GIANO-preslit: user manual, description and performances
Contents
1. The second one is the slicer that can be aligned using the six axes regulations of the commercial stage by Thorlabs on which it is mounted and the third one is the output fiber connectors that is a custom device as visible in Fig 27 etnei as x ita Fig 27 The Fiber out custom connector and angular regulation Using the fine fiber angle regulation it is possible to fine align the two foci on the slit in a range of 3 5 after this using the six axes regulation of the slicer it is possible to tune position and forms of the four half moons generated by the slicer To unlock the fiber regulation mechanism you have to unlock before the Screw 1 and the Screw 2 After this you can rotate of some degrees the fiber end of the science fiber 4 3 The Image Slicer The image slicer is a particular optical component that is able to divide an input beam into two or more slices and to reassemble the single slice side by side in the output beam In Fig 28 a photo of the Image Slicer is shown where in red is represented the only input beam and in green the two sliced beams Fig 28 Photos if the Imge Slicer prisms In red the input in green the output The idea of the slicer is to recover the lost light that falls out of the slit as visible in the side figure The use of the slicer permits to rearrange the shape of the focus without changing the Lagrange Invariance recovering the lights that otherwise would be los2. 2c A exp hc AKT 1T Apix Adpix Qpix emissivity of the calibration source area of one pixel pixel size 18um failure of the original science grade array solid angle of light cone illuminating a pixel GIANO preslit user manual description and performances 14 Nov 2013 Page 38 of 41 Efficiency of doublet window spectrometer 0 25 0 20 is On S fd Jul 22 2013 Giano doublet looking at black body gue d L E J e i i Cielo ig 2 L o2 B E T 108 C 5 T 150 C 4 F T 200 4 H O T 250 4 L AtT 300 4 m A T 350 Ha ti a d o ap slot a a i 1 2 1 3 14 15 16 17 18 1 9 20 2 1 22 2 3 2 4 Wavelength um Fig 34 Absolute efficiencies of the GIANO spectrometer without fibers interfaces GIANO preslit user manual description and performances 14 Nov 2013 Page 39 of 41 5 2 The end to end absolute efficiency of GIANO The measurements were performed during the night of 2013 July 30 using the same black body source described in the previous section The measurement setup is shown in Fig 35 Fiber GIANO interface including image slicer GIANO spectrometer OIG fiber Black body aperture k D 60mm interface science fiber Input focus 660mm Fig 35 Schematic layout of the setup used to measure the end to end absolute efficiency of GIANO The spectrometer was at operative condi
3. Silver EFL 27 22 mm P4 Edmund 63 192 protected Off axis angle 30 1 parabola 1 gold _ P5 Edmund 69 156 protected FEE Oa n 2 Off axis angle 15 parabola 1 gold _ P6 Edmund 69 154 protected PESA 3 Off axis angle 15 parabola 1 gold P7 Edmund 47 086 protected PPE DO n 4 Off axis angle 30 parabola Pecchioli Bowen SLC Custom Wallraven Image slicer 5 Research prism FM4 FM8 Thorlabs PF10 03 P01 ee 3 6 protected LI Gestione Silo Custom Car snel 7 lens L2 Gestione Silo custom Car smelt 8 lens Tab 7 Bill of material for the optical components for the Preslit OIG Box GIANO preslit user manual description and performances 14 Nov 2013 Page 35 of 41 4 6 Preslit GIANO box Dismount Mount Procedure echanical blocks i locks to lock the Preslit GIANO box i Fig 32 Figure shows the mechanical b The Preslit Giano box can be dismounted and mounted on the mechanical support structure that is fixed to the entrance windows flange of giano s cryostat The alignment blocking system is completely the same as used for the OIG Box and described in section 3 5 here the mechanical blocks are at least the four shown in the figure 31 but we are intentioned to add other two ones Because of the critical alignment of the focus with respect to the incoming cold slit of Giano no dismounting procedure is declared In case it is absolutely necessary to ask to the Arcetri Observatory infra
4. The results are summarized in Fig 36 The peak values of efficiency are about 0 091 which once compared with the results shown in Fig 33 indicates a total throughput of the fiber interfaces of about 41 This value is compatible with the measurement performed in Arcetri in June 2013 which yielded a total throughput of about 50 without the image slicer GIANO preslit user manual description and performances 14 Nov 2013 Page 41 of 41 Jul 30 2013 Giano end to end looking at black body it bee e a rn a ei e ea eri et a i 0 12 0 10 S e F e J D 0 08 e da a TD oO H e J n l __ g 0 06 JI l O o c x 0 04 F H T 150 C 4 0 02 F pie es Pe H i RR lt I eee i 1 2 13 14 15 16 17 18 19 2 0 2 1 2 2 Ro SA Wavelength um Fig 36 End to end absolute efficiencies of GIANO including the fiber interfaces 5 3 Efficiencies on sky The scientific observations of stars with known fluxes performed in the last run October 2013 were used to compute the instrumental efficiencies In the relatively few cases where the sky transparency and seeing conditions were acceptable the derived throughput was a factor of about 2 below end to end value measured with a black body Sect 5 2 This is compatible with light losses at the entrance of the fiber caused by seeing or non perfect centering of the object Although a significant margin of improvement
5. This because of the different operating modality we have for this board In particularly in Fig 5 the observing configuration in which one fiber looks at the sky and the other looks at the calibration lamp is schematically shown while in GIANO preslit user manual description and performances 14 Nov 2013 Page 8 of 41 DM PI P2 f 11TNG is en ii Calib NE U Halegen solenoid FM3 Fig 5 Conceptual plot of the Preslit OIG box in the downstream modality Dashed lines represent motorized axis BS solenoid Fig 6 Conceptual plot of the Preslit OIG box in the upstream modality P3 is an identical off axis parabola as P2 Fig 6 the Upstream modality is represented an Infrared LED is remotely switched on in the Preslit Giano Box and placed in front of the fibers using a motorized system This is Fiber Viewer modality and is described in Light path description of the Fiber Viewer camera paragraph In Fig 5 and Fig 6 the dashed lines represent the movable axis remotely controlled that are 1 The motor stage M 111 for the position regulation of the D shape mirrors located on f 11 TNG focus based on a Mercury PI commercial driver 2 The motor stage for the Neutral Density filter wheel based on a custom step motor driver 3 The solenoid to insert remove the light stop for the fiber viewer The Zemax designs for the different optical path are below listed and described GIA
6. 2100 11700 E _ i 38 2 019 225 1440 8490 39 1 967 146 980 6070 3 40 1 918 92 665 4195 3 2 41 1 871 5 435 2950 a E 42 1 827 i 295 2090 10050 A 43 1 784 z 202 1505 7490 _ 44 1 743 135 1050 5490 i 45 1 705 7 725 3940 E 46 1 668 _ 501 2895 47 1 632 3 340 1995 11550 i 48 1 598 230 1450 6330 3 49 1 565 155 1040 4705 50 1 534 3 110 745 3500 12450 51 1 504 2 520 2495 9595 52 1 475 _ 380 1900 7205 53 1 447 3 E E 270 1370 5395 54 1420 z 5 1002 4250 55 1 394 a E 740 3195 56 1 369 1 _ 2400 57 1 345 3 E 1870 58 1 322 i f 1410 59 1 299 E E 3 E 1080 60 1 278 z z 3 830 61 1 257 1 z 630 Tab 8 Measured fluxes with GIANO spectrometer looking directly at a black body source The photons flux expected from the calibration source at a given temperature T is given by photons s pix where Ebb 0 97 Apix 3 24 10 cm Quix 27 1 cos Opix 0 061 sr The spectrometer absolute efficiency is the ratio between the measured flux of photo electrons and P pix The results are summarized in Fig 34 The peak values of efficiency occur in the K band and are about 22 this value is very close to the 23 measured in Arcetri before shipping GIANO to the TNG The decrease of efficiencies toward the shorter wavelengths is caused by the intrinsic drop of quantum efficiency of the replaced detector which was sent to us in 2011 after the major Da pix
7. TABAN IR Photonics Custom core diam SMA connectorized 12 Fiber 400 micron Tab 5 Bill of material for the optical components for the Preslit OIG Box GIANO preslit user manual description and performances 14 Nov 2013 Page 20 of 41 3 5 Dismounting Mounting procedure The Preslit OIG Box is aligned on the f 11 TNG beam using the seven micrometers described above After this the mechanical blocks see Fig 18 can be inserted to avoid the possibility of accidental movements of the box itself especially during the rotation of the OIG flange Fig 18 Figure shows the mechanical block to lock the OIG box The dismount procedure of the OIG Box is the following 1 first of all it is necessary to remove the two mechanical blocks It is important to note that there is no need to move the micrometers from their original positions 2 it is necessary to open the cover of the OIG box removing the four corner screws on the top side wall 3 The OIG Box has six functional connections 4 electrical cables and 2 optical fibers that will be necessarily unplugged as shown in Fig 19 Four of these six connections are externally located and can be easily removed on the back side wall of the OIG Box But two of these connections the Science Fiber Optic and the PI M111 Motor Cable have the connectors located INTO the OIG box In Fig 19 their positions are marked by red triangles IMPORTANT NOTE 1 the science fiber is NOT symmetr
8. doing we are limited by the background noise in the K band due to the bigger dimension of the slit In fact the detector field of view permits to the detector to look at the two fibers image but also to look at the zone around the two fibers that is hot This is the main source of photon noise with respect to the use of S050 slit the background if 1 5 times more S050 slit with slicer the focus diameter if 175 micron again but because of the slicer we actually have four half moons with a height of 88 micron The slit is 93 micron so nominally it is possible to use this configuration but it leads to a challenging alignment A slightly rotation angle error in the positioning of fiber head sends the half moons out of the slit losing the image S075 slit with slicer in this case we have not round foci again but two couples of half moons see Fig 29 one for each fiber The height of the four semicircles is half a focus diameter that means 88 micron with respect to the slit height of 140 micron In this case we do not loose light in the matching the alignment is simpler than case 3 but we have again a factor 1 5 of background noise more that using S050 slit This is the configuration used for the Commissioning in July 2013 It is interesting to point out that using the image slicer we don t need the slit from the point of view of the spectrograph resolution but it continues to be important for the background light reduction w
9. fibers normally used for the scientific measures on the sky The outgoing light from these two fibers is collimated by P2 parabolic mirror on the FM2 folding mirror Then is partially reflected by the Beam Splitter BS and totally reflected back again from FM3 folding mirror This mirror is normally covered by a black stop placed in front of it but this cover can be remotely controlled and removed The light from FM3 passes through the beam splitter BS and follows the same optical path of the incoming light from star normally reflected by the dichroic beam Splitter BS On Finger Lake CCD FLI CCD an image of the two fibers is generated on the CCD Guider simultaneously or not with the scientific target FLI CCD Fiber outs 3D LAYOUT TWO 90 DEGREE PARABOLAS MON SEP 9 2013 THG OIG VERG FIBER VIERER 1ZZ_1 ZMX CONFIGURATION OF 1 Fig 12 Zemax optical design for the Fiber Viewer branch P2 and P3 are commercial identical parabolas BS is the dichroic beamsplitter FM3 is a folding mirror ND is a neutral density filter wheel BF is a passband filter File TNG_oig_ver6_fiber viewer_tzz_1 zmx The image of the two fibers is reimaged by the two identical off axis parabolas P3 and P2 on the CCD guider and so the magnification factor is equal to one The position of the two fiber images can be recorded and that coordinates on the CCD F1 x1 y1 and F2 x2 y2 will represent the correct position in which to align the
10. is shown You can find the optical devices already mentioned and stepper motor MT identical to that one used for the ND filter wheel in the OIG box and to that one used for the optical switch in the calibration unit box In this case it moves an IR LED that can be inserted into the optical collimated beam between P4 and PS it is directed versus P4 and generates an f 5 beam that is focalized by P4 to the fiber ends This light is the used one by FLI CCD to locate the fiber positions in the OIG box Observation modality fiber viewer In Fig 24 the alignment micrometers are shown It is the same system used for OIG box and the positions of the micrometers are listed in Table 6 Front Front Front cs Back a Description Vertical Orizzontal Focus Left Right Vert Left Right Acronym FV FO FF BOL BOR BVL BVR Value 17 70 0 95 4 00 20 50 4 95 18 25 17 50 mm Tab 6 Micrometer positions of the Preslit GIANO Box on 24 Oct 2014 Position and identification names of the micrometers are reported in Fig 24 GIANO preslit user manual description and performances 14 Nov 2013 Page 26 of 41 x 2 o oO 5 i v 2 ra Fig 23 Inventor design of the Preslit Giano Box In red the backup optical path NOT USED and not described in the present document In green the used one P4 P7 are Parabolic Mirrors FM4 FM8 are plane Folding Mirrors L1 L2 custom Lenses M116 a rotational stage MT a m
11. is still possible e g by using fibers with better FRD and adding a proper fiber viewer mechanism we nonetheless conclude that the instrument is fully ready for scientific operation
12. scientific target under investigation during scientific observation This is true provided that the folding mirror FM3 has not changed position in the course of time otherwise a recalibration procedure will be necessary and an offset to the two CCD pixel coordinates F1 and F2 will be necessary GIANO preslit user manual description and performances 14 Nov 2013 Page 15 of 41 TS DIF LIMIT 50 1250 0 0000 MM TS 0 0000 2 0000 MM s 0 0000 0 1250 MM TS 0 1250 0 0000 MM s 0 0000 2 1250 MM 1 0 T T T T T MODULUS OF THE OTF 0 0 i L l L i i ie nmaa J a 19 38 57 76 95 14 133 152 17 190 SPATIAL FREQUENCY IN CYCLES PER MM POLYCHROMATIC DIFFRACTION MTF TWO 92 DEGREE PARABOLAS MON SEP 9 2013 DATA FOR 2 9000 TO 1 1000 um SURFACE IMAGE TNG_OIG_VER6_FIBER VIEWER_TZZ_1 ZMX CONFIGURATION 1 OF 1 Fig 13 MTF of the Fiber Viewer system optics 3 2 Observing modes We now illustrate the Observing Modes OM The inputs of the two optical ZBLAN fibers are vertically disposed in the Preslit OIG box This fact permits to operate in different observation modality only moving the translation stage M 111 on which the two D shape mirrors are mounted as visible in the detailed design photo of Fig 14 and Fig 15 Fig 14 Detailed view of the D mirror placed on the f 11 TNG focus Mirrors are vertically mounted and the shape of these mirrors is like a D where the
13. 4 cables Top wire TLILAB cun ui Ho FL poser 2 cir HE BTLLL motori PI Input N2plant sin sheet avin int iii Qut Nz gas f2 soleroick 2 vin p F i h TNG Nasmyth A platform Fig 16 Giano general interface scheme electrical blue and yellow perimetric boxes gas grey brown and green boxes and light red The Giano instrumente internal cabling is represented too Below in the table the interfaces between Giano instrument and the TNG structure are listed In Fig 17 the photo shows the locations of the listed interfaces GIANO preslit user manual description and performances 14 Nov 2013 Page 18 of 41 Letter color Name Type Giano device TNG location Cryogenic Nasmyth A al Ac power line 220 Vac two phases pren wall i Nasmyth A a2 AC power line 380 Vac try phases Giano Cryostat wall i Preslit Nasmyth A a3 AC power line 220 Vac two phases si wall Preslit Nasmyth A b Ethernet RJ45 connection Rackmount wall i Cryogenic Nasmyth A c Ethernet RJ45 connection Rackm unt wall d Input Dry air Silicon tube Giano Cryostat pee e Out line for N2 Metal tube Giano cryostat A A f Out line pump Rotative pump jacket Giano cryostat a A g Out line for N2 Metal tube Giano cryostat BEDA platform f i Nasmyth A h Input N2 plant Standard cryogenic tube Giano cryostat platform i 11 beam Light from tertiary mirror Preslit OIG Nasmyth
14. A M25X1 tap is provided side derotator Tab 4 Giano s Instrumente interface list Colors are referred to Fig 5 Fig 17 Locations of the Giano s interfaces with TNG are shown 3 4 Inventory Of Optical Material of OIG box In the following Table the bill of material of the optical components for the Preslit OIG Box is listed GIANO preslit user manual description and performances 14 Nov 2013 Page 19 of 41 Acronym Manufacturer Type model Description notes 1 Silver EFL 152 4 mm Pl Thorlabs eee protected Off axis angle 90 1 parabola same of Edmund 63196 1 gold _ P2 Edmund 63 193 protected PR SG mm 2 Off axis angle 60 parabola 1 gold _ P3 Edmund 63 193 protected EROE 3 Off axis angle 60 parabola Pecchioli 2 Infrasil Coating Tafelmeier BS Research Custom SEA X PELPFI 1 surf 4 Tafelmeier AR 2nd surf FM 1 FM2 1 Silver FM3 Thorlabs PF10 03 PO1 protected 5 Long pass E BE Thorlabs FEL 750 filter short Mounted in series on the 6 FES 950 i same mechanical support pass filter ND Thorlabs NDC 100S 4 step vanale Ten position rotary sectors 7 grey filters CCD FLI 8 LI Thorlabs LB5766 DIE 9 singlet lens Thorlabs D shape gold Assembled by DM Pecchioli Res FEDAS Oo MO mirror Pecch Resea Calibration 2 ZBLAN SMA custom i IR Photonics Custom core diam 11 Fiber connectorized 85 micron Scientific
15. GIANO preslit user manual description and performances 14 November 2013 Ver 2 Name Affiliation Signature Ernesto Oliva INAF Arcetri AFA Andrea Tozzi INAF Arcetri ddl mn Marcella Iuzzolino INAF Arcetri Marella Juoko Livia Origlia INAF Bologna Le Ju 31 Quis GIANO preslit user manual description and performances 14 Nov 2013 Page 2 of 41 Modification Record Version Date Feras Reason Remarks affected 1 19 Sep 2013 all First release of the document 2 14 Nov 2013 3 5 Adjusted axis of fiber improved efficiency new values of pre slit micrometers GIANO preslit user manual description and performances 14 Nov 2013 Page 3 of 41 Content Contenti 3 IUS RIESI RISE MRC IE SIINO TEO ERIC IERI EE TENETE 4 2 IMFOCUCHOf scrl 4 3 Thefibers telescope interface cccsscssssscccsssscsssscecscsssscssssccesscssssssssscssesesssssosssoeseesees 5 3 1 Opto mechanical desteny onni ish ETERO Ai ad eee eee 6 3 2 Observing modes conen ili RAR 15 3 3 Giano s interfaces description i 17 3 4 Inventory Of Optical Material of OIG box eseseeeeeeenneeeeeeneeeeeesaaeeeeseneeeeeeeaeees 18 3 5 Dismounting Mounting procedure 20 3 6 Electronic plat iaia ea enne 22 4 The fibers spectrometer interface ccccssssccscssccsscessssscessccscessscssessssceseesssssseees
16. N 2 RAY Y MAX 22 TNG_DIG_VER6_FIBERIN_TZZ_1 ZMX MAX RADIUS 425 WAVELENGTH 2 4800 CONFIGURATION 1 OF 1 The following table shows the scale factor of the different foci present in Preslit OIG Box Scale Focus Position f number micron arsec sky TNG focus on OIG flange f 11 187 0 Fiber In on ZBLAN fibers 4 9 83 4 CCD Guider plane 4 9 83 4 Tab 2 Focus scale factor for the Preslit OIG box The magnification factor from f 11 TNG focus to f 4 9 Fiber focus is 2 24 GIANO preslit user manual description and performances 14 Nov 2013 Page 11 of 41 Light path description in the calibration mode The calibration mode optical design is represented in Fig 9 A fiber optics of 400 micron core diameter in ZBLAN feeds the Preslit OIG box the calibration NE U and Halogen lamps are in the box located into the rackmount placed on the Nasmity A platform The light is refocused by L1 commercial CaF singlet of 15 mm focal length on the f 11 nominal position of the TNG focus where a D shape mirror is located and can be easily positioned using a remote controlled motor linear stage M111 of MICOS PI Then the light follows the same optical path of the natural star and is focused on the fiber input terminations DM NPI f 4 8 fiber P focus hae ELE 30 LAYOUT MON SEP 9 2013 ING OIG VERG_CALIBPATION ON FIGERS_T22_1 74K CONFIGURATION 1 OF 1 Fig 9 Zemax optical de
17. NO preslit user manual description and performances 14 Nov 2013 Page 9 of 41 Light path description in the downstream working mode The F 11 beam from the telescope is collimated and re imaged at the fiber F 4 9 focus using two off axis parabolae and two bending mirrors The output F 4 9 beam has a diffraction limit optical quality and is pseudo telecentric nominally the exit pupil in Zemax design is located 151 mm far from the focus and has a diameter of 31 mm but the chief ray angle for a field of 2 arcsec in sky far from on axis one is only 3 5 arcmin This implies a lateral shift of the pupil of 0 017 A dichroic beam splitter on the collimated beam reflects the blue lt 850nm light to the guider An image of the TNG pupil is accessible before the dichroic as visible in the photo on this side taken during daytime placing a piece of paper in front of the dichroic The dome was opened during the test so the primary mirror and spiders are well visible f 11 TNG focus PI f 4 9 fiber focus FM1 30 LAYOUT GIANO OPTICS V5 9 HRI MON SEP 9 2012 TNG_OIG_VER6_FIGERTN_ bare 1 ets CONFIGURATION 1 1 Fig 7 Zemax optical design of the downstream mode P1 and P2 are commercial a BS is the dichroic beamsplitter FM are folding mirrors File TNG_oig_ver6_fiberin_tzz_1 zmx Fig 7 shows the design of the downstream mode The first off axis parabola P1 is placed 152 4 mm after the f 11 TNG focus s
18. e ND 0 1 1535 ND 0 6 735 ND 0 2 95 ND 1 0 895 ND 0 3 255 ND 2 0 1055 ND 0 4 415 ND 3 0 1215 ND 0 5 575 ND 4 0 1375 Tab 3 Neutral Density values Ts DIFF LIMIT TS TS 0 0000 0 0000 DEG DEG TS 0 0000 0008 DEG DEG 1 0 T T T T T T 0 9 H DE r nl LL bart LU T 0 6 H 4 E IL DS ot Y 0 4 H sel sal a 5 L 4 0 3 m 02 4 DI 0 0 i i i i i a 24 48 T2 96 120 144 168 192 216 240 SPATIAL FREQUENCY IN CYCLES PER MM POLYCHROMATIC DIFFRACTION MTF GIANO OPTICS Wa 9 TOR MON SEP 9 20213 DATA FOR 80 9000 TO i 1000 um SURFACE IMAGE TNG_OIG_VER6_GUIDER_TZZ_1 ZMX CONFIGURATION OF 10 Fig 11 MTF of the guider system optics We are intentioned to modify the Bandpass Filter to increase the throughput on the guider especially for very red intrinsically or reddened stars This can be easily done changing the filters in particular the FEL one that are mounted on a standard Thorlabs mechanical fixed mount GIANO preslit user manual description and performances 14 Nov 2013 Page 14 of 41 Light path description of the Fiber Viewer camera The Fiber Viewer is based on the same CCD camera used by the Guider On the optical beam in the Giano Preslit Box an IR LED can be inserted and switched on varying the intensity The light is partially collected into the two ZBLAN fibers and reaches the Preslit OIG box using the same
19. e box itself and the support structure is attached to the Giano input flange by 12 M6 screws The total mass is 35 Kg im 0 4 DL 4 1 Opto mechanical design The 3D opto mechanical design in shown in Fig 23 and the Zemax design in Fig 25 The green beam is the optical path to feed the Image Slicer SLC actually used The greater complexity of the operative optical beam is related only to the introduction of this last optical component SLC The red beam is a backup optical path if for some reasons we will decide to dismiss the Image slicer So this backup beam is not deeply described in the present document The starting point of the design of the Fiber Spectrometer interface is the incoming minimum f number that Giano Cryogenic optics can accept This value is mechanically defined by the ratio of the distance cold stop cold slit and the diameter of the cold stop itself nominally it is f 9 5 This choice comes from the hard definition of the fiber s f number due to the fiber focal ratio degradation FRD as used quality parameter for fiber The FRD varies with the incoming f number and because of the polishing procedure of each single fiber The output beam coming from the Preslit OIG Box via the Science fiber optics is collimated by the first Parabolic Mirror P4 with 30 off axis angle and EFL 27 22 mm the incoming beams from the two fibers are approximately f 4 9 The collimated beam is refocused by P5 off axis Parabo
20. e work in a fiber limited condition in which the image of the fiber is itself the slit and the spectral resolution is set by the slicer The Giano Detector pixel size is 18x18 micron Each pixel on the input cold slit has a nominal dimension of 18 micron 11 4 2 47 micron GIANO preslit user manual description and performances 14 Nov 2013 Page 31 of 41 Fig 29 Images of the f 16 focus using calibration light taken at TNG Left without the use of the slicer Right with the slicer In Fig 31 a Zemax simulation of the Bowen Wallraven prism is shown Bowen Walraven image slicers use a thin glass plate where the light is transmitted along by total internal reflection A base prism with a sharp edge is glued to the plate by molecular contact to cut the internal reflection of the transmitted beam By choosing an appropriate configuration the slices are arranged on a line simulating the slit of a spectrograph G Avila 8446 370 SPIE 2012 During the commisiong in July 2013 the used mode was number 4 In this condition we have measured an increasing signal in the GIANO s detector the gain G of using the slicer is equal to 1 6 the case in which we don t use it see Fig 30 On one hand the efficiency n of the image slicer optical element is 0 8 and this value can be found in an hypothetical GIANO working mode without the slit S050 On the other hand the efficiency of the slit S050 is 0 5 due to the required sp
21. ectral resolution for GIANO and the consequent slit dimension with respect to the fiber image size So this second value can be found in a GIANO working mode A without the image slicer and with the slit included The GIANO working case B that includes both the image slicer and the slit S050 has a light efficiency equal to 0 8 because the presence of the image slicer ensures that no light loss happens through the slit way The ratio between the light efficiency of the B working mode and A working mode gives the resulting gain coming from the image slicer use G 0 8 0 5 1 6 n1 0 8 I sila PP nee i 80 SPECTROMETER elementN L I n end 0 8 I I t_ ________ REA SERE I EN eee GIANO Working mode A I n2 0 5 1 I I I I 0 100 X 50 _ SPECTROMETER I ISLIT S050 i element N 2 I EER rg J Working mode B S A n n1 0 8 I n2 1 100 IMAGESLICER 22 element N 1 I ISLIT S050 nend 0 8 1 0 8 I alement N 2 gt Fig 30 The efficiency of Giano is increased by the use of the Slice Image working in B modality the total efficiency is 0 8 with respect 0 5 of A modality GIANO preslit user manual description and performances 14 Nov 2013 Page 32 of 41 Fig 31 The Image Slicer of the Giano s preslit based on a Bowen Wallraven prism GIANO preslit user manual description and performances 14 Nov 2013 Page 33 of 41 4 4 Fiber scrambler mecha
22. ertical bearing attached to the ex OIG flange At first the fiber telescope interface of GIANO was designed with minimal size resulting in a non easily adjustable matching After the 2012 commissioning a new interface has been introduced the new preslit system is composed by two different optical benches one mounted on the OIG Telescope interface and the other mounted directly on one side of the Giano Cryostat They have been realized mainly using commercial components in particular for the optomechanical devices this because of the short time used for the assembling This system has some new features with respect to the previous one PRESLIT OIG BOX 1 a full controlled telescope s optical axis fiber s axis alignment thanks to the available visible pupil check the adjustable optical components inside the OIG board and the possibility to align the whole OIG box using seven external micrometers realizing a full 3D alignment system 2 The possibility to look at the fibers position on the guider camera This is the upstream mode that is referred to the light going from a calibration source to the guider camera through the fibers in order to check the fiber alignment with respect to the telescope s axis PRESLIT GIANO BOX 1 a full controlled Giano optical bench fiber s axis alignment thanks to the adjustable optical components inside the Giano side box board and the possibility to align the whole box using seven external micromete
23. h the calibration source stabilized at T 150 C Data at other temperatures were not taken because of the long time necessary to change and stabilize the black body temperature The photo electrons flux from the detector was determined as the flux per spectral resolution element 2 pixels measured on the extracted 1D spectrum which includes all the signals from the two fibers The measured fluxes are summarized in Tab 9 the values can be transformed in flux of photo electrons using the conversion factor of GIANO array electronics 2 2 el ADU GIANO preslit user manual description and performances 14 Nov 2013 Page 40 of 41 Order i um Measured ADU per tee element in 10s 32 2 398 66900 33 2 325 53200 34 2 257 39600 35 2 192 30400 36 2 131 23000 37 2 074 16400 38 2 019 11200 39 1 967 7510 40 1 918 4840 41 1 871 3220 Tab 9 Measured fluxes with end to end GIANO system looking at a black body source The photons flux expected from the calibration source at a given temperature T is given by Py five 2c A exp hc AkT 1 w Afb AA Qm photons s where Epp 0 97 emissivity of the calibration source AX M47 000 width of spectral resolution element Afb 5 8 10 cm projected area of the fibers at F 11 Qap 27 1 cos 0 5 11 0 0065 sr solid angle of F 11 light cone The end to end absolute efficiency is the ratio between the measured flux of photo electrons and fin
24. ical so if you unplug the SMA connector you lose the position of the two fibers that has to be vertically disposed with respect to the optical bench The female SMA connector is placed on a standard post mountable XY translation stage Thorlabs model LM1XY that has the possibility to adjust the rotation angle of the fiber after it is mounted and screwed When you will remount the OIG box this is the correct device to rotate to find the correct alignment of the two Science fibers looking at the FLI CCD used in the Fiber Viewer configuration you have to place the image of the two fibers vertically in the same position you have before starting the dismount procedure GIANO preslit user manual description and performances 14 Nov 2013 Page 21 of 41 IMPORTANT NOTE 2 the motor cable of PI M 111 linear stage has a standard DB15 connector It is located under the Traco Power downconverter visible in Fig 19 that MUST be removed in order to have direct access to the DB15 connector Fig 19 Connection cables and fibers of the OIG box 4 Now the OIG Box can be removed It is 20 Kg heavy and first of all you have to uplift of 1 2 centimeters the box in the front zone This to unplug the mechanical joint located in the bottom side that is the ONLY mechanical constrain of the OIG Box The Joint is free to move itself and pay attention not to lose it In any case it is an RS components 689 215 5 The OIG Box can be run on the two ver
25. icrometers are visible OIG interface Fig 3 Inventor design of the Preslit OIG box FM are Folding plane Mirrors Pare parabolic mirrors BS is the dichroic Beam Splitter ND the neutral Density sector wheel DM the D shape Mirror L1 is a lens BF a Pass Band filter In dashed red arrow the input of the fiber calibration light in green the science output fiber GIANO preslit user manual description and performances 14 Nov 2013 Page 7 of 41 for each ones the correct nominal position is given in Tab 1 The positions of the micrometers are the following Front Front Front ieee a Back re Description Vertical Orizzontal Focus Left Right Vert Left Right Acronym FV FO FF BOL BOR BVL BVR Value 11 32 5 00 7 13 15 49 10 20 6 44 5 27 mm Tab 1 Micrometer positions of the Preslit OIG Box on 24 Oct 2013 Position and identification names of the micrometers are reported in Fig 4 The mounted size of the Preslit OIG box is 600mm x 300mm x 120 mm and its weigh is 20kg this box can be easily removed and it is the part of the system that will be aligned on the telescope f 11 beam using the micrometers The total weight of the interface including the flange adapter and support system is about 39kg In Fig 5 and Fig 6 are represented the conceptual designs of the Preslit OIG Box The optical design is composed by at least four optical designs described in the following paragraphs
26. inary test of Giano and form a refocusing relay lens to well match the outcoming f number of the preslit system with the nominal incoming f number of the cold optics that if f 9 5 the nominal f is in fact 10 and the diameter of the two foci on the slit is 175 micron with respect to the slit dimension of 150 micron in the maximum resolving power position The slit is mounted on a rotary stage that has several slits and other support alignment devices but actually this wheel is fixed on the 150 micron slit and the motor driver is kept switched off permanently DON T switch on this motor no movement of the slit rotary wheel is permitted without the approval of GIANO Technical team GIANO preslit user manual description and performances 14 Nov 2013 Page 25 of 41 coldslit D 1754m y 8 _ Sold stop O gt max P9 5 gt C HID Giano window nosicer slicer L1 L2 i with slicer P7 oo D 280um Calib _____T _ errato 3 _ ie ee 46 Ee alli SLC Pe _ ee Y lt lt with slicer gt O Fig 22 Schematic representation of the Fiber Spectrometer interface assembled into the Preslit Giano Box P4 P7 are Parabolic mirrors FM8 is the rotator folding mirror SLC the sclicer In the top right red box the matching between the slit and the foci is represented in case the slicer is used or not used In Fig 23 the 3D design of the Preslit Giano Box
27. ith respect to the Preslit OIG box optical bench plane this will be important for the definition of the observing modes as described in chapter 3 2 Observing modes It is important to say that the core dimension is 1 arcsec on sky and that the distance between centers is 3 arcsec on sky Finally it is fundamental to underline that the axis of the fiber must be mechanically aligned relative to the optical axis of the pre slit optics This extra alignment which was performed during the last commissioning run October 2013 was the most important operation which allowed us to drastically improve the on sky efficiency of the system Indeed we found that the fiber axis was tilted by many degrees relative to the mechanical axis of the fiber connector and consequently most of the light from the telescope was entering the fiber with a large tilt angle GIANO preslit user manual description and performances 14 Nov 2013 Page 6 of 41 Fig 2 Optics of the Preslit OIG box 3 1 Opto mechanical design Description of the board optical parts size and weight are below reported The OIG box is based on a commercial 60X30 cm aluminum optical bench by Thorlabs onto which the optics are positioned as visible in Fig 3 The opto mechanical design is based on commercial elements including in particular three off axis parabolic mirrors which only recently became available as standard off the shelf optical elements In Fig 4 the alignment m
28. ition name AC gt star fiber up calib fiber down The top fiber is fed by the light from sky while the bottom fiber is optically conjugated to the calibration beam 4 M 111 15 mm position name AB gt 1 2 sky The D shape mirrors are placed in the bottom as far as possible from the mechanical axis of the input hole The whole sky is visible by the guider as already said the nominal FOV in this condition is 2X2 arcmin but it is partially vignetted by the mechanical mount that supports the D shape mirrors GIANO preslit user manual description and performances 14 Nov 2013 Page 17 of 41 3 3 Giano s interfaces description In the following figure Fig 16 it is represented the general Giano spectrometer interface and the internal cabling scheme All the interfaces with TNG are represented and are listed with letters a b h i and they are of different types electrical blue and yellow gas grey brown and green and light red TNG 2013 Nasmyth A side wall f c d c a3 b az al JPS out gas Out Nz Inputf Ether 1 UPS2 UPS1 nava rotativo pump pas fl dry air RO Var 20 vac Ether 2 PRESLIT Giano Box GIANO CRYOSTAT PLC CRIOGENIC 18 viec cob ed RACK PRESLIT Detector Sapt fiber RACK i electronics sci Fibers Faniiirerroneenne br neneneanesisiiiiveveneoneoneas don See PPE nann Col Fiber 2 pin cable wT July 13 PRESLIT OIG box GIANO INSTRUMENTE INTERFACE
29. lic GIANO preslit user manual description and performances 14 Nov 2013 Page 24 of 41 Mirror off axis angle of 15 and EFL 654 99 mm The generated focused beam has an f equal to 120 The necessity to have a so big f number is related to the difficulties to build an image slicer of small dimensions with a so big f number we have the images of the two fibers equal to 2 04 mm being their real core diameter of 85 micron and the focal ratio of PS and P4 of 24 and their center to center distance of 6 0 mm The beam is collected by P6 15 off axis parabolic mirror EFL 367 7 mm that collimates the beam again The last parabolic mirror P7 generates the correct f number in the correct position before entering in the matching lenses L1 L2 placed near the input window of Giano Cryostat P7 has an off axis angle of 30 and an EFL 54 45 mm it generates an f 16 beam whose focus includes an image of the two sliced cores of the Science Fiber Nominal diameter of the focus is 280 micron This auxiliary focus is very useful to check quality beam before entering the Giano Cryostat After this 16 focus the beam is folded by FM8 whose center is nominally placed on the axis of the cold stop of Giano This mirror is placed on a rotator stage to permit the alignment of the focus with respect to the slit that we remember in Giano is placed quasi horizontal Lens L1 and L2 are the same matching lenses used the last year for the prelim
30. nism The fiber scrambler mechanism is able to eliminate the Modal Noise that is usually present in an IR eschellogramme when a fiber optics is used to transport the telescope light to the spectrometer as discussed in the previous document of commissioning 2012 vi H It is based on a series of rotating disks that shakes the external fiber jacket Because of the fragility of these ZBLAN fibers the minimum static radius of torsion for these fibers is 50 mm due to the dynamic way of use we have doubled this specification The scrambler is positioned on the Nasmyth A platform near the Giano cryostat the fibers from OIG box enters in the mechanism from the top side and exits to the bottom To insert the fiber in the scrambling mechanism it is not necessary to unplug it the top and bottom blocks have two screws that can be removed when you have to insert extract the fibers The fiber has to pass in alternatively right and left of each rotating wheel as visualize in the photo aside The power supply to the DC motor is guaranteed by an electric cable pin to pin DB25 coming from the Preslit Rackmount GIANO preslit user manual description and performances 14 Nov 2013 Page 34 of 41 4 5 Inventory Of Optical Material of Preslit Giano box In the following Table the bill of material of the optical components for the Preslit Giano Box is listed Acronym Manufacturer Type model Description notes 1
31. o the output beam is collimated by the P1 parabolic mirror having an Effective Focal Length EFL of 152 40 mm with an error of 1 The beam is folded and a pupil image is placed in the dichroic beam splitter So P1 realizes a real image of the primary mirror on the beam splitter The second off axis parabola P2 has an EFL of 67 74 mm with an error of 1 and generates and f 4 9 output beam focalized on the input fiber termination The scale of this focus is 83 4 micron arcsec in sky and the whole system is diffraction limited in the full wavelength range 900 2400 nm as shown in Fig 8 GIANO preslit user manual description and performances 14 Nov 2013 Page 10 of 41 L a 21 42 63 Ll B4 10 T T T T T T ooh 4 n8 H 4 E Oo Bh 4 Ww IT tb 4 a L asp 4 a u ap 4 a aL a Q CS 4 Bie ALL 4 0 0 i i i i i i 105 126 147 168 SPATIAL FREQUENCY IN CYCLES PER MM POLYCHROMATIC DIFFRACTION MTF V5 9 CHRI MDN SEP DATA _ FOR 0 TO 2 4800 SURFACE US TNG_OIG_VER6_FIBERIN_TZZ_1 ZMx CONFIGURATION 1 OF 1 aes n ne x ti a x D 7 x 1 H a 4 D ee S T AJ oO S a E APERTURE DIAMETER p849 4 RAYS THROUGH 100 007 FOOTPRINT DIAGRAM GIANO OPTICS V5 9 HRI MON SEP 9 2013 SURFACE 24 RAY X MIN 425 RAY X MAX RAY Y MI
32. otor to control the LED position and SLC is the Image SLiCer The procedure to dismount remount this box is the same of the OIG one and it is described in section 4 6 Fig 24 Alignment details of the Preslit GIANO box External micrometers are visible and for each ones the correct nominal position is given in Tab 6 GIANO preslit user manual description and performances 14 Nov 2013 Page 27 of 41 FM4 30 LAYOUT TWO 9 DEGREE PARABOLAS WED SEF 11 2013 TNG_FIBER_DUT_VERS_2BIS ZMX CONFIGURATION 1 OF 1 Fig 25 Zemax optical design for the Preslit Giano Box P are commercial parabolas File TNG_fiber_OUT_ver5_2bis zmx GIANO preslit user manual description and performances 14 Nov 2013 Page 28 of 41 4 2 Slit centering mechanism The slit center mechanism visible in Fig 26 is based on a commercial rotary stage PI M116 that can control the vertical tilt angle of the folding mirror FM8 you find before L1 L2 optical system This plane mirror is nominally positioned vertically with respect to the optical bench and has its center located on the mechanical axis of the cold stop of Giano Fig 26 The slit centering mechanism Because of the large field of view of L1 L2 reimaging system the vertical position of the f 10 foci can be changed without affecting the optical quality of the foci themselves The stage is based on a commercial Physik Instruments device M 116 and has the app
33. red team the permission of such hazardous thing and to verify their availability for the realignment procedure GIANO preslit user manual description and performances 14 Nov 2013 Page 36 of 41 5 Measurements of efficiency This section summarizes the most significant measurements of absolute and relative efficiencies of GIANO and interfaces 5 1 The absolute efficiency of the GIANO spectrometer The measurements were performed on 2013 July 22 using a commercial certified black body source model CS500 manufactured by DIAS Infrared GmbH emissivity 0 97 The measurement setup is shown in Fig 33 GIANO Black body source i spectrometer 1 Window_____ Detector Input focal plane of GIANO 7 2 7 Cold stop lA 19 5 a EE ERA BB aperture D 60mm 11454 lt _ _ gt _Doublet SORRISE swrsdeckkrkco a 8 eolie ssaa Fig 33 Schematic layout of the setup used to measure the absolute efficiency of the GIANO spectrometer The spectrometer was at operative conditions with all the cryogenic parts stabilized at a temperature of about 80K The only optics at ambient temperature were the lenses and window used to re image the input focal plane of GIANO onto the cold slit As cold slit we used S050 whose width and length 0 093 x 1 12 mm projects onto 2 x 24 pixels of the detector The spectral resolution of the data is determined by the slit width and amo
34. ropriate angular resolution to realize a scan procedure of the slit with the purpose to maximize the signal on the Giano s detector The whole mechanism is mounted on a mechanical support structure that can be manually rotated using two micrometer screws The vertical rotary axis of this regulation is positioned on the center of FM8 within 0 2 mm error This regulation is necessary to the horizontal fine positioning of the foci in the Giano cold slit while using the external box micrometers you can roughly adjust the horizontal position of the foci by tilting and translating the whole Preslit Giano Box The translation rate of the foci with respect to the rotating angle of FM8 is 90 micron arcmin being the dimension of the slit the following S075 1 120 x 0 140 mm Actually inserted S050 1 120 x 0 093 mm so to cover the whole height of the S075 slit you need to rotate the M 116 of 1 6 arcmin It can be done easily with great resolution using the PI stage e the minimum incremental motion of the stage is 50 microrad 10 31 arcsec e unidirectional repeatability is 12 microrad 2 50 arcsec The slit centering mechanism is one of the three devices that can move the image of the focus The Giano Detector pixel size is 18x18 micron Each pixel on the input cold slit has a nominal dimension of 18 micron 11 4 2 47 micron GIANO preslit user manual description and performances 14 Nov 2013 Page 29 of 41
35. rs realizing a full 3D alignment system 2 The possibility to increase the efficiency using a slicer prism 3 The possibility to look at an intermediate focus before the beam enters in the cryostat GIANO preslit user manual description and performances 14 Nov 2013 Page 5 of 41 3 The fibers telescope interface The fiber telescope interface is realized by the Preslit OIG Box described in the following paragraphs First of all it is important to remember that the two Preslit boxes are optically connected by a couple of fibers optics assembled as shown in the following design in the same SMA connector IMPORTANT NOTE according to our measurements it is crucial do not modify the fiber cladding Fiber acrylate buffer diameter has the appropriate diameter to permit placing side by side the two fibers SMA fiber connector for example Thorlabs 10510A ZIE _ rar SI e ga EE iN 7 LLLLLLLY AZZ ZBLAN fiber optics 85 micron core 247 micron external diameter Polished surface of SMA connector parallelism between fiber axis lt 5 arcmin Yellow core diameter 85 micron Orange cladding diameter 125 micron Blu buffer diameter 247 micron Glue Ferrule hole 250 micron ZBLAN fibers Fig 1 Design of the custom fiber optics patch cord Core diameter of each fiber is 84 micron 1 arcsec on sky Distance between centers is 250 micron 3 arcsec on sky The two fiber terminations are placed vertically w
36. scesees 23 4 1 Opto mechanical design iene 23 4 2 Sht centering mechanism lla 28 4 3 The Imag Shicer rele aliene LI Iaia 29 4 4 Fiber scrambler mechanism eitan anir rnoet ae EE aa SEE EE a ee 33 4 5 Inventory Of Optical Material of Preslit Giano box 34 4 6 Preslit GIANO box Dismount Mount Procedure i 35 5 Measurements of efliclelty cain 36 5 1 The absolute efficiency of the GIANO spectrometer 36 5 2 The end to end absolute efficiency of GIANO i 39 5 3 Efficiencies on SKY noens aeaee i a a E a EE 41 GIANO preslit user manual description and performances 14 Nov 2013 Page 4 of 41 1 Scope This document describes the new fibers interface of GIANO which was mounted and tested at the TNG telescope during the commissioning runs in 2013 It also includes the maintenance procedures and summarizes the results of the measurements of efficiencies performed during the same runs 2 Introduction In the first Giano s cryostat commissioning on July 2012 the spectrograph was located in the TNG Nasmyth A and was positioned on the floor of the rotating building detached from the telescope As a consequence Giano is feed via special fibers with extended transmission to the infrared wavelengths which are interfaced to the telescope at the ex OIG focus The interface is mounted on a quasi gravity invariant structure consisting of a horizontal bench fixed to a v
37. sign for the Calibration mode P1 and P2 are commercial parabolas BS is the dichroic beamsplitter FM are folding mirrors DM is D shape couple of mirrors remotely controlled File TNG_oig_ver6_calibration on fibers_tzz_1 zmx The M111 MICOS PI translation stage controls the position of two D shape mirrors that are custom assembled to permit different observing operating modes as described in the following chapter The final f number of the calibration beam is approximately f 4 with a scale factor of approximately 1 The nominal magnification from the fiber source 400 micron fiber to the final focus is equal to one so the input terminations of the scientific ZBLAN fiber can be fed by the incoming light from the calibration light source that can be chosen between the Ne U lamp and the Halogen lamp The calibration sources are located into the Preslit Rackmount GIANO preslit user manual description and performances 14 Nov 2013 Page 12 of 41 Light path description of the guider camera The Guider is based on a CCD camera made by Finger Lake based on a CCD having 512X512 pixel array of 20 micron pixel size The focal camera is realized using an off axis parabola P3 identical to P2 The scale on CCD is 83 micron arcsec on sky that it means there is a magnification of 0 44 from f 11 TNG focus to the focus on the guider CCD The nominal FOV of the guider is 2X2 arcmin but during sky observation the FOV is partially vignetted b
38. straight side is very well worked to generate a knife Two of these mirrors have been mounted on the same mechanical mount using Millbond optical glue the two parallel sides form a slit of about one GIANO preslit user manual description and performances 14 Nov 2013 Page 16 of 41 millimeter located at the nominal f 11 TNG focus The tilt regulations of the mechanical mount on which the D mirrors are placed are useful to align the outgoing calibration beam from lens L1 to be overlapped to the f 11 TNG telescope chief ray Fig 15 The two D mirrors are glued on an iron ring to take them in position one with respect the other Changing the value of M 111 linear stage position it is possible to have the following OMs 1 2 3 M 111 0 mm home position name CC gt 1 2 calib The Light from sky is blocked by the back surface of the D shape mirrors In this position the light from calibration input can be reflected by the bottom D shape mirror to the outgoing fibers and the guider along the input optical axis of the Preslit OIG box M 111 1 7 mm position name CB gt star fiber down calib fiber up The bottom fiber is fed by the light from sky while the top fiber is optically conjugated to the calibration beam It is important to remember that the two parabolas M1 and M2 generate an inverting optical system magnification from focus is 0 44 so the top fibers looks at the bottom f 11 focus M 111 2 7 mm pos
39. t GIANO preslit user manual description and performances 14 Nov 2013 Page 30 of 41 In case of Giano spectrometer there are two main slits called SO50 and S075 whose dimensions with respect to the dimension of the core of the science fiber 85 micron are in one case too small and in the other a little bit too large No other change was possible because of the pixel size dimension of the IR detector equal to 18x18 micron that corresponds to 47x47 micron on input Cold Slit optical plane noslicer slicer As visible in Fig 22 the core diameter of the two fibers is 85 micron that are reimaged on the Cold Stop with a magnification of 2 06 so the diameter of the image is 175 micron Now we have to consider the dimension of the slit already mentioned in the previous paragraph S075 1 120 x 0 140 mm nominal collecting angle in sky of 0 75 arcsec Actually inserted S050 1 120 x 0 093 mm nominal collecting angle in sky of 0 50 arcsec The possible alignments fiber slit modes are four 1 2 3 S050 slit without slicer in this case we have a focus of 175 micron with respect to a slit of 93 micron that means we lost approximately half light of the total transported by the fiber In this case the spectrometer works slit limited as normally happens in standard spectrometers S075 slit without slicer in this case the focus is again 175 micron and the slit 140 micron We reduce the lost light but so
40. tical micrometer So doing the box can be removed by its support and alignment structure The mounting procedure is the same of the dismount one but from the last point to the first one great attention MUST be paid to the IMPORTANT NOTE 1 GIANO preslit user manual description and performances 14 Nov 2013 Page 22 of 41 3 6 Electronic plan Fig 20 sketches the electronic cabling Power supplies box Filter Whee calibration box Electronic box TNG Nasmith OlG Lantronics Portserver N ZBLAN zalib D e O Oe BE pera 2 i O Ce P ZED cesT PI motar Mason Dstep 2 pin cable 2 D a PI Moto cable 15 pin cd a ZELAN doublefibor O Fig 20 Schematic representation of the electronic cabling el The electronic Preslit Rackmount contains all the electronics needed for the preslit It is composed by PC Xill Lantronix Ethernet RS232 portserver Calibration box Ne Uranium driver lamp Electronic box Power supplies box mmo w gt Below a spare volume for future devices if needed GIANO preslit user manual description and performances 14 Nov 2013 Page 23 of 41 4 The fibers spectrometer interface The interface between the science fiber and Giano spectrometer is realized in the Preslit Giano Box visible in Fig 17 and Fig 23 Inventor 3D design The box has the following dimensions 606 X 456 X 140 mm and has a mass of 25 Kg The whole system composed by th
41. tions with all the cryogenic parts stabilized at a temperature of about 80K As cold slit we used S075 whose width and length 0 14 x 1 12 mm projects onto 3 x 24 pixels of the detector This slit is larger than the image of the fibers It is used as field stop to minimize the thermal background at the longer wavelengths The spectral resolution of the data is determined by the width of the image of the fiber produced by the image slicer see below The light was taken to the spectrometer through all the sub systems which constitute the interface between GIANO and the telescope In particular the measurement included the same fiber and image scrambler used for scientific observations The black body source whose aperture has a diameter of 60mm was positioned at 660mm from the focus of the OIG fiber interface Thus the interface was illuminated with a beam aperture of F 11 identical to that of the telescope In this configuration the spectrometer slit is the image of the fibers produced by the fiber interfaces The image of two fibers de projected onto the entrance F 11 focus of the OIG fiber interface consists of 4 half circles with radius 0 096 mm aligned along the direction perpendicular to the dispersion Therefore the total area illuminated by the black body at F 11 is 0 058 mm The spectral resolution of the data is determined by the slit width of the fibers image It amounts to R A AA 47 000 The measurements were performed wit
42. unts to R A AA 47 000 thus each pixels sees a wavelength range AApix A 47 000 of the continuum emission from the calibration source The angular aperture of the light seen by the detector is defined by a cold stop positioned before the cold slit The semi angle of the cone is 0pix 8 0 equivalent to a focal ratio of F 3 6 Measurements were performed with the black body source stabilized at different temperatures namely 108 150 200 250 300 and 350 C For each temperature we used the data at a dozen of wavelengths corresponding to the centers of the orders of the echellogram i e the measurements correspond to the wavelengths of maximum efficiency of each order We included only the parts of the spectrum which were well detected and far from the saturation limit lt 13 000 ADU pix The measured fluxes ADU pix are summarized in Tab 8 the values can be transformed in flux of photo electrons using the conversion factor of GIANO array electronics 2 2 el ADU GIANO preslit user manual description and performances 14 Nov 2013 Page 37 of 41 Measured ADU pix in 10s multiply 0 22 to get photons s pix Order Am 12108 C T 150 C T 200 C T 250 C T 300 C T 350 C 32 2 398 2090 9820 33 2 325 1480 7350 3 7 i 34 2 257 1015 5280 2 i 35 2 192 735 4050 E 3 36 2 131 520 3000 3 37 2 074 340
43. y the D shape Mirror support located on the f 11 TNG focus and necessary to change the observing mode P3 ND f 11 TNG focus BF 30 LAYOUT GIANO OPTICS V5 9 CHR MON SEP 3 2013 TNG_OIG_VER6_GUIDER_TZZ_1 ZMX CONFIGURATION OF 10 Fig 10 Zemax optical design for the Guider branch P1 and P3 are commercial parabolas BS is the dichroic beamsplitter FM ais a folding mirror ND is a neutral density filter wheel BF is a passband filter file TNG_oig_ver6_guider_tzz_1 zmx After the Dichroic Beam Splitter there are positioned a BandPass filter BF and a multi position Neutral Density Wheel having the following ND values 0 1 0 2 0 3 0 4 0 5 0 6 1 0 2 0 3 0 and 4 0 The transmission can be calculated by T 10 The non perfectly parallelism of the two surfaces that compose the grey filters have been measured and it is negligible so the translating effect of the stars measured by the guider is not affected by the ND filter wheel and no look up table is necessary Before the ND filter wheel a Bandpass Filter BF is placed on the optical path It has been realized using two commercial filters of thorlabs cut on FEL 750 cut off FES 950 GIANO preslit user manual description and performances 14 Nov 2013 Page 13 of 41 Neutral density values and their motor step positions are the following Neutral density name Motor step value Neutral density name Motor step valu
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