You will have the opportunity to make two different holograms in this experiment, a simple two-beam transmission hologram, and a holographic interferogram.
Each holographic setup will be arranged by us about two weeks apart. You should plan to do the first part of this experiment in early November, and the last part late in the month. You must do both holograms to complete this experiment. Do not make any changes in the positions of the lenses or clamps on the table. It may be necessary to make minor adjustments to mirrors, but do this only on the advice of the teaching assistant.
Holography must be done on a vibration-free bench. We use a commercial table manufactured by Newport Corp. It is supported on four innertubes that isolate it from building vibrations. During all exposures it is essential that you not interfere with the isolation. Do not rest anything against the table and do not touch it during an exposure. It is also a good idea to check that the innertubes are really inflated. Make sure the isolated table is not touching the lab tabletop. Let us know if you find a problem and we will inflate the tubes again (they tend to leak a little).
Begin each exposure by gently pulling up a card that blocks the laser. When the card is not touching the table wait a few seconds for things to stop vibrating and then pull it all the way out to expose the film to laser light. Exposures are fairly short. You are using a 5 milliwatt helium-neon laser. Use the exposure times recommended in this manual, not those in the holography handbook.