Optical Review最新文献

Intensity diffraction tomography (IDT) encompasses a class of optical microscopy techniques designed to reconstruct the three-dimensional refractive index (RI) distribution of a sample from a series of two-dimensional intensity-only measurements. However, reconstructing artifact-free RI maps remains a fundamental challenge in IDT owing to the loss of phase information and the missing-cone problem. Neural fields (NF), a deep learning framework increasingly adopted in computer vision and graphics, offer a promising approach by using a neural network to map 3D spatial coordinates to optical properties—such as color, opacity, and refractive index. we propose a method called Intensity Diffraction Tomographic Compressed Imaging based on Residual Neural Fields (IDTCI-RNF). Our approach integrates a compressed sampling mechanism into the IDT imaging model and employs a self-supervised deep learning framework enhanced with 3D Total Variation (3DTV) regularization to preserve edge details. The proposed method enables high-quality reconstruction of 3D refractive index distributions from low-dimensional discrete intensity measurements. Experimental results demonstrate that IDTCI-RNF produces high-contrast, artifact-free RI maps and outperforms existing methods in retaining structural edges and fine details.

A new optical single-channel security system based on Schur decomposition, biometric random phase encoding in fractional Fourier transform domains is proposed. In this technique, the grayscale iris image is decomposed by Schur decomposition. Unitary matrix U and upper triangular matrix T are encoded and modulated independently by a random phase mask to produce a biometric random phase mask (BRPM). An original color image is split into R-, G- and B- channels. Each channel is decomposed by Schur decomposition. The unitary matrix U. of each channel is combined to construct a single-channel image as an input image. The upper triangular matrix T of each channel is utilized as decryption key. A single-channel image is modulated with U- BRPM and then fractional Fourier transformed. The fractional Fourier spectrum is amplitude- and phase-truncated to obtain first encrypted image and first decryption key. The first encrypted image is modulated with T- BRPM and then fractional Fourier transformed. The fractional Fourier spectrum is amplitude- and phase-truncated to get final encrypted image and second decryption key. The proposed cryptosystem has three main advantages. First, the proposed system has four decryption keys to evade potential attacks. Second, U- BRPM and T- BRPM are utilized as unique encryption keys to resist unauthorized access. Finally, the fractional orders of the fractional Fourier transform provide sensitive encryption keys. The proposed method can be executed using a hybrid optoelectronic system. The viability, efficiency, and security of the proposed system can be shown by numerical simulation results.

We propose a novel method for measuring circular dichroism (CD) using polarization-modulated dual-comb spectroscopy (PM-DCS). This method utilizes two tightly phase-locked optical frequency combs to realize rapid and precise polarization modulation, eliminating the need for mechanical polarization modulators, and achieves high-speed, high-precision control of the polarization states. The experimental results demonstrated successful polarization switching between left- and right-circularly polarized light, enabling accurate detection of the CD spectra. Moreover, this method supports customizable polarization switching, realizing applications such as simultaneous circular-linear dichroism measurements. Our findings offer a pathway for high-sensitivity, broadband, and dynamic polarization measurements, extending applications in the analysis of chiral materials, particularly in the fields of chemistry, biology, materials science, and device characterization, where the ability to perform real-time high-sensitivity measurements is essential.

Information transmission capacity in optical fiber networks can be rapidly escalated using Dense Wavelength Division Multiplexing (DWDM). However, non-linearities in fiber such as Four Wave Mixing (FWM) cause adverse effects in DWDM and ultra-DWDM networks. In this work, differential quadrature phase shift keying (DQPSK) modulation is employed to minimize the impact of FWM effect. The system performance can be improved by properly adjusting the switching and bias voltage of the dual-port Mach-Zehnder Modulator (MZM). Here, the performance of the proposed method is compared with other advanced modulation techniques such as Quadrature Phase Shift Keying (QPSK), Differential Binary Phase Shift Keying (DBPSK) and 16-Quadrature Amplitude Modulation (QAM). The results reveal optimal performance with maximum FWM minimization for the proposed method at a switching voltage of 3 V.

Concerns about sun exposure have increased, leading to increased interest in the quality of sunscreen products, particularly regarding their content of heavy metals that may pose a health risk. This study aims to evaluate the concentrations of some heavy metals in sunscreens using two analytical techniques: atomic absorption spectroscopy (AAS) and laser induced breakdown spectroscopy (LIBS), and to compare the results of both methods. Two commercial samples representing two different quality products were analyzed: a low-quality sample (R10) and a high-quality sample (R11). Sunscreen samples were dried at 55 °C for 1 h (before LIBS analysis) to remove excess moisture and to provide a stable plasma, as the sunscreen matrices had high contents of water and oil. Two computational methods were used to estimate element concentrations The first is an electron density method to determine the concentrations of elements such as Zn, Ni, Pb, Hg, and Cd. The second is a new method known as the relative density method (LIBS-Qc), a simplified method that does not rely on electron temperature and has proven highly efficient in calculating concentrations. The results showed that the mercury concentration was higher in sample R10 (11.083) than in sample R11 (6.607). The new method (LIBS-Qc) also showed good agreement with the results of the AAS technique, indicating its potential as an effective and rapid alternative for the analysis of heavy elements in commercial products.