An imaging polarimeter (IMPOL) for multi-wavelength observations A. N. Ramaprakash, R. Gupta, A. K. Sen and S. N. Tandon Astron. Astrophys. Suppl. Ser., 128 2 (1998) 369-375 Published online: 15 March 1998 DOI: 10.1051/aas:1998148