the same as red lighting. White and red lighting did not differ significantly (p < 0.01) at low intensities (mesopic range) but did at the higher intensities (photopic range). After exposure to blue/green and white light, it will take longer to reach the same level of dark-adaptation than after exposure to red. These time differences increase with" increased intensities. The brightness ratio between red and white lights to produce the same dark-adaptation increases with an increase in intensity. At the upper mesopic region the differences between the effects of white and red lighting on subsequent dark-adaptation become irregular due to the inability to accurately equate non-monochromatic lights in the mesopic range.

The present study is a part of a long-time cooperative study of the Home Economics Department of the North Texas State Teachers College, begun in 1940. The purpose is to compare the dark adaptations of second and third-grade children made in 1940 with those made of the same children in 1941 and in 1942. Also included in this study is the comparison of a group of freshmen college men made in 1940 with a group of twenty-five men made in 1942. An attempt is also made to determine whether an individual has higher dark adaptation on sunshiny days than on cloudy days.

This study was formulated for the following purposes: (1) To determine if a learning factor is involved when repeated tests are made with a dark adaption instrument, (2) To determine if the dark adaption of a group of second and third grade children showing poor dark adaption can be improved by the daily administration of Haliver oil capsules, (3) To obtain a dark adaption curve for two hundred twenty-three grade children of Denton, Texas.

Ce travail de thèse, effectué en collaboration avec la société PHOTONIS, un des leaders mondiaux dans la conception de tubes intensificateur de lumière, et l'Institut d'Électronique du Sud de l'Université de Montpellier, a pour but l'optimisation des photocathodes de 3e génération à base d'(In)GaAs pour lunettes de vision nocturne. Après avoir décrit le principe d'un tube intensificateur de lumière et présenté les performances atteintes par ces différentes générations de dispositifs, le cas plus spécifique de la photocathode est abordé. Par la simulation des performances, deux structures photocathodes sont proposées. L'une pour la détection des faibles niveaux de lumière résiduelle dans le visible, l'autre pour l'extension de la réponse spectrale vers le domaine du proche infrarouge (λ=1,06µm). Le processus technologique pour la fabrication de photocathodes de hautes performances est décrit étape par étape puis les caractérisations électro-optiques, associées aux composants réalisés, sont présentées. Les résultats obtenus montrent des performances en termes de réponse spectrale qui dépassent régulièrement les 1600µA/lm. / This thesis reports on the optimization of 3rd generation photocathode based on (In)GaAs materialfor night vision google. It is realized in collaboration between the PHOTONIS Company, one of the world leaders in conception of image intensifier and the Institut d'Électronique du Sud from Montpellier University. After a description of an image intensifier operation and a presentation of the state of the art of the image intensifier devices, the more specific case of the photocathode is described. Two photocathodes structures are deduced from simulation of performances, one for detection of low levels of visible residual light and the other for infrared extension of spectral response (λ=1.06µm). The different steps of the technological process for the manufacturing of high efficiencies photocathodes are described and the electro-optical characterizations made are presented. The results show performances as hight as 1600$µA/lm.

<p>At night or in bad weather, the task of driving is very complex since the amount of visual information available is severely reduced. Vision Enhancement Systems may compensate for parts of the missing information by supplying the driver with a picture of the world where warm objects are made visible. This thesis investigates the impact of Vision Enhancement System display types on cognitive capture and driving performance. 16 subjects were recruited for a simulator study. It was hypothesised that when the contrast of a transparent display is high enough for the driver to separate the picture from the background and make out enough details to interpret it, the risk of cognitive capture is higher than when using an opaque display with the same objects visible. The subjects’ driving performance and opinions about the driving experience were also investigated. No significant differences in driving performance or level of cognitive capture was found. However, questionnaire answers indicate that this question needs to be investigated further to find out whether one display type is preferable because of better and safer driving performance or if individual differences between drivers require the possibility to choose the display type of their personal preference.</p>

The task for this master thesis was to create a specification for a second prototype of Scandilumen´s handheld gated night vision system. Current prototype is analogue and is to be upgraded with a digital interface. The specification was to contain information about manufacturers and performance on critical components such as image intensifier tube, image sensor and display. Scandilumen have previous experience with CCD cameras and wanted to know if the CMOS technology were sensitive enough to work properly in gated systems where high sensitivity is critical. Different image processing techniques was analyzed to find out the possibility to enhance image quality with an FPGA built-in into the system. When the specification is implemented, Scandilumen will have a prototype up-to-date with a digital interface and real time image enhancement. / Uppdraget i denna magisteruppsats var att ta fram en specifikation för en andra prototyp av Scandilumens grindade mörkerkamera. Nuvarande prototyp är analog och skall uppgraderas till en digital variant med display och anslutningsmöjlighet till dator. Specifikationen skall innehålla uppgifter om vilka ingående komponenter som skall användas samt vilken prestanda de skall ha. Exempel på dessa komponenter är bildförstärkarrör, bildsensor och displayer. Stor vikt har lagts vid att avgöra vilken typ av bildsensor som skall ingå i systemet. Scandilumen har tidigare erfarenhet av CCD-kameror men ville undersöka om CMOS-tekniken var känslig nog för denna typ av applikation. En jämförelse gjordes mellan de olika teknikerna med fokus på de höga krav som ställs på känslighet. Dessutom analyserades olika typer av bildbehandling som är lämpliga för systemet och som också går att implementera i en FPGA på lämpligt sätt. Om specifikationen följs kommer Scandilumen ha en prototyp uppdaterad med ett digitalt format och den senaste tekniken.

<p>The purpose of the project, which led to this thesis, was to investigate the possible effects different horizontal Fields of View (FoV) have on driving performance when driving at night with a Vision Enhancement System (VES). The FoV chosen to be examined were 12 degree and 24 degree FoV, both displayed on a screen with the horizontal size of 12 degree FoV. This meant that the different conditions of FoV also had different display ratios 1:1 and 1:2. No effort was made to separate these parameters. </p><p>A simulator study was performed at the simulator at IKP, Linköping University. Sixteen participants in a within-group design participated in the study. The participants drove two road sections; one with a 12 degree FoV and the other with a 24 degree FoV. During each section four scenarios were presented in which the participants passed one of three types of objects; a moose, a deer or a man. In each section, two of the objects stood right next to the road and two were standing seventeen meters to the right of the road. As the drivers approached the objects standing seventeen meters to the right of the road, the objects moved out of the VES when the vehicle was 200 meters in front of the object with a 12 degree FoV. The objects could be seen with the naked eye when the vehicle was 100 meters in front of the object. When the drivers approached the objects with a 24degree FoV the objects moved out of the VES display when it was possible to see them unaided. </p><p>Results show that a 24 degree FoV displayed with a 1:2 ratio gives the drivers improved anticipatory control, compared to a 12 degree FoV displayed with a 1:1 ratio. The participants with a broader FoV were able to make informed decisions whereas with a narrow FoV some participants started to reaccelerate when they could not see an object. Results also show that any difference in recognition distance that may exist between a 12 degree and a 24 degree camera angle displayed in a 12 degree FoV display do not seem to have any adverse effect on the quality of driving.</p>

Thesis (M.A.Sc.)--Naval Postgraduate School, 2001 / Includes bibliographical references (p. 163-166). Also available in electronic format via the Defense Technical Information Center website.

Thesis (M.A.Sc.)--Naval Postgraduate School, 2000. / Includes bibliographical references (p. 157-159). Also available in electronic format via the Defense Technical Information Center website.

The purpose of this thesis was to determine which perceptual cues drivers use to identify pedestrians that may constitute a risk in traffic. Methods chosen were recordings of pedestrian behaviour in Linköping by means of a stationary video camera as well as video camera mounted in a car. Interviews on the recordings from the mobile camera were conducted with taxi drivers and driving instructors. Results include that drivers not only react to pedestrians they believe will behave in a dangerous way, but also react to pedestrians that probably not will behave in such a way, but where the possibility still exists. The study concluded that it was not possible to determine how risky a pedestrian is considered to be by only using behavioural factors such as trajectory or position on the sidewalk, and distance. It is necessary also to include environmental factors, mainly where the pedestrian and car are positioned in relation to the side of the road, so that the behaviour of the pedestrian can be interpreted.