平面线聚焦菲涅尔透镜的聚焦变化研究

The design parameters of a flat-plate linear-focusing Fresnel lens were analyzed based on the influences of its structure，material refractive index，and tilt incident angle of sunlight on focal length. The analysis aimed to achieve large allowable tilt incident angles and small focal length changing ranges. An example was designed with a width of 200 mm，focal length of 300 mm, and material refractive index of 1.5. The characteristics of the Fresnel lens’focal length variation were examined，and an optimal receiver width and mounting position suitable for the lens were determined by shortening the mounting distance between it and the receiving surface. With an allowable light tilt incident angle range reaching ±40° or more, nearly six hours of daily effective working time can be maintained.