Dr. Gabor receiving his Nobel Prize
I constantly hear people new to holography using the term holographs. It’s a logical conclusion to make considering the medium is known as holography, but holograph has a very different meaning and a part of the initiation into this medium is to understand that difference.
The word hologram was coined by the inventor of Holography, Dr. Dennis Gabor, a Hungarian born scientist living and working in the UK. The word is derived from the Greek words “holo” meaning whole and “gram” meaning message - the Whole Message. That’s the important piece to grasp about holograms, they contain another level of information that goes beyond photography, they contain information about the phase of the light that is used to record them.
To further clarify things there is something known as a holograph, the dictionary gave me the following definition
"holograph |ˈhäləˌgraf, ˈhōlə-|
a manuscript handwritten by the person named as its author: [ as modifier ] : a holograph letter by Abraham Lincoln.
ORIGIN early 17th cent.: from French holographe, or via late Latin from Greek holographos, from holos ‘whole’ + -graphos ‘written, writing."
The definition of a hologram is that it is a recording of a three dimensional image by exposing an interference pattern of light onto a photosensitive medium - a very different kettle of fish.
Dr. Gabor developed the basic theory that underlies holography around 1947 but it wasn’t until the development of the first lasers in the early 60’s that holograms (as we know them) became possible because the laser is necessary to generate that interference pattern of light. He received a Nobel Prize for his work in 1971.
Now that you understand the term “hologram” - I’ve often speculated as to why the medium became known as “holography”. If you start with the term hologram, it’s a lot easier to talk about holography than about hologrametry or hologramy or even hologrametrics...... ;-)