fig1 is a front view for explaining a light radiator described in claims 1 to 3 . fig2 is a side view of the light radiator , and fig3 is a sectional view of the light - receiving portion of the light radiator . the light radiator , according to the present invention , is composed of a light - guiding cable 1 , a light - receiving portion 2 , a transparent tubular container 3 , a convex lens 4 , a transparent plate 5 having a transparent part 5a and a reflecting part 5b , a supporting base 6 , a motor 7 , a rotary shaft 8 , a transparent center shaft 9 , a transparent supporting plate 10 , a holder 11 of the light - guiding cable , a holder 12 of the tubular container and a bearing 13 . the solar rays focused through a lens system , not shown , are transmitted through the light - guiding cable 1 and pass through a convex lens 4 having a focal point at the light - emitting end of the light - guiding cable 1 and are converted thereby into substantially parallel light rays which are then introduced into the tubular container 3 . in the tubular container 3 , a larger number of transparent plates 5 are slantingly mounted at a specified distance from each other as shown in fig2 . in this embodiment , the tubular container is made in a cylindrical form and contains therein oval transparent plates 5 and round supporting plates 10 . in this case , all transparent plates 5 and supporting plates 10 have been previously attached to the transparent center shaft 9 by the use of an adhesive or the like in order to form an integrated element to be inserted into the cylindrical container 3 . the supporting plates 10 serve as reinforcements for said element . each transparent plate 5 has a transparent part 5a and a reflecting part 5b which may be formed by evaporating a metal film or by bonding a metal plate to a given part of the transparent plate 10 . it is also possible to combine a separate reflecting plate and a separate transparent plate to form one plate 10 . as shown in fig1 the plates 10 , positioned farther from the light - introducing portion 2 , have step - wise , larger reflecting surfaces . the plates , having a partial reflecting surface of a chordal form are shown , their reflecting parts possibly concentrically circular , segmental or of another suitable form . the tubular container is not always made in a circular form but may have a section shaped in any other form as for example a square . the transparent plates should comply in form to the tubular container . the light rays emitted from the light - emitting end of the light - guiding cable 1 and converted into substantially parallel light rays , are partially reflected by the reflecting surfaces 5b of the plates 5 and finally all discharged outwardly through the side wall of the tubular container 3 . since the reflecting surfaces 5b of the transparent plates 5 are evenly spaced from and overlap with each other in the direction of the light rays , the light rays not reflected by the preceding reflecting surface , are reflected by the next reflecting surface and thereby all the light rays can be discharged outwardly through the side wall of the tubular container . consequently , it may be possible to obtain evenly distributed light radiation through the side wall of the tubular container by suitably designing the size of the reflecting surfaces of the transparent plates . plants use solar energy to synthesize their own food from carbon dioxide and water and distribute it to their trunks , fruit etc .. the transportation of food in plants can be effectively performed under the conditions where no light is given and / or oxygen is present and / or temperatures are lower . in other words , in order to effectively cultivate plants , both the photosynthesis and the transportation of the food in them are promoted . for this purpose it is effective to periodically supply light rays at a given time interval i . e . to alternately repeat a light radiation period ( for photosynthesis ) and a period of darkness with no light radiation ( for the purpose of transporting the food ). furthermore , in case of plant cultivation , intermittent light radiation to the plants ( at an interval of several microseconds to several milliseconds ) is preferable to continuous light radiation . namely photosynthesis is encouraged by a light reaction coupled with a dark reaction , and a plant &# 39 ; s growth can be promoted by supplying it with intensive light radiation for the light reaction period and with no radiation or weak light radiation for the dark reaction period . moving the light radiator is also effective for distributing the light rays widely over the plants with increased efficiency and for the full utilization of the light energy in comparison with the case of radiating the plants from a fixed light radiator . in other words , in the case of using light radiators of the same capacity , the traveling one can grow plants within a wider cultivating area and , furthermore , it can effectively promote the plant &# 39 ; s growth by virtue of the repetition of light and dark periods since the plants are periodically radiated and shaped by each other while the radiator travels over them . fig3 is a view showing , by way of example , a light - introducing portion of the light radiator . in fig3 a light - guiding , cable - holding portion 11 holds therein the output end of the light - guiding cable and is secured to a suitable element . said portion is also provided at its periphery with a bearing 13 so as to rotatably support the upper part of the tubular container 12 . the lower part of the tubular container 3 is supported by a rotary shaft 8 to be driven by a motor 7 with a revolving mechanism . consequently , when the light radiator is installed in the center of a vegetable garden , it can be rotated all around ( 360 °) by the motor 7 to supply the light rays to all the plants . when the light radiator is installed in a corner of a vegetable garden , it may be rotated within a given range by the motor 7 to supply light rays only to the area where plants are being cultivated . in the case shown , each tubular container ( light radiator ) is provided with a driving motor . however , it is also possible to rotate a plurality of tubular containers at the same time by using a single motor . although the radiator is vertically installed in the case shown , it may also be installed horizontally on the ceiling or on the ground . in such cases the rotation angle of the motor may be limited so as to radiate the light from the radiator downward only or upward only to the plants . when a semi - circular portion ( shown in fig2 ), from which the light rays are not radiated , of the tubular container 3 , is made as a reflecting surface , an almost even amount of light rays , introduced into the tubular container , can be radiated in the arrow &# 39 ; s direction and thereby the light energy may be more efficiently utilized . while in the above - described embodiment the transparent plates are secured to the tubular container which can be rotated , it is also possible to design the light radiator wherein , as described in claim 4 , a tubular container is firmly secured together with a light - guiding , cable - holding portion and where transparent plates are mounted on the center shaft which can be rotated inside the tubular container . as is apparent from the foregoing description , according to the present invention , it may be possible to provide a low cost and simply designed light radiator which is capable of receiving the light energy transmitted through a light - guiding cable and capable also of evenly and effectively radiating the same to the plants . fig4 is a construction view illustrating , by way of example , a solar ray collecting device previously proposed by the present applicant . in fig4 numeral 20 is a transparent protective capsule , 21 is a fresnel lens , 22 is a lens holder , 23 is a solar position sensor , 24 is a number of optical fibers or a fiber optic cable consisting of a number of optical fibers located on the focal plane of the fresnel lens , 25 is an optical fiber or fiber optic cable holder , 26 is an arm , 27 is a pulse motor , 28 is a horizontal shaft to be rotated by said pulse motor 27 , 29 is a base for mounting the protective capsule 20 thereon , 30 is a pulse motor , 31 is a vertical shaft to be rotated by said pulse motor 30 , 1 is a bundle of fiber optic cables 24 . the direction of the sun is detected by means of the solar position sensor 23 and its detection signal which controls the pulse motors 27 and 30 for rotating the horizontal shaft 28 and 31 respectively so as to always direct said solar position sensor 23 toward the sun , and the sunlight focused by each lens 21 is guided into the corresponding light guide 24 through its end surface set at the focal point of said lens . the light guides 24 , with their end faces placed at the corresponding lens focal planes , are bundled together in a fiber optic cable 1 , which is led out from the solar ray collecting device and laid wherever the light is needed for illumination , cultivation of plants , nurturing of animals , for human sunbathing etc . fig5 is a view for explaining how to guide the light rays collected by the lens 21 into the light guide . in fig5 is a fresnel lens or the like and 24 is a light for guide for receiving the sunlight focused by said lens and transmitting the same there - through to any desired place . in the case of focusing the sunlight through the lens system , the solar image has a central portion consisting of almost white light and a circumferential portion containing therein a large amount of the light components having wave - lengths corresponding to the focal point of the lens system . namely , in the case of focusing sunlight through the lens system , the focal point and the size of the solar image will vary in accordance with the component wave - lengths of the light . for instance , the blue color light having a short wave - length makes a solar image of diameter d1 at position p1 . furthermore , the green color light makes a solar image of diameter d2 at position p2 and the red color light makes a solar image of diameter d3 at position p3 . consequently , as shown in fig5 when the light - receiving end - surface of the light guide is set at position pl , it is possible to collect sunlight containing plenty of the blue color components at the circumferential portion thereof . when the light - receiving end - surface of the light guide is set at position p2 , it is possible to collect sunlight containing plenty of the green color components at the circumferential portion thereof . when the light - receiving end - surface of the light guide is set at position p3 it is possible to collect sunlight containing plenty of the red color components at the circumferential portion thereof . in each case , the diameter of the light guided can be selected in accordance with the light components to be collected . for instance , the required diameters of the light guides are d1 , d2 and d3 , respectively , depending on the colors of the light rays desired i . e . blue , green or red . in such a way , the required amount of the fiber optic cable can be saved and thereby the sunlight containing therein plenty of the desired color components can be collected most effectively . furthermore , as shown in fig5 if the diameter of the light - receiving , end - surface of the fiber optic cable is enlarged to d0 , it may be possible to collect light containing therein all of the visible wavelength components but not containing therein any ultraviolet or infrared rays . it is also possible that the light - receiving surfaces of the light guides 24 can be fixed at the focal plane of the lens system beforehand by a manufacturer or said light - receiving surfaces of the light guides can be made adjustable in the direction of the light &# 39 ; s axis and regulated by the user so as to obtain the desired colored light components . as mentioned above , when the sunlight is focused through a lens system , the solar image has a central portion of white color light and a circumferential portion , the content of which varies depending upon the distance from the lens system . namely , at a short distance from the lens system , the blue colored light is gathered and at a large distance from the lens system the red colored light is gathered . by adjusting the set position of the light - receiving faces of the light guides it is possible to eliminate the infrared and ultraviolet rays and thus obtain sunlight that is suitable for sunbathing and for cultivating animals and plants .