# Holograms "pieces" **URL:** \ **Category:** Factual Questions\ **Created:** [January 14, 2000, 7:18pm UTC](https://boards.straightdope.com/t/holograms-pieces/6213 "2000-01-14T19:18:00Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![Jinx](https://avatars.discourse-cdn.com/v4/letter/j/c6cbf5/32.png) [@Jinx](https://boards.straightdope.com/u/Jinx)\ **Post date:** [January 15, 2000, 6:57am UTC](https://boards.straightdope.com/t/holograms-pieces/6213/1 "2000-01-15T06:57:00Z")
When viewing a show on how holograms are made and how they work, the show stated that even a piece of a hologram could recreate the whole image! How is that possible? It seems like the interference pattern would have to be homogeneous for this to be true. The interference pattern recorded on film can’t be homogeneous, or else the image would be a homogeneous, amorphous image, right? ---
**Author:** ![pluto](https://avatars.discourse-cdn.com/v4/letter/p/f08c70/32.png) [@pluto](https://boards.straightdope.com/u/pluto)\ **Post date:** [January 14, 2000, 7:18pm UTC](https://boards.straightdope.com/t/holograms-pieces/6213/2 "2000-01-14T19:18:00Z")
The interference pattern isn’t homogenous, just scattered. ## The information to reconstruct the hologram is distributed throughout the recording medium. Any piece of the medium has some information about all parts of the image. It doesn’t contain all the information though. So a hologram reconstructed from just a portion of the recording would be cloudy or grainy – degraded somehow – but would contain the whole image. “To do her justice, I can’t see that she could have found anything nastier to say if she’d thought it out with both hands for a fortnight.” Dorothy L. Sayers _Busman’s Honeymoon_ ---
**Author:** ![torq](https://avatars.discourse-cdn.com/v4/letter/t/dfb087/32.png) [@torq](https://boards.straightdope.com/u/torq)\ **Post date:** [January 14, 2000, 7:47pm UTC](https://boards.straightdope.com/t/holograms-pieces/6213/3 "2000-01-14T19:47:00Z")
I _think_ that statement only applies to certain kinds of holograms. Or maybe some things are called “holograms” that really aren’t. I know from experimentation that cutting the dove hologram on a Visa card in half does not result in two smaller images of a dove. It results in a left half of a dove and a right half of a dove. ---
**Author:** ![bda](https://avatars.discourse-cdn.com/v4/letter/b/5e9695/32.png) [@bda](https://boards.straightdope.com/u/bda)\ **Post date:** [January 15, 2000, 11:38pm UTC](https://boards.straightdope.com/t/holograms-pieces/6213/4 "2000-01-15T23:38:00Z")
i believe each piece contains the whole image yet your view is limited to the size of the piece, angle of view and its orignal relative position to the object. an excellant book for holography study is “the holography handbook” by fred unterseher. it contains in depth instructions for making your own holograms plus several fascinating chapters on holographic theory in relation to human brain function and physics. ---
**Author:** ![PrivyQueen](https://avatars.discourse-cdn.com/v4/letter/p/85e7bf/32.png) [@PrivyQueen](https://boards.straightdope.com/u/PrivyQueen)\ **Post date:** [January 16, 2000, 5:56am UTC](https://boards.straightdope.com/t/holograms-pieces/6213/5 "2000-01-16T05:56:00Z")
Ok, this comes from my class on Holography Laser Photography that I took three years ago. A hologram is a photograph of the 3-dimensional impression left on the surface of a light wave _after_ it has bounced off an object. The word hologram is derived from the Greek word “holos”, meaning whole or complete, and “gram”, meaning message. A hologram can be seen as a window that stores memories. Similiar to looking through a partially covered window, you can see an entire image by looking through a part of a hologram. This is because the light bouncing from each point on the object is not focused to a point on the film, but is allowed to spread out through space between the object and the film. Ummm…I could go on a little more. It was one of my favorite classes. Hope this helps. ---
**Author:** ![PrivyQueen](https://avatars.discourse-cdn.com/v4/letter/p/85e7bf/32.png) [@PrivyQueen](https://boards.straightdope.com/u/PrivyQueen)\ **Post date:** [January 16, 2000, 6:05am UTC](https://boards.straightdope.com/t/holograms-pieces/6213/6 "2000-01-16T06:05:00Z")
Interference patterns - In holography there are two basic waves that come together to create the interference pattern. First and foremost is the wave that bounces off the object we are making a hologram of. Since it bounces off the object, thereby taking its(the object’s) shape, it is called the _object_ wave. You can’t have interference without something to interfere with. So a second wave of light that has _not_ bounced off the object is used. This is called the _reference_ wave. As light waves cross paths and interfere, the pattern they make is called a _standing_ wave. Called that because it stands still, and since it stands still it can be photographed… When an object wave meets a reference wave creating a standing wave pattern of interference it is photographed and called a hologram. * * * I could _hear_ you not saying anything. You’ve got the loudest silences I ever did hear from anyone who wasn’t dead! _Granny Weatherwax_