horizontally or vertically hatched rectangles reference numerals 601 to 603 represent band pass filters dot filled rectangles reference numeral 701 represents a half wave plate a plain rectangle and reference numeral 6 represents a relay optical system for compensating the optical path length as shown in fig6 the illumination light a white light beam composed of the light coming directly from the white light source 1 and the light reflected from the reflector 2 first passes through the polarization converter 3 which transmits the s polarized light component and converts the p polarized light component into s polarized light and then reaches the dichroic mirror 101 here out of the now wholly s polarized white light beam only the blue b component is transmitted and the other green g and red r components are reflected the b component transmitted through the dichroic mirror 101 is then reflected from the first reflecting mirror 401 passes through the relay optical system 6 is further reflected from the second reflecting mirror 401 has its polarization direction aligned by the polarizing plate 505 and then reaches the polarizing beam splitter 205 a here the s polarized b component is reflected this component is then further reflected from the dichroic polarizing beam splitter 204 a has its wavelength range trimmed by the band pass filter 601 and then illuminates the pixels on the reflection type liquid crystal display device 301 on the reflection type liquid crystal display device 301 at every moment those pixels which ate used for screen display are turned on so that the s polarized b component incident on.