TPF-I SWG Report - Exoplanet Exploration Program - NASA

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C HAPTER 5 Figure 5-9 shows the first section of the beamcombiner beamtrain. A coarse pointing mirror controlled from a sensor further down the beamtrain directs the light through the compressors and K-mirrors. The K- mirrors are controlled by tilt sensors located next in line, allowing small angular deviations in the polarization vector of the science beam to be controlled. Next the beams pass the metrology injection/extraction point (Figure 5-10) where laser metrology beams are directed up to the telescope retro and also down to the beamcombiner retro at the end of the beamtrain following the cross-combiner. The beams enter the delay lines, which are controlled by inputs from the downstream fringe trackers and also from the laser metrology gauges. The high-speed delay line is in fact located separately slightly further down the beamtrain. The beams are then accurately aligned in shear and pointing prior to entering the adaptive nullers. Accurate pre-alignment is necessary here because the adaptive nullers function by controlling beam shear at the output and require accurate pointing onto the focal plane, so these parameters must be fixed at the input. Therefore, the pointing and shear sensors immediately precede the adaptive nullers; these same sensors also control the coarse pointing mirrors previously mentioned. Each laser metrology beam has its own alignment mirror, which would only be adjusted occasionally. The adaptive nuller is set up during the calibration phase using data acquired by the science camera, removing small amplitude and phase differences across the waveband so that the nulling performance can be optimized. Figure 5-11 shows the final section of the beamtrain. Only one set of nullers is shown, but there would also be a split to separate the 7- to 11-μm waveband from the 11- to 17-μm waveband. After the split, a second set of pointing sensors is required to actuate fast-pointing mirrors, which control the final part of the beamtrain. The beams then enter the nullers, and at the exit an optical path chop (OPD is used rather than phase chop because there is only a small efficiency reduction) is applied in one beam, controlled by the OPD control system utilizing both fringe tracker and metrology data. The science beams are then cross-combined, and the internal laser metrology is retroreflected to the launchers. Finally, the science beam is filtered to a single spatial mode, angularly dispersed, and focused onto the science camera. 5.4.2 Optical Metrology A polarized laser beam is launched from behind the FOR mirror on each collector towards the combiner. See Figure 5-11. This beam is used throughout the beamtrain for the pointing and shear metrology and for polarization rotation metrology. 5.4.3 Pointing Metrology Short wavelength radiation from the star (0.8 to 1.0 μm) is focused onto a sensor behind the dichroic mirror on the collector spacecraft. Its position on the sensor is controlled by the FOR mirror, thus forming a loop controlling the angle of the starlight with respect to the beam train. A polarized laser beam of wavelength 850 nm is launched behind the FOR mirror and sensed on another sensor behind the dichroic mirror also shown in Figure 5-12. The laser beam is pointed using a tilt mirror behind the FOR mirror, thus forming another closed pointing loop. Calibrations can be made to co-align the stellar beam and the laser beam by integrating the starlight on the laser sensor with the laser turned off. Thus, a bright reference beam for the science beam is formed and can be used downstream for maintaining alignment. 110
<strong>TPF</strong>-I F L I G H T B ASELINE D ESIGN The beam angle is also sensed and corrected on the beamcombiner spacecraft just before entering the adaptive nullers. Simple lens and quad cell assemblies suffice for sensing and a high speed tip/tilt mirror corrects the angle in conjunction with a coarse pointing mirror located at the input to the compressors. An additional stage of pointing correction is needed before entry to the beamcombiner to allow for misalignments introduced by the switch and the 11–17 μm split. Figure 5-12. Telescope ancillary optical components. Figure 5-13. Transfer mirror shear sensor. 111
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JPL Publication 07-1 Terrestrial Pl
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Abstract Over the past two years, t
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Acknowledgements Twenty-two represe
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Table of Contents 1 Introduction...
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4.8.3 Post-Nulling Calibration.....
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6.4.5 Double Fourier Interferometry
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I NTRODUCTION 1 Introduction Over 2
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I NTRODUCTION et al. 2004), and res
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I NTRODUCTION Standard Interferomet
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I NTRODUCTION 1.4 References Angel,
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C HAPTER 2 0.7 to 1.5 AU scaled by
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C HAPTER 2 Table 2-2. Illustrative
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C HAPTER 2 Classical interferometry
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C HAPTER 2 trivial in the absence o
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C HAPTER 2 Figure 2-3. Simulated mi
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C HAPTER 2 would be in atmospheres
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C HAPTER 2 Figure 2-6. The mid-infr
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C HAPTER 2 Lines of constant stella
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C HAPTER 2 presence of zodiacal clo
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C HAPTER 2 S EZ 2π ∫ θ max ∫
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C HAPTER 2 Figure 2-11. Observation
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C HAPTER 2 Figure 2-12. Models of t
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C HAPTER 2 Beichman, C. A., Fridlun
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C HAPTER 2 2.7.4 Suitable Targets E
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C HAPTER 2 Reach, W. T., Franz, B.
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C HAPTER 3 3.1.1 Darwin/TPF-I Prope
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C HAPTER 3 clouds or an OB associat
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C HAPTER 3 Figure 3-3. Three possib
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C HAPTER 3 the circumstellar disk,
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C HAPTER 3 Figure 3-6. (Left panel)
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C HAPTER 3 Continuum interferometry
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C HAPTER 3 Figure 3-9: Simulated im
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C HAPTER 3 3.3 Conclusions Darwin/T
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C HAPTER 3 Nguyen, H. T., Kallivaya
Page 73 and 74: D ESIGN AND A R C H I T E C T U R E
Page 111: D ESIGN AND A R C H I T E C T U R E
Page 114 and 115: C HAPTER 5 Heavy launch vehicle. Th
Page 116 and 117: C HAPTER 5 5.3.2 Combiner Spacecraf
Page 118 and 119: C HAPTER 5 5.3.5 Beam Transfer betw
Page 120 and 121: C HAPTER 5 Figure 5-8. Control sche
Page 122 and 123: C HAPTER 5 Figure 5-9. First sectio
Page 126 and 127: C HAPTER 5 5.4.4 Shear Metrology Sh
Page 128 and 129: C HAPTER 5 Figure 5-15. TPF-I Fligh
Page 130 and 131: C HAPTER 5 secondary mirror along t
Page 132 and 133: C HAPTER 5 a) c) b) d) IWA = 43 mas
Page 134 and 135: C HAPTER 5 planets found. Figure 5-
Page 136 and 137: C HAPTER 5 30 25 5 M earth 3 M eart
Page 138 and 139: C HAPTER 5 5.8.4 Angular Resolution
Page 140 and 141: C HAPTER 5 Table 5-3. Angular Resol
Page 142 and 143: C HAPTER 5 The optimization works b
Page 145 and 146: T E C H N O L O G Y R OADMAP FOR TP
Page 173 and 174: F UTURE D EVELOPMENTS 7 Preparatory
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F UTURE D EVELOPMENTS • To comple
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F UTURE D EVELOPMENTS Table 7-1. Pr
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D ISCUSSION AND C ONCLUSION 8 Discu
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Appendices 167
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T E C H N O L O G Y A DVISORY C O M
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F L I G H T S YSTEM C ONFIGURATION
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F L I G H T S YSTEM C ONFIGURATION
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A PPENDIX C 2. Identical FACS fligh
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A PPENDIX C 2. Recall that the coef
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A PPENDIX C Once the formation has
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A PPENDIX C Figure C-3. Example of
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A PPENDIX C Figure C-4. FAST Flight
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A PPENDIX C The “true” time of
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A PPENDIX C References Cohen, S., a
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A PPENDIX D DC DCB DM DM DOCS DOD D
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A PPENDIX D NaCl NAR NASA NASTRAN N
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A PPENDIX E Appendix E TPF-I Review
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A PPENDIX F Alice Quillen, Universi
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A PPENDIX F Figure 3-1 - Original f
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TPF-I SWG Report - Exoplanet Exploration Program - NASA

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