Spectral Camera based on Ghost Imaging via Sparsity Constraints

Abstract

The image information acquisition ability of a conventional camera is usually much lower than the Shannon Limit since it does not make use of the correlation between pixels of image data. Applying a random phase modulator to code the spectral images and combining with compressive sensing (CS) theory, a spectral camera based on true thermal light ghost imaging via sparsity constraints (GISC spectral camera) is proposed and demonstrated experimentally. GISC spectral camera can acquire the information at a rate significantly below the Nyquist rate, and the resolution of the cells in the three-dimensional (3D) spectral images data-cube can be achieved with a two-dimensional (2D) detector in a single exposure. For the first time, GISC spectral camera opens the way of approaching the Shannon Limit determined by Information Theory in optical imaging instruments.

Single-frame wide-field nanoscopy based on ghost imaging via sparsity constraints

“…According to the theory of GISC imaging which is applied to GISC camera [30], the fluorescent light field is modulated into speckle pattern by a random phase modulator mounted before detector. GISC nanoscopy consists of two parts: 1) Calibration process, we collect the speckle patterns ( ', ') ( , ) r ij I i j corresponding to each position in the sample plane as the priori information, which can be measured online or pre-determined.…”

“…2) Imaging process, we can obtain the speckle pattern intensity distribution ( ', ') t ij I from all fluorophores within the imaged specimen to achieve a super-resolution reconstructed image by calculating the second-order intensity correlation between the calibration speckles and one imaging speckle. The second-order correlation function is expressed as [26]   ' ' In GISC nanoscopy, the resolution of imaging is determined by three aspects: 1) Resolution of GI, which is related to the mutual-correlation function of speckle patterns and can be optimized by adjusting the position of random phase modulator between the tube lens and detector and the parameters of the random phase modulator [30]. Fig.…”

“…To ensure the accuracy of the reconstruction, two key issues should be addressed in calibration process: 1) Selection of calibration source, which requires high fluorescence brightness, high stability and small difference in size and spectral with the dye used in imaging process. Therefore we use microspheres (20 nm) as the calibration source because the size difference with fluorophore is negligible to the effects of noise and pixel size of detector demonstrated by system simulation or the deconvolution, and the spectral difference is limited by the bandpass filter selected according to the spectral resolution of GISC imaging [30]. Thus any fluorescent sample can be used at the same excitation wavelength with the microsphere, which makes this technique more widely used in sample preparation and dye selection.…”

Optimization of light fields in ghost imaging using dictionary learning

“…As a novel technique for optical imaging, ghost imaging (GI) was initially implemented with quantum-entangled photons two decades ago [1,2]. In recent years, owing to its realization with thermal light and other new sources [3][4][5][6][7][8], GI has gained new attention and developed applications in various imaging areas, such as remote sensing [9,10], imaging through scattering media [11,12], spectral imaging [13,14], photon-limited imaging [15,16] and X-ray imaging [17,18].…”

A Review of Ghost Imaging via Sparsity Constraints

“…In Section 2, we introduce the theoretical framework of GISC with an emphasis on that the ensemble average required by GI could hardly be satisfied in real applications. In Section 3, we present a brief review of application researches of GISC conducted in Shanghai Institute of Optics & Fine Mechanics (SIOM), including two imaging applications in real space, GISC LiDAR [18,19] illuminated by pseudo-thermal light and GISC spectral camera [20] illuminated by natural light, and two imaging applications in Fourier space, X-ray Fourier-transform GISC [21] and lensless Wiener-Khinchin telescope based on high-order spatial autocorrelation of thermal light [22]. Section 4 is devoted to a discussion of the prospect of GISC.…”