Optisch stelsel voor bundelvorming en een optische opneeminrichting die daarvan gebruik maakt.

摘要

A beam from a light source 51 is shaped by a cylinder lens 53 and plates 55,57. The beam may be shaped from an elliptical cross-section to a circular cross-section, by reducing the long-axis of the ellipse, or vice versa. The cylinder lens 53 may have a surface with a negative power 533 and a surface with a positive power 535 of greater magnitude. An optical pickup employs such a beam-shaper and further includes an objective lens 60 for focusing light from the plates 55,57. The pickup may also include a collimating lens 59. One surface 555 of the first plate 55 may act as a beam-splitter and reflect light transmitted from the second plate 57 to a photo detector 63. The photo detector 63 may detect light according to an astigmatic method.