Laser optical power monitoring using thermal sensor of a head transducer

摘要

A light source is configured to produce light, a waveguide is optically coupled to the light source and configured to direct the light to an intended focus location, and a slider is configured to use the light as an energy source for heating a region of a magnetic recording medium. A thermal sensor is situated on the slider at a location outside of a light path that includes the intended focus location. The thermal sensor is configured for sensing a short time constant change in temperature resulting from light source heating of the thermal sensor, wherein the sensed change in thermal sensor temperature is representative of optical intensity of the light delivered to the intended focus location.

主权项

1. An apparatus, comprising:
a light source configured to produce light; a slider configured to communicate the light to a near-field transducer that uses the light as an energy source for heating a region of a magnetic recording medium; a thermal sensor situated on the slider at a location for sensing a change in temperature resulting from direct heating of the thermal sensor by the light and from waste heat communicated from the light source to the thermal sensor, wherein the sensed change in thermal sensor temperature due to direct heating of the thermal sensor is representative of optical intensity of the light delivered by the light source; a circuit coupled to the thermal sensor and configured to measure a change in resistance of the thermal sensor in response to the sensed change in thermal sensor temperature due to direct heating of the thermal sensor rather than from waste heat generated by the light source; and a processor coupled to the circuit and configured to:
compare the measured change in resistance to a threshold indicating that desired light intensity is being delivered; andproduce a signal indicating whether or not the threshold has been reached.