Deformation corrected real-time terahertz imaging

Abstract

The authors have developed a method of real-time terahertz imaging in which image deformation due to nonuniformity of residual birefringence in the electro-optic ͑EO͒ sampling crystal is corrected. Real-time terahertz imaging using intense terahertz pulses and two-dimensional EO sampling can suffer from birefringence nonuniformity of the EO crystal since the birefringence is explicitly used for the linear detection of the terahertz field. In the proposed method, the distribution of the residual birefringence of the EO crystal is measured and used for image correction. Deformation-free images of the spatial profile of a focused terahertz pulse were obtained.

Coherent electro-optical detection of terahertz radiation from an optical parametric oscillator

“…For the EO detector, a crossed-polarizer-type configuration is used, in which a quarter-wave plate works as the compensator [22][23][24]. This configuration will make the transition to multipixel detection straightforward.…”

Terahertz generation by means of optical lasers

“…Developing of OR schemes for THz generation was started just with the first explorations of subpicosecond and femtosecond lasers in the 1970-s [134][135][136] and is steadily continued up to now. Due to a considerable progress achieved, devices based on this general principle are considered to be the best for a lot of important practical applications, especially for the THz time-domain spectroscopy [1,2] and imaging [3][4][5]108].…”

“…And, on the other hand, a vast number of eigenfrequencies which are typical for vibrations or rotations of large molecules, molecular chains, electron transitions in nano-structured materials, and so on, keep in resonance with THz-range waves and can be used for the investi-gation and diagnostics of relevant objects. Among the attractive applications of the THz radiation there are THz spectroscopy for chemical identification of large complex molecules, sensing of chemical processes, industrial or environmental diagnostics, single-shot THz imaging, noninvasive biomedical imaging and medical tomography, manipulation of charged and magnetic particles, as well as of nanoparticles [1][2][3][4][5], monitoring of electronic intersubband processes and carrier dynamics in semiconductors, gases, dielectrics, liquids and nanostructured materials [6][7][8][9][10][11][12]. Another group of applications is concerned with THz radio-vision [5]: communication, radioastronomy, aeronomy.…”

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

“…Among imaging demonstrations, two-dimensional electro-optical imaging of THz beams, first demonstrated in the mid-1990s [8], is an important method for capturing streaming images in the time domain. This method has undergone several improvements over the years, including two-dimensional birefringence correction to smooth out imperfections in the EO crystal [9,10], dynamic background subtraction to reduce noise [11], access to the near-field region with a thin EO crystal [12], and improved sensitivity and resolution through spectral filtering of the probe light [13], to name a few.…”