Abstract: A method for formatting a texture in a frame buffer is accomplished by receiving a lock signal from a processor, where the lock signal is associated with the texture. A pointer to a location in the frame buffer is provided in response to the lock signal, whereupon the processor stores the texture in the frame buffer at the specified location. An unlock signal is then received from the processor, indicating that the texture has been stored. The texture is then copied from the frame buffer to a memory based on a tiling algorithm to produce a tiled version of the texture in the memory. The tiled version is then copied from the memory back to the frame buffer at the specified location.

Abstract: A method and apparatus for tiling a block of image data is accomplished by first receiving a set of parameters that describe the block of image data. An address is determined based on the set of parameters, and the address is translated to a corresponding tiled address. In translation, the address is first separated into horizontal and vertical coordinates. The horizontal coordinates are applied to a horizontal lookup table to obtain a horizontal component of a destination offset, and the vertical coordinates are applied to a vertical lookup table to obtain a vertical component. The horizontal and vertical components are then combined to produce the destination offset. The destination offset is added to a destination base pointer to produce the corresponding tiled address. Data is copied from the address to the corresponding tiled address. The address is then incremented, and the process is repeated for each address in the block of image data.

Abstract: This invention is concerned with display apparatus of the Head-Up-Display (H.U.D.) type which finds utility in e.g. fighter aircraft. The invention is concerned with providing an H.U.D. which has a profile depth which is substantially and preferably much less than the diameter of the exit lens. The arrangements of the H.U.D. include a cathode ray tube (C.R.T.) display source, a collimating optical means having a plurality of lenses with at least an entrance lens and an exit lens together with a prism and combining means for combining displayed visual information with the view of the scene or object. The prism is so arranged in relationship to the display source that internal reflection of light from the display source within the prism and transmission of light towards the combining means is such as to enable the modular unit profile depth to be between 40% and 60% less than the exit lens diameter.

Abstract: Optical viewing apparatus has an obective lens for focussing radiation from a scene or object to form an image on a detector and means for producing a visible display of the image which is viewed through an eye-piece lens. The objective lens is designed to impose a substantial level of barrel distortion on the image and the eye-piece lens imposes a substantial level of pincushion distortion on the observer's view to give improved central resolution. The radiation focussed by the objective lens may be visible or invisible, e.g. infra-red.

Abstract: An "eye-piece" system for an infra-red afocal telescope comprises a back element of positive power having a convex front surface and a curved back surface, and a pair of elements closely spaced to define a gas lens therebetween, the front element of the pair having a concave front surface whose radius of curvature is equal to or greater than that of the convex back surface of the back element of the pair, the pair of elements in combination with the gas lens therebetween being of positive power. The "eye-piece" system can be used in combination with an objective lens system, which may be catadioptric or all refractive, to provide a collimated magnified view of a scene or object, from which infra-red radiation is received, at a real exit pupil where a scanner operates.

Abstract: Optical apparatus for biocular viewing of relatively low cost and light weight comprises a solid Cassegrain configuration in a solid meniscus element having a negative lens element cemented to its convex face and an associated corrector lens element which provide a magnified collimated image of an object for viewing by a pair of telescopes having light folding means to provide an exit pupil separation suitable for two eye viewing. At least some of the lens elements may be of plastics material and aspheric surfaces may be employed. The apparatus is particularly useful for night vision goggles having a single image intensifier tube.

Abstract: An "eye-piece" system for an infra-red afocal telescope comprises a positive back element having a concave or convex back surface and a convex front surface, and a pair of elements closely spaced to define a gas lens therebetween, the back element of the pair having a convex back surface and the front element of the pair having a concave front surface, the pair of elements in combination with the gas lens therebetween being of positive power. The "eye-piece" system can be used in combination with an objective lens system to provide a collimated magnified view of a scene or object, from which infra-red radiation is received, at a real exit pupil where a scanner operates, and can provide a wide field of view of around 70 degrees or more in the scanner space.

Abstract: A transfer lens comprises a first field-flattening component of negative power, a second component of positive power providing overcorrect astigmatism, a third component of positive power consisting of a plurality of positive members providing most of the power of the overall lens and whose undercorrect astigmatism is corrected by the overcorrect astigmatism of the second component, and a fourth component of negative power which increases the field angle. The lens is particularly useful in a head-down display having two primary displays from which light travels to a combiner so that the transfer lens produces a combined image. A Fresnel field lens is preferably located at the image position.

Abstract: The invention provides an objective lens with a front lens group and a rear lens group spaced apart from the front group. The front group comprises at least two doublet components one of which is a crown positive element cemented to a flint negative element which has a higher refractive index and dispersion values than those of the crown glass. The other doublet component of the front group is a crown positive element and a flint negative element in which the flint and crown glasses have similar refractive indices but dissimilar dispersions with the flint glass having a positive red relative partial dispersion deviant.

Abstract: The "eye-piece" for a non-Gallilean afocal infra-red telescope comprises a front element which is meniscus with a convex back surface of greater radius of curvature than its concave front surface but which has a thickness such that it is of positive power, and a back element of positive power with a convex front surface and a convex or concave back surface. Such an "eye-piece" can be used in combination with a variety of objective lens systems.

Abstract: A biocular magnifying lens suitable for use as an eyepiece in a night vision device comprises from front to back a positive element which is bi-convex or meniscus convex towards the front, a negative meniscus element concave towards the front, a positive singlet or doublet element which is convex towards the front, a positive element which is bi-convex or meniscus convex towards the front, and a positive meniscus element convex towards the front.

Abstract: The invention provides a telephoto lens with a positive front group of lens elements, a negative middle group of lens elements and a rear positive part comprising a lens element or group of lens elements. The front group of elements includes at least one positive doublet consisting of a positive element of a crown glass type in front of a negative element of a flint glass type having a positive red relative partial dispersion coefficient deviation. The middle group of elements includes a positive lens element of a crown glass type and a negative lens element of a flint glass type having a positive red relative partial dispersion coefficient deviation. The rear element or group of elements may consist of a doublet component comprising a negative bi-concave element and a positive bi-convex element, the rear part of the telephoto lens being well separated from the negative middle part.

Abstract: An objective lens particularly for use in a low light level or night vision system designed to introduce a controlled amount of barrel distortion at the edges of its field of view to permit use with a flat input faced imaging tube.

Abstract: Apparatus for biocular viewing comprises a collimating magnifier lens and a prismatic assembly providing inclined partially transmitting/partially reflecting interfaces between solid parts and reflecting faces parallel to the interfaces which give multiple light paths by which an observer can view with each eye a magnified image produced by the lens.