We are currently constructing FalconSAT-7 for launch in mid-2014. The low-Earth, 3U CubeSat solar telescope
incorporates a 0.2m deployable membrane photon sieve with over 2.5 billion holes. The aim of the experiment is to
demonstrate diffraction limited imaging of a collapsible, diffractive primary over a narrow bandwidth. As well as being
simpler to manufacture and deploy than curved, polished surfaces, the sheets do not have to be optically flat, greatly
reducing many engineering issues. As such, the technology is particularly promising as a means to achieve extremely
large optical primaries from compact, lightweight packages.

FalconSAT-7: A Membrane Photon Sieve CubeSat Solar Telescope

Photon sieve is a kind of diffractive optical element modulating either amplitude or phase and thus suffers from
chromatic aberration or low diffraction efficiency The narrowband imaging properties of photon sieve are illustrated
with point spread function test and resolution target test Hybrid lens consisting of both refractive optical surfaces and
photon sieve are suggested to correct the chromatic aberration Phase-photon sieve technology and surface plasmon polaritons technology may be promising approaches to improve the diffraction efficiency

Experimental characterization of optical properties of photon sieve

Zur funktionalen Erweiterung von Head-up Displays als ergonomisches Fahrerassistenzsystem wird ein autostereoskopischer Ansatz untersucht, bei dem ein raumlicher Tiefeneindruck durch die Fusionierung zweier dargebotener Teilbilder entsteht. Speziell entwickelte Simulationsmethodik dient dabei als Basis fur die optische Auslegung. Es werden technologisch verschiedene Konzepte entwickelt, simulativ untersucht, sowie in prototypischen Aufbauten realisiert und charakterisiert. In order to extend the functionality of head-up displays as an ergonomic driver assistance system an autostereoscopic approach is investigated. Thereby, depth perception is gained by the fusion of two separated images. Adapted simulation methods are developed and used as a basis for the optical design process. Different technological concepts are developed, analyzed in simulation, as well as realized and characterized in prototypical setups. Umfang: IV, 264 S. Preis: €52.00 | £48.00 | $91.00

Simulation, Aufbau und Charakterisierung von autostereoskopischen Display-Systemen im Fahrzeugbereich

Physiological changes in the retinal vasculature are commonly indicative of such disorders as diabetic retinopathy, glaucoma, and age-related macular degeneration. Thus, various methods have been developed for noninvasive clinical evaluation of ocular hemodynamics. However, to the best of our knowledge, current ophthalmic instruments do not provide a true color blood flow imaging capability. Accordingly, we propose a new method for the true color imaging of blood flow using a high-speed pulsed laser photography system. In the proposed approach, monochromatic images of the blood flow are acquired using a system of three cameras and three color lasers (red, green, and blue). A high-quality true color image of the blood flow is obtained by assembling the monochromatic images by means of image realignment and color calibration processes. The effectiveness of the proposed approach is demonstrated by imaging the flow of mouse blood within a microfluidic channel device. The experimental results confirm the proposed system provides a high-quality true color blood flow imaging capability, and therefore has potential for noninvasive clinical evaluation of ocular hemodynamics.

True color blood flow imaging using a high-speed laser photography system

: The USAF Academy Department of Physics is building FalconSAT-7, a membrane solar telescope to be deployed from a 3U CubeSat in LEO. The primary optic is a 0.2m photon sieve-- a diffractive element consisting of billions of tiny holes in an otherwise opaque polymer sheet. The membrane, its support structure, secondary optics, two imaging cameras and associated control/recording electronics are all packaged within half the CubeSat volume. Once in space the supporting pantograph structure is deployed to pulling the membrane flat under tension. The telescope will then be steered towards the Sun to gather images at H-alpha for transmission to the ground. Due for launch in 2015, FalconSAT-7 will serve as a pathfinder for future mission in lightweight, high-resolution space-based surveillance. We are currently investigating two possible options optimized for Earth observing and SSA. Our preliminary designs have a 0.3m aperture deployed from a 6-12U satellite. Such a telescope would be capable of providing sub-meter resolution of ground or space-based objects depending on the orbital characteristics.

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FalconSAT-7: Towards Rapidly Deployable Space-Based Surveillance

We present the lithography scheme that use high-numerical-aperture photon sieves array as focusing elements in a
scanning X-ray maskless nanolithography system. The system operating at wavelength of 0.5~2nm synchrotron light
sources radiated, each of a large array of photon sieves focuses incident X-ray into a diffraction-limited on-axis
nanoscale spot on the substrate coated photoresist. The X-ray intensity of each spot is modulated by means of a spatial
light modulator. Patterns of arbitrary geometry are exposed and written in a dot matrix fashion while the substrate on a
stepping stage is precisely driven in two dimensions according to the computer program. The characteristics of
synchrotron radiation light, resolution limits and depth of focus of the lithographic system are discussed. The design and
fabrication of photon sieve are illustrated with a low-numerical-aperture amplitude-photon sieve fabricated on a chrome-coated
quarts plate by means of laser-beam lithographic process, which minimum size of pinhole was 5.6um. The
focusing performance of the photon sieve operating at wavelength of 632.8nm was simulated and tested.

Photon sieve array x-ray maskless nanolithography

The use of lasers in a projection display enables the creation of vibrant images with extensive color coverage. By
adding a phase modulators in illumination systems and keeping the most part structures of the classic projection,
speckle on the screen and retinas of the observers were restrained. The speckle's form and restraining were
simulated. It was obtained form simulations that the contrasts of residual speckle on screen and on retinas are
0.0107 and 0.0132. The simulation proves that speckle on screen and on retinas can be suppressed by phase
modulation of the illumination light in projection. It also indicated that the numerical aperture of projector affect
the residual speckle on retinas. Experiments of speckle restraining were performed. It confirmed the results of the
simulations.

Speckle reduction in laser projection display by modulating illumination light

Photon sieve is a novel diffractive optical element modulating either amplitude or phase which consists of a great number of pinholes distributed appropriately over the Fresnel zones for the focusing and imaging of light. Photon sieve has the advantages of the diameter of pinholes beyond the limitation of the corresponding Fresnel zone width and the minimum background in the focal plane. Furthermore, photon sieve can be fabricated on a single surface without any supporting struts required unlike the Fresnel zone plate. Photon sieve can be used as EUV telescope for solar orbiter, space-based surveillance telescope operating at visible light, or other imaging components. Photon sieve can also be used as one of the promising lithographic tools for nanoscale science and engineering to obtain the lower cost, higher flexibility and better resolution. The approaches to enhancing imaging resolution of photon sieve are presented in detail. According to Fresnel-Kirchhoff diffraction theory, the diffractive field of photon sieve is described by means of the discrete fast Fourier transform algorithm. The related contents include the calculation of point spread function, the suppression of side lobes, the imaging bandwidth, the physical limit of resolution, and the diffraction efficiency. Imaging properties of photon sieve are analyzed on the basis of precise test.

Guanxiao Cheng

Papers

Experimental characterization of optical properties of photon sieve

Photon sieve array x-ray maskless nanolithography

Speckle reduction in laser projection display by modulating illumination light

Resolution enhancement of photon sieve based on apodization