Anyone looking for a whistle stop literary tour of the milestones that map out the history of holography are fortunate, as two articles have appeared this month that chart the course of the technology – from before Gabor’s invention to future applications in the Metaverse.
In the Innovation Section of Interesting Engineering 1 an article, written by journalist and researcher Rupendra Brahambhatt, talks about the various types of holograms, giving an easy-to-understand description of the different recording and reconstruction regimes of reflection and transmission holograms.
The primer into the science behind holograms starts with how a camera captures a photograph and from there takes the reader into the realms of superposition, interference and diffraction. This is probably the weakest section of the piece, as I suppose it is bound to be, since without assuming prior knowledge of coherent optics the author is left with relying on phrases such as ‘through a complex process, the light source converts the interference fringes into a reflection identical to the original object.’
The author is back on more solid ground with the history and development of holography – which starts by explaining the Victorian-period theatrical illusions, such as Pepper’s Ghost, that used the partially-transparent properties of glass to project an image of a person or object into the air from a hidden location away from the audience’s eyes.
The article then moves on to 1947 and Gabor’s invention of wavefront reconstruction, originally devised for improving the performance of the electron microscope. And then onto the development of the laser which paved the way for recording and reconstructing optical holograms.
The article concludes with cataloguing some of the applications of holography and lists some of the research going on in different parts of the world that are coming up with some exciting developments related to hologram technology. These new findings reveal numerous hologram applications in fields such as marketing, advertising, banking and gaming.
The second article ‘What Is a Hologram?’ 2 in the augmented reality (AR) section of XR TODAY, introduces holograms as ‘an effective way to blend physical realities with virtual ones… to project 3D images on a physical surface and simulate virtual designs in real-world surroundings.’ Of course, this description does give the impression that holography was invented in an algorithm, rather than a laboratory, but then redeems itself with basic definitions of what holograms are and how they work.
The use cases set out in the article include the familiar applications of art, security and fraud prevention, medical imaging and telepresence, then goes on to list the leading companies developing holographic technologies for building the Metaverse.
The technical media is littered with accounts of display devices that use the term ‘hologram’ to bolster their viewing credentials. So, it’s nice to see an article, written in a popular science style, that actually explains what a hologram is.
1 - https://interestingengineering.com/holography-and-holograms
2 - https://www.xrtoday.com/augmented-reality/what-is-a-hologram/
