An optical apparatus that prevents unevenness in color and brightness from occurring in an image display, and can improve the color purity of transmitted light and color reproducibility of the image display and is excellent in practical use. A method for producing a permanent magnet includes integrating material powders judged as good in the step of judging the quality as raw material powders by the method for producing a raw material powder of a permanent magnet. The single channel black-and white image is replicated into all three channels at the output of the storage memory.