Shock Wave Emission during Cavitation Bubble Collapse in Free Liquid

Shock wave emission due to cavitation bubble collapse was studied. Four or five time collapses occurred in a single oscillation of a cavitation bubble. The secondary cavitation bubble appeared in the rebound process. When the cavity was split during the first collapse, double shock waves were radiated with separate centres in the following collapse. A gross distortion and multiple shock waves were radiated due to multiple breakdown

Keselamatan dan orientasi laser

Buku ini mengandungi maklumat mengenai had sinaran dan jarak selamat bagi pendedahan penglihatan ke atas cahaya laser. Turut dimuatkan ialah keterangan bagi langkah-langkah untuk mencegah bahaya sinaran laser dan bekalan voltan tinggi. Ini disusuli pula dengan kaedah mengendalikan komponen optik yang dapat menjanakan kualiti cahaya yang baik. Sehubungan dengan ini, beberapa jenis material optik disenaraikan supaya pemilihan dapat dibuat bertepatan dengan spektrum laser yang digunakan. Kaedah mengorientasi laser melalui bantuan komponen optik yang sepadan turut dibincangkan. Pendek kata, buku ini merangkumi aspek-aspek keselamatan dan kaedah pengendalian laser yang dapat dimanfaatkan oleh semua pengguna laser yang meliputi pelajar, penyelidik di institusi pengajian tinggi, pengguna di industri, pengamal bidang perubatan, pertahanan, metrologi dan bidang-bidang lain yang terlibat secara langsung dalam pemakaian laser sebagai sumber tenaga

Elasticity measurement using holographic interferometry double exposure technique

Holographic measurement of modulus elasticity was performed on samples of aluminum can. It is based upon the measurement of the displacement as a function number of fringes appeared on the body of the loaded can. The value of the modulus elasticity for the aluminum can is obtained as (1.00 ± 0.03) × 108 nm–2. This result is found in good agreement with a mechanical measurement by taking into account any experimental erro

Detection of Pb in Whitening Creams via Laser Induced Breakdown Spectroscopy

Recently whitening creams have been widely used to protect UV light exposure due to the depletion of ozone layer. The demand attracts the rapid growth of various whitening creams in the market. The detection is required in order to determine the constituent of the whitening cream, whether it contains dangerous element like heavy metal (Pb, Hg or Cr). In this attempt, laser induced breakdown spectroscopy (LIBS) technique was deployed to analyse the existence of heavy metal. Several whitening creams available in retail shop and open market were investigated. Cryogenically frozen technique was utilized to convert the emulsion into solid form. Lead Pb was detected in all the tested samples in the range of 2 - 5 ppm.  The LIBS results were validated by Inductive Couple Plasma Mass Spectroscopy (ICP-MS) technique.  The high sensitivity, portable and in-situ LIBS system allow simple, faster and easy heavy metal detection.  This enhances the procedure of inspection in cosmetic industrie

Investigation of angular distribution on copper ions using faraday cup technique

A Q-switched Nd:YAG laser with fundamental wavelength of 1064 nm delivering pulse energy of 125 mJ and pulse duration of 8 ns was employed as a source of energy to generate plasma. The laser was focused on copper as a target material. The angular distribution of ejected ions species were collected by a developed Faraday cup. The cups were arranged radialy at the range of angles from 5o to 90o with two radiuses of 5 cm and 10 cm. The cups were coupled to high speed oscilloscope to display and measure the ion flux and charge state. The exposed Faraday cup was also studied by metallurgical technique. The results obtained show that the maximum flux of copper ion collected by Faraday cup was 11.7 x 1016 charge /sec. The maximum number of charge state was Cu+4 at 5 cm and Cu+3 at 10 cm. In general the angular distribution of ions flux is maximum in axial direction and decreases in radial direction. Various elements are found deposited on Faraday cup with majority lines of copper cluste

Study of Laser – Induced Plasma Using Two Focusing Techniques

Plasma plays an important role in laser fusion research. High power laser is used to drive the reaction. Hence the laser turns to become very crucial devices to form plasma. Generation of plasma can be done by various focusing techniques. Therefore the aim of this project is to determine the best focusing techniques in order to produce strong plasma. Two focusing techniques were considered, that are a single lens technique, and combination lenses technique. A high-speed photographic system was developed in conjunction with image processing system to visualize and record the plasma activities in the focused region. An electrical spark was observed at the focal region which indicates the existence of an optical breakdown. The results shown that the maximum plasma widths were obtained correspond to the peak power of 22.21 MW using a combination lenses technique in comparison to 21.93 MW for the single lens technique. In general, combination lenses technique produces more consistent plasma, although it size is small. A single lens technique induced large plasma but associated with turbulence condition as indicated by blurred image

Formation of Fe-Ni composite on pure aluminum substrate by laser surface alloying

Aluminum is recently attracted the attention of several researchers due to its unique properties; however, it has low hardness, corrosion and mechanical properties. The technique of Laser surface alloying of aluminum substrate with nickel and iron under various processing conditions has been studied. In this paper, a low power CO2 laser was used to alloy pure aluminum substrates with Fe-Ni mixture of various exposures between 10-60 s. It indicates that the laser surface alloying technique using mixed powder with a ratio of 66.67%Ni–33.34%Fe can considerably enhance the hardness of aluminum surface. Microstructures of alloyed layers were studied by scanning electron microscope, optical microscope and the phases were identified by X-ray diffraction analysis. In addition, the micro-hardness of the surface alloyed layer was measured. The hardness was increased from 27 HV0.1 for untreated surface to as high as 53.9 HV0.1 for treating surface due to the formation Al6Fe, Al5Fe2, AlFe3, Al5FeNi, Al0.9Ni1.1 and Al76.8Fe14

Surface Profiling Of Paper Radiated With Focused Infra-Red Nd:yag Pulsed Laser

A Nd:YAG pulsed laser with wavelength of 1.06 mm can cause a tremendous damage when interacts with material. In this study the effects of Nd:YAG laser interactions onto paper are reported. A combination lens technique was used with different focal length of lens. The target material that is a photographic paper was positioned at a focal spot of the laser beam. IR laser pulsed with peak power up to megawatt (MW) is brought to focus thus interacts with the photographic paper. This high-power impact of the laser pulsed shockwave caused a tremendeous damage on the photographic paper. Measurement of the impact was base on the surface size of the damage. From the observation result it shows that the maximum damage diameter for short lens system is 0.613 mm at peak power of 21.93 MW, whereas the maximum damage diameter for long lens system is 1.224 mm at 22.25 MW peak power

Image Analysis of Plasma Induced by Focused IR Pulsed Laser

Plasma induced by focused laser beam is very essential especially in laser material interaction. Preliminary study leading to this research has been carried out. A Q-switch Nd:YAG laser was employed as a source of energy. The laser was focused using a wide-angle camera lens. The formation of plasma at the focal region was visualized perpendicularly using a CCD video camera interfaced to an image processing system. The dynamic expansion of the laser plasma was grabbed in conjunction with a high-speed photographic system. The observation results show that the plasma was formed in an ellipsoidal shape. The lateral width and the length of the plasma were found gradually increase

Elemental analysis of Nigella sativa via laser induced breakdown spectroscopy technique

The ablity to analyze solid sample for direct analysis of agricultural and environmental samples using laser induced breakdown spectroscopy LIBS technique is a well known analysis lechnique il-5]. A high energy laier was urlo to vaporize-and atomize a small amount from the target sample to create plasma. Emission of light produced Ou*rg plasma cooling become signature for each element contain from the samptl. The advantafe of ttris technique are including rapidness, capable to analyze all materials (solid, tiquiO inO gas;, in-situ or real-time and online analyiis, multi-elernental detection, with minimal sample preparation and minor sample damag