Real-time terahertz near-field microscope

TL;DR

This paper introduces a real-time terahertz near-field microscope capable of high-resolution imaging over large areas at 35 frames per second, enabling dynamic observation of biological and material samples.

Contribution

The authors develop a novel THz near-field imaging system combining tilted-pulse-front excitation and EO balanced detection for real-time, high-resolution imaging.

Findings

Achieved 35 fps imaging of 370x740 μm² area

Demonstrated subwavelength field quantification in real-time

Captured field enhancement at dipole antenna gap

Abstract

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.