Method for obtaining full-color hologram optical element using photopolymer, and head-up display apparatus with the same

A method of manufacturing a full-color holographic optical element in a full-color holographic optical element manufacturing apparatus including a lens and a holographic recording medium located farther away than a focal length of the lens, the method comprising:

• allowing a signal beam including a mixture of laser beams having wavelengths of R (Red), G (Green), and B (Blue) to be incident on the lens;
• and
• recording a hologram in such a manner that a reference beam, which includes a different mixture of laser beams having wavelengths of R, G, and B than the signal beam, is allowed to be incident on the holographic recording medium,
• wherein the holographic recording medium is configured with a single medium, and
• when a time period during which a reaction does not occur from a time when the photopolymer is irradiated with the laser beams and to a time when formation of the holographic grating is started is referred to as an inhibition period, the full-color holographic optical element manufacturing apparatus sets the intensities of the laser beams of R, G, and B so that the inhibition periods for the laser beams of R, G, and B are the same.