| 摘要 |
PURPOSE:To reduce the number of components by providing a beam shaping function, a polarizer function and a beam splitter function to one optical plane. CONSTITUTION:The light from a semiconductor laser 101 passes through a collimator lens 102 and is made incident from an optical plane 106 on a prism 108. A dielectric multi-layer film having the reflectance of 0% for P polarized light and the reflectance of 100% for S polarization, for example, is coated to the plane 106. Thus, the incident light is made nearly circular by the plane 106, the optical path is bent by a total reflection face 107, a spot is formed to an optical recording medium 105 to write/read a data. The reflected light from the medium 105 passes through an opposite path to the said path, is reflected totally in the face 106 and reaches a 4-split photosensor 104. Through the constitution above, since the plane 106 has three functions as beam shaping, polarizer and beam splitter altogether, the number of components is less, the assembling is facilitated and the optical head with small size and low cost is obtained.
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