Mold design and pre-compensation of precision molding for diffractive optical elements

The diffractive optical elements (DOE) have great advantages in correcting chromatic aberration compared with spherical and aspheric optical selements, especially in the field of infrared optics, the application of DOE can further increase the design freedom of optical systems. With the further expansion of infrared optics market, the conventional single point diamond turning technology of diffraction optics is difficult to meet the large-scale demands, so the precision molding technology has become the key technology to solve the above problems. The mold design is one of the key points of precision molding. In order to reduce the mold design cycle, the pre-design and pre-correction of mold were carried out by using the finite element simulation method, and then the mold was processed. The single-station precision molding machine was adapted for precision molding test of designed molds. The test results show that, with the reasonable process parameters, the PV value of the surface shape accuracy of DOE can reach 0.56 μm, the position error is less than 0.011 mm, and the height error of the band is less than 0.12 μm, which verifies the effectiveness of the simulation pre-compensation in the design of diffractive optical molds.