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Single Beam Reflection

Click here for illustrations and explanations. No plateholder or card blockers. Just the basics.

Single Beam Transmission

Click here for illustrations and explanations. No plateholder or card blockers. Just the basics.

Split beam reflection

Split beam transmission

Path Length Matching Tips for Pulsed Ruby Holograms

H1 to H2

The H1 to H2 copy technique is commonly used for production and copying of commercial art holograms. Though the setup is more complex and difficult than a simple single beam arrangement, the result can be MUCH brighter than the original H1 because during the copying process one has complete control over the Beam Ratio. Commercially, the savings in time when making many copies from a master H1 make it indispensible.

Here is a discussion on using Brewster's angle in H1 to H2 setups.

One fact, that if not taught, will be learned very quickly, is very evident in the final hologram and can waste a lot of time, energy and materials. That is, it is the pseudoscopic real image that is being made from the H1 onto the H2. Because this image is pseudoscopic an overhead reference beam used in creating the H2 will create a hologram that if displayed also with an ovehead display light will display a pseudoscopic image. I doubt this is what is desired. Thus it is important that in the copy set up the reference beam needs to enter the plate from the bottom and what is actually the back of the hologram if the display lighting is needs to come in from the top front. I tried to illustrate this in the image below and this is for a reflection H2 copy.


Rainbow holograms

A Rainbow hologram is a white light viewable transmission hologram. The vertical parallax is sacrificed so that the hologram can be viewed in white light. Most Rainbow holograms are displayed with a silver backing so that even though they are transmission holograms, they can be viewed as a reflection hologram, that is, with the light behind you and over your shoulder.

A rainbow hologram (H2 transmission) can be made from any transmission H1 hologram. The key is to restrict the image from the H1 down to a slit. There are a variety of ways to do this (briefly describe below in the “Embossed Holography” section) but the simplest, and one we will explain here, is to set your table geometry up as a standard transmission H1 to transmission H2. Then simply mask the full size H1 down to a slit approximately 1cm in width along the horizontal relative to the object. If you have a white card in where the H2 should be you will see as you mask down the H1 the image’s depths on the white card become more visible or more in focus. Then expose as needed. Then when viewed with white light as a transmission the hologram will have full horizontal parallax when you move you head side to side but as you move your head up and down the image will scroll through the colors of the rainbow, thus the name. If you take your credit card outside and look at it in the sunlight, you can easily observe these phenomena.

Saxby bypass

Multiple coherence volumes

Click here Multiple Coherence Volumes

Path Length Matching

Click here Path Length Matching


Stereograms are also called Muliplexed holograms. The idea behind the proceedure is very straight forward but depending on the number of slits, the actual technique can very difficult or to say the least, time consuming to produce.

The basic building block of this hologram is the master H1 hologram. The master hologram is made up of individual holographic slits, which usually are simple 2D objects. But like the frames of a movie, each slit has a slightly different perspective. If you want to really invision this, take a completed tranmission hologram of an object and cut the film into very narrow slits, about 3mm in width. Now illuminate each slit and project the image onto a white screen. Because of the narrowness of the slit you will notice in the illumination of one slit that the real image, when projected on a screen, has most of it's depth focused on the screen at one plane. This is similar to the slit technique in the Embossed Holography section below.

To make the individual slits, simply set your geometry up to make a tranmisson hologram. Usually the object used is a tranmission LCD screen in which the "object" can be rotated via a computer for the subsiquent frames or slits. A diffusing screen is also placed against the LCD screen on the opposited side of the LCD screen with respect to the holographic plate. The idea is to diffuse the laser light before it goes through the LCD screen and finally on to the plate. This technique can also be applied to transparancies or negative photographic or movie film instead of and LCD screen.

When the LCD screen has the first of a series of consecutive images on it, the holographic plate is masked at one end down to a few millimeters slit. The exposure is then made. Now the next image is advanced on the LCD screen and the slit mask is moved to the adjacent spot on the holographic plate and the second exposure is made. This is repeated for every "frame".

After development in essence what you have is a holographic plate that has many slits side by side on it with the slits containing subsiquent views of an object or scene all from a slightly different but adjacent perspective. When this master is copied onto another holographic plate (H1 to H2 copy set up) all perpectives form at the same relative location in space at the H2 plate. Then when this plate is processed and viewed a 3d image can be seen because one eye sees one perspective and the other eye sees another perspective allowing the brain to create a 3d image of the object.

This is truely a great technique for scaling down holograms of people or places to smaller sizes which can fit on 4x5 plates. Because the hologram is made from 2d images is is also possible to holograph what normally could not be holographed, as is something that cannot be brought into the lab.

Frank DeFreitas has great and easy step by step intstructions to get you started in Stereogram Portraits on his web site.

Embossed Holography

Embossed Holograms