Volume hologram, one of the most commonly and widely used transmission hologram, is a hologram when the angle of difference between object beam and reference beam is from 90 degrees to 180 degrees.

At 90 degrees the angle is great enough and fringe spacing becomes small enough for us to say that the recording process is taking place throughout the volume of thickness of the emulsion.

In a volume reflection hologram the reference beam makes an arc clear around so that it hits the film from the opposite side as the modulated object beam.

Volume hologram is recorded by two coherent beams in which one is called signal beam and the other is call reference beam. If the reconstruction beam used to probe the volume hologram is identical to the original reference beam respected to the wavefront profile and propagating direction, a strong diffraction is generated. The diffraction propagates along the signal beam propagating direction and preserves identical wavefront profile. In this case, the volume hologram is called Bragg matched.

Advantages of volume holographic imaging systems:

• More design freedom
• Higher light efficiency
• Lower building cost
• Large storage capacity
• Parallelism of information readout

Applications of Volume Hologram

• Microelectronic packaging
• Food packaging
• Optic packaging
• Electrical packaging
• Isotopic labelling