COSMO Large Coronagraph (COSMO LC) is a telescope dedicated to the measurement of the Sun magnetic field. This project is currently at a design phase funded by the National Science Foundation under the technical direction of the High Altitude Observatory.
COSMO LC is a refractive telescope whose objective lens has a clear aperture of 1.4m, it will be the largest refractive telescope in the world. This telescope can observe the Sun corona thanks to the internal occulter which is able to obscure the solar disk. This device needs to accomplish two main functions: 1) adapt its diameter to the Sun apparent size, 2) reject all the incoming heat to not start any air turbulence which leads to the degradation of image quality (seeing).
Diameter change is accomplished by means of a cam mechanism which actuates 14 petals arranged azimuthally while the occulter cooling is obtained through cold water running through internal channels and forced air convection.
This article describes the mathematical models employed to quantify the seeing effect on image resolution and the technical solutions adopted to implement the above-mentioned functions. In addition, the tests performed on this device are described along with the results.
WindCube is a NASA HFORT funded mission to study the coupling of thermospheric winds with the earth’s ionosphere. The optical system is based on a limb sensing Fabry-Perot etalon designed to measure the Doppler shift of the 630 nm oxygen airglow emission. The instrument payload is designed to fit within a 6U volume in a 12U CubeSat. The accuracy requirement for the wind speed retrieval is 5 m/s. This is the driving requirement for the opto-mechanical stability of the etalon system. Active temperature control of the etalon is employed to keep the mounted etalon within a +/- 0.1 C range. This paper discusses the design and analysis of the mounted etalon system to meet the accuracy requirement as well as surviving the rigors of vibration testing and the launch environment.
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