| 摘要 |
The present invention relates to a reproduction recording device, and to a method to recognize a focusing state. The present invention object is to provide a method of this kind and a recording or reproducing device, with the easiness of producing significant astigmatism in reflected light beam (15) simply at an efficient cost without elaborated alignment. This object is achieved by using a birefringent means (23, 24). The present invention particularly is suitable to be utilized in a recording or reproducing device to write towards or reproduce an optical recording means (11) such as CD, video discs, DVD and the like.
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