Journal des lasers, optiques et photoniques

Current electronic countermeasure, radar warning, and electronic knowledge frameworks all greatly benefit from the ability to recognise the recurrence of obscure obstructed microwave signals. Microwave recognised proof framework demands smaller size, greater data transfer, higher objective, and reduced idleness due to the increasing interest in limit and the expansion of wise turn of events. Due to this, a number of photonicbased microwave recurrence ID methods have been taken into account. The microwave photonic frameworks' size, weight, and complexity were specifically reduced by the use of the photonic combination approach, which is essential for airborne and remote applications.

Toys of different brands were analyzed by Laser Induced Breakdown Spectroscopy (LIBS) technique employed for the analysis of toxic and nontoxic elements. All samples were irradiated without sample preparation treated under the ambient environment of argon gas. The analysis of emitted spectra reveals the presence of different elements in the samples which was verified by the National Institute of Standard and Technology (NIST) database. Both toxic and non-toxic elements like lead, tin, mercury, potassium and magnesium are found indifferent concentrations. The concentration of heavy metals like lead, mercury and tin in different toys were in the range of 897.2 ppm-320.5 ppm, 88.2 ppm-140.4 ppm and 8.4 ppm-10.2 ppm respectively which is much higher than the permissible value set by US Environmental Protection Agency (US EPA), US Food and Drug Administration (US FDA) and other regulatory authorities. The concentration of non-toxic elements like magnesium and potassium are within safe permissible limits.

Direct Metal Deposition (DMD) is a metal deposition technique, which is well- known for high-quality and high-productivity level of fabrication. In the current economic situation with worldwide trend for developing new products, the importance of time and cost reduction increases day-by-day. To achieve this goal the man-machine-material interaction should be maximized. Direct Laser Metal Deposition (DLMD) is one of the most famous approaches for this. DLMD is one kind of 3D printing technology (additive manufacturing) together with laser cladding process. In DLMD, it is possible to fabricate fully functional metallic parts directly from CAD data, which involves a feeding of metal powders through a nozzle into a high power laser beam and creates a melt pool on the surface of the solid substrate upon which a metallic powder is injected. DLMD process are now acknowledged worldwide and is also known to all by several other names such as Laser Metal Deposition (LMD), Direct Laser Deposition (DLD), Laser Engineered Net Shaping (LENS), Direct Light Fabrication (DLF), Laser Deposition Welding (LDW) and Powder Fusion Welding (PFW). After development of this process in 1995, lot of researchers for several years work on various aspects of high quality deposition with dimensional accuracy such as good clad geometry, clad height, and microstructure study of the mechanical properties. An attempt has been made to focus on proper selection of the set up configuration for direct laser metal deposition to fulfill the requirement and help to achieve high quality deposition. Empirical-statistical models have been produced since the advent of LDMD as they avoid the complexity of analyzing the physical phenomena of the process itself. Direct metal deposition is typically described as having three “primary” process inputs of laser power, powder mass flow rate, and traverse speed. Most models have concentrated on relating these to final track geometry, typically using regression methods to relate input and response variables. Permitting materials to grow along specific orientation by means of directional solidification technique can optimize their structural or functional properties. Ni-based super alloys are the preferred material for turbine blades given their high temperature strength, microstructural stability, and corrosion resistance. Casting methods have been improved from conventional investment casting, which produces an Equiaxed (EQ) grain structure, to Directional Solidification (DS), which produces Columnar-Grain (CG) and Single Crystal (SC) structures. Although polycrystalline Ni-based super alloys are inherently strong, their properties can be further improved through processing. Ensuring crystal cohesion during solidification by avoiding the formation of cracks and pores is a major challenge in materials science. Under others, the safety of gas turbine components and of laser welds for the aerospace and automotive industries depends on it. Solidification cracking (also called hot cracking or hot tearing) is characterized by extended openings that form during solidification in the mushy zone.

A homemade Copper Vapor Laser (CVL) operating at 510 nm (green) and 578 nm (yellow) outputs was applied to vaporize the Mg metal target in the acetone liquid medium. The Mg plate surface was ablated under a 10 kHz repetition rate and maximum pulse energy of 3 mJ and 35 ns pulse duration. Structural, morphological, optical, and chemical-bond properties of synthesized Mg and MgO nanoparticles were investigated using the X-ray diffraction (XRD) analysis; scanning electron microscopy (SEM) observations, UV-VIS absorption spectroscopy and Fourier transform infrared spectroscopy (FTIR) analysis, respectively. The XRD results confirmed the formation of both Mg and MgO nanoparticles. The crystallite size and the strain of final powder were estimated about 57 nm and 0.017 from XRD data calculated using the Williamson-Hall method. The Mg/MgO ratio was also calculated to be about 67% according to Alexander & Klug formula. The chemical bands of products were correctly identified using the FTIR characterization. The SEM images revealed the presence of spherical and plateletlike structures in a range of 50-80 nm in diameter that confirmed the XRD results. UV-VIS absorption spectrum of Mg/MgO nanoparticles synthesized by laser ablation of Mg target in acetone shows a broad peak at about 417 nm attributed to the plasmon absorption band at this wavelength. The derivative method was applied to measure the Eg equal to 2.3 eV for Mg/MgO nanoparticles synthesized in acetone medium under CVL ablation.

In the modern age, due to the rapid development of communication techniques, individuals can be secured by the application optical signal processing technology. In this paper, we have proposed a new technique that is using a multiplexing tactic for optical encrypting mechanism to secure the individuals for multiple users. Here in this paper, we are modifying the classical joint transform correlator to provide more security which is easy in implementation. Our proposed technique that is using encoding and decoding procedure provides more security than the previous techniques. In this approach, amplitude random mask was used for encoding as well as decoding procedure but in a holographic format that modulates the input information and enables us to recover the input information from modulated signal which is difficult for other people. For encoding process, we project the spectrum of the scattered beam of the amplitude random mask on the object that capture the object information in random manner and Fourier transformation gives the spectrum of the coded object. The split beam of the mask is multiplexed to the coming spectrum at the CCD plane for the decoding process unlike the classical joint transform architecture discussed. There is no need of the mechanical moment of the mask. This technique is more efficient than the techniques available in the literature because the advantage of the method introduced in this paper is the decryption performed using the same key code. We present a theoretical explanation, along with computer simulations results that support our proposal.