Night vision

About: Night vision is a research topic. Over the lifetime, 6004 publications have been published within this topic receiving 67372 citations.

Glare sensitivity and optical side effects 1 year after photorefractive keratectomy and laser in situ keratomileusis

Abstract: Purpose: To compare the outcome of low-contrast visual acuity and glare sensitivity after photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK). Setting: Department of Ophthalmology, Cantonal Hospital of Lucerne, Lucerne, Switzerland. Methods: In this prospective study, patients selected PRK or LASIK after the advantages and disadvantages of both had been described. Snellen visual acuity and disability glare were measured with the Berkeley glare test preoperatively and 1 year postoperatively. At the 1-year follow-up, haze was graded and patients had to assess their quality of vision subjectively. Results: One-year follow-up of 58 patients in the PRK group and 64 patients in the LASIK group was achieved. In both groups, the mean uncorrected visual acuity was 20/32 (P = .63) and the mean best corrected visual acuity, 20/20 with no statistically significant difference (P = .20). There were no preoperative or postoperative differences between the 2 groups in low-contrast visual acuity under 4 glare conditions. At 1 year, LASIK eyes had significantly lower postoperative haze scores than PRK eyes (P = .0013). The number of eyes with visually moderate and disturbing halos or disturbances in night vision did not differ considerably between the groups (P = .88). Conclusions: Efficacy outcomes were generally similar in the PRK and LASIK groups. Both achieved good objective and subjective results after treatment with a second-generation excimer laser.

Training aid for use with night vision apparatus

Abstract: A filter arrangement is described which is incorporated with a night vision device. The filter arrangement consists of a variable density polaroid filter array and a blue-green filter all contained in a common housing and directed along a given optical path. The filter arrangement serves to control the amount of light directed to an input port of a night vision device such as a pair of goggles. In this manner, a user can be trained to employ the night vision device under direct supervision in daylight conditions and by variation of the polarizing plates is enabled to simulate nighttime conditions.

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).

Optical arrangements for Head-up Displays and Night Vision Goggles

Abstract: An optical arrangement suitable for use in night vision goggles and head-up display units comprising an optical projector (19) which forms a real image of optical data (F) to be displayed and an eyepiece (21) comprising a body of light refractive material (55) with input and output surfaces (59 and 63) and a mirror surface (54) angularly mutually so disposed that rays emanating from the real image and entering the body (59) at its input surface (63) are refracted at the input surface (59), totally internally reflected at the output surface (63), reflected at the mirror surface (54) and finally transmitted through the output surface (63) for viewing by an observer. For night vision goggle use the projector provides an image of the forward scene and incorporates an image intensifier (33). Where the observer is required to have a direct view of the forward scene the mirror surface (54) is a partially light-transmissive, partially light reflective surface at the interface between the light refractive body (55) and a second body of light refractive material (57) having an input surface (67) parallel to the output surface (63) of the first-mentioned refractive body (55).

Using Image-Based Metrics to Model Pedestrian Detection Performance With Night-Vision Systems

Abstract: The primary purpose of night-vision systems in civilian vehicles is to help drivers detect pedestrians. Pedestrian detection distance with night-vision systems has been modeled based on image metrics. However, the probability of pedestrian detection, in particular considering the factor of distance, has not been modeled based on image metrics. In this paper, we first describe a model of the probability of pedestrian detection, which compares several combinations of image-based clutter, contrast, and pedestrian size metrics using a simple mathematical equation. Next, we describe a model of the probability of pedestrian detection as a function of distance and image-based metrics by combining the model of pedestrian-detection probability and a model that represents the relationship between the distance to a pedestrian and an image-based pedestrian size metric. In the final model, image-based metrics are used to predict pedestrian-detection performance and can also be used to evaluate and support the development of night-vision systems in vehicles.