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Tom D. Milster

Publications and source records attributed to Tom D. Milster.

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A Differentiable Ray-Wave Framework for Hybrid Refractive-Diffractive System Modeling and Optimization

Hybrid optical systems combining refractive and diffractive optical responses have the potential to support new types of optical behavior, but they are difficult to model and optimize due to the disparate spatial scales and physics exhibited by ray and wave phenomena. In this work, we present a differentiable ray-wave framework for modeling hybrid refractive-diffractive optical systems that operates as a plug-and-play module within standard ray tracing pipelines. Our model uniquely applies to both planar and curvilinear diffractive surfaces and accommodates arbitrary scalar holographic profiles with high spatial frequency responses, with each simulation evaluated at a single wavelength. We analyze ray-wave modeling regimes that optimally account for the spatial frequency properties and spatial curvature of the diffractive surfaces, and we demonstrate the gradient-based end-to-end optimization of hybrid refractive-diffractive systems featuring planar and conformal diffractive surfaces. We anticipate that these modeling capabilities will enable new classes of hybrid optical systems relevant to computational imaging and display applications.

physics.optics

A Thousand Earths: A Very Large Aperture, Ultralight Space Telescope Array for Atmospheric Biosignature Surveys

An outstanding, multi-disciplinary goal of modern science is the study of the diversity of potentially Earth-like planets and the search for life in them. This goal requires a bold new generation of space telescopes, but even the most ambitious designs yet hope to characterize several dozen potentially habitable planets. Such a sample may be too small to truly understand the complexity of exo-earths. We describe here a notional concept for a novel space observatory designed to characterize 1,000 transiting exo-earth candidates. The Nautilus concept is based on an array of inflatable spacecraft carrying very large diameter (8.5m), very low-weight, multi-order diffractive optical elements (MODE lenses) as light-collecting elements. The mirrors typical to current space telescopes are replaced by MODE lenses with a 10 times lighter areal density that are 100 times less sensitive to misalignments, enabling light-weight structure. MODE lenses can be cost-effectively replicated through molding. The Nautilus mission concept has a potential to greatly reduce fabrication and launch costs, and mission risks compared to the current space telescope paradigm through replicated components and identical, light-weight unit telescopes. Nautilus is designed to survey transiting exo-earths for biosignatures up to a distance of 300 pc, enabling a rigorous statistical exploration of the frequency and properties of life-bearing planets and the diversity of exo-earths.

astro-ph.IM