Telescope windows: low-vision scopes to cloaks

Lead Research Organisation: University of Glasgow
Department Name: School of Physics and Astronomy

Abstract

We propose building several novel optical instruments that extend the possibilities of conventional ray optics designs by utilising pixellated ray optics.

The Glasgow team has pioneered micro-structured sheets called telescope windows (TWs), currently at the early demonstrator stage, that can perform very general light-ray-direction changes. They consist of arrays of micro-telescopes and can be understood as pixellated optical components (each telescope being a pixel) which introduce, at the boundaries between neighbouring pixels, discontinuities in the transmitted light beams. TWs therefore remove the global continuity of wave fronts, which in turn is assumed in the derivation of a number of properties (and therefore limitations) of light-ray fields. If the pixel size is chosen appropriately, the pixellation can be almost unnoticeable. The vision of this work is that, by replacing globally continuous wave fronts with piecewise continuous wave fronts, the possibilities offered by optics, specifically ray optics, can be significantly extended.

The first applications of this technology form the focus of this proposal:
* TWs can form pixellated transformation-optics (PTO) devices that work across the entire visible wavelength range.
* TWs can distort the view as if the observer was moving at relativistic speed.
*TWs form the basis of novel, low-cost, high-comfort, low-vision aids.

Together, the applicants have the expertise to realise this wide-ranging project: DR is a world leader in micro-machining, enabling us to manufacture TW devices. GL and JG's ophthalmology and commercialisation expertise places us ideally to develop novel low-vision aids. We are also experts in pixellated ray optics (JC), relativity (MH, NG), mathematical physics (CW), and outreach (MH).

We are applying for funding now to enable us to produce demonstrators of TW devices, illustrating the wide applicability of our technology, evaluating the limitations and quality of such devices, and investigating the production methods required for this new class of optical instrumentation.

Planned Impact

Beneficiaries and impact arising from this project include the following:

1) Impact on the health and wellbeing of partially-sighted people.

Partially-sighted people will benefit from more comfortable, improved performance and less unsightly low-vision aids. It is expected that the optical elements in our low-vision aids, which are closely related in structure to 3D postcards, in the long term will be manufactured at low cost using a simple replication method. We will also investigate the potential for our low-vision aids to be suited to help partially sighted people in the developing world. For the purposes of CE marking, our low-vision aids are not classified as a medical device, which means they require no complex clinical assessment/medical device marking. We therefore believe that our low-vision aids could be on the market within 5 years from project completion.


2) Economic impact and creation of new ventures exploiting the commercial opportunities from our research.

This could range from manufacturing low-vision aids for both the developed and developing world to science communication exhibits. We will also explore the potential of telescope windows in fields such as architecture, where large-scale transformation optics with windows could have potential applications such as making openings in the wall appear much bigger than they actually are (thereby reducing heat loss but increasing natural lighting) by "funnelling" sunlight through small openings in the wall. We also anticipate that the new freedom in optical design will have applications in areas we are not currently aware of, hence one aspect of the pathways to impact will be to connect with "known unknown" potential users.


3) Impact on science communication to school children and the general public as well as advanced teaching aids for university students.

We will deliver a new exhibit, enabled by our transformation-optics devices, which will demonstrate and facilitate an intuitive understanding of visual aspects of Special Relativity. The Glasgow Science Centre has already expressed an interest in hosting the exhibit, which will be ready in time for the centenary of General Relativity (2016). Secondly, we envisage creating a pane of telescope glass to be used as a novel instrument through which a group of people can simultaneously view astronomical objects. More generally, there is scope for many more ways to utilise the properties of telescope windows to provide an intuitive understanding of otherwise abstract mathematical concepts such as making the space behind the window look like it has a different metric, for example as a means of introducing the concept of Riemannian spaces in Mathematics or in the context of General Relativity. Finally, Tardis-window and invisibility-cloak exhibits will be used to demonstrate the ideas of transformation optics.


Additionally, we will train skilled people in an environment that ranges from Theoretical Physics to industrial applications. The postdoctoral researchers on the project will interact with a range of industries and the clinical environment, increasing their experience for subsequent further employment in a wide range of sectors. We will also expose the methods of diamond machining to a new cohort of potential industrial users.

Publications

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Belín J (2019) Imaging with two skew ideal lenses. in Journal of the Optical Society of America. A, Optics, image science, and vision

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Belín J (2019) Ideal-lens cloaks and new cloaking strategies. in Optics express

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Chaplain GJ (2016) Ray optics of generalized lenses. in Journal of the Optical Society of America. A, Optics, image science, and vision

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Courtial J (2018) Experimental demonstration of ray-rotation sheets. in Journal of the Optical Society of America. A, Optics, image science, and vision

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Georgantzis Garcia D (2020) Optical triangulations of curved spaces in Optica

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Gray N (2020) Relativistic photography with a wide aperture. in Journal of the Optical Society of America. A, Optics, image science, and vision

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Oxburgh S (2017) Ideal-lens stars

 
Description We have greatly improved the understanding of telescope windows (TWs). Specifically, we have quantified, theoretically, the angular blur due to pixel visibility and diffraction (which are competing effects).

We have developed ideas for overcoming the shortcomings of TWs. Specifically, we now understand how to optimise the pixel size; how to remove effects due to pixel visibility entirely; and how to remove crosstalk between pixels.

We have built a number of prototypes to test out manufacturing techniques; to study the effect of pixel size on image quality; and to demonstrate our approaches for removing pixel-visibility effects and crosstalk.

We have gained new insights into subtle effects of relativistic photography (i.e. photography when the scene moves at relativistic speeds with respect to the camera), specifically the role of the "shutter model", which determines the precise way the camera's shutter opens.

We have constructed, theoretically, a structure of ideal thin lenses that functions as a ray-optical transformation-optics (TO) device. This was meant to be the first step in the standard optical-design procedure of designing a TO device from real lenses, and we are working on replacing the ideal lenses with real lenses. But the ideal-lens TO device on its own is very interesting: in addition to being a standard invisibility cloak, it can also function as a completely new type of cloak and an omnidirectional lens, a new type of optical element.

We have invented several new types of adaptive integral lenses.
Exploitation Route Most promising in this regard are currently applications of telescope windows as low-vision aids for patients with certain eye conditions.
Sectors Healthcare

URL https://www.researchgate.net/project/Telescope-windows-low-vision-scopes-to-cloaks
 
Description Impact is still developing. 1) Over the course of the project we have improved our understanding of the requirements for the optical components in medical low-vision aids and why current TWs do not meet these requirements, but we have also identified techniques to overcome every single one of these. However, as the solution to some problems make other problems worse, this requires further investigation. Currently, we have still not reached a stage where TWs produce images of a quality sufficient for medical applications. 2) We have identified new potential medical applications of TWs. 3) We have invented new pixellated devices with potential medical applications. An EPSRC funding application by a subset of the investigators, proposing to advance these, was submitted and rejected. We are currently planning to build a technology demonstrator and then resubmit.
Sector Healthcare
Impact Types Societal,Economic

 
Title Dr TIM 
Description We continue to develop our open-source raytracing software Dr TIM. It is written in such a way that it is at the same time a research tool and an outreach tool, by publishing cut-down versions aimed at encouraging interactive exploration by others. We publish those versions that are related to the "Telescope windows" projects on a project log at https://www.researchgate.net/project/Telescope-windows-low-vision-scopes-to-cloaks . 
Type Of Technology Software 
Year Produced 2017 
Open Source License? Yes  
Impact The software is a very valuable tool for exploring and testing of ideas and for disseminating results. We use it daily in our research. To a certain degree, it is to us what a complicated experiment with unique capabilities, developed over many years, can be for experimental groups. 
URL https://www.researchgate.net/project/Telescope-windows-low-vision-scopes-to-cloaks
 
Description Talk to student society 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Undergraduate students
Results and Impact Together with my PhD student Jakub Belin, I was invited to present our work on invisibility cloaks. What was particularly great about it is that one of the students in the audience made an excellent suggestion for a new type of invisibility cloak, which we are now working on, together with that student.
Year(s) Of Engagement Activity 2019