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Abstracts
Design of an all-reflective freeform viewfinder
Jannick P. Rolland and Arron Bauer
University of Rochester, Rochester, NY, USA
Freeform optics is opening new spaces for optical design solutions with all reflective optics. Specifically, refractive design forms that are limited by chromatic aberrations are prime candidates to be converted to all-reflective designs. However, axially symmetric reflective systems are limited by obscuration, which cannot be sufficiently addressed using conventional surface shapes. With the advent of freeform optics, it is now possible to eliminate the obscurations in reflective systems while maintaining quality imaging performance. In this work, we present the optical design of a five mirror freeform electronic viewfinder. We will provide insight into the design of this system leveraging the understanding of freeform aberration theory. This design was subsequently fabricated and assembled into a system that provided excellent imaging quality.
Initial Survey Results of Four-Mirror Freeform Imagers
Jonathan C. Papa1, Joseph M. Howard2, Jannick P. Rolland1
Affiliation: 1 - University of Rochester, Rochester, NY, USA
2 - NASA Goddard Space Flight Center, Greenbelt, MD, USA
We apply constraints using first, second, and third-order aberration theory to reduce the 20 degrees of freedom associated with the construction parameters of plane-symmetric conic four-mirror systems down to an eight-dimensional search space. An exhaustive search is performed over the 8 dimensions, and higher order surface terms beyond the conic are optimized to provide freeform solutions. The resulting systems are sorted by performance and volume.
Next Generation Space Lasers for future Earth Observation Missions
Michael Damzen
Photonics Group, Imperial College London, UK
Lasers can reach out to great distances and acquire information. From space on a satellite-based platform, lasers can provide global mapping of the atmosphere for weather prediction, understanding atmospheric and climate change science and by monitoring ground-based ecosystems provide global 3-D mapping of vegetation (e.g. rain-forests, agriculture), ice sheets thickness, coastal water depths and other altimetry measurements.
This presentation will describe our progress in a European Space Agency (ESA) supported programme to develop a new laser technology (diode-pumped Alexandrite) to meet the future needs of satellite-based Earth Observation missions. We will describe: i) the benefit of our new laser technology as the first tunable space laser with flexible wavelength tunability in “difficult to address” NIR and UV spectral regions; ii) a high energy pulsed system for atmospheric remote sensing and a single-photon micro-pulse lidar system for vegetation/forest canopy monitoring; and iii) the advances we are making to address the challenging laser engineering requirements (vibration; thermal cycling; radiation; laser-induced damage; lifetime) for space compliancy.
Rapid starting-point generation of freeform imaging systems
Fabian Dürr
Department of Applied Physics and Photonics,
Vrije Universiteit Brussel
We have developed a novel method that greatly facilitates the optical design of various unobscured off-axis freeform imaging systems from scratch. This design tool allows exploring a wide range of possible layouts in both a rigorous and fast manner once the overall geometry constraints are defined. All surfaces coefficients are calculated automatically up to sixth order (higher orders are possible) by minimising a user-defined and weighted set of aberrations. Several examples showcase the capability and versatility of this approach.
Optical Design of HARMONI VIS and NIR Spectrograph Cameras
Paloma Matia-Hernando1, Mª Pilar Urizar1, Marta de la Fuente1
Myriam A. Rodrigues2, Matthias Tecza2, John Capone2
Andrea Hidalgo2
Affiliation: 1 - ASE Optics Europe
2 - University of Oxford, Oxford, U.K.
HARMONI is a visible and near-infrared (0.46 to 2.45 μm) integral field spectrometer that will be part of the E-ELT. HARMONI comprises a set of collimators, dispersers, and cameras. In particular, it includes a visible camera (0.46 to 0.82 μm) and a NIR camera (0.79 to 2.45 μm). Both work for input collimated beams 146mm diameter, FOV ±10.15ºx±0.17º and must provide image quality better than 248nm WFE rms with little lateral color to fit the slit images into the 4Kx4K detectors.
Excursions in aberration theory based optical design
Andrew Rakich
Mersenne Optical Consulting, Wellington & Wairarapa, New Zealand
The use of aberration theory based approaches to optical design has been in decline ever since the development of good ray tracing software. However, as will be shown, the insights and conceptually accessible solution spaces offered by certain forms of third-order analysis of optical systems can still turn up powerful and original design concepts, that have been missed by generations of "ray-tracers". In this paper some useful visualization tools for third-order aberration theory are introduced and it is demonstrated how the successive decadal developments in the early design of three-mirror anastigmats might have been achieved much more quickly if these tools had been employed. Next it will be shown how this approach has led to the realization that a famous relay system is actually a special case of a general family of solutions, and significant improvements on the well-known system have been found in some of the newly uncovered "family members". Finally a very powerful system, a novel and practical example of an "Ideal Imaging System", as first described by James Clerk Maxwell, will be revealed. This is a system capable of providing well corrected images for ANY object conjugate.
Light-sheet fluorescence microscope designs for high-speed and high-content imaging of biological samples
Christopher Dunsby
Photonics Group, Imperial College London, London, UK
Light-sheet fluorescence microscopy (LSFM) is a 3-D fluorescence imaging method providing low out-of-plane photobleaching and phototoxicity that enables high-speed and long-term imaging of live biological samples.
The conventional LSFM configuration employs two microscope objective lenses orientated at 90° to one another. The first objective is used to generate an illumination light sheet and the second objective is used to collect fluorescence from the illuminated plane.
We present the design, development and application of two different types of LSFM system.
The first system is based around a conventional LSFM configuration and has been designed to study calcium dynamics in heart muscle cells. This system is flexible, in order to enable samples to be imaged in a range of orientations, and provides high speed video-rate volumetric imaging as well as lower speed imaging at a higher spatial resolution.
The second system uses an alternative approach where a single high numerical aperture objective lens is used to provide both the fluorescence excitation and detection. This method is called oblique plane microscopy (OPM) and is implemented on a standard fluorescence microscope frame to rapidly image volumes with subcellular resolution. We present the development and application of a stage scanning OPM (ssOPM) approach for light sheet fluorescence imaging of arrays of samples in commercially available 96 and 384-well plates.
Improving freeform surface manufacturability estimates by leveraging orthogonal polynomials in design
Nick Takaki, Aaron Bauer and Jannick Rolland
University of Rochester, Rochester, NY, USA
In this paper, orthogonal polynomial freeform surface descriptions are leveraged to constrain manufacturability estimates of freeform surfaces during design. The mathematical construction of this constraint is shown in general for orthogonal polynomials and in particular for both Zernike polynomials and Forbes 2D-Q polynomials. Two design studies are then explored with this optimization constraint: an unobscured, ball geometry three-mirror telescope for use in LWIR imaging and a freeform prism combiner for use in AR/VR applications.
Modeling & Analysis of Random Mid-Spatial Frequency Errors on Optical Surfaces
David Hasenauer
Optical Solutions Group, Synopsys Inc., USA
The mid-spatial frequency surface error (MSFSE) metrology metric is becoming more popular to describe one class of errors that often occur on machined optical surfaces (such as freeform mirrors). MSFSE describes surface errors with higher spatial frequencies across the beam (not the part) than "figure errors" (which can generally be modeled using lower order Zernike surface deformations), and lower in spatial frequency than "surface roughness".
In this paper, we will introduce a computationally efficient statistical method for modeling this error in optical software, along with an analysis approach using general diffraction beam propagation. Several examples will be presented to illustrate the impact of MSFSE on metrics important to the optical designer, such as MTF and encircled/ensquared energy.
An integrated spinning disk confocal microscope with simultaneous
low- and high-magnification imaging paths
Mark Neil1, Rimas Juskaitis2, Alessandra Carmichael Martins3
Affiliation: 1 - Imperial College London, London, UK
2 - Aurox Ltd, UK
3 - University College Dublin, Dublin, IE
We present results from an integrated confocal microscope system based on spinning disk technology and LED illumination. The particular benefits of the optical system include separate low and high magnification imaging paths that are combined onto the same camera detectors to allow low-resolution for navigation and high-resolution for imaging without changing objectives. A conventional high NA objective lens views the sample in epi-Illumination from below while a custom, low-NA, low-magnification lens incorporating a focus-tunable element views the sample from above, providing an image over a 4mm field of view.
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