| 摘要 |
In a magneto-optical head assembly, a source beam is directed onto a magneto-optical recording medium and light returning from it is focussed through a birefringent member to a light detector. The birefringent member is formed with a diffraction pattern for splitting incident light into a zeroth-order component and plus and minus first-order components. The light detector includes a first light sensing area having two sensors for receiving the zeroth-order component, a second light sensitive area having a first pair of diagonally arranged sensors and a second pair of diagonally arranged sensors for receiving one of the plus and minus first-order components, and a third light sensitive area having two sensors for receiving the other first-order component. In one embodiment, the birefringent member has an off-axis lens effect and is divided into two regions of different diffraction patterns and in a modified embodiment, it has a first diffracting plane for diffracting a particular polarization component of incident light and a second diffracting plane for diffracting a polarization component of light from the first plane which polarization component is oriented in a direction normal to the direction of orientation of that particular polarization component. Each diffracting plane has two regions different diffraction patterns.
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