| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a multi-wavelength compatible optical pickup device with a beam shaping mirror which can shape one-wavelength beam and does not cause aberration of respective wavelengths. <P>SOLUTION: Laser beams B1 to B3 are made incident on a beam shaping mirror 7 in infinity system. The blue laser beam B1 is made incident on an objective lens 9 in infinity system, and the red and infrared laser beams B2 and B3 are made incident on the objective lens 9 in finite system. The beam shaping mirror 7 is provided with a transparent member 7c including, in nonparalell, a first optical surface 7a equipped with a wavelength selective film Ft and a diffraction grating Gr, and a second optical surface 7b equipped with a full-reflective film Mr and constituted of a reflective surface. The wavelength selective film Ft transmits the blue laser beam B1, and reflects the red and infrared laser beams B2 and B3. The blue laser beam B1 transmitted through the wavelength selective film Ft is reflected on the second optical surface 7b, and then transmitted through the wavelength selective film Ft to convert a beam intensity distribution from an elliptical shape to a circular shape. <P>COPYRIGHT: (C)2008,JPO&INPIT |
