Different kinds of holograms
(For details and setup examples, see the Holography_Technology page.)
(For a more technical description see Holograms.)
Single Beam Reflection
Also called a Denisyuk Hologram this is the most common first hologram. It is fairly easy to set up and can be viewed in white light. This type of hologram is one of the least expensive as there are minimal optics and the stability requirement can be minimized by touching the plate to the object.
Single Beam Transmission
This is actually easier than a Single Beam Reflection however since it requires a laser for viewing it is not as common. The depth of field shown is often much better. This type of hologram is one of the least expensive as there are minimal optics and the stability requirements can be minimized.
Split Beam Reflection
This hologram is also known as an off-axis reflection hologram, or a "straight reflection" hologram. The laser beam is split into two beams with an partially mirrored beamsplitter, which can be mounted on a variable slide. One portion of the divided beam is spread with lenses or diffusion glass to illuminate the object, set in front of the holographic recording medium. The other portion of the laser is spread through a lens array or spacial filter, then reflected off of a collimating mirror, which is directed at the back of the hologram-to-be at the reference angle. The reference angle is determined by: practicality in the optical set-up; Bragg's angle and the frequency of the recording laser; and the angle of the intended viewing light; with a range of 38 to 46 degrees giving good interference fringes. The reference angle will become the illumination angle of view for the finished hologram. Steering mirrors are needed to complete this set-up.
This type of hologram can be more expensive to produce as there are additional optics needed and more stringent stability requirements. It can be much brighter than a Single Beam Reflection. It can also contain relatively vast parallax. Depth is limited as in a Denisyuk hologram. (Image plane reflection holograms offer greater depth and projection possibilities, but their parallax potential is not as great as in a straight reflection hologram)
Split Beam Transmission
This is the most common way to make a transmission hologram. It requires a beamsplitter and is most often used to make an H1 for copying. This type of hologram is going to be more expensive as there are additional optics needed and more stringent stability requirements.
H1 to H2 Copies
This is making a copy of a hologram. It is a more complicated set up requiring a beamsplitter and a good Master Hologram (H1). It allows the hologram to bisect the film plane with some of the scene in front of the plate and some behind.
This is a special case of an H2 copy. It is a transmission hologram made by masking the master hologram (H1) to a horizonantal slit. It is viewable in white light but the color changes with viewing position.
This is a very complicated set-up and has to do with storing many close views or perspectives of an object onto a single holographic plate in the form of slits. Then those slits are imaged to the same relative location in space creating a focused, multi perspective image. A hologram is then made of the combined image projections creating 3 Dimension hologram.
Holographic Optical Element (HOE)
HOEs are holograms that work like optical elements (mirrors and lenses).
By computing the interference patterns, it's possible to simulate a hologram in software. The result when printed to a transparency using a standard printer is usually low resolution and inefficient, but can work.