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Introduction

Overview

Optical Table

Environment

Laser

Beamsplitter

Mirrors/Lenses

Table Mounts

Optic Mounts

Plate Holder

Objects/Scenes

Hardcopy

Resources

Objects ⁄ Scenes

I will be using "object scene" to mean just one object or a scene of objects. Your object scene should have certain characteristics. It should be three dimensional if you want your holographic image to be three dimensional (having depth-of-field and parallax). You could use a two dimensional object as your subject, like a photograph, but your final image will be a three dimensional image of a two dimensional photograph floating in space. There would be no depth-of-field or parallax in the photograph itself.

Figure 13a shows four, three dimensional geometrical shapes that are painted white, red, green, and blue when illuminated with normal room light.

objects illuminated with normal room light image
Figure 13a: Illuminated with normal room light.

Be aware that these colors on the objects will be different shades of the laser's beam color in the recorded hologram. Since your laser's beam is monochromatic, so the colors will be monochromatic in the hologram. The objects' colors will not be white, red, green, and blue. Figures 13b & 13c show the objects in Figure 13a illuminated with red laser light and green laser light.

objects illuminated with red laser light image
Figure 13b: Illuminated with red laser light.

Under red laser light, the white cone and red sphere reflect more of the red laser light, making them a lighter shade of red. The green square and blue cylinder absorb more of the red laser light, making them a darker shade of red.

objects illuminated with green laser light image
Figure 13c: Illuminated with green laser light.

Under green laser light, the white cone still reflects more of the green light as does the green square and blue cylinder, making them a lighter shade of green. The red sphere absorbs more of the green laser light, making it a darker shade of green.

The size of your object scene should be smaller than the size of the recording plate you are using if you plan to make a white light reflection display hologram from your transmission hologram. Why? The recorded and processed multi-beam transmission hologram (called H1) will be used to project its real image of your object scene as the "new" object scene to be recorded by the multi-beam white light reflection hologram (called H2). H1 is essentially a window that H2 is looking through. If the object scene of H1 is larger in size than H1's recording plate size, then H2 will not be able to see all of the scene in H1 since H2 will be located a certain distance away from H1. Imagine looking through a window. If you're face is right up to the window, your view is wider, probably 180 degrees. If you're face is 2 feet away from the window, your view is narrower. H2 is usually placed several inches from H1. More on this later in Creating Transmission & Reflection Holograms. If you plan to make just a single-beam transmission hologram or a single-beam reflection hologram, your object scene can be as big as the coherence length of your laser.

Figure 13d shows a 3-3/4 inch x 3-3/4inch x 1/2inch thick piece of Plexiglas used as a mount to place the geometrical shapes on. Using a 3/16 inch bit, drill a 1 inch deep hole centered on the length and width of one side of this mount. Use a 1/4-20 tap to create threads. Spray paint the mount with enamel flat black paint. Attach a 3 inch short rod with a 1/4-20 bolt to this mount using the tapped hole. You can use any type of platform for your object scene that you want. Just make sure it is rigid, sturdy, or won't move during the exposure. Or you can just place your object scene directly on the table top surface, attaching it securely.

objects on mount image
Figure 13d: Mount for three dimensional geometric shapes.

You can attach your objects to any surface with double-sided tape, epoxy, or rare earth magnets. If your objects are heavy enough, you may not have to attach them at all. Whatever way you go about securing your objects to a surface, they must be mounted rigidly enough so they absolutely won't move during the exposure. Another important property of your objects is that they must be rigid themselves. I have never been successful in recording live flowers.

You are now ready to move on to Creating Transmission & Reflection Holograms.

 

Revised 5/2/2017