Real-Time Megapixel Electro-Optical Imaging of THz Beams with Probe Power Normalization

Abstract

In this work, we present a simple method to improve the spatial uniformity of two-dimensional electro-optical imaging of terahertz (THz) beams. In this system, near-field THz images are captured by fully illuminating a sample using conventional optical microscope objectives. Unfortunately, due to the linear relationship between the optical probe power and the measured THz electric field, any spatial variation in probe intensity translates directly into a variation of the recorded THz electric field. Using a single normalized background frame information map as a calibration tool prior to recording a sequence of THz images, we show a full recovery of a two-dimensional flat field for various combinations of magnification factors. Our results suggest that the implementation of dynamic intensity profile correction is a promising avenue for real-time electro-optical imaging of THz beams.

Technological Evolution of Image Sensing Designed by Nanostructured Materials

“…Figure shows the vertical S and horizontal P picture subtraction operations (on–off images). THz waves are fully safe, unlike X-rays, and can penetrate clothing, items, and packages to identify the interior materials and chemicals in the fields of digital imaging and biomedical engineering, because THz imaging and detection technology make it possible to quickly identify opaque objects with distinct borders. , …”

“…(c) Dynamic background subtraction followed by the vertical S and horizontal P pictures subtraction operation (on–off images). (a–c) Reproduced with permission from ref . Copyright 2022 MDPI.…”

“…THz waves are fully safe, unlike X-rays, and can penetrate clothing, items, and packages to identify the interior materials and chemicals in the fields of digital imaging and biomedical engineering, because THz imaging and detection technology make it possible to quickly identify opaque objects with distinct borders. 98,99 Virus epidemics such as Ebola, Zika, MERS, and others have wreaked havoc on humanity in the last ten years, and the coronavirus (SARS-CoV-2) pandemic, as well as its constantly evolving variants, has put the entire technological advancement of healthcare in jeopardy. Although conventional methods of viral detection have been somewhat successful though they are expensive and time-consuming and require specialized human resources.…”

Exposure Time Control Method for Higher Intermediate Frequency in Optical Heterodyne Imaging and Its Application to Electric-Field Imaging Based on Electro-Optic Effect

“…Furthermore, when the probe is combined with an image sensor, multiple points can be measured at once, and the electric field distribution can be visualized quickly [ 20 ]. EO crystals respond to high frequencies on the order of terahertz [ 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 ], but they cannot be directly observed using slow optical detectors such as image sensors. Therefore, frequency conversion using optical heterodyne detection is necessary.…”

Broadband heterodyne electro-optic sampling using a lithium niobate ridge-waveguide

“…5,6) As this method involves direct observation of the difference and sum frequency generation (DFG, SFG) beams generated by the interaction of the THz wave with the probe light, it bypasses the problem of birefringence, a common challenge in EO sampling. [7][8][9] Indeed, in the heterodyne EO sampling method, it is the change in intensity of the probe beam that is detected, not the change in polarization induced by the phase delay in the beam. 5,6) It should therefore be a very versatile detection method.…”