A lenticular screen is an optical device consisting of a transparent sheet or panel into which a regular array of small, precisely formed lenses - known as lenticules - have been moulded or embossed in closely spaced rows or grids. Each individual lenticule is a miniature lens element, typically cylindrical or spherical in form, that refracts light passing through it in a controlled and predictable direction. The collective optical behaviour of the entire array of lenticules gives the lenticular screen its distinctive and useful optical properties, which have found application in several distinct areas of photographic and optical technology.
In exposure metering, lenticular screens have been used as light gathering elements in certain types of photographic exposure meter, where the array of small lenses serves to collect incident light arriving from a broad range of angles and direct it efficiently onto the light sensitive cell of the meter. The optical properties of the lenticular array also help to define the angle of acceptance of the meter - the angular range over which the instrument is sensitive to incoming light - allowing the meter to be designed to respond to light arriving from a specific solid angle that approximates the angle of view of a particular lens or category of lens, improving the relevance and accuracy of the meter's readings for the intended photographic application.
The second and perhaps more visually striking application of lenticular screens in photography is in the production of stereoscopic and autostereoscopic images - three dimensional images that can be viewed without the need for special glasses or viewing devices. In this application, a lenticular screen consisting of rows of cylindrical lenses is precisely aligned over a specially prepared interlaced print that contains two or more slightly different perspective views of the same scene, each corresponding to the viewpoint of one eye in normal binocular vision. As the viewer's position relative to the screen changes, the lenticular lenses direct slightly different portions of the interlaced image to each eye, synthesising the binocular parallax that the human visual system interprets as three dimensional depth perception and creating the compelling illusion of a three dimensional image within the flat plane of the print.
Lenticular stereoscopic prints were used in a variety of novelty, advertising, and scientific applications throughout the twentieth century, and the technology has seen renewed interest and development in the digital era, where the precise interlacing of multiple perspective views can be achieved with great accuracy using digital printing and image processing techniques. Lenticular displays are used today in advertising, packaging, point of sale materials, and novelty printing to produce images that appear to change, animate, or reveal three dimensional depth as the viewing angle varies, exploiting the same fundamental optical principles that underpin their photographic predecessors.