The main focus of this dissertation is to seek scientific knowledge and fundamental understanding of molding process for freeform optical lens fabrication by integrating freeform optical design, precision freeform molding making, numerical modeling of polymer lens forming process, and evaluation of the molded freeform optics. Compared with conventional optics, freeform optics provides more flexibilities and better performance.However, due to the complex nature of freeform optics manufacturing processes, the productivity and quality is difficult to improve, which subsequently results in higher manufacturing cost. Therefore, in order to create affordable freeform lenses with high quality, the method combining ultraprecision diamond machining and optical molding is proposed. Ultraprecision diamond machining is a process that allows us to generate precision freeform optical features on mold surfaces without post polishing, while microinjection/compression molding is proven high volume manufacturing process used to reduce production cost. The diamond machining for both regular metal materials and brittle materials are discussed to obtain high quality molds with optical finish. In addition, two novel process designs are presented to fabricate hybrid glass-polymer achromatic lenses using compression molding and injection molding, respectively.Once the low cost molded freeform optical components are achieved, their optical performance needs to be characterized to ensure quality in mass production. The refractive index variation and geometric deformation are two important factors that influence the final optical performance considerably. So, finite element method is utilized to simulate the manufacturing processes to obtain inhomogeneous refractive index distribution and thickness variation. The obtained FEM information is used to derive and predict the optical performance based on wavefront optics theory. In order to verify the simulated results, conventional measurement setups are modified based on characteristics of specific freeform optics to evaluate its optical properties. The numerical simulation and experimental results are in good agreement with each other.Therefore in order to solve the major challenges in manufacturing affordable high quality freeform optics, this dissertation will include several key steps: 1) Establish point-to-point mapping freeform optics design strategy using freeform microlens array for uniform beam shaping as an example; 2) Evaluate ultraprecision mold machining on both regular metal materials and brittle materials to achieve high quality molds with optical finish; 3) Develop novel manufacturing process designs to fabricate compression molded hybrid achromatic glass-polymer microlens array and injection molded hybrid glass-polymer achromatic lens; 4) Establish a methodology combining finite element method and wavefront optics theory to model the optical performances of molded freeform lenses; 5) Design proper measurement systems including Shack-Hartmann sensor and wet cell based optical interferometer to evaluate the molded freeform lenses and verify the previously modeled results.Overall, this dissertation describes a comprehensive understanding of affordable freeform optics manufacturing.