Good Vibrations

VIBRATION

Vibration is in itself NOT a problem in holography. A holographic camera could be shaking like mad without in any way disturbing thehologram. You see, vibration is not the problem. To understand the problem you have to think about how holograms are made. Basically, two waves of light meet and interfere on a film plane. The interference of the light waves form a pattern. If one wave moves it smears this pattern. By smearing the pattern, its like taking your hands and smearing a fingerprint. It loses its information as a blur. The same happens with the hologram. The more one wave moves, the more the overall wave interference pattern is destroyed, until you dim totally out. But if both light waves vibrate in unison no smearing occurs.

 Now, if your table is stiff, there is much less chance of one wave moving. The stiffness prevents the table from bending. And it is the bending that allows one of the light paths to change thereby moving that light wave in the interference pattern. So, stiffness is the real consideration in building an isolation table. The stiffer the table, the brighter the hologram.

RESONANCE

 Another interesting related topic is resonance. Too many people build isolation tables based on some drawing they saw in a badly written book. Usually, they end up making layers of crap to absorb vibration while totally failing to deal with stiffness! In so doing they create a whole new problem. Resonance. Do you remember seeing an old film clip about this bridge in the Seattle Tacoma region called “Galloping Gertie”? The winds in the canyon hit the bridge at a resonant frequency and caused it to wave like a flag before collapsing.

 Or, when you sing in the shower and hit a note that makes the whole room seem to amplify that note. That’s resonance. It happens when waves combine VERY constructively, adding as they match in size with the container they are placed in.

 In table construction, too many layers is like putting a spring on a spring. You can bet it will resonate. And instead of canceling the harmful vibrations, you are now amplifying them. Not a good idea. So be very careful not to build a system that only makes your work harder. Keep it simple. Make it a stiff one!

LIGHT

 There seems to be great confusion about the nature of light. Actually, it is pretty simple. Think of a basic atom. You have a nucleus and electrons spinning around it. Electrons are the stuff that makes electricity. They have an electrical charge. Normally, the atom is a fairly balanced system. But, if you put energy into this system, you can pump it up. For instance, if you send electricity in, the electrons of the electricity bump up against the electrons of the atom. As they collide its like a billiard ball hitting another billiard ball. The first ball (electron) transfers some of its energy into the second ball (electron) and sends it off. In the case of an atom, the electron is sent up temporarily into a higher orbit. Its something like blowing air into a balloon. The sphere the balloon occupies gets larger. Now, if you don’t tie off the end of the balloon the air you just blew into it will come back out. The same thing happens in the atom. And as the electron returns to a lower orbit it releases the energy that originally sent it flying up into the higher orbit.

 A good way to envision the release of energy is to think of yourself in a pool of water chest high. If you sweep your arm just below the surface of the water you make little whirlpools. This is the energy transferring from the movement of your arm into the water. The energy swirls like a vortex. I like to think of it as a “corkscrew”. A wave of light is a corkscrew or whirlpool of electromagnetic energy released as an electron returns from an excited orbit. The sweeping motion of the electron back to its normal or ground state is like the sweeping motion of your arm in the water. The electrical charge of the electron is transferred into a whirlpool of electromagnetic energy spinning off the atom. And it looks like a corkscrew. Think of how a typical corkscrew that you use to open a wine bottle looks. Now, turn it on its side and look at it. Its a sine wave. But that’s only if you look at it sideways. Most drawings in books show light waves in this way. However, light waves are three dimensional. Hence the corkscrew model.  You can think of the electron as being sheathed in an electromagnetic field. When it is energized by a collision it gains a bit too much of this electromagnetic jacket. As the electron returns a little bit of it twists free and tears off, becoming a free electromagnetic field twisted like a corkscrew. It twists because of the spinning motion of the electron. This a photon -a single wave of light.