发明名称 |
Compound objective lens having two focal points and apparatus using the lens. |
摘要 |
<p>A compound objective lens is composed of a hologram lens for transmitting a part of incident light without any diffraction to form a beam of transmitted light and diffracting a remaining part of the incident light to form a beam of first-order diffracted light, and an objective lens for converging the transmitted light to form a first converging spot on a front surface of a thin type of first information medium and converging the diffracted light to form a second converging spot on a front surface of a thick type of second information medium. Because the hologram lens selectively functions as a concave lens for the diffracted light, a curvature of the transmitted light differs from that of the diffracted light. Therefore, even though the first and second information mediums have different thicknesses, the transmitted light incident on a rear surface of the first information medium is converged on the its front surface, and the diffracted light incident on a rear surface of the second information medium is converged on the its front surface. That is, the compound objective lens has two focal points. <IMAGE></p> |
申请公布号 |
EP0610055(A2) |
申请公布日期 |
1994.08.10 |
申请号 |
EP19940300717 |
申请日期 |
1994.01.31 |
申请人 |
MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD |
发明人 |
KOMMA, YOSHIAKI;MIZUNO, SADAO;NISHINO, SEIJI |
分类号 |
G02B5/32;G02B3/10;G02B5/18;G02B13/00;G02B21/02;G02B21/18;G02B21/20;G03F9/00;G11B7/00;G11B7/007;G11B7/085;G11B7/09;G11B7/095;G11B7/12;G11B7/135;G11B7/24;G11B19/12;(IPC1-7):G11B7/135 |
主分类号 |
G02B5/32 |
代理机构 |
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代理人 |
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主权项 |
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地址 |
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