Dot character display using a negative-film diffraction grating matrix

A diffraction grating matrix made of negative film is applied to display dot characters. Using an X-Y plotter of a personal computer, a multiple grating pattern is plotted in a matrix form. The photograph of the pattern is the negative-film diffraction grating matrix. When a laser light illuminates the grating matrix, the diffracted light displays a dot character. Several alphabetic characters are displayed in this way.