Patent ID: 8727543

Claim:
A projection type image display apparatus that carries out image display by projecting light onto a screen ( 400 ), comprising: a spatial light modulator ( 200 ) that modulates incident light according to an incidence position based on an image as a display object, and emits the light; an illumination unit ( 100 , 110 ) that supplies illumination light (L 45 , L 46 ) to the spatial light modulator ( 200 ); and a projection optical system ( 300 , 350 ) that guides illumination light (L 300 ) modulated by the spatial light modulator ( 200 ) to the screen ( 400 ), and projects the image onto the screen, wherein the illumination unit ( 100 , 110 ) includes: a coherent light source ( 50 ) that generates a coherent light beam (L 50 ), a hologram recording medium ( 45 , 46 , 85 ) on which an image ( 35 ) of a scatter plate ( 30 ) is recorded, and a light beam scanning device ( 60 , 65 ) that irradiates the light beam (L 60 , L 65 ) onto the hologram recording medium ( 45 , 46 , 85 ), and scans the light beam (L 60 , L 65 ) so that the irradiation position of the light beam on the hologram recording medium ( 45 , 46 , 85 ) changes with time, the image of the scatter plate ( 30 ) is recorded as a hologram on the hologram recording medium ( 45 , 46 , 85 ) by using reference light (L 23 , Lref) irradiated along an optical path, the coherent light source ( 50 ) generates a light beam (L 50 ) with a wavelength capable of reproducing the image ( 35 ) of the scatter plate, the light beam scanning device ( 60 , 65 ) scans the light beam (L 60 , L 65 ) so that the irradiation direction of the light beam (L 60 , L 65 ) with respect to the hologram recording medium ( 45 , 46 , 85 ) is along the optical path of the reference light (L 23 , Lref), and the spatial light modulator ( 200 ) is disposed at a production position of the reproduction image ( 35 ) of the scatter plate ( 30 ) obtained from the hologram recording medium ( 45 , 46 , 85 ).