included within the range of the led light emission wavelength 610 nm lt u03bb lt 650 nm in this embodiment the filter unit 11 b is disposed on the front surface of the photometric sensor 11 a so that p polarized light in the wavelength region of 610 nm to 650 nm is blocked from being incident upon the photometric sensor 11 a it should be understood that the p polarized light component having the same wavelength region with regard to light other than the display light is also blocked as a result it is possible for the photometric sensor 11 a to perform photometry without experiencing any influence from the display light as the functional member which is used for the filter unit 11 b for eliminating p polarized light of the specified wavelength region in this manner there may be used a holographic filter which diffracts p polarized light of the specified wavelength region or a wavelength selective pbs which is obtained by making a multi layered thin film in either case its function as the polarized light element of the filter unit 11 b is to pass only the s polarized light whose light polarization direction is perpendicular with respect to the light polarization direction of the display light it should be understood that although in the above described embodiment the polarized light plate 104 was provided to the illumination unit 10 so that the illumination light incident upon the diffracting optical element 9 was made to be only p polarized light because principally the light which is diffracted by the display section 24 b is only p polarized.