A method of fabricating a diffractive optical element includes the steps of: etching a negative of a desired multi-level diffraction pattern onto a molding surface of a quartz master element using photolithography, assembling the master element as a portion of a mold, and injecting a plastic molding composition into the mold and against the molding surface of the master element to injection mold a diffractive optical element, whereby the optical element has the desired diffraction pattern on its surface. The diffraction pattern is preferably formed on the quartz master using VLSI photolithography.