Optical EngineeringFabrication of continuous surface-relief gratings using a high-precision diamond-cutting process
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Direct fabrication of continuous surface-relief gratings on acrylics using a high-precision diamond-cutting process is reported. Critical conditions such as the diamond-tip radius and cutting step were selected by taking account of a designed grating profile and an expected roughness on the obtained grating surface. Experimental results for a 13-fanout continuous phase grating are presented. The phase profile was optimized using a stochastic design algorithm. A 3-mm-thick acrylic plate was carved into a grating that provided a measured efficiency of 85% with Fresnel reflection losses uncorrected. The diffracted intensity distribution was rather sensitive to any departure from the designed profile, the 0th-order intensity being particularly affected. Compensating the material's springback was found critical to the grating's performance.