Image Display Optical Apparatus and Image Generation Method Thereof

A method of generating an image for an optical apparatus including at least one first diffractive element which receives beams and a plurality of second diffractive elements arranged at predetermined intervals and which output the beams, wherein the at least one first diffractive element and the plurality of second diffractive elements are located on a substrate arranged as one or more layers, the method comprising:

• determining a position of a pupil;
• determining an output position of a beamlet that outputs a pixel and is output to the pupil by using a beam let output position function defined by input values of an angle at which the pixel is incident to a first diffractive element, a distance between the substrate and the pupil, and a parameter of each diffractive element;
• determining an output angle of the beamlet based on depth information of the pixel and the output position of the beam let;
• determining a shifting amount of each pixel based on a ratio of the output angle to an angle formed by a size of one pixel;
• and
• performing, for each layer of the substrate, a process of generating a shift image by shifting each pixel of an original image according to the shifting amount.