A thermo-optical analysis method for a space optical remote sensor optostructural system

Ding, Yulong

doi:10.1117/1.1797872

Cited by 13 publications

(6 citation statements)

References 19 publications

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“…The goal of the thermal design is to make the scanning mirror insensitive to the environment as much as possible, so that the mirror will not cause distortions due to the varying temperature conditions [11,12]. The combination of the material and structure is the feature that defines the mirror's structural and thermal characteristics.…”

Section: B Scan Mirror Thermal Designmentioning

confidence: 99%

Thermal Analysis of Radiometer Onboard a Geostationary Satellite

Liu

Sun

2009

Journal of Spacecraft and Rockets

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In this paper, a detailed thermal model of the radiometer onboard a geostationary satellite is established and transient analyses are performed to obtain the temperature response of a scan mirror and a telescope secondary mirror assembly. The temperature distributions of the radiometer instruments are calculated based on an advanced finite difference method with control volume approach, which can deal with the radiation boundary condition efficiently. Oppenheim's method is used to calculate the radiation heat transfer inside the radiometer, and the calculation of radiation view factor of boundary surface is based on a blockage criterion. The thermal control design for the radiometer is presented, which contributes to its channel registration and focus stability. The thermal consideration for the scan mirror is discussed to obtain acceptable temperature range, which directly affects the performance of the radiometer. The results show that the scan mirror temperature can be reduced to a low level, obviously after appropriate structure design is adopted and a thermal coating is applied on it. The peak temperature of the scan mirror and secondary mirror assembly occurs during the period of the local middle night when they are exposed to the direct view of the sun. The temperature variations of radiometer key instruments are given for several typical solar declinations. Nomenclature A = area, m 2 A 0 = illuminated area of surface element, m 2 c = heat capacity, J=kg K F, F s = view factors, dimensionless G = conductance between calculation points, W=K g = conductance between boundary elements, W=K k = thermal conductivity, W=m 2 K L = length of boundary element, m Q = heat flow, W Q b = heat flow across the control volume boundary, W Q 0 = heat generated within the control volume, W q = heat flow across boundary, W q s = solar constant, W=m 2 R = distance between two surfaces, m T = temperature, K t = time, s U = internal energy, J V = volume, m 3 x, y, z = coordinates, m , , = angle between the normal vector and the axis of coordinates, deg = element thickness, m " = emissivity, , dimensionless = angle between the element surface normal and the solar vector, deg = density, kg=m 3 = Stefan-Boltzmann constant, W=m 2 K 4 = angle between the element surface normal and the connecting line, deg Subscripts b = boundary element CG = element center (center of gravity) i, j = ith and jth element or calculation point

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Section: B Scan Mirror Thermal Designmentioning

confidence: 99%

Thermal Analysis of Radiometer Onboard a Geostationary Satellite

Liu

Sun

2009

Journal of Spacecraft and Rockets

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“…Since the RSI is a high precision optical instrument, selection of low thermal expansion materials and strict temperature control are required. It is reported that a small temperature fluctuation may result in a big decline in image quality [5]. The temperature variation of the primary mirror could also impact the image performance if the mirror was not made of low Coefficient of Thermal Expansion (CTE) material [6].…”

Section: Introductionmentioning

confidence: 99%

Integrated analysis of FORMOSAT-5 remote sensing instrument in space

Chen

Yang

et al. 2013

SPIE Proceedings

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FORMOSAT-5 is the first space program fully developed by National Space Organization (NSPO). The Remote Sensing Instrument (RSI) will provide spatial resolution of 2 meters in panchromatic band and 4 meters in multi-spectral bands. The optical system is composed of two reflective aspheric mirrors and spherical corrector lens set. CFRP structure is used for the optomechanical system to reduce mass. Although the telescope system can be well aligned on ground, the space thermal environment can result in thermal distortion of telescope system and impact the final image quality. Flight predictions of FORMOSAT-5 RSI were done to get the quantitative thermal distortion of mirrors and structural system. The system optical performance, i.e. MTF, was also derived by the optical model with the input from thermal distortion results, i.e. Zernike polynomials. RSI performance in space is location-dependent. Detailed analysis results and discussions are revealed in this paper.

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“…In this paper we have examined the impact of relatively less explored but nonetheless important 'thermal print-through' issue associated with the lightweighted structure operating in thermally dynamic environment. The thermo-optic analysis, as it is increasingly recognized, is a vital component of the overall system design and necessary to predict and verify the satisfactory performance of the mirror [18,19]. Here, we have used FEA to solve the time dependent 3-D heat transfer equation to predict the mirror deformation arising from the thermally induced stress and temperature inhomogeneities of a lightweighted structure.…”

Section: Introductionmentioning

confidence: 99%

Opto-thermal analysis of a lightweighted mirror for solar telescope

Banyal,

Ravindra,

Chatterjee

2013

Preprint

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In this paper, an opto-thermal analysis of a moderately heated lightweighted solar telescope mirror is carried out using 3D finite element analysis (FEA). A physically realistic heat transfer model is developed to account for the radiative heating and energy exchange of the mirror with surroundings. The numerical simulations show the non-uniform temperature distribution and associated thermo-elastic distortions of the mirror blank clearly mimicking the underlying discrete geometry of the lightweighted substrate. The computed mechanical deformation data is analyzed with surface polynomials and the optical quality of the mirror is evaluated with the help of a ray-tracing software. The thermal print-through distortions are further shown to contribute to optical figure changes and mid-spatial frequency errors of the mirror surface. A comparative study presented for three commonly used substrate materials, namely, Zerodur, Pyrex and Silicon Carbide (SiC) is relevant to vast area of large optics requirements in ground and space applications.

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A thermo-optical analysis method for a space optical remote sensor optostructural system

Cited by 13 publications

References 19 publications

Thermal Analysis of Radiometer Onboard a Geostationary Satellite

Thermal Analysis of Radiometer Onboard a Geostationary Satellite

Integrated analysis of FORMOSAT-5 remote sensing instrument in space

Opto-thermal analysis of a lightweighted mirror for solar telescope

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