Retroreflective materials and optical imaging.
A retroreflective sheet returns each ray toward its source. If intercepted by a semireflecting plane mirror, the rays form a real image which lies as far behind the mirror as the source is in front. This principle can be used to make imaging systems with large apertures but without the usual aberrations.
Constant-deviation reflection with a microlens array
A novel form of reflector, incorporating an array of microlenses, is described. Incident illumination is reflected through an angle of deviation that is nominally independent of the angle of incidence. The reflector performs a function that is similar to a retroreflector but differs in that the angle of deviation is other than 180 degrees . This dispenses with the need to use a beamsplitter to extract the reflected wavefront, making for more efficient use of the available illumination.
Head-up displays—A Review
Part 1 of this review traces the background parameters which generate and specify requirements for head-up displays Taking the most common type as an example, the design of the optical unit, collimating lens and combiner glass is broadly described. Further applications of the concept are briefly discussed with reference to their impact on the optical industry. In Part 2 a more specific discussion of existing and proposed optical solutions to the airborne head-up display problem will be given.