| 摘要 |
PROBLEM TO BE SOLVED: To obtain an optical modulation element capable of obtaining light of a selected wavelength from white light without loss of light. SOLUTION: A liquid crystal 15 having a helical pitch is held between a pair of transparent substrates 11, 12 on which transparent electrodes 16, 17 are formed, respectively. A mirror 14 is provided so as to reflect all the light refracted within and transmitted through the liquid crystal out of the incident white light with an angle θ in the parallel and reverse direction with respect to the transmitted light. Furthermore, a mirror 13 is provided so as to reflect all the light reflected by the mirror 14 and again incident on the liquid crystal layer and selectively reflected thereby in the parallel and reverse direction with respect to the selectively reflected light. The selective reflection wavelength is varied by making an electric field applied to the liquid crystal layer 15 with the transparent electrodes 16, 17 variable and by varying the helical pitch of the liquid crystal 51. Out of the white light incident on the transparent substrate 11 side from a light source, only the light in the specified wavelength region determined by the magnitude of voltage applied between the transparent electrodes 16, 17 is selectively reflected and the light outside the specified wavelength region is returned to the light source side. |
