| 摘要 |
PURPOSE:To attain detection of a focus error signal having no shift to the temperature variation by securing the coincidence between the relative shift direction due to the difference of heat expansion coefficients between a base and a photodetector and the boundary line direction of the photodetector. CONSTITUTION:A photodetector is attached to a distributing board 8 and this board 8 is fixed to a base 7 by screws 9a and 9b at hole parts 8a and 8b on the same straight line as a boundary line 5a of a photodetector. When the temperature of an optical pickup is changed, the position of the photodetector is shifted toward a straight line connecting screws 9a and 9b against the base 7 owing to the difference of heat expansion coefficients between the base 7 and the board 8. However the coincidence is secured between the direction of the line 5a and the shift direction of the photodetector. Thus the shift of a focus error signal can be eliminated. |
