Abstract: An optical collector head comprises a beam splitting device (5) capable of producing at least three output beams (9) in different directions; a single objective lens (4) to provide a collimated beam to the beam splitting device (5); and an assembly of: (a) a quarter wave plate (6), or plate producing a similar effect; (b) a polarizer acting as an analyzing element; (c) a lens; and (d) a recording device (3/1, 3/2, 3/4) for the simultaneous capture of phase-stepped images from each output beam. The invention also includes a polarimetric device comprising an optical collector head as defined above and a source (12) of polarized light; and a polarimetric device comprising an optical collector head as defined above and a source (12) of polarized light.