Journal of Lasers, Optics & Photonics

Laser forming of materials can help produce the desired shapes from sheets or tubes, which is not possible through conventional methods. Molds, dies, and external force are not needed for the laser forming of materials. Furthermore, the process is flexible and can be controlled by making changes to the materials, their geometry, and the laser parameters, either individually or in combination with each other. Investigations into laser tube bending are scarce in the literature pertaining to this field of study despite its potential and industrial importance. In contrast, much research has been conducted on laser sheet forming, which employs the same mechanism. In this study, laser tube bending is compared with laser sheet forming in order to develop a better understanding of the laser forming process. This review elucidates upon the mechanisms employed in laser forming (in general) and laser tube bending (in particular). A number of investigation methods are reviewed and analytical models of the process are also described. The principle of laser tube bending is explained, and the influence of various parameters (such as materials, geometry, laser, edge, and cooling effects) on the process is analyzed. Additionally, large tubes bending and preloading, or laser assistance, are examined.

In a contactless photo conductance measurement system the radio-frequency (RF) probe transmission (ΔV/ V0) should be proportional to the product of laser-induced carrier concentration and carrier mobility (ϕΣμ) through a sensitivity factor (A). We use 532 nm laser (pump)-millimeter wave (mmw-probe) system whose concentrations (ϕ) are calculated by considering single-surface reflection of the laser beam and mobility (Σμ) derived from a model. In order to ascertain A we use five c-Si (100) samples having resistivity in the range 15-130 Ω-cm. For relating (ΔV/V0) with ϕΣμ to find A, we take their ratio and quantify A once using a quadratic-fit functional form of the ratio of sample resistivity to air resistivity (ρ/ρ0), and another time using product of free-space impedance and sample thickness (ρ/Z0t). A is ascertained for (ΔV/V0)-laser fluence linear region while fluence is in range 0-1.7 μJ/cm2 and probe frequency is fixed at 140 GHz. Value of A is further fine-tuned by multiplying with 0.85 (to linearize the ratio with the non-dimensional function) and finally obtain sensitivity A=0.291. Standard error in mmw photo conductance (obtained using calculated A) between the two approaches diminish with laser attenuation roughly at a rate ± 0.53 × 10-5 S, per decimal neutral density filter size.

A method for measuring and unambiguous interpretation of the results of measuring the speed of synchrotron radiation (speed of light) is developed.

Background: Adhesion of braces to dental enamel is critical for orthodontic treatments, for that purpose, phosphoric acid has been used successfully to prepare dental enamel surface before bonding braces. ER:YAG laser has proved ability to do the same over buccal surfaces of dental enamel, but the increasing interest for lingual orthodontics leaded to the question whether ER:YAG laser can prepare equally palatal and buccal surfaces for bonding lingual braces.
Material and methods: 15 teeth that were extracted for clinical purposes were microscopic electronic scanned (MES) before treatment, after phosphoric acid 37%, and after ER:YAG laser irradiated, images of buccal and palatal faces after each treatment were analyzed by image J software.
Results: After all treatments enamel surfaces were mostly type 1, no statistically significant differences were found between groups.
Conclusion: Phosphoric acid 37% and the used dose of Er:YAG laser can successfully prepare dental enamel surface before bonding braces over buccal and palatal faces of teeth.

The aim of this research work is to measure the concentration and absorption cross-section of artificial uric acid in the Ultraviolet (UV) region using UV-Vis spectrometer. The uric acid sample comes in powder form which has to be dissolved with distilled water to convert it into liquid form. Therefore, it can be placed in the cuvette for the analysis purposes. This research study was proposed to make a comparison with the previous research studies that uric acid was normally extracted from human serum as a real sample. This research study was carried out using an artificial sample of uric acid with the suspended or grits of uric acid which were not totally dissolved. These grits might be artificially assumed as crystallites which is common with Gout disease. Based on the medical perspective, crystallites normally inhibit the human joints which may cause intense pain to the human bones or tissues. In the experiment, the distilled water was used a background or reference spectrum which can be stored and automatically deducted using the Spectra suite software application. Thus, Spectra suite only measures the pure concentration and UV absorption wavelength of the uric acid through the use of the spectrometer. The absorbance data was extracted and substituted into Beer’s Lambert Law formula to calculate the value of absorption cross-section. The result shows that the value of UV absorption wavelength and absorption cross-section is really close as reported in the previous research studies. It proves that even the artificial sample of uric acid with the grits still can give a very close result. The UV absorption of uric acid was obtained at 293.99 nm by four different concentrations. The response time was successfully done in 3 seconds. The resulting curves have noise signals which can be analyzed and reduced using an averaging method to make the curve look sharper and lack of noise.