How to make a hologram
Holography is described scientifically as a wavefront reconstruction process. Unlike a camera which forms and records the two-dimensional image of an object on film, a hologram records and reconstructs the light field propagating from a three-dimensional object to the viewer. A good analogy is the recording and play back of sound. The sound waves (e.g. music) are encoded and recorded on a disk. Upon proper decoding, the original sound waves are reconstructed. With holography, the field is encoded in the form of an interference pattern and recorded as refractive index variations on a clear window. The decoding is achieved by illuminating the hologram with laser light and the light field that was propagating from the object scene to the hologram window is reconstructed. Thus, a viewer cannot tell if the three-dimensional image he sees is "live" or a holographic reconstruction.
The Holographic sight makes use of the capability of a hologram to construct a three-dimensional image to produce a reticle that is projected out to the target plane. This is achieved by using a large, high quality aberration free lens to project the pattern as illustrated. The reticle image could be of any light pattern, any geometric shape or size, and produced in either 2 dimensional or 3 dimensional form. The holographic reticle is uniformly bright and distortion-free regardless of image size. A parallax free image is created with a large and bright aiming pattern allowing quick target acquisition, particularly in close quarter combat situations. At the same time, the HWS can produce an aim point as small as the human eye can resolve to achieve the highest aiming accuracy possible without magnification.