Multiplex holograms are used very widely today in various applications. The multiplex hologram is a popular type of hologram depicting the holographic storage of photographic information. It is a type of hologram which is produced by combining a large number of photographs in a holographic manner.

We all know that a hologram usually provides a way to record and reproduce a three-dimensional, still image of an object. The method of recording and replaying a three-dimensional, moving picture is called a multiplex hologram. In multiplex hologram, a three-dimensional image is viewed in a slowly turning transparent cylinder. In other words, multiplex holograms represent large number of flat pictures of an object which is viewed from different angles. These pictures are then combined into a single, 3D image of the subject. In case of a rainbow hologram, the same image of the object appears in a different color when viewed from different angles.

Property of Multiplex Hologram

Multiplex holograms are an interesting type of hologram. Some important properties of these holograms are as follows:

• Multiplex holograms not only represent a three-dimensional image but also have the possibility of capturing movements.
  
  
• Usually a multiplex hologram creates horizontal parallax and not vertical parallax. This is because the camera usually moves around and does not usually pass over the subject. The subject moves around in front of the camera.

Stages of Production of Multiplex Hologram

• First stage: A group of photographs of the object is taken. The number of photographs taken depends on how much of an angle of view you want to view of the object in your finished hologram. For example if 360 degree view of the subject is required, then you can expose 3 frames or stills per degree of movement around the subject. This will result in the exposure of 1080 frames.
  
  
• Second stage: When your film is developed, the next step is to make a series of "slit" holograms. Here you use each frame of film as a subject for each slit of holographic film. This is done in the holographic lab, using a laser. The slits are usually about one millimeter wide. These narrow strips capture the movement process only two-dimensionally, and then they are subsequently recorded on the hologram plate. They are packed together so close to each other that there is no "dead space" in between.
  
  
• Third stage: Also the hologram is bleached so that the strips disappear. The result is a hologram comprising more than 1000 different strip holograms.

For example, the right eye can view an image which is stored further to the right in the hologram than the image of the object which is seen by the left eye. Since during recording, the camera is moved around the object, each image has a different angle of viewing the object. The brain thereby creates a three-dimensional structure from the images. If the viewer now moves around the hologram, he or she can see one strip of hologram after another. Since the images are different from each other chronologically, the movement is clearly observed. This is the multiplex hologram.

The above is an example of multiplex hologram where the lady in the photograph throws you a kiss and winks at you as you walk by the hologram from left to right. The photographs above show the multiplex hologram at the beginning and the end while walking across from left to right.

Advantages of Multiplex Hologram

The advantage of multiplex hologram is that without the use of the expensive, clumsy pulse ruby laser, you can have hologram of almost anything you can capture on ordinary film. Multiplexing hologram can have a very firm place in the growing field of display and advertising holography.

Disadvantage of Multiplex Hologram

The disadvantage of multiplexing hologram is that it is not really a hologram in the true sense. Rather, it is photographic information holographically stored.