Hologram is a special type of image made with a laser in which the flat objects look solid as if they are real. With recent advances in computer science, we can reconstruct a hologram from a picture programmatically without using physical technology (digital sensors, cameras, lasers, etc.)
It seems that digital holography means the future in many areas of human communication. The Meta’s CEO Mark Zuckerberg explains the vast amount of money flowing into Augmented Reality and projects the future where holograms are integral parts of it:
"In the future, instead of just doing this over a phone call, you’ll be able to sit as a hologram on my couch, or I’ll be able to sit as a hologram on your couch, and it’ll actually feel like we’re in the same place, even if we’re in different states or hundreds of miles apart. I think that is really powerful." (BBC News, 2021).
Also, Google recently unveiled Project Starline, a Hologram-like video chatting tool. Imagine looking through a holographic window, and through that window, you see another person in three dimensions. You can talk, gesture, and make eye contact as if the person was in front of you. Project Starline is currently available in just a few of Google’s offices, and it relies on custom-built hardware, but we can expect its spread to standard Google’s products soon.
This article stays in this line. It will provide a highly practical introduction to digital holography and introduce HoloPy, a python-based tool for working with digital holograms. Instead of building complex machinery, we can code a hologram from the comfort of the office.
HoloPy: Digital holography in Python environment
HoloPy is a software package for computational light scattering and digital holography created by Harvard University’s Manoharan Lab. It provides tools for managing meta-data, reconstructing holograms from 2D images, fitting scattering models to digital holograms, and lots of other applications.
The theory behind HoloPy is described in detail in Barkley et al. (2020).
Hologram examples
Let’s prepare some simple holograms with HoloPy. With some editing, they are adopted from the HoloPy documentation. The following piece of text covers (a) Python implementation and (b) created holograms in high resolution.
How do you see the hologram?
- zoom out with the mouse until the picture gets small
- slowly zoom in until hidden patterns start appearing
- when the image has normal size, move the head back and forth a couple of times to see some more new hidden motives.
Holograms can be seen well on at least 14ʺ size desktop monitors or laptops. Here is the implementation:
A simple code produces a grey-scale hologram:
The next example is a single-center colored hologram that lacks some background motives. Here is the python code followed by a holographic image:
It is really worth experimenting with different spheres, colors, parameters, and theories that Holopy offers to reconstruct holograms, do scattering calculations, and fitting models to the data.
Conclusion
This article has provided a practical introduction to digital holography with HoloPy in python. Holograms also have many applications in other domains. In marketing, for example, Tohana (2020) and Ardolf (2021) highlight three reasons why holographic marketing is booming:
- X-Factor – holograms have a unique way of breaking through the noise
- demonstrable & experiential – they provide a real-life experience
- memorable – **** a memorable experience allows to share it with friends and family.
Digital holography is a broad discipline of science whose overview goes beyond the scope of this article. The field is moving forward very fast, and research and innovations are prioritized in academia and the private sector. A thrilling example is the work the Sussex University scientists developing a 3D image that moves, recreates sounds, and even mimics the sensation of touch.
All of these advances look very promising. Naturally, any 3D images get compared to Star Wars __ holograms. But the images created by current technology are still small and far from photorealistic. Gibney (2019), however, in a Nature article, is optimistic and cites a Qiong-Hua Wang at Beihang University:
"Creating the kind of 3D effect in Star Wars by any means could take ten years, or even longer" (Gibney, 2019).
These projections are stirring and worth waiting for…
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References:
[1] Ardolf, M. (2021). Hologram marketing – the future of digital marketing. 16 August, 2021. Retrieved from: https://youdontneedwp.com/mathewardolf/hologram-marketing-the-future-of-digital-marketing.
[2] Barkley, S., Dimiduk, T., G., Fung, J., Kaz, D., M., Manoharan, V., N., McGorty, R., Perry, R., W., Wang, A. (2020). Holographic Microscopy with Python and HoloPy. Computing in Science & Engineering, vol. 22, no.5.
[3] BBC News (2021). Zuckerberg wants Facebook to become online ‘metaverse’. BBC News Service, 23 July 2021. Retrieved from https://www.bbc.com/news/technology-57942909.
[4] Gibney, E. (2019). Star Wars-style 3D images created from single speck of foam. Nature, 575, pp. 272–273. Retrieved from: https://www.nature.com/articles/d41586-019-03454-y.
[5] Tohana, L. (2020). Advantages of Holograms and What It Means for the Future of Marketing. The Future of Marketing Institute, 23 September, 2020. Retrieved from: https://futureofmarketinginstitute.com/advantages-of-holograms-and-what-it-means-for-the-future-of-marketing/.
