Martinez-Galarce D.,Lockheed Martin |
Boerner P.,Lockheed Martin |
Soufli R.,Lawrence Livermore National Laboratory |
Harvey J.,University of Central Florida |
And 11 more authors.
2nd International Conference on Space Technology, ICST 2011 | Year: 2011
High-resolution observations with Hinode have shown that understanding the interface between the solar photosphere and the corona requires the ability to study the transition region by imaging plasma heated to around 500,000 K on spatial scales of ∼ 0.2 arc seconds and at a cadence of ∼5 seconds or less. And how this interface of the solar atmosphere ranges in temperatures from 104 - 107 K continues to be an area of active research in heliophysics. Although the much celebrated launch of the Atmospheric Imaging Assembly (AIA) is revealing activity of the Extreme Ultraviolet (EUV) corona and chromosphere, down to ∼1 arc seconds resolution with ∼10 seconds cadence, there is a continuing need to improve our observational capabilities at EUV wavelengths. Therefore, the next generation EUV imager for use in heliophysics will need to have the capability of improving performance in all three of these observational categories in order to obtain higher thermal, spatial and temporal resolution of the solar atmosphere. Herein, we present results that demonstrate our ability to estimate EUV performance as well as experimental data that show the viability of using SiC for fabricating the next-generation of space-based EUV telescopes. © 2011 IEEE.
Kong J.,Precision Asphere Inc |
Young K.,Precision Asphere Inc
Advanced Optical Technologies | Year: 2014
Growing applications for astronomical groundbased adaptive systems and air-born telescope systems demand complex optical surface designs combined with ultra-smooth finishing. The use of more sophisticated and accurate optics, especially aspheric ones, allows for shorter optical trains with smaller sizes and a reduced number of components. This in turn reduces fabrication and alignment time and costs. These aspheric components include the following: steep surfaces with large aspheric departures; more complex surface feature designs like stand-alone off-axis-parabola (OAP) and free form optics that combine surface complexity with a requirement for ultra-high smoothness, as well as special optic materials such as lightweight silicon carbide (SiC) for air-born systems. Various fabrication technologies for finishing ultra-smooth aspheric surfaces are progressing to meet these growing and demanding challenges, especially Magnetorheological Finishing (MRF) and ion-milling. These methods have demonstrated some good success as well as a certain level of limitations. Amongst them, computer-controlled asphere surface-finishing technology (CAST), developed by Precision Asphere Inc. (PAI), plays an important role in a cost effective manufacturing environment and has successfully delivered numerous products for the applications mentioned above. One of the most recent successes is the Gemini Planet Imager (GPI), the world's most powerful planet-hunting instrument, with critical aspheric components (seven OAPs and free form optics) made using CAST technology. GPI showed off its first images in a press release on January 7, 2014 . This paper reviews features of today's technologies in handling the ultra-smooth aspheric optics, especially the capabilities of CAST on these challenging products. As examples, three groups of aspheres deployed in astronomical optics systems, both polished and finished using CAST, will be discussed in detail. © 2014 THOSS Media and De Gruyter.
Kong J.,Precision Asphere Inc. |
Young K.,Precision Asphere Inc.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2010
Critical to the deployment of large surveillance optics into the space environment is the generation of high quality optics. Traditionally, aluminum, glass and beryllium have been used; however, silicon carbide becomes of increasing interest and availability due to its high strength. With the hardness of silicon carbide being similar to diamond, traditional polishing methods suffer from slow material removal rates, difficulty in achieving the desired figure and inherent risk of causing catastrophic damage to the lightweight structure. Rather than increasing structural capacity and mass of the substrate, our proprietary sub-aperture aspheric surface forming technology offers higher material removal rates (comparable to that of Zerodur or Fused Silica), a deterministic approach to achieving the desired figure while minimizing contact area and the resulting load on the optical structure. The technology performed on computer-controlled machines with motion control software providing precise and quick convergence of surface figure, as demonstrated by optically finishing lightweight silicon carbide aspheres. At the same time, it also offers the advantage of ideal pitch finish of low surface micro-roughness and low mid-spatial frequency error. This method provides a solution applicable to all common silicon carbide substrate materials, including substrates with CVD silicon carbide cladding, offered by major silicon carbide material suppliers. This paper discusses a demonstration mirror we polished using this novel technology. The mirror is a lightweight silicon carbide substrate with CVD silicon carbide cladding. It is a convex hyperbolic secondary mirror with 104mm diameter and approximately 20 microns aspheric departure from best-fit sphere. The mirror has been finished with surface irregularity of better than 1/50 wave RMS @632.8 nm and surface micro-roughness of under 2 angstroms RMS. The technology has the potential to be scaled up for manufacturing capabilities of large silicon carbide optics due to its high material removal rate. © 2010 Copyright SPIE - The International Society for Optical Engineering.
Kong J.,Precision Asphere Inc |
Young K.,Precision Asphere Inc
Optics InfoBase Conference Papers | Year: 2012
The method offers higher material removal rates, a deterministic approach to achieving the desired figure, minimizing contact area and the resulting load on the optical structure, and low surface micro-roughness and low midspatial frequency error. © 2012 OSA.