Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Real-time terahertz near-field microscope   Terahertz (THz) waves have been significantly developed in the last fifteen
years because of their great potential for applications in industrial and
scientific communities1,2. The unique properties of THz waves as transparency
for numerous materials and strong absorption for water-based materials are
expected to broadly impact biosensing3 such as medical imaging4, chemical
identifications5, and DNA recognition6. In particular, for accessing
information within a scale comparable to the cell size where interactions
between cell membrane and other organelle structures occur, micron size spatial
resolution is required. Due to the large wavelength, however, the joint
capability of THz near-field imaging with real-time acquisition, which is a
highly desirable ability for observing real-time changes of in vivo sample,
remains undone. Here, we report a real-time THz near-field microscope with a
high dynamic range that can capture images of a 370 x 740 {\mu}m2 area at 35
frames per second. We achieve high spatial resolution on a large area by
combining two novel techniques: THz pulse generation by tilted-pulse-front
excitation7 and electro-optic (EO) balanced imaging detection using a thin
crystal. To demonstrate the microscope capability, we reveal the field
enhancement at the gap position of a dipole antenna after the irradiation of a
THz pulse. Our results are the first demonstration of a direct quantification
of a 2-dimensional subwavelength THz electric field taken in real-time.

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The categories of this paper are: astro-ph
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The categories of this paper are: nlin
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The categories of this paper are: q-fin
20
The categories of this paper are: acc-phys
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The categories of this paper are: eess
29
The categories of this paper are: funct-an
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The categories of this paper are: adap-org
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The categories of this paper are: chao-dyn
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The categories of this paper are: stat
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The categories of this paper are: dg-ga
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The categories of this paper are: cs
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The categories of this paper are: hep-ex
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The categories of this paper are: nucl-th
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The categories of this paper are: cmp-lg
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The categories of this paper are: gr-qc
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The categories of this paper are: alg-geom