Class Note for ASTR 518 with Professor Rieke at UA
Class Note for ASTR 518 with Professor Rieke at UA
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This 32 page Class Notes was uploaded by an elite notetaker on Friday February 6, 2015. The Class Notes belongs to a course at University of Arizona taught by a professor in Fall. Since its upload, it has received 16 views.
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Date Created: 02/06/15
2x84m LBT f1 14f 150 Gregorian 18m VATT f 1 0f90 aplanatic Gregorian 7x84m GMT f07f 80 aplanatic Gregorian Aplanatic Gregorian elli soid p eIIIpSOId SE C D DART MIHHDF39 5 F Evil t m Advantages of AG Advantages of RC Easier to construct mirrors Shorter telescope 45 Larger FOV lO Smaller obstruction 40 Field concave upward Field convex upward Field slightly less curved Real exit pupil allows stop Accessible prime focus Speckle image a mosphere speckle imerferogram elescope 6 m elescope YOri 9n 500 nm speckle imerferogram field of View 184 arcsec Scintillation For D ltlt r0 eg the eye wavefront can be broken and refracted completely out of line of sight Think of shadow patterns on the bottom of a swimming pool Results u 7 A v in rapid ickering of a star Resolved sources eg quot39 i planets remain steady in brightness Also seen in radio due to motions of plasma clouds in the ISM Atmospheric turbulence at the pupil Resolution of a telescope I F w 2 I 1 u i 3 I P I 1 I I quot la i i r l 7 i l I fquot Young s I singleslit y ll y I ll experlment 1 JD 1 I Iquot III a 39I I quot fTquot39x g A I lllll jquot a I In39 Irquot iquot i fquot I af x 39hl 1399 quotla HF up My C g V g V destructive interference When ml w sin 9 Wavefront Sensing WF S ShackHartmann Sensor Illa khm t n o z e V a W 0 e m r m e d pupil plane image plane Sample ShackHartmann images Telescope defocus Typical image Automatic spot identification Wavefront Sensing WFS Shearing Interferometer Interfere two wavefronts with small lateral offset Difference measures wavefront slope to first order Generally abandoned in favor of 8H WFS pupil plane Analogous to Fizeau fringe formation Wavefront Sensing WF S Curvature Sensor CDC392 inside focus outside Requires displacement lltlt F so difficult to use for highorder corrections Adaptive 0ptics basics Tman Incoming di orlcd wnwefmu Highamen lipvmllnillw 111 whoquot ml 1 E 2 Eczmipliuer 5 k DelommbIe 1 1 mm 4 Sticlm u r insme p 1 Driver y 39 39 HI 1 wk MMTf15 d t d mggggmrm J 2 a a we SGCOH ar Hipmmgn 77 A was ml mm Flgure 5115 Madapt39we 39 aquot syncs sys em The distorted E waveivant 21 is anaryznd and WW Sigfigiimi i lo 3 1w c gtw 1 1 lwaurmm Wemmm conventional AO system G Z7 Coma allquot Wavefront sensing is essential for telescope CO 1 l n H Z8 3rd ul39dcr Spherical tOO pupil phase psf 6w Atmospheric refraction dispersion 4 y Zenith dist secz Refr Disp Azquot I 5500A U to 1 2 7 30 115 34quot 11quot F 45 141 59quot 20quot 0 60 200 101quot 34quot 2 75 386 215quot 72quot 80 576 319quot 106quot Measured re ectivity of silicon 65 Sipolarization 60 k 3 rr gt 95 N o 8 angle ofmcxdenoe g 50 v 45 angle of incidence E o a 45 Mr 11M n 200 300 40D EDD 600 700 800 900 Wavelength nm Re ection from a dielectric I Boundary conditions for EM waves at an interface 1 ZEW ZEt g 2 ZDW ZDng 3 ZHM ZHLg Where D 8 E 1 and 2 become Equot s 6a E cos 9 2 E9 os Hg eaEa sin 60 60E sin 69 E9 sin Hg 219 it due to phase shift of 180 upon re ection from denser medium 2 and 3 are equivalent for this case EM wave polarized in the plane of the figure Re ection from a dielectric II Let n EEm use Snell s law my sin 99 no sin 6a and 9a 2 9 Ea 30s 9a E9 cos 99 i V i 2 V nie Ea nie Ea s111 6a 2 ngenEg 5111 99 r 2 g i 2 1 0r Ea Ea77as11163 ngEg sin 69 Solving for Eq and 0111bining11 2 cos 9 39n sin 9 71 En E quot Ea E Ea E i 039 ms 99 0 sin 99 39 a n9 Re ection from a dielectric IV If we consider medium 1 to be vacuum z air and note that radiant ux ocE2 we nd re ected uX Fresnel re ections Glass Index of refraction ul39 1 69 s39 39 I 139 Fr quot Pk 39 1 my u If Loss 1 airglass interface Crown 6563A Crown 4100A Flint 6563A Flint 4100A Fused quartz 4100A Mng 4100A Silicon 5000A 1520 1538 1663 1698 1468 1389 4298 43 45 62 67 36 27 39 Interference by multiple re ections I E0 E E5 o aa1r 11ayer V ggms vibfV 5W E mg g Let E Portion of E a which is re ected b 39 air la or interface I Portion of E which is re ected by layer glacss interface E3 Portion of E 5 which is trainimitted by air layer interface Interference by multiple re ections II To minimize net re ections we want Ea39Ea and a phase shift of 7 between the two n i n E a Eu from 222 no n 277 s f g E 2 Eu m Ea from 223 710 m if m 15 E 08190 and we will nd that it is much closer than this Then El 2 I 1 Ea 711 719 771 my 271 m 77 E E m E 930 Interference by multiple re ections III So our criterion of no re ections reduces to 710 m m nq N Ea a nu n m nq V3422 Settin n 1 and solvin 39 for n we obtain a l Anti Re ection Coating In To get 75 phase difference 2Z1 112 or ll lair4111 14 MgF2 coating performance Glass Without With 1 interface Crown Mng 4100A 45 16 Flint Mng 4100A 6 7 01 Fused quartz Mng 4100A 36 18 Silicon 5000A 39 145 Dmse rum rusnn Mamaslxn Flmrme mm m llva u M Example of M4 MgF2 coating L Unwed nom a n1 nan man man man man xnnn ma man i w vamata Multilayer dielectric i quotAm iner a coatings MW v A A7 400 500 500 700 800 we won Moo Wuvvhlmylh um Back to the problem of silicon 65 Sipolarlzation 60 k 3 rr gt 95 N o 8 angle ofmcxdenoe g 50 v 45 angle of incidence E o a 45 Mr 11M n 200 300 40D EDD 600 700 800 900 Wavelength nm Transmittance 145 nm tun Optimizing CCD QE with dielectric films Hafnium oxide Refractive index up Measured CCD QE curves Measured QE Sample Curves 100 90 1 lays r 500 30 g 70 1 3 60 E 50 65 A Q 40 g i 20 10 0 1 1 1 1 1 1 1 1 1 03 04 05 06 07 08 09 1 11 Wavelength um M Lam Srzu md 0b521wttoljr CCD Labomrmy Solgel coatings 39 Colloidal suspension the 41 of generally inorganic metal salts that can be deposited by dipping in gel form onto an optical surface Advantages 39 Can form nearly ideal quarterwave transparent coating with re ectance never exceeding that of uncoated substrate W 39 Tendaney to absorb oils from air and surroundings compromising performance Fragile structure Can be scratched or rubbed off with rather little effort Solgel coating for MMT corrector zf Re ectance Mn N mu 3 Hr Hutu fM jm 7 77 7 mmquot 0 in m sin m am an m 15m Wavelength nm Lens lens who s got the lens Solgel coated element of MMT f5 corrector Enhancedre ection coatings Can also use dielectrics atop metallic surfaces to enhance re ectivity Use doublethickness 12 This may also offer protection against oxidation of the underlying metal here silver La lyrv The Haly Grail Coating crass 0V r at 3390 l 12 VIII 1 year old Murmnum Vitness XAl Brown39s 4713767 Recipe H L V4 suck oasooA 7 46A Cu 4 1021A Ag SSA 0 225A 545 4 291A Zr0TiO h innlmnml u r I I x l A 5 fl Wavelength um a 3 39a Figure 3 Re ectivity of the Holy Grail coating relative to aluminum
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