研究目的
To develop a scanning laser terahertz (THz) near-field reflection imaging system for high spatial resolution measurements without any sub-wavelength probes and demonstrate its capability for industrial applications requiring micron-scale resolution.
研究成果
The developed scanning laser THz near-field reflection imaging system achieved a spatial resolution of 20 μm (λTHz/34) and demonstrated its capability for high spatial resolution THz reflection imaging of metallic structures and human breast tissue. Future improvements could enhance the spatial resolution, imaging speed, and imageable region.
研究不足
The spatial resolution is limited by the THz wave divergence inside the GaAs crystal. The imageable region is limited to about 500 μm × 500 μm, and the imaging speed is 90 s per image for 128 × 128 pixels.
1：Experimental Design and Method Selection:
The system uses a fiber-coupled femtosecond laser source to generate THz waves at a laser focusing spot in a non-linear optical crystal (NLOC). The THz waves interact with a sample set on the crystal.
2：Sample Selection and Data Sources:
Metallic structures and paraffin-embedded human breast tissue samples were used.
3：List of Experimental Equipment and Materials:
A
4：56 μm fs fiber laser (TOPTICA FEMTOFIBER pro), a 500 μm-thick (110)-oriented GaAs crystal as the 2D-THz emitter, and a spiral-shaped low-temperature-grown (LT-) GaAs photoconductive antenna detector. Experimental Procedures and Operational Workflow:
THz wave pulses are generated at the laser focusing spot in the NLOC, interact with the sample, and are detected by the antenna detector. THz reflection images are obtained by scanning the pump pulses over the GaAs crystal.
5：Data Analysis Methods:
The spatial resolution and imaging capability were analyzed based on the THz reflection images obtained.
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