| 摘要 |
PROBLEM TO BE SOLVED: To make eliminable a focal point deviation between two wavelengths. SOLUTION: In an exposing light path, a 1st tracking error signal is detected from the light reflected from a substrate 21 with track grooves. Also, in a focusing light path, a 2nd tracking error signal is detected from the light reflected from the substrate 21 with track grooves. And, a focal point of exposure light is detected by detecting the peak amplitude of the 1st tracking error, and the collimation of the focus light is adjusted by adjusting the position of the focus light source so that the focal position of the focus light detected by detecting the peak amplitude of the 2nd tracking error signal is made to coincide with the focal position of the exposure light.
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