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The optimum condition for the reactive gas-assisted Nd:YAG laser cuttings is described in this article. The cut kerf width is investigated for a laser power range of 50–170 W and a gas pressure of 1–6 bar for steel and mild steel materials. Variation of sample thickness, material type, gas pressure and the laser power on the cut width and slot quality are considered in this study. An overall 338 experiments at different experimental conditions are performed and the kerf results are compared. Optimum conditions for the steel and mild steel materials with a thickness range of 1–2 mm are obtained. The optimum condition for the steel cutting results in a minimum kerf width of 0.2 mm at a laser power of 67 W, cutting speed of 7.1 mm/s and an oxygen pressure of 4 bar. A similar investigation for the mild steel-cutting results in a minimum kerf width of 0.3 mm at the same laser power of 67 W, cutting speed of 9.5 mm/s, and an oxygen pressure of 1 bar. Comparison of the results for the two material types indicates that for cutting mild steel, a lower oxygen gas is required for the optimum condition while the kerf width is a little higher for this case. For the same pressure, workpiece thickness, and cutting speed, the threshold power is lower for the mild steel in comparison with the steel. For the case of steel, it is possible to have a lower kerf width and a better kerf quality.

Laser enhanced mobility in the case of PbI₂ single crystal has been investigated on the basis of the experimental results of photoconductivity measurements using high power Nd:YAG laser. Its dependence on energy area density/photon density and charge carrier concentration has been studied. The obtained results of PbI₂ have been compared with that of CdI₂ and ZnS crystals studied under similar experimental conditions. The laser enhanced mobility has also been compared with the theoretical study in the case of GaAs crystal using CO₂ laser.

This paper describes the pulsed Nd:YAG laser machining characteristics on 6351 aluminum reinforced with silicon carbide (SiC) and boron carbide (B₄C) particles. The composites are prepared using stir casting route by varying the weight percentage of B₄C (0, 5, and 10 wt.%). During experimentation, the traverse speed (5, 15, and 30 mm/s) and the laser pulse frequency (5, 9, and 15 kHz) are considered to evaluate the groove width. The results reveal that the lower pulse frequency produced poor groove surface quality. Higher thermal energy dissipation at lower traverse speed may also result in the formation of recast layer and heat-affected zone. This is evident from the microscopic image and the EDS analysis. Thus, the optimum condition (composite with 10 wt.% B₄C machined at 30 mm/s and 15 kHz) to achieve minimum grove width with improved surface morphology is identified by desirability analysis. Additionally, the regression model is developed to predict future values ($R$² at 91.86% and $R$² (adj) at 87.55%). Finally, the probability plot confirms the effectiveness of the proposed model at 95% confidence level.

This work aimed to study the photo disruptive effect of a Q-switched Nd:YAG laser with two different energy protocols on the rheological properties of the vitreous humor after treatment of posterior vitreous detachment (PVD). Twenty-one New Zealand albino rabbits were used in this study and divided into three groups. One group was used as control (n = 6 eyes), the second group (n = 18) was treated with Q-switched Nd:YAG laser energy of 5 mJ × 100 pulse (× means times) delivered to the anterior, middle and posterior vitreous respectively (n = 6 eyes for each). The third group (n = 18 eyes) was treated with 10 mJ × 50 pulse delivered to the anterior, middle and posterior vitreous respectively (n = 6 eyes for each). After two weeks, the protein content, refractive index (RI) and the rheological properties of vitreous humor were determined. The protein content, refractive index, consistency, shear stress and viscosity were increased especially for irradiation of the mid-vitreous, and posterior vitreous. The flow index remained below unity indicating the non-Newtonian behavior of the vitreous humor. Application of Q-switched Nd:YAG laser on mid-vitreous and posterior vitreous induce deleterious effect on the gel state of the vitreous humor.

A Bis-Nickel passively Q-switched Nd:YAG laser is experimentally studied. According to the obtained results for the laser output energy, we found that: (i) the laser output energy has a step by step behavior. (ii) In any step, the output energy has approximately constant value. (iii) The highest output energy is obtained from lowest initial transmission in this work. (iv) As the initial transmission decreases, the laser output energy increases. We deduced to increase the single pulse energy, a Q-switch with lower initial transmission should be used. Apparently, this behavior is true in the passive Q-switches.