Paramagnetic Metal Shocked by Laser-Driven Acoustic Waves: A Morphological Aspect | Chapter 2 | Current Research Progress in Physical Science Vol. 4

The laser-induced shock wave was studied using two different laser intensities in both air and water for a 7 ns pulse. The laser intensity used was 3 and 6 GW/cm². The results indicated an increase in surface temperature with laser energy, reaching 29,7958 degrees Celsius for 3 GW/cm² and 15836 °C for 6 GW/cm², and the temperature in water was found to be more significant than in air, ranging from 7983 to 15957 °C. The shock wave pressure increased with laser intensity, reaching 0.1 to 0.18 GPa in air and 7.54 to 10.66 GPa in water. The shock wave wavelength was longer in water than in air, and its duration decreased in water. When shocking aluminium is in water, the affected area is also reduced. After laser-induced breakdown spectroscopy (LBS) in water, the surface roughness decreased from 1.68 to 0.53 µm, and there was a minimization of optical aberrations that eliminated "hot spots" in the focal length of the laser.

 

Author (s) Details

Narjis Zamil Abdulzahra
Department of Physics, College of Sciences, Al-Nahrain University, Jadriya, Baghdad, Iraq.

 

Please see the book here:- https://doi.org/10.9734/bpi/crpps/v4/2441

Compact Measurement of the Optical Power in High-Power LED Using a Light-Absorbent Thermal Sensor: A Recent Study | Chapter 9 | Newest Updates in Physical Science Research Vol. 6

 When compared to traditional lighting, LED (Light-Emitting Diode) offers advantages such as luminosity, reliability, and durability. It's been used in a variety of applications, including life, healthcare, smart farming, industry, and lighting, ranging from indoor to vehicle headlamps. The LED, on the other hand, is susceptible to thermal damage caused by the high junction temperature, which is especially true in high-power applications. As a result, to ensure reliability, exact certification of the optical power and junction temperature from the pilot line is required. The photo-thermal sensor is proposed in this study, which uses a sheet-type thermocouple made up of a photo-absorbent metal film and a thermocouple. This sensor is designed to provide low-cost certification in a pilot line for high-power luminous devices and optical monitoring of expensive luminaires such vehicle LED headlamps. From the transferred thermal power and absorbed optical power, the sensor is designed to detect the increasing temperature response of LED hot spots. Based on the introduced sensor equation, the temperature response of each sheet-type thermocouple is used as a signal output of the absorbed optical power and hot spot temperature. The sensor equation is modelled using the lumped capacitance model of each sheet-type thermocouple, with the view factor and additional optical power absorption component taken into account. The experiment is compared to the measured reference value from the integrating sphere and the associated thermocouple at a junction to evaluate the proposed thermal sensor. For an optical power of 645 mW, the experiment result reveals a maximum inaccuracy of 3%.

Author(S) Details

Youyoung Kim
School of Mechanical Engineering, Gwangju Institute of Science and Technology, Gwangju 61005, Korea.

Jae-Young Joo
Korea Photonics Technology Institute, Gwangju 61007, Korea.

Jong-Min Kim
School of Mechanical Engineering, Gwangju Institute of Science and Technology, Gwangju 61005, Korea.

Sun-Kyu Lee
School of Mechanical Engineering, Gwangju Institute of Science and Technology, Gwangju 61005, Korea.

View Book:- https://stm.bookpi.org/NUPSR-V6/article/view/4666