| 摘要 |
<p>An apparatus measures a property of an optically absorbing layer (416) by using a lens (415) to focus a heating beam (403) for a laser (401) on a region of the layer (416), modulating the power from a laser driver circuit (421) to the laser to modulate the heating beam (403) at a predetermined frequency that is selected to be sufficiently low to ensure that at any time the temperature of the layer is approximately equal to a temperature of the layer when heated by an unmodulated beam, and using a detector (420) to measure the power of another beam from another laser (405) that is reflected from the heated region. The measurement can be used to adjust a process parameter that controls a fabrication process.</p> |
