TIR collimating lens design based on freeform surface

In order to achieve the required lighting in a specific angle range and meet the requirements of various types of LED lighting systems, we put forward a design method for total internal reflection (TIR) compound surface LED lens. According to the principles of non-imaging optics, we determined reflection surface type, calculated the divergence angle, and designed free-form surface lens. We provided the design idea and method, designed a LED lens with emergence half angle of 2.5 degree, and analyzed the influences of error on the actual results.