Measurement of Instrumental Polarisation of the Kodaikanal Tunnel Tower Telescope

  • K. Sankarasubramanian
  • J. P. A. Samson
  • P. Venkatakrishnan
Part of the Astrophysics and Space Science Library book series (ASSL, volume 243)


The measurement of the instrumental polarisation for any obliquely reflecting telescope is necessary to measure the polarisation state of the input beam precisely. To find out the instrumental polarisation of the reflecting mirror(s), the complex refractive index of the reflecting coating has to be measured with fairly good accuracy. Here we present the complex refractive index measurements for the aluminium-coated mirrors of the Kodaikanal tower tunnel telescope using an ellipsometer. The design of the ellipsometer using a Babinet Compensator and the results of the experiment will be discussed. These results will be used to remove the instrumental polarisation contribution from the observed Stokes profile of magnetic regions on the sun.

Key words

Instrumental polarisation Babinet compensator solar magnetic fields ellipsometer 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Azzam, R.M.A. and Bashara, N.M.: 1977, Ellipsometry and Polarized Light, North Holland publishing company, New York.Google Scholar
  2. Balasubramaniam, K.S., Venkatakrishnan, P. and Bhattacharyya, J.C.: 1985, Solar Phys. 99, 333.ADSCrossRefGoogle Scholar
  3. Bappu, M.K.V.: 1967, Solar Phys., 1 151.ADSCrossRefGoogle Scholar
  4. Burge, D. K. and Bennett, H. E.: 1964, J. Opt. Soc. Amer 54, 1428.ADSCrossRefGoogle Scholar
  5. Capitani, C., Cavallini, F., Ceppatelli, G., Landi Degl Innocenti, E., Landi Degl Innocenti, M., Landolfi, M. and Righini, A.: 1989, Solar Phys. 120, 173.ADSCrossRefGoogle Scholar
  6. Demidov M. L.: 1991, Solar Phys. 135, 193.ADSCrossRefGoogle Scholar
  7. Heavens, O.S.: 1991, Optical properties of thin solid films, Dover publications, New York.Google Scholar
  8. Kawakami, H.: 1983, Publ. Astron. Soc. Japan 35, 459.ADSGoogle Scholar
  9. Lide, D. R.: 1995, Hand Book of Chemistry & Physics, CRC Press, New York.Google Scholar
  10. Livingston, W. and Harvey, J.: 1971, Kitt Peak National Observatory Contribution No. 558.Google Scholar
  11. Makita, M., and Nishi, K.: 1970, Ann. Tokyo Astron. Obs. 253, 2857.Google Scholar
  12. Sankarasubramanian, K. and Venkatakrishnan, P.: 1996, Solar Phys. 167, 1.ADSCrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media Dordrecht 1999

Authors and Affiliations

  • K. Sankarasubramanian
    • 1
  • J. P. A. Samson
    • 1
  • P. Venkatakrishnan
    • 1
  1. 1.Indian Institute of AstrophysicsBangaloreIndia

Personalised recommendations