| 摘要 |
PURPOSE:To convert a laser beam having an astigmatism into a plan or spherical wave by employing a hologram having the same astigmatism as that of the laser beam. CONSTITUTION:When the dispositions of a reference light source R and a reproduced illumination light source C are different, or when the wavelengths of a recording light and a reproduced light are different, the reproduced focused light point I has an astigmatism of the magnitude¦RIS-RIM¦. When a light source having the astigmatism equal to¦RIS-RIM¦is disposed at the point I and the hologram is emitted from the position ISIM, the reproduced light converged to the point C by the conjugate reproduction can be obtained. More concretely, a hetero junction semiconductor laser is disposed in parallel with the X-Z plane of the layer 3 at the distance of RIS from the center of the hologram 5 to the beam emitting end surface, and the laser light is incident obliquely at alphaI to the hologram 5. In this case, when the astigmatism¦RIS-RIM¦due to the hologram 5 and the astigmatism DELTAR of the semiconductor laser beam are equal to each other, the refracted light is focused to the point C, and the light of the light source having the astigmatism can be converted to spherical wave. |
