Apparatus and method for compensating coma aberration

摘要

An optical pick-up apparatus includes a light source, an objective lens, a beam splitter, a detector, a first optical compensating device and a second optical compensating device. The objective lens converges a light beam emitted from the light source at one point on an optical axis. The beam splitter separates the light beam emitted from the light source from a returning light reflected on an optical disc. The detector detects the returning light separated from the light beam emitted from the light source. The first optical compensating device has a convex aspherical surface represented by +E,ovs X+EE alpha R4 and is located on an optical path where the light beam is emitted from the light source. The second optical compensating device has a concave aspherical surface represented by + alpha R4 and is located on an optical path where the light beam is emitted from the light source.