| 摘要 |
PURPOSE:To obtain a deflection quantity sufficient for optical scan, and to make a lattice disk small in size by making a luminous flux section shape of a laser light made incident on the lattice disk elliptic, and making a long axis direction of this ellipse conform with a radial direction of the lattice disk. CONSTITUTION:When a laser light L' from a semiconductor laser 10 is converted to a parallel luminous flux by a collimating lens 11, its luminous flux section becomes an elliptical shape L2 in which a Y direction is a long axis direction. This laser light L' transmits through a 1/2 wavelength plate 12, and is made incident on a hologram diffraction grating on a hologram lattice disk 1' through a cylindrical lens 4' and a plane mirror 5. Also, in order that the scanning spot shape is formed to an elliptical shape which is long a little in the sub-scanning direction, the long axis direction of a luminous flux section L'1 is made parallel to the main scanning direction. Also, in order to set an object point of the scanning line to the center part of the scanning area, the direction of a lattice line in a hologram diffraction grating 1'-i is made parallel to the direction of a B-B line, namely, the direction for connecting the center part of the diffraction grating 1'-i and the rotation center of the hologram lattice disk 1'.
|
