light component and the p polarised light component by rotating the first phase difference plate 15 the optical element 25 a is configured of for example a dichroic prism having wavelength selectivity the dichroic prism has an inclined surface k at an angle of 45 u00b0 with respect to the optical axis ax 1 the inclined surface k also has an angle of 45 u00b0 with respect to the optical axis ax 2 the optical element 25 a is disposed so that an intersection point of the optical axes ax 1 and ax 2 orthogonal to each other and an optical center of the inclined surface k coincide with each other moreover the optical element 25 a is not limited to the prism shape such as the dichroic prism and a parallel plate shaped dichroic mirror may be used the polarization separation element 50 a having wavelength selectivity is provided in the inclined surface k the polarisation separation element 50 a has a polarisation separating function to separate the light beam flux k 1 passing through the first phase difference plate 15 into the s polarized light component and the p polarized light component with respect to the polarization separation element 50 a specifically the polarisation separation element 50 a reflects the s polarized light component in the incident light and transmits the p polarised light component in the incident light the s polarised light component light beam flux bls is directed to.