What is the single most important factor when making a hologram?
Stability! For simple holograms the required stability can be achieved by making sure that the plate and object touch and that there is no motion or vibration in the room during the exposure. For more complex set-ups involving a beamsplitter, all of the components after the beamsplitter need to be stable to within 1/4 of a fringe. Since fringe spacings range from about 600 to 2000 lines per mm the stability requirements can be quite high and involve building a Vibration Isolation Table/Bench. Pulse holography negates the need for stability but a suitable laser is expensive and dangerous to set up.
