TECHNOLOGY FOCUS - CHEMICAL ENGINEERING - Preferred Device: In the bending wave solar energy gathering device, the plate Fresnel lens is a rectangular Fresnel line-focus lens or point-focus lens whose periphery is preset by one or two pairs of assembling ridges; the lens is made of transparent high molecule material such as PMMA, PC, CR-39; the Fresnel lens comprises one or more focus lines or focus points; the surface is hardened by materials such as organic silicon so as to increase the surface hardness to more than 4H. The surface of the plate Fresnel lens is adhered by a layer of super hydrophilic material made of titanium oxide (TiO2), which makes the Fresnel lens capable of self-cleaning. The section of the linking gibs is sectional material with a groove; the shape of the groove is matched with the assembling ridge which is on the edge of the plate Fresnel lens; the assembling ridge can be inserted in the groove of the linking gibs directly along the length direction and is clamped by the narrow mouth of the groove of the linking gibs in the width direction, the assembling ridge and the groove can be embedded with each other conveniently without being pulled out transversely under tension. The elastic tension device can be divided into two types which are ready-packaged tension device and spiral tension device; typical ready-packaged tension device is a manpowered turnover self-locking elastic pull clasp; a handle bracket (7) is fixedly linked on a sliding seat (8); a central hole of a turnover handle (6) is hinged with a hole on the handle bracket (7) through a pin shaft (9) and capable of rotating around the pin shaft (9); an elastic pull clasp (5) is hinged with a pair of eccentric holes on the lateral lower part of the turnover handle (6); the sliding seat (8) is installed in a sliding slot (10), which is fixedly linked on the top face of the rigid frame (1). The elastic pull clasp (5) on the ready-packaged tension device is an elastic ring which is wounded by a spring steel wire; one end of the elastic pull clasp comprises a loop hook; the upper part of the loop hook comprises a single ring or multiple rings or two symmetric rings; both ends of the spring steel wire are extended to the other end of the elastic tension device; the both tails are formed into two opposite vertical inner hooks, respectively; the pair of inner hooks can be installed in the pair of eccentric holes on the lateral lower side of the turnover handle (6). The sliding slot (10) on the ready-packaged tension device has a concave section; the both vertical sides are equipped with a limiting slot, respectively; the sliding seat (8) can be inserted along the longitudinal direction and sliding correspondingly; the sliding journey can be limited by a limit screw nail (11). The lateral view of the turnover handle (6) on the ready-packaged tension device is as follows: one end is a semicircular head and the other end is a flat handlebar; a pin hole is equipped on the circular centre of the semicircular head; another pair of eccentric holes for installing elastic pull clasp (5) are equipped on the lower right side of the pin hole. The typical spiral elastic tension device is composed of a compression spring (12) and a screw bolt (13); the elasticity of the compression spring (12) is transmitted to the Fresnel lens through a screw rod (13) and a linking gib (3) so as to generate tension. The inner lateral edge of the rigid frame comprises constant or uniform locating bosses; the bosses can be shaped by drawing all in once by frame material or combined by general material such as corner material or square material; the bosses are used for supporting the components after the plate Fresnel lens is embedded in the linking gibs and locating it in longitudinal direction.