Projection type image display apparatus

A projection type image display apparatus comprising:

• a diffraction image display unit for performing at least one of operations of producing and displaying a Fraunhofer diffraction image of an original image;
• and
• an image projecting unit for converting said Fraunhofer diffraction image to the original image and projecting the original image obtained by conversion on a screen;
• wherein said diffraction image display unit comprises:
• a calculation processing unit for non-recursively and synthetically calculating amplitude information and phase information of said Fraunhofer diffraction image of the original image;
• and
• an image display unit for performing at least one of said operations of producing and displaying said Fraunhofer diffraction image in accordance with the amplitude information and phase information calculated by said calculation processing unit;
• said calculation processing unit comprising a synthetic data calculating unit for obtaining synthetic data on a display face of said image display unit and a complex conjugate calculating unit for finding a complex conjugate of an output from said synthetic data calculating unit, in a case where spherical waves are projected from points of an image to be projected on said screen on the display face of said image display unit.