MuSICa image slicer prototype at 1.5-m GREGOR solar telescope

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1 MuSICa image slicer prototype at.5-m GREGOR solar telescope A. Calcines* a, R. L. López a, M. Collados a,b, N. Vega Reyes a a Instituto de Astrofísica de Canarias, c/ Vía Láctea s/n, La Laguna, Tenerife, Spain b Avda. Astrofísico Fco. Sánchez, s/n, La Laguna, 38200, Tenerife, Spain. ABSTRACT Integral Field Spectroscopy is an innovative technique that is being implemented in the state-of-the-art instruments of the largest night-time telescopes, however, it is still a novelty for solar instrumentation. A new concept of image slicer, called MuSICa (Multi-Slit Image slicer based on collimator-camera), has been designed for the integral field spectrograph of the 4-m European Solar Telescope. This communication presents an image slicer prototype of MuSICa for GRIS, the spectrograph of the.5-m GREGOR solar telescope located at the Observatory of El Teide. MuSICa at GRIS reorganizes a 2-D field of view of 24.5 arcsec 2 into a slit of arcsec width by arcsec length distributed horizontally. It will operate together with the TIP-II polarimeter to offer high resolution integral field spectropolarimetry. It will also have a bidimensional field of view scanning system to cover a field of view up to by arcmin 2. Keywords: image slicer, IFU, MuSICa, POP, IFS, GREGOR, EST, GRIS, SIFS.. INTRODUCTION TO SOLAR IFS (SIFS) Although IFUs (Integral Field Units) have been implemented at night-time spectrographs in the last decades, SIFS, Solar Integral Field Spectroscopy, is a technique in recent development for the largest ground-based and space solar telescopes. The magnetic structures observed in the Sun evolve in very short time scales and, using standard long-slit spectrographs, these structures can move out of the slit field of view in large exposure times. Thus, the optimum way to study a solar region is to apply 3-D spectroscopy and to obtain the spectra of all its points simultaneously. For this reason, an integral field spectrograph [] is being designed for the 4 meters European Solar Telescope (EST) [2]. A new concept of image slicer [3], called MuSICa (Multi-Slit Image slicer based on collimator-camera), is designed for this spectrograph and a prototype, whose characteristics and design are described in this communication, is being designed for the.5 meters GREGOR solar telescope [4], at the Observatory of El Teide, Tenerife. Figure.Scheme of Solar Integral Field Spectroscopy (SIFS). A 3-D datacube (x, y, λ) is obtained from a bidimensional entrance field of view. This scheme corresponds to the multi-slit image slicer of EST, in which the 2-D field of view is reorganized in eigth slits. *azcr@iac.es; phone ; fax ; Ground-based and Airborne Instrumentation for Astronomy V, edited by Suzanne K. Ramsay, Ian S. McLean, Hideki Takami, Proc. of SPIE Vol. 947, 9473I 204 SPIE CCC code: X/4/$8 doi: 0.7/ Proc. of SPIE Vol I- Downloaded From: on 0/02/204 Terms of Use:

2 2. MuSICa PROTOTYPE TECHNICAL CHARACTERISTICS The prototype image slicer will be coupled to GRIS [5], the GREGOR infrared spectrograph. GRIS [6] is a long slit spectrograph that operates in the near-infrared, from to 2.3 μm with very high resolution (R~500,000) for measurements of the photospheric and chromospheric magnetic field. It presents a Czerny-Turner layout using off-axis parabolic mirrors with a focal length of 6 meters, a focal-ratio F/39.79 and an echelle diffraction grating with 36 grooves/mm and a blaze angle of 63.4º. The entrance slit has 80 arcsec length (50 mm) by 0.26 arcsec width (72 μm). GRIS also presents the possibility of polarimetric observations coupling the TIP-II polarimeter [7] before the spectrograph slit. MuSICa for EST [8] reorganizes an 80 arcsec 2 field of view into 8 slits of 200 arcsec length by 0.05 arcsec width using slicer mirrors of 50 μm. MuSICa prototype reorganizes a 24.5 arcsec 2 field of view into one slit with 66.8 arcsec length by arcsec width. Since this slit corresponds to the spectro-polarimetric mode of observation, the slit will be duplicated in its two orthogonal linear polarizations illuminating the spectrograph with a slit of 33.6 arcsec length by arcsec width. The requirements and specifications of the image slicer prototype for GRIS are presented in Table and the technical characteristics of its optical components are shown in Table 2. Table. Specifications and requirements for the IFU prototype design. SPECIFICATIONS AND REQUIREMENTS FOR THE IFU PROTOTYPE Input focal-ratio F/39.79 Output focal-ratio F/39.79 FoV 24.5 arcsec 2 Number of slices 8 Slices width 00 μm Number of output slits Generated slit field of view 66.8 x arcsec 2 Optimum illumination telecentric Table 2. Technical characteristics of the IFU prototype optical components. TECHNICAL CHARACTERISTICS OF THE IMAGE SLICER PROTOTYPE OPTICAL COMPONENTS SLICER MIRROR ARRAY Size 0.8 mm width x 2.28 mm length Curvature Flat Size of each mirror 0. mm width x 2.28 mm length Field of view per slice 0.37 x 8.36 arcsec 2 COLLIMATOR MIRROR ARRAY Diameter mm Curvature Spherical Distribution 2 rows of 4 mirrors Focal length 250 mm PUPIL MASK Number of apertures Size Circular Diameter 0 mm CAMERA MIRROR ARRAY Diameter mm Curvature Spherical Distribution 2 rows of 4 mirrors Focal length 250 mm Proc. of SPIE Vol I-2 Downloaded From: on 0/02/204 Terms of Use:

3 MuSICa for GRIS is a : telecentric system in which the input and output focal-ratios are the same, F/ It is composed by three arrays of mirrors: slicer mirror array, collimator mirror array and camera mirror array. The slicer mirrors are flat, they are located at the telescope image focal plane and each slicer mirror has a different orientation (tilt X, tilt Y) to reflect a part of the entrance field of view and send it to a collimator mirror. The optical path of each sliced part of the field of view is described by the reflection of the beam in one mirror of each array to generate a part of the output slit. The second optical element is the collimator mirror array, composed by eight spherical mirrors with a diameter of mm. Different focal lengths have been studied and the current solution has a focal length of 250 mm. The focal length was fixed as the minimum with which an optical quality at diffraction limit was obtained (evaluated at μm). In front of the collimator mirrors the camera mirrors are placed, also spherical, with mm diameter and a focal length of 250 mm. Collimator and camera mirrors have antisymmetric correspondences, so that the intermediate pupil images, generated between them lie at the same position and are all overlapped. At the pupil position a mask is placed to avoid the contribution of scattered light. In this layout the mask has only one circular aperture with a diameter of 0 mm. These steps are represented in Figure 2. The image slicer optical components are pointed out in the STEP. The beam reflected by a slicer mirror array follows this optical path (STEP 2): it is sent to a collimator mirror, which collimates it; a pupil image is generated at its focal length, between the collimator and the camera mirror arrays; the camera mirror focuses it and generates its image at its focal length. This image is a piece of the output slit. The final slit is generated alternating focusing beams of each one of the two columns of camera mirrors to compensate the angles of incidence and improve the optical quality. The images of each part of the sliced field of view are aligned composing the output long slit (STEP 3). The pupil images are overlapped in an intermediate plane between the slicer mirror array and the generated slit. I:-ER EA 4.4í;R ARRAY CAIAERA I.I:FROR ARRAY Figure 2. This figure summarizes in 3 steps the optical components of MuSICa (STEP ) and shows the optical path of the beams (STEP 2). The beam reflected by a slicer mirror array is sent to a collimator mirror, which collimates it. A pupil image is generated at its focal length, between the collimator and the camera mirror arrays. The camera mirror focuses it and generates its image at its focal length. This image is a piece of the output slit. The final slit is generated alternating convergent beams of each one of the two columns of camera mirrors to compensate the angle of incidence and improve the optical quality. The images of each part of the sliced field of view are aligned composing the output long slit (STEP 3). The pupil images are overlapped at an intermediate plane between the slicer mirror array and the generated slit 'i ' MuSICa prototype uses eight flat slicer mirrors with a width of 00 μm and a length of 2.28 mm. The entrance slit of the GRIS spectrograph is horizontal. For that reason the entrance field of view for the IFU has its larger side on this way, 2.93 arcsec height by 8.36 arcsec length (0.8 mm height by 2.28 mm length). MuSICa layout has some particularities as: the slicer mirrors are flat and their width is the thinnest possible to manufacture right now (00 μm); it was designed as a multi-slit image slicer, however, the prototype generates one slit. Its design for EST is compatible with two modes of observation (pure spectroscopic or spectro-polarimetric), however, it will operate only in polarimetric mode at GREGOR due to scientific interests. The original MuSICa layout uses sixteen slicer mirrors of 50 μm and the prototype will have eight slicer mirrors of 00 μm, since this is the thinnest width currently guaranteed. A feasibility study of 50 μm slicers mirrors will be carried out for EST. The antisymmetric correspondence of collimator and camera mirrors makes possible the overlapping of the pupil images. With this, the pupil mask presents only one circular aperture and the fabrication and alignment of the system are easier, reducing also the fabrication costs. The mirrors of the different arrays are geometrically distributed parallel to the output slit. The MuSICa layout is versatile enough to be fixed to different geometrical distributions. Proc. of SPIE Vol I-3 Downloaded From: on 0/02/204 Terms of Use:

4 The stray light analysis is currently under study and probably two masks will be needed, a field mask at the slicer mirror array and a pupil mask at the intermediate pupil images, what will reduce significantly the stray light contribution. 3. COUPLING AT GREGOR SOLAR TELESCOPE The idea to couple an integral field unit (IFU) to the GRIS spectrograph was made after the design and development of the spectrograph itself. For that reason, the image slicer has to be adapted to the available space at GREGOR solar telescope (Figure 3). The IFU is preceded by a field of view scanning system to allow the observation of a larger field of view, up to x arcmin 2, in consecutive observations. Both, field of view scanning system and integral field unit will be coupled to each other and integrated in the reduced available space. The polarimeter will be located behind the generated slit and it will duplicate the slit as a result of the separation of the two orthogonal linear polarizations of light. The GRIS spectrograph is integrated in two floors. The slit, the polarimeter (optional for spectro-polarimetric observations) and a folding mirror, FM, are located in the upper floor, while the rest of optical elements are in the lower floor. The available volume to couple: the image slicer, the scanning system and the polarimeter is defined by a box with 60 mm length by 775 mm width by 505 mm height. The integration of these subsystems at the entrance of the spectrograph has the restriction that the IFU generates a slit whose optical path should keep the nominal distances without the image slicer. CURRENT DISTRIBUTION FMII FOLDING MIRROR POLARIMETER INSIDE SLIT-JAW IMAGING SYSTEM..Ms._ SPECTROGRAPH SLIT (TELESCOPE FOCAL PLANE) Figure 3. Current distribution at GREGOR. The space between the spectrograph slit and the folding mirror FM will be used to couple the field of view scanning system, the IFU and the polarimeter, in a box with 60 mm length by 775 mm width by 505 mm height. Proc. of SPIE Vol I-4 Downloaded From: on 0/02/204 Terms of Use:

5 4. DIFFRACTION LIMITED DESIGN 4. Optical performance The image slicer prototype for GRIS has been designed using ZEMAX sequential (Figure 4) and non-sequential modes (Figure 5). As can be seen in Figure 4, a folding mirror has been used to drive the generated slit to the spectrograph entrance. The output long slit is composed by the aligned distribution of the images of each part of the sliced field of view. The layout of MuSICa for GRIS presents an optical quality limited by diffraction as shown in the ZEMAX spot diagram of Figure 6. The possible aberrations have been compensated distributing the mirrors of each array adequately to minimize off-axis distances and angles of incidence. slicer mirror array collimator mirror array camera mirror array overlapped pupil images Figure 4. ZEMAX sequential mode optical layout of the image slicer prototype for EST designed for GREGOR. Although the angles of reflection seem to be bigger in this view, the tilts of the mirrors are equal or smaller than 4.4º artsec 2.28 mm aresec 00 Nm SLICER MIRROR ARRAY Figure 5. ZEMAX non-sequential mode layout of the slicer mirror array composed by eight flat slicer mirrors, each one of them with 8.36 arcsec length by arcsec width disposed horizontally. Proc. of SPIE Vol I-5 Downloaded From: on 0/02/204 Terms of Use:

6 Conti," Costi(' 2 Coatlo 3 Contra 4 Consti," s Coati," 4 Contro Cootie e I Ideol O Ide,"l 0 S uifac :: t).: CUTP 7S SLIT Configuration Matrix Spot Diagram 33/04/204 Omits are pa. Airy Radius: µa XuSlCa GRIS 2S0um POP. ralx Scale Dar : 00 Pkterence : Ccmtroid Configuration: All 8 Figure 6. Spot diagram at diffraction limit of the GREGOR image slicer design of Figure 5 evaluated at μm. Each column represents a piece of the output slit. The beams are contained within the Airy disk for all of them. 4.2 Diffraction effects analysis ZEMAX layouts are based on geometrical optics ray tracing. Rays are traced considering its propagation without interfering between them. This ray tracing does not consider, thus, other important effects, such as diffraction. This can be studied applying Physical Optics Propagation (POP) tool of ZEMAX. A pupil is generated before the image slicer using a : reimaging system. This pupil is then propagated through each surface of the image slicer. The first surface is the slicer mirror array, whose width is 00 μm. The Airy disk diameter for a focal-ratio of evaluated at μm is μm. Thus, it is expected to have the first diffraction ring contained within the slicer mirror size and, consequently, at least the 83.3% of the energy. This is demonstrated in Figure 8, in which the POP analysis has been done at the slicer mirror number 4 (the one with the largest off-axis distance) for a defined central field point. Equivalent results have been obtained for the eight slicer mirrors. After passing through a surface, the convolution of the pupil diffraction pattern with the diffraction produced by the own surface is observed. This analysis is consecutive until the last surface, the output slit in this case (see Figure 9). Proc. of SPIE Vol I-6 Downloaded From: on 0/02/204 Terms of Use:

7 Total Irradiance surface 0 SLICER MIRROR 22/04/204 Wavelength µm in index at , mm Display X Width =.4700E+000, Y Height =.4699E+000 Millimeters Peak Irradiance = 2.347E+003 Watts/Millimeters^2, Total Power = E+000 Watts Pilot: Size= E-002, Waist= 2.597E-002, Pos= E-002, Rayleigh= 2.0E+000 Figure 7. ZEMAX physical optics propagation analysis of a defined pupil at a slicer mirror. This analysis has been done for the eight slicer mirrors obtaining equivalent results. As expected, the first Airy disk, whose diameter is μm, is contained within the slicer width (00 μm), as shown in the diffraction pattern projected over the slicer mirror. This is represented in logarithmic scale in Figure mm E +4 E +3 loo um :4KOWlile _E +2 E + E +0 E - Total Irradiance file POP SLICER CONF4 CAMPO2 modif.zbf 22/04/204 Wavelength }mi in index Display X Width =.4700E+000, Y Height =.4699E+000 Millimeters Peak Irradiance = 2.347E+003 Watts/Millimeters-2, Total Power = E+000 Watts X Pilot: Size= E -002, Waist 2.597E -002, Pos= E -002, Rayleigh 2.0E+000 Y Pilot: Size= E -002, Waist= 2.597E -002, Pos=e E -002, Rayleigh 2.0E+000 Figure 8. ZEMAX physical optics propagation analysis of a defined pupil at a slicer mirror represented in a logarithmic scale. The slicer mirror width is 00 μm and, as shown in the figure, the PSF, evaluated at μm, has a diameter is of μm and, at least the 83.3% of the energy is contained within the slicer mirror. Proc. of SPIE Vol I-7 Downloaded From: on 0/02/204 Terms of Use:

8 I I E+4 E+3 E+2 i :: i E+ E+0 E- Total Irradiance file POP slit_conf_campo2_modif.zbf 22/04/204 Wavelength µm in index Display X Width =.4529E+000, Y Height =.4529E+000 Millimeters Peak Irradiance = 2.243E+003 Watts/Millimeters^2, Total Power = E+000 Watts X Pilot: Size= E-002, Waist= 2.592E-002, Pos= E-002, Rayleigh= 2.08E+000 Y Pilot: Size= E-002, Waist= 2.592E-002, Pos= E-002, Rayleigh= 2.08E+000 Figure 9. ZEMAX physical optics propagation analysis using the POP tool of a defined pupil over the output slit generated by the image slicer. This figure is represented in logarithmic scale and it correspondences to a central field point.,,,,, _ I :.6 - -I t _I i t i 3. i - : Square width Ensauared Power file POP SLICER CONF CAMPO2 modif.zbf 22/04/204 Wavelength gm in index Display X Width =.4700E +000, Y Height =.4700E+000 Millimeters Peak Irradiance = 2.345E +003 Watts/Millimeters -2, Iotal Power = E+000 Watts X Pilot: Size= E -002, Waist= 2.598E -002, Pos= E -002, Rayleigh= 2.03E +000 Y Pilot: Size= 2_S926E -002, Waist= 2_S93E -002, Pos= +S_494E -002, Payleigh= 2_03E+000 Figure 0. Ensquared energy evaluated at the slicer mirror number for a central field point. The red discontinuous line represents the size of the slicer mirror width, 00 μm. The slicer mirror width has been adapted to the diffraction limit and the loss of energy is ~2%. Proc. of SPIE Vol I-8 Downloaded From: on 0/02/204 Terms of Use:

9 Since an extensive object is defined in ZEMAX as a list of point objects defined by field points, the fields for the slicer mirrors have been defined using three field points, using the central values and the edges. A diffraction pattern for each source is then obtained, three per slicer mirror and per the other surfaces. The ones associated to the slicer mirror number, decentered 50 μm with respect to the optical axis, are shown in the mosaic of Figure, which is represented in logarithmic scale (Log-5). E+4 E+3 E+2 :4(( E+ E+0 E- Total Irradiance file POP SLICER_CONF_CAMPO_modif.ZBF E+4 E+3 :[( ).: E+2 E+ E+0 E- Total Irradiance file POP SLICER_CONF_CAMPO2_modif.ZBF E+4 E+3 E+2 CO0; E+ E+0 Total Irradiance file POP SLICER_CONF_CAMPO3_modif.ZBF Figure. POP analysis at slicer mirror number, decentered 50 μm with respect to the optical axis. From top to bottom the figures shows the diffraction pattern of the pupil over the slicer mirror for the fields of the left edge, center and right edge, consecutively. The slicer mirror inverts the image. E- Proc. of SPIE Vol I-9 Downloaded From: on 0/02/204 Terms of Use:

10 5. THERMAL ANALYSIS Temperature affects materials and may lead to possible modifications in the final performance. Thermal control is highly recommended, as well as the use of materials, either for substrates or mounts, with a low thermal expansion coefficient. At GREGOR telescope, the IFU will be integrated in a room thermally controlled at 20 ºC, however, a thermal analysis between 9º C to 22º C has been done using ZEMAX to analyze possible variation ranges in parameters as the focus position. MuSICa image slicer will be made of zerodur glass, whose coefficient of thermal expansion is very small, ~0.0 ± 0.0 x 0-6 K -. The thermal analysis using ZEMAX has been done considering all the mirrors made of this material. The different parameters, such as: radii of curvature, thickness, semidiameters and the degrees of freedom of the mirrors of each array, decentered X, decentered Y, tilt X and tilt Y, have been analyzed. Insignificant modifications in these parameters were obtained in a thermal interval of 3 degrees with respect to the nominal values. The first study of thermal effects using ZEMAX has been done without considering mechanical mounts. For them, zerodur and invar have been considered. Invar is a nickel-iron alloy, consisting of around 36% nickel and 64% iron, with very low coefficient of thermal expansion,.2 x 0-6 K -. Once the mounts are designed, they will be implemented in ZEMAX and the thermal study will be repeated. It is not expected a significant change with respect to the present results, taking into account the low coefficient of thermal expansion of the considered material. 5. Optomechanical concept Preliminary conceptual optomechanical design starts focusing on maximizing performance of the instrument once established tolerances budgets, after analyzing the sensitivities of aberrations to component positional errors. Alignment and positioning restrictions require a good balance among the following factors to achieve accuracy demanded (a tolerance of 5 μm in a focal length of 6 meters): - Materials - Structural design - Mounts and mount interfaces - Assembly and alignment Integral Field Unit reflective components (slicer, collimator and camera mirrors) have their own sets of mounting issues because they are more sensitive to surface distortions than refractive optics. Support small mirrors semikinematically is a solution for many cases, in such an interface, all six degrees of freedom (three tilts and three translations) are uniquely constrained against reference surfaces by forces delivered through small areas, but optical layout does not allow an individual kinematic or cuasi-kinematic mount for each mirror due to optical components are too close to each other. This alternative became infeasible, not only for that reason if not because it is not possible to ensure accuracy and repeatability as small mechanical components. To satisfy accuracy requirements it is needed: a mount insensitive to thermal distorsions, a small number of pieces to minimize manufacturing errors and an effective and accurate mounting system. Two of these requirements can be achieved using zerodur glass, for both mirrors and mounts. Zerodur has a coefficient of thermal expansion nearly zero and offers very high finished tolerances, what makes it suitable for this purpose. For each mirror three degrees of freedom (displacement along Z-axis and rotation around X and Y axis) are constrained by coupling the rear part and the mating surface of the mount. Displacement on X-Y plane are locked using three radial restrictions, two of them are fixed and other with a preload system. After optical alignment of the system, mirrors are bonded to their supports using multiple small adhesive areas. Thus, the entire optical system will keep the alignment transferring the problem to the interface with the support table. Preliminary thermal and stress analysis have been done using Ansys to simulate how affects a face to face contact between zerodur mirror and the zerodur mount under a thermal gradient of 3 grades (9-22 ºC). The maximum values of displacements and stresses are contained within the allowable limits, so currently, the alignment system to validate the concept is being designed before the preliminary design phase. Proc. of SPIE Vol I-0 Downloaded From: on 0/02/204 Terms of Use:

11 Figure2. Conceptual optomechanical mount design for multiple mirrors, made of zerodur. Displacement on X-Y plane are locked using three radial restrictions, two of them are fixed and other with a preload system. Displacement along Z-axis and rotation around X and Y axis are constrained by coupling the rear part of the mirrors and the mount surface (coplanar conctact), both are high quality finish tolerance (around λ/20 - λ/40). After optical alignment, mirrors are bonded to the mount using multiple small adhesive areas. k Mirror Total Deformation Type: Total Deformation Unit: m tn,e: 26/05/204 5: e -5 Max 3,7624e 5 3,3005e 5 2,8385e5 2,3766e -5,946e -,4527e-'- 9,907 5,287 t4 Directional DeforwatIon Type: Directional Defonnation(ZAxis) Unit m Global Coordinate System Time: 26/05/ e -4 Max 5,2834e 4 3,9026,.4 2,528e -4,4.4-2,3985e -5 -,6207e -4-3,905e 4, (m) , ,9023 Figure 3. Mirror deformations ( mm of diameter made of zerodur) constrained with a zerodur mount is less than a nanometer. Multiple adhesive contact areas are being analyzed with different thickness between the mirror mount and the frame. Left: Ring contact. Right: Three point contact. Tensions in the mirror are very small compared to the elastic limit. Proc. of SPIE Vol I- Downloaded From: on 0/02/204 Terms of Use:

12 6. CONCLUSIONS Integral Field Spectroscopy is a powerful technique highly recommended for new generation spectrographs. Its application for Solar Physics is very useful and, at present, this technique is under study in the largest ground-based and space solar telescopes. A prototype image slicer for the European Solar Telescope (EST) has been designed to be coupled to GRIS, the GREGOR Infrared Spectrograph, at the.5 m GREGOR solar telescope. This IFU is based on the layout designed for the integral field spectrograph of EST (MuSICa) using three arrays of mirrors: slicer mirror array (flat), collimator mirror array (spherical) and camera mirror array (spherical), with eight mirrors for each array. The image slicer prototype reorganizes a 2-D field of view of 24.5 arcsec 2 into a slit of arcsec width by arcsec length. It will operate together with the TIP-II polarimeter to offer high resolution integral field spectropolarimetry. It will be preceded by a bidimensional field of view scanning system to cover a field of view up to by arcmin 2 in consecutive expositions. The slicer mirrors have a width of 00 μm. The diffraction effects have been considered and the width of the slicer mirrors has been adjusted to the PSF guaranteeing at least an 83.3% of the energy. The ZEMAX layout has an optical quality at diffraction limit. The image slicer will be fabricated in zerodur to improve the stray light and thermal effects. The final studies, such as tolerances and stray light analysis, are currently under study and the final design will be closed before the end of 204 for its fabrication. ACKNOWLEDGMENTS This work is carried out as a part of the Project SOLARNET, funded by the European Commission s 7 th Framework Programme under grant agreement no The design of the IFU for EST was carried out as a part of the Collaborative Project EST: "The large-aperture European Solar Telescope: Design Study", funded by the European Commission s 7 th Framework Programme under grant agreement no Financial support by the Spanish Ministry of Economy and Competitiveness through the project AYA (Solar Magnetism and Astrophysical Spectropolarimetry) is gratefully acknowledged. Part of the work presented in this communication was carried out at IA-UNAM during a stay in 204 under the supervision of Dr. Salvador Cuevas. Proc. of SPIE Vol I-2 Downloaded From: on 0/02/204 Terms of Use:

13 REFERENCES [] Calcines, A., López, R. L., Collados, M., A HIGH RESOLUTION INTEGRAL FIELD SPECTROGRAPH FOR THE EUROPEAN SOLAR TELESCOPE, Journal of Astronomical Instrumentation, Vol. 2, No., (203). [2] Sánchez-Capuchino, J., Collados, M., Soltau, D., López, R., Rasilla,J. L., Gelly, B., Current concept for the 4m European Solar Telescope (EST) optical design, Ground-based and Airborne Telescopes III. Edited by Stepp, Larry M.; Gilmozzi, Roberto; Hall, Helen J. Proceedings of the SPIE, Volume 7733, article id , 9 pp. (200). [3] Calcines, A., López, R. L., Collados, M., MuSICa: THE MULTI-SLIT IMAGE SLICER FOR THE EST SPECTROGRAPH, Journal of Astronomical Instrumentation, Vol. 2, No., (203). [4] Collados, M., López, R., Páez, Hernández, E., Reyes, M., Calcines, A., Ballesteros, E., Díaz, J. J., Denker, C., Lagg, A., Schlichenmaier, R., Schmidt, W., Solanki, S. K., Straameier, K. G., von der Lühe, O., Volkmer, R., GRIS: The GREGOR Infrared Spectrograph, Astronomische Nachrichten, Vol. 333, Issue 9, p.872 (202). [5] Calcines, A., Collados, M., López, R. L., MuSICa at GRIS: a prototype image slicer for EST at GREGOR, Highlights of Spanish Astrophysics VII, Proceedings of the X Scientific Meeting of the Spanish Astronomical Society (SEA), Eds.: J.C. Guirado, L.M. Lara, V. Quilis, and J. Gorgas., pp (203). [6] Collados, M., Calcines, A., Díaz, J. J., Hernández, E., López, R., Páez, E., A high-resolution spectrograph for the solar telescope GREGOR, Ground-based and Airborne Instrumentation for Astronomy II. Edited by McLean, Ian S.; Casali, Mark M. Proceedings of the SPIE, Volume 704, article id. 7045Z, 8 pp. (2008). [7] Collados, M., Lagg, A., Díaz García, J. J., Hernández Suárez, E., López López, R., Páez Mañá, E., Solanki, S. K., Tenerife Infrared Polarimeter II, The Physics of Chromospheric Plasmas ASP Conference Series, Vol. 368, Proceedings of the conference held 9-3 October, 2006 at the University of Coimbra in Coimbra, Portugal. Edited by P. Heinzel, I. Dorotovič, and R. J. Rutten. San Francisco: Astronomical Society of the Pacific, p.6 (2007). [8] Calcines, A., López, R. L., Collados, M., Preliminary design of a multi-slit image slicer for EST, Groundbased and Airborne Instrumentation for Astronomy IV. Proceedings of the SPIE, Volume 8446, article id , 9 pp. (202). Proc. of SPIE Vol I-3 Downloaded From: on 0/02/204 Terms of Use: