Fabrication Technology of the Centrosymmetric Continuous Relief Diffractive Optical Elements

Diffractive Optical Element (DOE) can be used to simplify optical systems such as lightening its mass, reducing elements numbers and so on. In the paper, Laser Direct Writing Method was used to fabricate centrosymmetric continuous relief Diffractive Optical Element's mask and ion beam reaction etching method was used to realize transferring micro structures from photoresist layer to substrate. Before the mask's fabrication, we used polar coordinate pattern Laser Direct writing system to study the response rule of photoresist layer to the laser exposure, and then the mask were fabricated successfully. During transferring process, the speed ratio of etching between photoresist layer and substrate was measured and the measuring experiment for flux of the gas which was used to produce ion beam was done. In the end, we combined the Laser Direct Writing Method with ion beam reaction etching method to realize the fabrication of a plane diffractive focusing lens with continuous relief micro structure successfully. The technology can also be used to fabricate other Centrosymmetric Continuous Relief Diffractive Optical Elements