Method and apparatus for simultaneous measurement of electric field and temperature using an electrooptic semiconductor probe
AssigneeThe Regents of the University of Michigan
InventorsRonald M. Reano, John F. Whitaker, Linda P. B. Katehi
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Abstract
An apparatus and method to simultaneously measure electric and thermal fields with a single probe. Using an electrooptic semiconductor probe, the Pockels effect is employed to measure electric field magnitude and phase, and the effect of photon absorption due to bandtail states in the semiconductor is used to measure temperature. Techniques to scale relative electric-field measurements to absolute units (volts/meter), stabilize electric-field phase drift, and calibrate electric-field data that is corrupted when the probe is used in regions where temperature gradients exist are provided.
Claims30
An electro-thermal field mapping apparatus for scanning a workpiece comprising:
- means for generating an optical signal;
- an electro-optic field-mapping sensor for receiving the generated optical signal and for generating an output optical signal influenced by a free-space electric field associated with the workpiece passing through an operable range of the sensor;
- means for sensing a characteristic of the output optical signal containing electric field information;
- and
- bandgap modulation means for compensating the sensed characteristic of the output optical signal containing electric field information for corruption due to temperature variations.
A method for scanning a workpiece with an electro-thermal apparatus comprising the steps of:
- generating an optical signal;
- receiving the generated optical signal and generating an output optical signal with an electro-optic field-mapping sensor influenced by a free-space electric field associated with a workpiece passing through an operable range of the sensor changing a characteristic of the optical signal;
- sensing a characteristic of the output optical signal;
- and
- compensating the sensed characteristic of the output optical signal for corruption due to temperature variations with bandgap modulation of at least a portion of the output optical signal.
An electro-thermal field mapping apparatus for scanning a workpiece comprising:
- means for generating an optical signal;
- an electro-optic field-mapping sensor for receiving the generated optical signal and for generating an output optical signal influenced by an electric field associated with the workpiece passing through an operable range of the sensor;
- means for sensing a characteristic of the output optical signal containing electric field magnitude and phase information;
- and
- means for deriving the sensed characteristic independent of temperature variations.
Dependencies are inferred from the claim text.