A set of laser beam shaping optics is designed by an iterative method using an adaptive additive algorithm to transform a Gaussian beam into a pitchfork beam. Two diffractive optical elements are designed based on Fresnel diffraction to reduce the amount of energy in the first-order diffraction ring and to increase the depth of focus for the optical system. These two beam properties are found to depend on the diameter of the desired beam and the Airy disk diameter. If the diameter of the desired beam is large, then the optical system yields better results in achieving the above-mentioned two beam properties. The performance of the diffractive optical elements is compared to a previous laser beam shaping system designed by the ray-tracing technique. A pinhole scanning power meter is used to measure the laser irradiance profile at the focal plane to verify the existence of the pitchfork beam. The irradiance profile measurement shows that diffractive optical elements allow better control for reducing the amount of energy in the diffraction side lobes.