高速波面収差検出によるDVD光ヘッドアライメント

概要

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The objective lens for DVD optical-heads must have high optical performance, being aligned in high accuracy on the optical head For high speed of this alignment process, a method based on wave aberration included in exit light from the objective lens on the optical head has been studied An optical system based on stable shearing interference with diffraction grating has been devised, as well as algorithm that can detect coma aberration from fringe patterns formed in this optical system. This algorithm processes divisional area of patterns therefore this algorithm can detect coma at high speed, besides independently of spherical aberration or astigmatism. Alignment system of the objective lens on DVD optical head based on these optical system and algorithm has been developed. This system detects coma at s intervals and repeatability of tilt measurement 0.01°. This alignment system has achieved high-accuracy alignment of 0.14°at 3σ that is enough for DVD optical-heads, attaining 1/3 to 1/4 alignment time of conventional jitter method or spot method.
2001-07-05