Apparatus and method for dynamic characterization of materials

1. An apparatus for dynamic characterization of a sample of a material under test comprising:

a terahertz (THz) time-domain spectroscopy system configured and arranged to generate and detect terahertz waves to interrogate the sample;

a shock wave loading system configured and arranged to produce a shock wave in the sample;

wherein the sample undergoes changes in an index of refraction in response to the produced shock wave in the sample that are detected by the terahertz time-domain spectroscopy system during the interrogating; and

a non-contact interferometer positioned with respect to the sample to further detect free-surface displacement in the sample.

2. The apparatus of claim 1 , wherein the THz time-domain spectroscopy system comprises one or more optical and terahertz components excited by an optical laser pump.

3. The apparatus of claim 1 , wherein the terahertz time-domain spectroscopy system comprises:

an optical laser pump;

a transmitter for receiving a beam from the optical laser pump and generating a terahertz wave propagating through the sample; and

a receiver for receiving a terahertz wave from the sample and generating an electrical signal.

4. The apparatus of claim 3 , wherein the optical laser pump comprises a femtosecond laser, the transmitter comprises a photoconductive antenna transmitter, and the receiver comprises a photoconductive antenna receiver.

5. The apparatus of claim 3 , wherein the terahertz time-domain spectroscopy system further comprises:

a beam splitter that receives the beam from the optical laser pump and emits output laser beams along at least a first path leading to the photoconductive antenna transmitter and a second path leading to the photoconductive receiver; and

a selectively adjustable delay leg disposed in the first and/or the second path.

6. The apparatus of claim 5 , wherein the delay leg comprises one or more optical dielectric mirrors.

7. The apparatus of claim 1 , wherein the ultrafast shock wave loading system comprises a Q-switch laser having an energy of at least 0.1 J and a short pulse duration.

8. The apparatus of claim 1 , wherein the shock wave loading system comprises a dielectric elastomer actuator.

9. The apparatus of claim 1 , further comprising:

a chamber for housing the sample.

10. The apparatus of claim 9 , wherein the chamber comprises an inert gas purged container.

11. The apparatus of claim 9 , further comprising:

an environmental control device for inducing an environmental change in the sample.

12. The apparatus of claim 11 , wherein the environmental control device comprises one or more of a cryogenic stability chamber, a convection heater, an induction coil, a Peltier element, one or more electromagnetic field generators, an ultraviolet light generator, or a supercooled gas.

13. The method of claim 1 , wherein the THz time-domain spectroscopy system is configured to interrogate the sample concurrently with the shock wave loading system produce the shock wave in the sample.

14. The method of claim 1 , wherein the THz time-domain spectroscopy system is configured to interrogate the sample at least partially after the shock wave loading system produces the shock wave in the sample.

15. The method of claim 1 , further comprising:

a sample made from a polymer.

16. An apparatus for dynamic characterization of a sample of a material under test comprising:

a terahertz (THz) time-domain spectroscopy system configured and arranged to generate and detect terahertz waves to interrogate the sample;

a shock wave loading system configured and arranged to produce a shock wave in the sample;

wherein the sample undergoes changes in an index of refraction in response to the produced shock wave in the sample that are detected by the terahertz time-domain spectroscopy system during the interrogating;

wherein the shock wave loading system is an ultrafast shock wave loading system comprising a laser,

wherein the ultrafast shock wave loading system comprises a Q-switch laser having an energy of at least 0.1 J and a short pulse duration.

17. The apparatus of claim 16 , wherein the ultrafast shock wave loading system further comprises a mode conversion prism to receive an output from the laser and exfoliate a sacrificial surface to generate an ultrafast shock wave through the sample.

18. The apparatus of claim 16 , further comprising:

a non-contact interferometer positioned with respect to the sample to detect free-surface displacement in the sample.

19. A method for testing a sample of a material under test, the method comprising:

producing a shock wave in the sample; and

generating and detecting terahertz waves to interrogate the sample, wherein the sample undergoes changes in an index of refraction in response to the produced shock wave in the sample;

generating electrical signals in response to the detected terahertz waves;

detecting free-surface displacement of the sample during said generating terahertz waves; and

analyzing the generated electrical signals in the time domain and the free-surface displacement to determine one or more mechanical properties of the sample.

20. The method of claim 19 , wherein:

(a) said generating and detecting terahertz waves is concurrent with said producing a shock wave in the sample;

(b) said generating and detecting terahertz waves is at least partially subsequent to said producing a shock wave in the sample;

(c) the produced shock waves comprise ultrafast shock waves;

(d) said detecting free-surface displacement of the sample uses an interferometer; and

(e) the sample is disposed in a chamber; and the method further comprises introducing at least one environmental change in the sample before or concurrently with said generating and detecting terahertz waves to interrogate the sample.