Practical Holography Back to Something Resembling Normality

SPIE 12026 on Practical Holography XXXVI: Displays, Materials and Applications

The Practical Holography conference is part of the SPIE Photonics West event in San Francisco. It is an international event in the field of holographic applications and recording materials. The conference provides a venue for all aspects of holography: art, display, metrology, scientific, security, storage, materials and processes, computer generated holograms (CGHs) and holographic optical elements (HOEs).

The conference brings together participants from all over the world. Last year it was an online event only, caused by COVID 19. This year it took place 25 January 2022 and was to a large extent back to normal with in-person presentations. However, there were several cancelled presentations caused by travel restrictions for international participants, with most of the presenters coming from the US.

All sessions were chaired by Deanna McMillen, Garmin International, USA. The presentations were divided into three main sessions: Materials and Processes, Applications of Display and Art Holography, and Digital and Computer-Generated Holography. There was also a Poster Session.

In the session on recording materials Jack Mills, Covestro LLC, USA, described new applications of the Bayfol® HX photopolymer films in the field of augmented reality such as head-up displays (HUDs) and head-mounted displays (HMD), in free-space combiners, in plastic optical waveguides, and in transparent screens. The film itself and its integration in respective parts were further optimised to show increased resilience against environmental conditions and a long-term stability of the final products.

Maria Isabel Azevedo, Univ. de Aveiro, Portugal, has been creating digitally printed art colour choreographic holograms. The video recordings took place at DeMontfort University in Leicester, UK, using the linear Holoshot camera system. Geola in Vilnius printed the digital holograms. One example was PobDog a hologram in which the dancer turns into a dog.

Sadman Sakib Rahman, Univ. of California, USA, reported about diffractive network-based all-optical reconstruction of inline holograms, eliminating twin-image artifacts without the use of a digital computer. These trained diffractive networks generalise very well to reconstruct unknown holograms of new, unseen objects at the speed of light propagation through the physical diffractive network.

Nafiseh Mohammadian, Univ. of Central Florida, USA, described a new type of HUD. Traditional HUDs suffer from a lack of compactness mainly due to the use of bulky optics. A technique of recording holograms in photo-thermo-refractive (PTR) glass materials was presented. It is possible to fabricate a diffractive 2D beam splitter for a head-up display eyebox which will result in an improved more compact HUD system.

Julian Gamboa Northwestern Univ. USA, reported on phenanthrenequinone doped poly(methyl methacrylate) (PQ:PMMA) holographic polymer. It is suitable for applications in free-space communications and metrology. Holograms recorded in this material fall into the Bragg regime gratings. Such holograms can operate at nearly any optical wavelength, albeit at different angles. The work described designing and recording holograms to multiplex radically distinct wavelengths (eg. 780 nm and 1550 nm) for diffraction profiles to be optimised according to the application without requiring retuning of the setup.

The SPIE Holography Technical Evening Event was also chaired by Deanna McMillen. As usual, it started to remember the holographers who left us last year. Progress on the new Geola Holography Lab in UK was reported. Bo Hess described his new Vintage Lasers and Hologram exhibition. An update on the postponed ISDH event was provided. ISDH2023 is now planned to take place between 26 June and 1 July, 2023 in Seoul, South Korea.