The q-plate is a new type of polarization optical element with engineered optical anisotropy. New and wide-ranging applications, such as spin-orbit beam generation, angular momentum coupling, signal processing, and realization of holonomic polarization transformations in higher polarization topological index optics, are made possible by this novel element. In this paper, we demonstrate that q-plates can be used in optical metrology for testing astigmatic optical systems. A beam suffering from astigmatism is passed through a q-plate, and the signature intensity patterns obtained at the nominal focal plane are used to estimate the astigmatism.

Secure optical encoding can be achieved by utilizing light fields with spatially varying polarization. This paper presents a security-enhanced optical color image authentication method that encodes information through non-uniform polarization distribution in vectorial light fields. In our method, Quick Response (QR) codes are embedded as a data carrier as a part of the scheme. By integrating engineered polarization states and the QR codes, the scheme offers a secure cryptographic framework for color image authentication. The proposed approach is validated through both simulation and experimental results, confirming feasibility and effectiveness of our approach. The results highlight the potential of polarization-based image authentication.

We propose a robust polarization-based optical encryption scheme combining random degree of polarization (DOP) and state of polarization (SOP) masks. The encrypted and decrypted images obtained using SOP mask based on pixelated half waveplate and pixelated polarizer are compared with original image based on mean-square-error (MSE) and correlation coefficient (CC). The degrees of freedom of the encryption system are further increased with the Radon transformation of the target image and random amplitude key. We have used Stokes-Müller formalism for this scheme to realize it with physically measurable quantities. The outcomes of the individual encryption approaches based on SOP/DOP and combined (DOP, SOP, and Radon transform) are compared both qualitatively and quantitatively. The effects of Gaussian noise and occlusion attack on the proposed scheme are also analyzed. We anticipate that this research would yield a novel, readily implementable security-augmented optical encryption scheme.

Introduction: Livistona chinensis (L. chinensis) or Chinese fan palm is a tropical and subtropical plant that is commonly planted across the world. Its fruits are fleshy, green in appearance, and contain a firm seed. The biochar produced from Chinese fan palm fruit is an excellent source for the adsorption of colours from bodies of water for subsequent disposal. Biosorption is a great and environmentally beneficial method of removing contaminants from the environment. Traditional Chinese medicine (TCM) practitioners utilised it to treat cancer. Experiments have indicated that extracts of L. chinensis fruits and seeds have antiproliferative and antiangiogenic effects. Flavanoids, phenolic acids, terpenes, alkaloids, and other compounds are found in L. chinensis. Methodology: The online database including Google Scholar, Scopus, PubMed, and Web of Science were searched using different keywords: L. chinensis phytochemistry, pharmacology and toxicology. The purpose of this review was therefore to summarize the previously reported phytochemicals, pharmacological status of the chosen Chinese plant species. Results: Our findings show that Livistona chinensis includes a wide range of physiologically active chemicals, such as flavonoids and terpenoids. Furthermore, past research has shown that L. chinensis plant extracts and extracted principles have substantial pharmacological action, including anti-tumour, anti-inflammatory, antioxidant, anti-melanogenic, and other properties. Discussion: According to the research listed below, L. chinensis has a high potential for developing medicines and supplements for prophylactic as well as therapy of cancer, ulcer, diabetes, and other diseases. Furthermore, clinical research has demonstrated that jujube is a safe and effective plant for human consumption, and as such, it should be included in dietary intakes as well as active ingredients in pharmaceutical formulations. Conclusion: L. chinensis is a great source of bioactive compounds that may be put into human meals and show promise in the treatment of minor to life-threatening medical conditions. This review will inspire other scientists to conduct more research on the selected plant species, particularly in the areas of toxicity and bioactivity.

In this paper, we propose a novel dual-user image authentication algorithm based on the double fractional Mellin transform. We perform a security analysis of the nonlinear cryptosystem based on the fractional Mellin transform and show its vulnerability. In the proposed algorithm, polar decomposition and sparse multiplexing are additionally applied to generate a ciphertext. During the encryption process, polar decomposition generates two private keys that can be utilized on the dual-user authentication platform. The proposed scheme has a large key space and is robust against several attacks such as contamination attacks (noise and occlusion), brute force attacks, plain-text attacks, and special iterative attacks. In addition, we carry out a comparison with a similar existing scheme for the proposed algorithm. Simulated results indicate that the proposed authentication algorithm is feasible and robust.

Recent advances in the field of digital sensors and computational facilities have turned digital holography (DH) into a powerful tool for many applications such as quantitative phase imaging, optical metrology, evaluation of cell parameters, optical cryptography, and optical pattern recognition among others.The transport of intensity equation (TIE) is one of the deterministic phase-retrieval methods, which does not use interferometric geometry.In this method, the phase is calculated directly from a set of intensities rather than iteratively approximating a solution.Recently, use of the TIE in the DH reconstruction process has been reported as a phase-retrieval method.Combining both DH and TIE provides better solution to the phase-retrieval.Refocusing property of the DH helps exploit the translation issue of digital sensor along the optical axis while capturing the intensity distributions at different depths.The issue of phase unwrapping is solved through the use of TIE.Hence, both the methods complement each other.In this paper, we review briefly the applicability of the combination of DH with TIE.

Remote sensing is the analytics of sensor data modalities to capture the earth's surface characteristics. The hyperspectral data widely used for surface material identification by using pixel-wise unique signature patterns. The true-color-composite (RGB) or/and a variety of false-color-composites (FCCs) used to classify various objects and features. In this paper, three novel FCCs have been proposed and compared with already existing popular FCCs. These FCCs have been analyzed using three different approaches viz., (i) k-means (ii) patch-based deep network and (iii) sample level mirror mosaicking (SLMM)-based deep network; for the classification of various objects or features viz., Vegetation, Soil, and Road. The open-source dataset provided by the National Ecological Observatory Network (NEON) has been used to show the efficacy of proposed FCCs and SLMM-based deep-network. Our proposed FCCs and SLMM-based deep networks outperform over all other considered FCCs and classification methods.

We implement a fully phase encryption system, using fractional Fourier transform to encrypt and decrypt a 2-D phase image obtained from an amplitude image. The encrypted image is holographically recorded in a barium titanate crystal and is then decrypted by generating through phase conjugation, a conjugate of the encrypted image. The decrypted phase image is converted into an amplitude image by the phase contrast technique using an electrically addressed spatial light modulator. Experimental results in support of the proposed idea are presented.

We have carried out a study of optical image encryption in the Fresnel transform (FrT) domain, using a random phase mask (RPM) in the input plane and a phase mask based on devil’s vortex toroidal lens (DVTL) in the frequency plane. The original images are recovered from their corresponding encrypted images by using the correct parameters of the FrT and the parameters of DVTL. The use of a DVTL-based structured mask enhances security by increasing the key space for encryption and also aids in overcoming the problem of axis alignment associated with an optical setup. The proposed encryption scheme is a lensless optical system and its digital implementation has been performed using MATLAB 7.6.0 (R2008a). The scheme has been validated for a grayscale and a binary image. The efficacy of the proposed scheme is verified by computing mean-squared-error (MSE) between the recovered and the original images. We have also investigated the scheme’s sensitivity to the encryption parameters and examined its robustness against occlusion and noise attacks.

We have carried out a few studies on image encryption and watermarking in various transform domains, for amplitude and phase images. We have used structured phase masks (SPM) based on devil's vortex Fresnel lens (DVFL) to enhance security by increasing the key-space. The proposed schemes have been validated by computer simulations and their efficacy is evaluated by computing mean-squared-error (MSE) between the original image and the decrypted image. They have been examined for their sensitivity to various encryption parameters, and robustness to noise and occlusion attacks.

In the present work excited states in 98,99Rh nuclei were populated in the fusion-evaporation reaction 75As(28Si,xpyn) at Elab = 120MeV. The de-excitations have been investigated through in-beam γ-ray spectroscopic techniques. The present level scheme of 98Rh and 99Rh has been established up to J ∼ 23ℏ and 29ℏ respectively. In the doubly-odd 98Rh nucleus new band structure and isomeric states have been identified at lower spins. New states below the previously assigned 2+ ground state (T1/2 = 8.5m) are identified. The low lying band structures in 99Rh are based on πp1/2 and πg9/2 quasiparticles which further evolve into high spin structures following (νh11/2)2 alignment. Multifragmentations at the positive and negative parity bands at spins around 20ℏ is observed, which are likely to be maximally spin aligned states similar to the ones observed in 101Rh.

A security enhanced double random phase-amplitude encryption (DRPAE) scheme is immune against the powerful known-plaintext attack, due to the insertion of an undercover amplitude random mask at the Fourier plane in the conventional double random phase encryption (DRPE) scheme. However, DRPAE, which nullifies the high level known-plaintext attack, is found to be susceptible to a simple impulse function attack. Information about the exact distribution of the amplitude mask as well as that of the Fourier plane random phase mask is divulged from an impulse function attack. A variant form of the impulse function attack is also able to show that the DRPAE scheme is as linear as the conventional DRPE scheme. Numerical simulation results validate the effectiveness of the simple impulse attack on the DRPAE scheme.

A technique for simultaneous encryption of a color and a gray-scale image is proposed, using single-channel double random-phase encoding in the fractional Fourier domain. Prior to the encryption, the segregated red, green, and blue components of the color image and the gray-scale image are encoded into a single image after changing their bit formats. The format of the encoded image is such that it cannot be perceived by the human eye. The fractional orders of the fractional Fourier transform and two random-phase masks act as key parameters for the encryption. Performance of the scheme is verified against chosen plain-text and known plain-text attacks, respectively. The effect of noise on the performance of the proposed technique is analyzed. (C) 2011 Society of Photo-Optical Instrumentation Engineers (SPIE). [DOI: 10.1117/1.3569688]

A negative phase velocity means that the phase of a wave advancing through the medium is negative rather than positive, which is usually the case. This fundamental reversal of propagation contains important implications related to all electromagnetic phenomena. [See for example, Victor Veselago, electrodynamics of substances with simultaneously negative values of e and μ Sov. Phys. Usp. 10 (1968) 509–514]. These materials result in modified Snell's law of refraction, and thus show many startling properties e.g. Refraction of light on the same side of the normal entering the material; Reversal of Doppler shift; Cerenkov radiation pointing the other way; and the time-averaged Poynting vector being antiparellel to phase velocity. Demonstration of the use of negative refractive materials (NRMs) for making perfect lenses with resolution capabilities not limited by the conventional diffraction limit has given an enormous impetus to the interest in NRMs. Considerable interest has been shown in using sub-wavelength structures to develop materials that qualitatively have new response functions that do not occur in nature. A very brief introduction of negative refraction covering its hypothesis, research, relevant materials and their preparation, and pertinent devices has been given. As these materials are becoming increasingly important for various studies in the fields of ‘Photonics and Microwave Technologies’, a qualitative bibliographic review of the investigations in these fields for the year 2006, has been presented in this paper. The books have been marked by an asterisk (*). No claim is made as to the completeness of the bibliography. However, an attempt has been made to include as many references as possible.

Interference-based optical encryption schemes have an inherent silhouette problem due to the equipollent nature of the phase-only masks (POMs) generated using an analytical method. One of the earlier methods suggested that removing the problem by use of exchanging process between two masks increases the computational load. This shortcoming is overcome with a noniterative method using the jigsaw transformation (JT) in a single step, with improved security because the inverse JT of these masks, along with correct permutation keys that are necessary to decrypt the original image. The stringent alignment requirement of the POMs in two different arms during the experiment is removed with an alternative method using a single spatial light modulator. Experimental results are provided to demonstrate the decryption process with the proposed method.

The holographic search engine based on defocused recording is investigated under rational conditions. New data page modulation coding schemes are introduced for removing the ambiguous correlation characteristics and performing a reliable data search.

An investigation was laid out to assess the genetic variability and correlation in 18 papaya cultivars under Bihar conditions. Wide range of variability was observed in node at fruit fruiting, plant height, fruiting height, fruiting length, fruit weight, number of fruit per plant and fruit yield per plant. Phenotypic coefficient of variation for all the characters was higher than that of genotypic coefficient of variation. The yield was significantly correlated with number of fruit, fruit weight, fruiting length and leaf length. Higher estimate of heritability and genetic advance were observed for fruit weight, fruiting length and fruit yield. High heritability estimates obtained showed that selection programme based on these characters would be more effective in improving the quantitative parameters of papaya.

A new method for image encryption using integral order radial Hilbert transform (RHT) filter in the fractional Fourier transform (FRT) domain has been proposed. The technique is implemented using the popular double random phase encoding method in the fractional Fourier domain. The random phase masks (RPMs), integral orders of the RHT, fractional orders of FRT, and indices of the Jigsaw transform (JT) have been used as keys for encryption and decryption. Simulation results have been presented and the schematic representation for optical implementation has been proposed. The mean-square-error and signal-to-noise ratio between the decrypted image and the input image have been calculated for the correct as well as incorrect orders of the RHT. Effect of occlusion and noise on the performance of the proposed scheme has also been studied. The robustness of the technique has been verified against attack using partial windows of the correct random phase masks. Similar investigations have also been carried out for the chosen-, and the known-plain-text attacks.