TPF-C Technology Plan - Exoplanet Exploration Program - NASA

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Chapter 3 (though not light-weight or off-axis) optics are compared in Figure 3-6 and fitted with a third order function given by A PSD(k) = ⎛ 1+ k ⎞ , where k = 3 ( k x) 2 + () k 2 5 2 2 y , A ≈ 6× 10 Å cm , and k 0 = 0.025cycles/cm . ⎜ ⎟ ⎝ k 0 ⎠ The TDM is to be manufactured with a PSD amplitude a factor of 2.5 below the fitted curve. For 5 2 2 the TDM, k 0 = 0.04cycles/cm and A ≈ 2.4× 10 Å cm are required with a goal of A ≈ 6 ×10 4 Å 2 cm 2 . The performance requirements vary with spatial frequency as summarized in Table 3-1. Manufacturing process development for the TDM will address materials effects, structural integrity, thermal impacts, and measurement and test methods; coating process development will address spatial reflective uniformity and experimental determination of coating performance. Going through the process of fabricating and testing the TDM will provide insight into achievable performance for the TPF-C PM and SM. • Each of the three mirrors is optically finished using different methods • Black represents a third order drop off with a knee at 40cm Magellan Kodak HST Figure 3-6. Power spectral density for three mirrors: Magellan (left) 6.5 m and made at the University of Arizona Mirror Laboratory for ground-based astronomy, HST (middle), and a 1.5- m development optic made at Kodak (right). PSD for the TDM is 2.5 times lower. 34
Optics and Starlight Suppression Technology Table 3-2. ITT Design Parameters Parameter Description Material/construction ULE/LTF/LTS Finished plate OD: back plate 1900 mm Finished plate OD: front plate 1875 mm Core OD (plano blank) 1880 mm Core depth 114.3 mm Core cell geometry (hex, flat-flat) 127.3 mm Initial plate thickness 12.7 mm Front-plate final thickness 9.3 mm Back-plate final thickness 5.1 mm Core strut thickness: Interior 1.4 mm Core strut thickness: Edge walls 1.9 mm Core strut thickness: Mount 2.8 mm Best fit ROC 7837.3 mm Mount pad location 665 mm Midspatial gravity quilting 3.6 nm-rms Number of cells 273 Progress to Date The TDM effort started with a three-month design effort by four large mirror companies, Brashear, Goodrich, ITT, and SSG. A careful review of the proposed designs led to award of the contract for the fabrication of the TDM to ITT. 7 ITT proposed a closed back, ULE mirror that will be slumped to near net shape, polished with a full tool active lap, and ion beam figured. A drawing of the ITT mirror and mounting struts with the core structure exposed is shown in Figure 3-7. The important design parameters for the ITT mirror are given in Table 3-2. Currently ITT is completing the design of the mirror, bipod supports, strongback, and handling equipment. Six boules of ULE have been produced and their coefficient of thermal expansion (CTE) uniformity has been measured. The ULE for the cores has been surfaced in preparation for water-jetting the core cells. The boules for the faceplates have been flowed out from the standard 1.5-m size to 2 m. The CTE properties are critical if the TDM is to meet the stability requirements. Based on the thermal requirements, ITT derived CTE requirements that Corning, the manufacturer of ULE, must meet. Most critical is the weighted average of the mirror’s CTE which must be between −10 and +10 ppb/ºC. It is also critical that the CTE for the same location on the front and back face sheet differ by no more than 5 ppb/ºC. The first critical specification 7 Cohen and Hull, “Selection of Mirror Technology for the 1.8m Terrestrial Planet Finder Demonstration Mission,” SPIE, Optical Fabrication, Metrology, and Material Advancements for Telescopes proceedings Eds. Eli Atad-Ettedgui and Philippe Dierickx, Volume 5494, pp. 350-365. 35
Page 1 and 2: JPL Publication 05-8 Technology Pla
Page 3: TECHNOLOGY PLAN TERRESTRIAL PLANET
Page 6 and 7: Recent Highlights Technical progres
Page 8 and 9: Figure i-4. Deformable mirror deliv
Page 10 and 11: Table of Contents Approvals........
Page 12 and 13: 7.5.2 Precision Hexapod............
Page 14 and 15: Chapter 1 Figure 1-1. Artist's impr
Page 16 and 17: Chapter 1 interferometry, continues
Page 18 and 19: Chapter 1 Back end coronagraph opti
Page 20 and 21: Chapter 1 Surrounding the whole tel
Page 22 and 23: Chapter 1 Pol. BS fold/steering Mic
Page 24 and 25: Chapter 1 1.6.5 Sunshield The teles
Page 26 and 27: Chapter 1 expected architecture dow
Page 28 and 29: Chapter 1 Table 1-3. TPF-C Technolo
Page 30 and 31: Chapter 1 3B: Demonstrate, using th
Page 32 and 33: Chapter 2 2 Error Budgets 2.1 Contr
Page 34 and 35: Chapter 2 Error Budget Validation G
Page 36 and 37: Chapter 2 Further, it is shown that
Page 38 and 39: Chapter 2 Table 2-1. Requirement on
Page 40 and 41: Chapter 3 3 Optics and Starlight Su
Page 42 and 43: Chapter 3 are in progress with cont
Page 44 and 45: Chapter 3 Figure 3-5. Coronagraph s
Page 48 and 49: Chapter 3 Table 3-3. ITT Metrology
Page 50 and 51: Chapter 3 observations. The time it
Page 52 and 53: Chapter 3 vacuum-compatible, low-po
Page 54 and 55: Chapter 3 blank size. Westerhoff et
Page 56 and 57: Chapter 3 configurations, performan
Page 58 and 59: Chapter 3 Figure 3-10: Plots showin
Page 60 and 61: Chapter 3 The wavefront quality of
Page 62 and 63: Chapter 3 Figure 3-13. Optical layo
Page 64 and 65: Chapter 3 algorithms have limitatio
Page 66 and 67: Chapter 3 simulated star source is
Page 68 and 69: Chapter 4 Figure 4-1. Overview of t
Page 70 and 71: Chapter 4 enclosures, and stable la
Page 72 and 73: Chapter 4 facilities from which dat
Page 74 and 75: Chapter 4 Figure 4-5. Microslip Tri
Page 76 and 77: Chapter 4 Figure 4-7. Calibration o
Page 78 and 79: Chapter 4 Figure 4-8. Comparison of
Page 80 and 81: Chapter 4 4.2 Subsystem and System
Page 82 and 83: Chapter 4 Figure 4-11. Schematic of
Page 84 and 85: Chapter 4 Figure 4-12. Fine guiding
Page 86 and 87: Chapter 4 (5) The Fine Steering Mir
Page 88 and 89: Chapter 4 Third, precise thermal co
Page 90 and 91: Chapter 4 giving confidence that fl
Page 92 and 93: Chapter 4 surface polish is nonethe
Page 94 and 95: Chapter 5 TPF-C is planning a suite
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Chapter 5 engineering judgment (i.e
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Chapter 5 categories, in reality ea
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Chapter 5 Table 5-3. Validation of
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Chapter 5 5.6.1 Modeling Methodolog
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Chapter 5 strength of computer simu
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Chapter 6 6 Instrument Technology a
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Chapter 6 Figure 6-1. Detailed conc
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Chapter 6 The first method is self-
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Chapter 6 super computers and is us
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Chapter 7 7 Plan for Technology Dev
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Chapter 7 Figure 7-1. TPF-C Technol
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Chapter 7 Improvements to the DM ov
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Chapter 7 7.3 Error Budgets 7.3.1 D
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Chapter 7 7.4 Optics and Starlight
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Chapter 7 7.4.2 Apodizing Masks and
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Chapter 7 7.4.4 Wavefront Sensing a
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Chapter 7 7.4.6 Transmissive Optics
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Chapter 7 7.4.8 Scatterometer Scope
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Chapter 7 7.5 Structural, Thermal,
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Chapter 7 7.5.3 Precision Structura
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Chapter 7 model of TPF-C and should
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Chapter 7 7.5.6 Secondary Mirror To
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Chapter 7 7.5.8 Sub-scale EM Sunshi
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Chapter 7 7.6 Integrated Modeling a
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Chapter 7 7.7.3 Advanced Concepts:
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Chapter 8 134
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Appendices Appendix B: TPF-C Detail
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Appendices Appendix D: TPF-C Techno
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Appendices Appendix F: Acronym List
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Appendices RWA SAO SBIR SIM SM SMFA
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TPF-C Technology Plan - Exoplanet Exploration Program - NASA

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