Proceedings Article | 22 September 1997
Proc. SPIE. 3135, Precision Plastic Optics for Optical Storage, Displays, Imaging, and Communications
KEYWORDS: Optical components, Optical design, Displays, Eye, Glasses, Resistance, Image quality, Plastic lenses, Head-mounted displays, Temperature metrology
Plastic optical elements are used extensively for high- volume, low-quality, commercial applications. The advantages of plastic over glass elements include low weight, ease of modeling, high shock resistance, and low price in mass production. The use of plastic optical elements in military systems is limited by stringent environmental demands, and by the high image quality which is usually required. The disadvantages of plastic from this point of view are softness, low chemical resistance, thermal defaces, and inhomogeneity. Display systems are located in the same environment as the user. In an enclosed space, such as a vehicle, the requirements for environmental conditions can be greatly eased. In addition, visual optical systems may incorporate a focusing adjustment which can be controlled by the viewer. In combination with a limited temperature range, this solves the problem of thermal defaces. The resolution required in display systems is generally far from the diffraction limit, which reduces the significance of inhomogeneity. In addition, the eye pupil is usually smaller than the lens diameters, so that inhomogeneity only produces a local effect in the field of view. It would thus appear that plastic optical elements are a practical option for display systems, despite relatively severe environmental conditions.In this paper, the application of these considerations will be illustrated by a practical optical design for an airborne military display system incorporating plastic optical elements. The points of image quality and environmental requirements will be addressed.
