Systems and methods for monitoring temperature using acoustic waves during processing of a material

1. A method of processing a material, the method comprising:

heating a first region of the material with a first energy source;

exciting a first acoustic wave in the material;

transmitting the first acoustic wave through the heated first region of the material, the heated first region of the material changing at least one property of the first acoustic wave;

detecting the change in at least one property of the first acoustic wave;

characterizing a temperature of the material in the heated first region based on the detected change in at least one property of the first acoustic wave;

comparing the characterized temperature of the material in the heated first region to a threshold; and

based on the characterized temperature of the material in the first region being less than the threshold or being above the threshold for an insufficient amount of time, modifying a property of the heated first region with a second energy source.

2. The method of claim 1 , further comprising, responsive to heating the first region of the material with the first energy source, melting a powder or a wire in the first region to form the material.

3. The method of claim 1 , further comprising, responsive to heating the first region of the material with the first energy source, excising a portion of the material.

4. The method of claim 1 , wherein the acoustic wave comprises one or more of a surface acoustic wave, a bulk acoustic wave, a guided acoustic wave, and a phonon.

5. The method of claim 1 , further comprising:

characterizing a defect in a morphology of the material in the heated first region based on the detected change in at least one property of the first acoustic wave; and

based on the characterized defect, heating the first region of the material to a temperature above the threshold with the second energy source.

6. The method of claim 1 , wherein modifying the property of the heated first region with the second energy source comprises heating the first region of the material to a temperature above the threshold.

7. The method of claim 1 , further comprising:

exciting a second acoustic wave in the material;

transmitting the second acoustic wave through a heated second region of the material, the heated second region of the material changing at least one property of the second acoustic wave;

detecting the change in at least one property of the second acoustic wave;

characterizing a temperature of the material in the heated second region based on the detected change in at least one property of the second acoustic wave;

comparing the characterized temperature of the material in the heated second region to a threshold; and

based on the characterized temperature of the material in the second region being less than the threshold or being above the threshold for an insufficient amount of time, modifying a property of the heated second region with the second energy source or with a third energy source.

8. The method of claim 1 , wherein the change in at least one property of the first acoustic wave comprises a change in an arrival time, a change in a disturbance amplitude, or changes both in the arrival time and the disturbance amplitude, of at least one frequency component of the first acoustic wave.

9. The method of claim 8 , wherein detecting the change in the arrival time, the change in the disturbance amplitude, or the changes both in the arrival time and the disturbance amplitude, of the at least one frequency component of the first acoustic wave comprises receiving laser light reflected from the material.

10. The method of claim 1 , wherein the first energy source comprises a first laser or a first particle beam.

11. The method of claim 10 , wherein the first laser excites the first acoustic wave.

12. The method of claim 10 , wherein the second energy source comprises a second laser or a second particle beam that is discrete from the first laser or the first particle beam.