Holography is a method of recording an objects image in a way that when viewed later, it appears three dimensional. A light field is created by a laser source that illuminates both the object and the recording media. The scattered light from the object interferes with the reference light and it is this interference pattern that creates the image. Light from a laser is split in two and, via optical components, is formed to illuminate the object and the recording media.
Holograms are used in many different areas such as artistic displays, security marking and data storage. This latter application is particularly interesting as it offers the possibility of storing far higher quantities of data compared to magnetic or 2D optical methods, with the added benefit of the data being read at far higher rates.
In order for the interference pattern to be encoded with information about the object, the coherence length of the illuminating light is an important factor, and due to the long exposure times needed, the available power, wavelength stability and divergence of the beam are critical.
The coherence length of the laser becomes less critical when being used to copy/print a hologram and many of our lasers are suitable, however the torus range from Laser Quantum are ideal for all holography applications as the beams have long (>100 m) coherence lengths, divergence and the mode stability that only active locking provides.