| Freeform optical elements have complex surfaces so that more freedom can becontrolled during the design. It can achieve optical mapping relationship which cannot be done by the conventional optical surfaces. There is not a applicable method forall freeform optics in the optical field till now. Therefore, the study of the designmethod of freeform optics has become an important area of the development offreeform optics. At the same time, with the development of ultra-precision machiningtechnology, it is possible to realize the machining of freeform optics, and the freefromoptics has more and more widely used in the aviation and aerospace, medicaltreatment, civilian and military applications.This paper studied the design methods of freeform optics, and made adevelopment in typical applications. It is proposed that using corresponding methodsfor different optical requirements, and realized the optical applications of freeformoptics in imaging and nonimaging optics, the main contents as follows:1. Based on the study of existing optical freeform design methods (SMS anddifferential methods), three-dimensional Geometric Construction Method (GCM) wasproposed, which can ensure the optical requirements and surface smoothnessrequirements simultaneously. A secondary optics was designed for LED to verify thecorrectness of the design method.2. Studied the freeform optics in photovoltaic concentrators of typicalnonimaging optical system applications, completed the design of three types ofconcentrators by GCM, and completed the ultra precision machining and opticalexperiments of them. The Fresnel concentrators can realize any size spot on the solarcell, and the secondary concentrators can effectively improve the uniform distributionof the sun light on the solar cell.3. Based on the ultra-thin and ultra-light design demand of concentrators in CPVsystems, proposed a new design method of ultra-short focus concentrators which usedthe differential method and GCM. The concentrator used a lens array and a freeformreflector to achieve the control of light precisely. The solar cells were placed at theside of the concentrators, and greatly reduced the overall thickness of theconcentrators module, which can meet the requirements of light and thin ofconcentrators;4. To verify the performance of the concentrators, made the study on the solar simulator, designed a solar simulator consisted of two freefrom reflectors to achieveuniform and collimated light. Beside, designed an off-axis optical reflective integratorwith faceted structure to transform a parallel beam into a uniform intensity beam witha rectangular cross section.5. Studied the applications of the freeform optics in imaging optical system,designed freeform surface by3D Geometric Construction Methods and opticalsimulation software, which can solve the problem of the complex optical freeformdesign, and verified this method by the design of short focal projector. |
