The VLT Interferometer - ESO

More documents

Recommendations

Info

5.1. STATUS OF ADAPTNE OPTICS Wavefront sensor Pupil transfer lens --0 ___ /vi! F/8 telescope focus Figure 5.1: VLT Adaptive optics prototype system Wavelength range Deformable mirror Tip jTilt mirror Wavefront sensor 1.25 to 5 /-lm piezoelectric actuators ±7.5/-lm stroke gimbal mount piezoelectric actuators Shack-Hartmann principle 5 x 5 and 10 x 10 subapertures 100 x 100 intensified Reticon detector built-in reference source additional field selection mirror Wavefront computer dedicated electronics host computer (Motorola 68020) Bandwidth greater 10 Hz (will be improved) Control algorithm modal correction scheme based on mirror eigenmodes Camera 32 x 32 lnSb array camera SAT detector additional chopping mirror M7 103
104 CHAPTER 5. ADAPTIVE OPTICS FOR INTERFEROMETRY The first observations have been very successful and the first results prove the feasibility of this technology for astronomy. Figure 5.2 shows the first result obtained on a binary star (-y2 AND). These images (from the monitor screen) were obtained at Observatoire de Haute Provence through a K-filter using the 1.52m telescope. On the left is shown ,2 AND without adaptive correction, on the right with the adaptive feedback loop activated. It is planned to upgrade this system in 1990 and 1991 to approximately 50 subapertures (actuators of the mirror) as a final step towards the large adaptive optics systems planned for the 8 m telescopes. 5.2 Adaptive Optics for the VLT It is foreseen to equip the 8 meter telescopes of the VLT with adaptive systems with the following specifications: approximately 250 actuators 30 to 50 Hz bandwidth wavelength for correction: 2 to 2.5J.im and longer partial correction at shorter wavelength wavefront sensor in the visible and/or near infrared This means that with such a system the 8 m telescopes will render diffraction limited images in the indicated wavelength range all the time if coherence length ro of the atmosphere in the visible is in the 10 to 20 cm range. For the 2 meter class auxiliary telescopes systems with approximately 15 to 25 subapertures are foreseen depending on the final size of the telescopes. The other parameter concerning wavelengths and bandwidth will be identical as for the 8 meter telescopes. A system similar to the existing and working prototype would be already sufficient for these telescopes. It is assumed that the large scale atmospheric effects which can be considered as piston type phase errors between the telescopes are corrected by separate means (see chapter 7). This type of wavefront aberration can not be detected and corrected by the individual adaptive systems of the unit telescopes. In order to extend the application range for adaptive optics towards the visible it has been proposed to generate an artificial reference source inside the isoplanatic patch of the source to be observed by sending a laser beam to the higher atmosphere. The back scattered light will be used to measure the wavefront for
Page 3 and 4:
FOREWORD In November 1988 I propose
Page 5:
INTRODUCTORY COMMENTS This document
Page 8 and 9:
3.6.2.1 Spectral Dispersion in Imag
Page 10 and 11:
9.4 Remote Observing . . . . . . .
Page 12 and 13:
7.1 Lay-out of the 8 meter telescop
Page 14 and 15:
Chapter 1 Introduction 1.1 General
Page 16:
1.2. PREMISES AND ASSUMPTIONS 3 and
Page 21 and 22:
8 CHAPTER 1. INTRODUCTION being rou
Page 23:
Chapter 2 Scientific Aspects of Int
Page 27:
14 CHAPTER 2. SCIENTIFIC ASPECTS Ta
Page 31 and 32:
18 CHAPTER 2. SCIENTIFIC ASPECTS Ta
Page 35 and 36:
22 CHAPTER 2. SCIENTIFIC ASPECTS ra
Page 37 and 38:
24 CHAPTER 2. SCIENTIFIC ASPECTS an
Page 39 and 40:
26 CHAPTER 2. SCIENTIFIC ASPECTS [H
Page 41:
28 CHAPTER 2. SCIENTIFIC ASPECTS ti
Page 45 and 46:
32 CHAPTER 2. SCIENTIFIC ASPECTS LM
Page 47 and 48:
34 CHAPTER 2. SCIENTIFIC ASPECTS fo
Page 50 and 51:
2.3. DERIVED DESIRED PROPERTIES FOR
Page 52:
2.3. DERIVED DESIRED PROPERTIES FOR
Page 55:
42 CHAPTER 2. SCIENTIFIC ASPECTS li
Page 65 and 66: 52 CHAPTER 3. OPTO-MECHANICAL ASPEC
Page 70 and 71: 3.2. POLARIZATION EFFECTS IN INTERF
Page 76: 3.3. FIELD-OF-VIEW EFFECTS IN INTER
Page 81: 68 CHAPTER 3. OPTO-MECHANICAL ASPEC
Page 86 and 87: 3.6. FRINGE ACQUISITION AND TRACKIN
Page 89 and 90: 76 FRINGE DETECTION CHAPTER 3. OPTO
Page 98 and 99: 3.7. "BLIND FRINGE ACQUISITION AND
Page 100 and 101: 4.1. COMPUTER SIMULATIONS OF MULTIS
Page 102: 4.2. REDUNDANT VS. NON-REDUNDANT AR
Page 107 and 108: 94 CHAPTER 4. IMAGE FORMATION ASPEC
Page 109 and 110: 96 CHAPTER 4. IMAGE FORMATION ASPEC
Page 115: Chapter 5 Adaptive Optics for Inter
Page 119 and 120: 106 CHAPTER 5. ADAPTIVE OPTICS FOR
Page 121 and 122: Chapter 6 VLT Site Considerations 6
Page 123: 110 CHAPTER 6. VLT SITE CONSIDERATI
Page 128: 6.3. DISCUSSION OF POSSIBLE CONFIG.
Page 132 and 133: 7.1. SUMMARY OF BASIC REQUIREMENTS
Page 134 and 135: 7.2. THE 8M TELESCOPES 121 Ml M 11
Page 137 and 138: 124 CHAPTER 7. DEFINITION OF THE VL
Page 141: 128 CHAPTER 7. DEFINITION OF THE VL
Page 146: 7.10. IMAGE, PUPIL, AND FRINGE TRAC
Page 155 and 156: Chapter 8 Implementation Plan 8.1 I
Page 158: 8.2. DESCRIPTION OF THE ADVANCED AR
Page 165 and 166: 152 CHAPTER 8. IMPLEMENTATION PLAN
Page 167:
154 CHAPTER 8. IMPLEMENTATION PLAN
Page 170 and 171:
B.B. ADDITIONAL SUPPORT NEEDED 157
Page 172 and 173:
9.2. OPERATION OF THE VLTI/ADVANCED
Page 174 and 175:
9.5. OTHER OPERATIONAL ASPECTS OF T
Page 176 and 177:
Bibliography [Afanas'jev et al1988]
Page 178 and 179:
BIBLIOGRAPHY [Foy 1988] [Forbes 198
Page 180 and 181:
BIBLIOGRAPHY [Reinheimer et al 1988
Page 182 and 183:
Chapter 11 Appendices List of Appen
Page 184 and 185:
171 6. encourage the funding and co
Page 186 and 187:
3.2 Koechlin's 12T Results I derive
Page 188 and 189:
Appendix C Polarization effects in
Page 190:
in Table I for incidence angles 9 e
Page 199:
186 3. W. A. Traub, "Polarization E
Page 210:
7. REFERENCES 1. J. M. Beckers, "Fi
Page 214:
telescope diameter d. That conclusi
show all

The VLT Interferometer - ESO

Create successful ePaper yourself

Delete template?

Save as template?