Patent ID: 8341825

Claim:
A method for manufacturing a thermally-assisted magnetic head that includes a slider and a laser diode unit, the slider including an air bearing surface (ABS) that faces a recording medium and including a waveguide with a core for light propagation that extends from a light entering surface, which is different from the ABS, to the ABS, the laser diode unit being attached to the light entering surface of the slider, and the thermally-assisted magnetic head performing magnetic recording while heating the recording medium with near-field light that is excited from linearly polarized laser light, the method comprising: a step of disposing the laser diode unit in a position facing the light entering surface of the slider, disposing a photo detector in a position facing the ABS of the slider, and disposing a polarizer between the ABS and the photo detector, the polarizer transmitting only light having a polarization component that is orthogonal to a polarization direction of linearly polarized laser light; a step of activating a laser diode of the laser diode unit, and enabling the linearly polarized laser light to enter into the core from the light entering surface of the slider; and a step of enabling light radiated from the ABS to enter into the polarizer, and performing an alignment of the slider and the laser diode unit while the photo detector detects the light that is transmitted through the polarizer.