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Building a large affordable optical-NIR telescope (I): an alternate way to handle segmented primary mirror

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Abstract

The use of innovative ideas and the latest technology have undoubtedly brought down telescope costs substantially. However, there are still ways to further reduce the cost of optical ground-based telescopes and make them affordable to much larger and wide spread astronomical communities. In this and subsequent papers we are presenting our studies carried out towards building affordable mid-size telescopes of 4.0-6.0m in size. In the present era, segmented mirror technology has become the first choice for building moderate to large-size telescopes. In any Segmented Mirror Telescope (SMT) the most important part is its primary mirror control system (M1CS). The conventional M1CS is based on edge sensors and actuators, but such a system introduces many design and implementation complexities. In this paper, we propose to make use of an Off-axis Alignment and Phasing System (OAPS), which is an active mirror kind of control system working in real time to maintain the figure of a segmented primary mirror without the use of edge-sensors. The alignment and phasing system which is an integral part of any segmented telescope can be used in the real time at the off-axis. Through extensive simulations we have explored the feasibility of using an OAPS for co-alignment, co-focusing as well as co-phasing of segmented mirror telescopes. From our simulations we find that the co-alignment and co-focusing of the segments can be achieved with a guide star as faint as 16-18\(^{th}\) magnitude. This implies that seeing limited performance for any segmented telescope can be easily accomplished without use of a complex edge sensor based control system. Whereas, to attain diffraction limited performance, mirror segments need to be co-phased with an accuracy of few tens of nanometers. In our simulations we have used a dispersed fringe sensor based phasing scheme, which can effectively work up to guide stars of 14\(^{th}\) magnitude.

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Availability of data and materials

The data that supports the findings of this study are available from the corresponding author, Radhika Dharmadhikari, upon reasonable request.

Notes

  1. https://model.obs-besancon.fr/modele_starcounts.php

References

  1. Abt, H.A.: Scientific Efficiency of Ground-based Telescopes. Astron. J. 144(4) (2012). https://doi.org/10.1088/0004-6256/144/4/91

  2. Anupama, G.C., Maheswar, G., Sriram, S., Sivarani, T., Parihar, P.S., Nagabhushan, S., Angchuk, D., Barway, S., Bhatt, B.C., Banyal, R., Basheer, A., Deshmukh, P., Divakar, D., Dorjai, T., Goswami, A., Govinda, K.V., Jorphail, S., Kamath, U.S., Kemkar, M.M., Mahay, T.T., Muneer, S., Muthumariappan, C., Ningombam, S.S., Pandey, G., Reddy, B.E., Sahu, D.K., Sandeep, D.S., Sethuram, R., Stalin, C.S., Subramanian, S., Tsewang, S., Subramaniam, A.: A 10-m class national large optical-IR telescope. J. Astrophys. Astron. 43 (2022). https://doi.org/10.1007/s12036-022-09819-6

  3. Bradley, L., Sipőcz, B., Robitaille, T., Tollerud, E., Vinícius, Z., Deil, C., Barbary, K., Wilson, T.J., Busko, I., Günther, H.M., Cara, M., Conseil, S., Bostroem, A., Droettboom, M., Bray, E.M., Andersen Bratholm, L., Lim, P.L., Barentsen, G., Craig, M., Rathi, S., Pascual, S., Perren, G., Donath, A., Georgiev, I.Y., De Val-Borro, M., Kerzendorf, W., Bach, Y.P., Quint, B., Souchereau, H., Weaver, B.A.: astropy/photutils: 1.0.2. Zenodo (2021). https://doi.org/10.5281/zenodo.4453725

  4. Buckley, D.A.H., Meiring, J.G., Swiegers, J., Swart, G.P.: Many segments and few dollars: SALT solutions for ELTs? In: Second Backaskog Workshop on Extremely Large Telescopes. SPIE Conf. Series, vol. 5382, pp. 245–256 (2004). https://doi.org/10.1117/12.566263

  5. Chanan, G.A., Nelson, J.E., Mast, T.S., Wizinowich, P.L., Schaefer, B.A.: W.M. Keck Telescope phasing camera system. In: Instrumentation in Astronomy VIII, Vol. 2198, pp. 1139–1150 (1994). https://doi.org/10.1117/12.176697

  6. Chanan, G.A., Nelson, J.E., Mast, T.S.: Segment alignment for the Keck Telescope primary mirror. In: Advanced Technology Optical Telescopes III, Vol. 628, pp. 466–470 (1986). https://doi.org/10.1117/12.963566

  7. Chanan, G., Troy, M., Dekens, F., Michaels, S., Nelson, J., Mast, T., Kirkman, D.: Phasing the Mirror Segments of the Keck Telescopes: The Broadband Phasing Algorithm. Appl. Opt. 37 (1998). https://doi.org/10.1364/AO.37.000140

  8. Chanan, G.A., Troy, M., Ohara, C.M.: Phasing the primary mirror segments of the Keck telescopes: a comparison of different techniques. In: Optical Design, Materials, Fabrication, and Maintenance. SPIE Conf Series, vol. 4003, pp. 188–202 (2000). https://doi.org/10.1117/12.391510

  9. Chanan, G., Ohara, C., Troy, M.: Phasing the Mirror Segments of the Keck Telescopes II: The Narrow-band Phasing Algorithm. Appl. Opt. 39, 4706–4714 (2000). https://doi.org/10.1364/AO.39.004706

    Article  ADS  Google Scholar 

  10. Chanover, N., Williams, B., Crenshaw, D.M., Tuttle, S., Morris, B., Golkhou, Z., Buzasi, D., Glenn, J., Bentz, M., Hebb, L.: The Importance of 4m Class Observatories to Astrophysics in the 2020s. In: Bulletin of the American Astronomical Society, vol. 51, p. 31. (2019)

  11. Cui, X.-Q., Zhu, Y.-T.: Chinese Large Optic/IR Telescope (LOT): planning for the next decade. In: Ground-based and Airborne Telescopes VI. SPIE Conf. Series, vol. 9906 (2016). https://doi.org/10.1117/12.2232263

  12. Doi, M., Miyata, T., Yoshii, Y., Kohno, K., Tanaka, M., Motohara, K., Minezaki, T., Kawara, K., Sako, S., Morokuma, T., Tamura, Y., Tanabe, T., Hatsukade, B., Takahashi, H., Konishi, M., Kamizuka, T., Kato, N., Aoki, T., Soyano, T., Tarusawa, K., Handa, T., Koshida, S., Bronfman, L., Ruiz, M.T., Hamuy, M., Mendez, R., Garay, G., Escala, A.: The University of Tokyo Atacama Observatory 6.5m telescope: project overview and current status. In: Ground-based and Airborne Telescopes VII. SPIE Conf. Series, vol. 10700. (2018). https://doi.org/10.1117/12.2313099

  13. Gajjar, H., Menzies, J., Buckley, D., Coetzee, C., Bester, D., Strydom, O., Love, J., Browne, K.: SALT: Active control of the primary mirror with inductive edge sensors. In: Ground-based and Airborne Telescopes VI. SPIE Conf. Series, vol. 9906 (2016). https://doi.org/10.1117/12.2234264

  14. Gajjar, H., Menzies, J., Swiegers, J., Rozière, D., Courteville, A., Buous, S., Luong, B.: Results from the capacitive edge sensing system for the active alignment of the SALT primary mirror. In: SPIE Conf. Series. SPIE Conf. Series, vol. 6267 (2006). https://doi.org/10.1117/12.672103

  15. Gonte, F., Yaitskova, N., Derie, F., Araujo, C., Brast, R., Delabre, B., Dierickx, P., Dupuy, C., Frank, C., Guisard, S., Karban, R., Noethe, L., Sedghi, B., Surdej, I., Wilhelm, R., Reyes, M., Esposito, S., Langlois, M.: The active phasing experiment: Part II. Design and developments. In: SPIE Conf. Series, Vol. 6267 (2006). https://doi.org/10.1117/12.672057

  16. Gutiérrez, C.M., Torres, M., Oria, A., Fernández-Valdivia, J.J., Arnold, D., Copley, D., Copperwheat, C., de Cos Juez, J., Franco, A., Fan, Y., García Piñero, A., Harvey, E., Jermak, H., Jiang, X., Knapen, J.H., McGrath, A., Ranjbar, A., Rebolo, R., Smith, R., Steele, I.A., Wang, Z., Wu, X., Xu, D., Xue, S., Yuan, W., Zheng, Y.: The 4 m New Robotic Telescope Project: An Updated Report. In: Revista Mexicana de Astronomia Y Astrofisica Conference Series, vol. 53, pp. 8–13. (2021). https://doi.org/10.22201/ia.14052059p.2021.53.03

  17. Jacob, A., Parihar, P., James, M.K.: Creating a large aspheric primary mirror using spherical segments. Exp. Astron. 50, 51–71 (2020). https://doi.org/10.1007/s10686-020-09663-y

    Article  ADS  Google Scholar 

  18. Khosroshahi, H.G., Jenab, H., Bidar, M., Mohajer, M., Saeidifar, M.: Iranian National Observatory: project overview. In: Ground-based and Airborne Telescopes VI. SPIE Conf. Series, vol. 9906. (2016). https://doi.org/10.1117/12.2241680

  19. Lee, H., Hart, M., Hill, G.J., Rafal, M.D.: Analysis of active alignment control of the Hobby-Eberly Telescope wide-field corrector using Shack-Hartmann wavefront sensors. In: Modeling, Systems Engineering, and Project Management for Astronomy IV, Vol. 7738 (2010). https://doi.org/10.1117/12.857121

  20. Li, Y., Wang, S., Rao, C.: Dispersed-fringe-accumulation-based left-subtract-right method for fine co-phasing of a dispersed fringe sensor. Appl. Opt. 56, 4267 (2017). https://doi.org/10.1364/ao.56.004267

    Article  ADS  Google Scholar 

  21. Lousberg, G.P., Mudry, E., Bastin, C., Schumacher, J.-M., Gabriel, E., Pirnay, O., Flebus, C.: Active optics system for the 4m telescope of the Eastern Anatolia Observatory (DAG). In: Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation II. SPIE Conf Series, vol. 9912 (2016). https://doi.org/10.1117/12.2234261

  22. Lubliner, J., Nelson, J.E.: Stressed mirror polishing. 1: A technique for producing nonaxisymmetric mirrors. Appl. Opt. 19 (1980). https://doi.org/10.1364/AO.19.002332

  23. Mahajan, V.: Optical imaging and aberrations, part iii: Wavefront analysis (spie, 2013), vol. PM221, 88–90 (2013)

  24. Marchiori, G., Busatta, A., De Lorenzi, S., Rampini, F., Perna, C., Vettolani, G.: A new era for the 2-4 meters class observatories: an innovative integrated system telescope-dome. In: Ground-based and Airborne Telescopes IV. SPIE Conf Series, vol. 8444 (2012). https://doi.org/10.1117/12.927117

  25. Minor, R.H., Arthur, A.A., Gabor, G., Jackson, H.G., Jared, R.C., Mast, T.S., Schaefer, B.A.: Displacement sensors for the primary mirror of the W. M. Keck telescope. In: Advanced Technology Optical Telescopes IV. SPIE Conf. Series, vol. 1236 (1990). https://doi.org/10.1117/12.19270

  26. Nagata, T., Kurita, M.: Seimei 3.8-m Telescope has been commissioned. In: SPIE Conf. Series, vol. 11445. (2020). https://doi.org/10.1117/12.2561272

  27. Nelson, J., Mast, T., Chanan, G.: Segmented Mirror Telescopes. In: Planets, Stars and Stellar Systems. Volume 1: Telescopes and Instrumentation, p. 99. Springer, (2013). https://doi.org/10.1007/978-94-007-5621-2_3

  28. Nelson, J.E., Mast, T.S., Faber, S.M.: The design of the keck observatory and telescope. Caltech (1985)

  29. Neufeld, C., Zolcinski-Couet, M.C., Keane, M., Ruthven, G.: The active primary mirror assembly for the SOAR telescope. In: Ground-based Telescopes. SPIE Conf. Series, vol. 5489, pp. 870–880 (2004). https://doi.org/10.1117/12.551375

  30. Ninane, N., Flebus, C., Kumar, B.: The 3,6 m Indo-Belgian Devasthal Optical Telescope: general description. In: Ground-based and Airborne Telescopes IV. SPIE Conf. Series, vol. 8444, p. 84441 (2012). https://doi.org/10.1117/12.925921

  31. Oswalt, T.D., McLean, I.S.: Planets, Stars and Stellar Systems, Volume 1: Telescopes and Instrumentation. Springer (2013). https://doi.org/10.1007/978-94-007-5621-2

    Article  ADS  Google Scholar 

  32. Rakoczy, J.M., Hall, D., Howard, R.T., Ly, W., Weir, J.T., Montgomery, I. Edward E., Adams, M.T., Booth, J.A., Fowler, J.R., Ames, G.H.: Primary mirror figure maintenance of the Hobby-Eberly Telescope using the Segment Alignment Maintenance System. In: Large Ground-based Telescopes. SPIE Conf. Series, vol. 4837, pp. 702–713 (2003). https://doi.org/10.1117/12.456734

  33. Roddier, N.A., Blanco, D.R., Goble, L.W., Roddier, C.A.: WIYN telescope active optics system. In: Telescope Control Systems. SPIE Conf. Series, vol. 2479, pp. 364–376 (1995). https://doi.org/10.1117/12.211446

  34. Rozière, D., Luong, B., Fuchs, B., Périn, A., Néel, C., Lévèque, S.: Inductive edge sensors: an innovative solution for ELT segmented mirror alignment monitoring. In: Ground-based and Airborne Telescopes II. SPIE Conf. Series, vol. 7012 (2008). https://doi.org/10.1117/12.789444

  35. Sagar, R.: Importance of small and moderate size optical telescopes. Curr. Sci. 78(9), 1076–1081 (2000)

    Google Scholar 

  36. Sawyer, D.G., Corson, C., Saha, A.: Optimizing the delivered image quality at the WIYN 3.5-m Telescope. In: Telescope Structures, Enclosures, Controls, Assembly/Integration/Validation, and Commissioning. SPIE Conf Series, vol. 4004, pp. 422–430 (2000). https://doi.org/10.1117/12.393896

  37. Schechter, P.L., Burley, G.S., Hull, C.L., Johns, M., Martin, H.M., Schaller, S., Shectman, S.A., West, S.C.: Active optics on the Baade 6.5-m (Magellan I) Telescope. In: Large Ground-based Telescopes. SPIE Conf. Series, vol. 4837, pp. 619–627 (2003). https://doi.org/10.1117/12.457899

  38. Schmidt-Kaler, T., Rucks, P.: Telescope costs and cost reduction. In: Optical Telescopes of Today and Tomorrow. SPIE Conf. Series, vol. 2871, pp. 635–640 (1997). https://doi.org/10.1117/12.269092

  39. Shelton, C., Mast, T., Chanan, G., et al.: Advances in edge sensors for the Thirty Meter Telescope primary mirror. In: Ground-based and Airborne Telescopes II. SPIE Conf. Series, vol. 7012 (2008). https://doi.org/10.1117/12.790415

  40. Shi, F., Redding, D.C., Green, J.J., Ohara, C.M.: Performance of segmented mirror coarse phasing with a dispersed fringe sensor: modeling and simulations. In: Optical, Infrared, and Millimeter Space Telescopes, Vol. 5487, pp. 897–908 (2004). https://doi.org/10.1117/12.552323

  41. Shi, F., Redding, D.C., Lowman, A.E., et al.: Segmented mirror coarse phasing with a dispersed fringe sensor: experiments on NGST’s Wavefront Control Testbed. In: IR Space Telescopes and Instruments, Vol. 4850, pp. 318–328 (2003). https://doi.org/10.1117/12.461113

  42. Shi, F., Chanan, G., Ohara, C., Troy, M., Redding, D.C.: Experimental Verification of Dispersed Fringe Sensing as a Segment Phasing Technique using the Keck Telescope. Appl. Opt. 43, 4474–4481 (2004). https://doi.org/10.1364/AO.43.004474

    Article  ADS  Google Scholar 

  43. Smith, E.H., Vasudevan, G., Reardon, R.D., Bernier, R., Triebes, K.J.: Coarse phasing of a segmented mirror using a dispersed fringe sensor. In: IR Space Telescopes and Instruments. SPIE Conf Series, vol. 4850, pp. 469–477 (2003). https://doi.org/10.1117/12.461577

  44. Smith, H.J.: A Decade of Cost-Reduction in Very Large Telescopes - the SST as Prototype of Special Purpose Telescopes. Astrophys. Space Sci. 160, 123–134 (1989). https://doi.org/10.1007/BF00642762

    Article  ADS  Google Scholar 

  45. Stahl, H.P., Henrichs, T.: Multivariable parametric cost model for space and ground telescopes. In: Modeling, Systems Engineering, and Project Management for Astronomy VI. SPIE Conf. Series, vol. 9911 (2016). https://doi.org/10.1117/12.2234088

  46. Stephan, C., Guisard, S., Bourget, P.: Long-term performance of the VLT UT active optics system. In: Ground-based and Airborne Telescopes VI. SPIE Conf Series, vol. 9906 (2016). https://doi.org/10.1117/12.2231892

  47. Townson, M.J., Farley, O.J.D., Orban de Xivry, G., Osborn, J., Reeves, A.P.: AOtools: Adaptive optics modeling and analysis toolkit (2019)

  48. van Belle, G.T., Meinel, A.B., Meinel, M.P.: The scaling relationship between telescope cost and aperture size for very large telescopes. In: Ground-based Telescopes. SPIE Conf. Series, vol. 5489, pp. 563–570 (2004). https://doi.org/10.1117/12.552181

  49. Walker, D.D., Beaucamp, A.T.H., Doubrovski, V., Dunn, C., Evans, R., Freeman, R., Kelchner, J., McCavana, G., Morton, R., Riley, D., Simms, J., Yu, G., Wei, X.: Automated optical fabrication: first results from the new Precessions 1.2m CNC polishing machine. In: SPIE Conf. Series, vol. 6273 (2006). https://doi.org/10.1117/12.671098

  50. Wang, S., Zhu, Q., Cao, G.: Dispersed Rayleigh interferometer. In: 4th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Optical Test and Measurement Technology and Equipment, Vol. 7283 (2009). https://doi.org/10.1117/12.828774

  51. Wirth, A., Gonsiorowski, T., Roberts, J., Bruno, T.L., Swiegers, J., Gajjar, H., Swat, A.: Developing and testing an optical alignment system for SALT”s segmented primary mirror. In: Ground-based Telescopes, Vol. 5489, pp. 892–902 (2004). https://doi.org/10.1117/12.551425

  52. Wolf, M.J., Palunas, P., Booth, J.A., Ward, M.H., Wirth, A., Wesley, G.L., O’Donoghue, D., Ramsey, L.W.: Mirror Alignment Recovery System (MARS) on the Hobby-Eberly Telescope. In: Large Ground-based Telescopes, vol. 4837 (2003). https://doi.org/10.1117/12.458034

  53. Yeşilyaprak, C., Keskin, O.: Eastern Anatolia Observatory (DAG): the status in 2020. In: SPIE Conference Series. Society of Photo-Optical Instrumentation Engineers (SPIE) Conf. Series, vol. 11445. (2020). https://doi.org/10.1117/12.2560942

  54. Zhao, W., Cao, G.: Active cophasing and aligning testbed with segmented mirrors. Opt. Express 19, 8670 (2011). https://doi.org/10.1364/OE.19.008670

    Article  ADS  Google Scholar 

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Acknowledgements

This research has made use of the High Performance Computing (HPC) system of Computer Center of the Indian Institute of Astrophysics, Bangalore. Use of Photutils, an Astropy package for detection and photometry of astronomical sources [3] is also acknowledged.

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Author notes

  1. Radhika Dharmadhikari, Padmakar Parihar and Annu Jacob contributed equally to this work.

Authors and Affiliations

  1. Indian Institute of Astrophysics, II Block Kormangala, Bangalore, 560034, India

    Radhika Dharmadhikari & Padmakar Parihar

  2. Inter-University Centre for Astronomy and Astrophysics, Pune, 411007, India

    Annu Jacob

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  1. Radhika Dharmadhikari
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Contributions

The simulation and design, which forms the core part of this paper is primarily carried out by Radhika Dharmadhikari. Whereas, the main manuscript is prepared by Radhika Dharmadhikari and Padmakar Parihar. Annu Jacob has provided a python based mirror segmentation tool to generate a grid sag surface. All authors have reviewed the manuscript.

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Correspondence to Radhika Dharmadhikari.

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Dharmadhikari, R., Parihar, P. & Jacob, A. Building a large affordable optical-NIR telescope (I): an alternate way to handle segmented primary mirror. Exp Astron 56, 569–604 (2023). https://doi.org/10.1007/s10686-023-09900-0

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