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We present two related techniques to measure the two-point correlation function and the power spectrum with edge correction in any spatial dimensions. The underlying algorithm uses fast Fourier transforms for calculating the two-point…

Astrophysics · Physics 2009-11-11 István Szapudi , Jun Pan , Simon Prunet , Tamás Budavári

At present spoofing attacks via which biometric system is potentially vulnerable against a fake biometric characteristic, introduces a great challenge to recognition performance. Despite the availability of a broad range of presentation…

Computer Vision and Pattern Recognition · Computer Science 2018-12-19 Avantika Singh , Gaurav Jaswal , Aditya Nigam

We demonstrate and study the enhancement of intermediate-field two-photon absorption by shaped femtosecond pulses having spectral phases of antisymmetric nature. The intermediate-field regime corresponds to pulse intensities, where the…

Atomic Physics · Physics 2015-05-14 Lev Chuntonov , Leonid Rybak , Andrey Gandman , Zohar Amitay

Free-space optics (FSO) is an attractive technology to meet the ever-growing demand for wireless bandwidth in next generation networks. To increase the spectral efficiency of FSO links, transmission over spatial division multiplexing (SDM)…

We demonstrate dual-frequency absorption spectroscopy (DFAS) using laser-cooled 87Rb and 85Rb atoms. Doppler-free resonances with high-contrast are produced, which suggest the suitability of using dual-frequency absorption spectroscopy…

Atomic Physics · Physics 2025-08-26 Gour Pati , Mauricio Pulido , Fredrik K. Fatemi , Gustavo Acosta , Renu Tripathi

A theoretical and experimental investigation of the intensity noise reduction induced by two-photon absorption in a Er,Yb:Glass laser is reported. The time response of the two-photon absorption mechanism is shown to play an important role…

Optics · Physics 2015-06-15 Abdelkrim El Amili , Gaël Kervella , Mehdi Alouini

We present an efficient approach and principle experiment for compressive sensing (CS) fluorescence spectral imaging. According to the dimension-reduced effect of CS, the spectral and spatial information was simultaneously obtained by using…

Instrumentation and Detectors · Physics 2017-07-07 Chao Wang , Xue-Feng Liu , Wen-Kai Yu , Xu-Ri Yao , Fu Zheng , Qian Dong , Ruo-Ming Lan , Guang-Jie Zhai , Qing Zhao

We propose a novel concept of differential coded aperture snapshot spectral imaging (D-CASSI) technique exploiting the benefits of using {-1,+1} random mask, which is demonstrated by a broadband single-snapshot hyperspectral camera using…

Optics · Physics 2022-08-03 Jiri Hlubucek , Jakub Lukes , Jan Vaclavik , Karel Zidek

Dual sideband (2SB) receivers are well suited for the spectral observation of complex astronomical signals over a wide frequency range. They are extensively used in radio astronomy, their main advantages being to avoid spectral confusion…

Instrumentation and Methods for Astrophysics · Physics 2018-05-17 Ricardo Finger , Patricio Mena , Nicolas Reyes , Rafael Rodriguez , Leonardo Bronfman

A distributed detection problem over fading Gaussian multiple-access channels is considered. Sensors observe a phenomenon and transmit their observations to a fusion center using the amplify and forward scheme. The fusion center has…

Information Theory · Computer Science 2016-11-17 Mahesh K. Banavar , Anthony D. Smith , Cihan Tepedelenlioglu , Andreas Spanias

Recent progress in image deblurring techniques focuses mainly on operating in both frequency and spatial domains using the Fourier transform (FT) properties. However, their performance is limited due to the dependency of FT on stationary…

Computer Vision and Pattern Recognition · Computer Science 2024-09-04 Subhajit Paul , Sahil Kumawat , Ashutosh Gupta , Deepak Mishra

A simple method for presenting a dynamic transition between Fresnel and Fraunhofer diffraction zones is considered. Experiments are conducted on different apertures and diffraction patterns are photographed at various distances between the…

Medical Image-to-image translation is a key task in computer vision and generative artificial intelligence, and it is highly applicable to medical image analysis. GAN-based methods are the mainstream image translation methods, but they…

Image and Video Processing · Electrical Eng. & Systems 2023-11-07 Zhuhui Wang , Jianwei Zuo , Xuliang Deng , Jiajia Luo

Flatbed scanners have emerged as promising devices for high-resolution, single-image material capture. However, existing approaches assume very specific conditions, such as uniform diffuse illumination, which are only available in certain…

An experimental realization of high-precision direct frequency comb spectroscopy using counter-propagating femtosecond pulses on two-photon atomic transitions is presented. Doppler broadened background signal, hampering precision…

Atomic Physics · Physics 2013-07-11 Itan Barmes , Stefan Witte , Kjeld S. E. Eikema

Entangled two-photon absorption can enable a linear scaling of fluorescence emission with the excitation power. In comparison to classical two-photon absorption with a quadratic scaling, this can allow fluorescence imaging or…

This paper presents a non-zoned discrete dielectric lens comprising two or three matching layers to reduce the 50-110 GHz frequency range reflections. Based on Chebyshev and binomial multi-section transformers, the designed models use…

Signal Processing · Electrical Eng. & Systems 2023-11-27 Juan Andrés Vásquez-Peralvo , José Manuel Fernández-González , Thomas Wong

Two-photon excitation spectroscopy with broad spectral span is demonstrated at Doppler-limited resolution. We describe first Fourier transform two-photon spectroscopy of an atomic sample with two mode-locked laser oscillators in a dual-comb…

Photoacoustic tomography (PAT) is a promising imaging technique that can visualize the distribution of chromophores within biological tissue. However, the accuracy of PAT imaging is compromised by light fluence (LF), which hinders the…

Image and Video Processing · Electrical Eng. & Systems 2023-12-11 Zhaoyong Liang , Shuangyang Zhang , Zhichao Liang , Zhongxin Mo , Xiaoming Zhang , Yutian Zhong , Wufan Chen , Li Qi

Random scattering is usually viewed as a serious nuisance in optical imaging, and needs to be prevented in the conventional imaging scheme based on single-photon interference. Here we proposed a two-photon imaging scheme with the widely…

Optics · Physics 2018-09-25 Peilong Hong