Method of and apparatus for adjusting the focus position of an optical pickup

A method of adjusting the focus position of an optical pickup, said method comprising:

• a first step in which a brightness measuring apparatus including a half mirror and an objective lens focusing on the half mirror and also including a signal processor for finding a highest brightness of a light image entering through the half mirror and the objective lens is disposed to face an optical pickup;
• and
• a second step in which the optical pickup is operated to start a focus servo, the positions of semiconductor lasers provided in the optical pickup or relative positions of a multi-lens and a light-receiving element of the optical pickup are changed continuously, the signal processor is operated to find a change in the highest brightness of a spot light image incident on the half mirror through an objective lens provided in the optical pickup, said positions are fixed once the semiconductor lasers or the multi-lens and light-receiving element have been moved to positions when the highest brightness has become a maximum highest brightness, thereby effecting an adjustment of the focus position of the optical pickup.