Do you need a tool to teach diffraction to kids (or adults) or do you need to see little hologram cats when you look at single points of light?
If so, then you need these diffraction glasses. The principle of diffraction is how light waves behave as they encounter obstacles. The bottom of these bifocals contains a grating of regularly spaced opaque lines. When light passes through a grating, it bends depending on the color of light and spacing of the lines. Since white light contains all colors, you see a rainbow effect. The top contains a computer-calculated hologram, which has an array of tiny elements arranged to diffract the light into a pattern (meow!) when you see a small or distant light.