Numerical study on visualization method for material distribution using photothermal effect

Abstract

Visualization and imaging techniques have become increasingly essential in a wide range of industrial fields. A few imaging methods such as X-ray imaging, computed tomography and magnetic resonance imaging have been developed for medical applications to materials that are basically transparent or X-ray penetrable; however, reliable techniques for optically opaque materials such as semiconductors or metallic circuits have not been suggested yet. The photothermal method has been developed mainly for the measurement of thermal properties using characteristics that exhibit photothermal effects depending on the thermal properties of the materials. This study attempts to numerically investigate the feasibility of using photothermal effects to visualize or measure the material distribution of opaque substances. For this purpose, we conducted numerical analyses of various intaglio patterns with approximate sizes of 1.2-6 mm in stainless steel 0.5 mm below copper. In addition, images of the intaglio patterns in stainless steel were reconstructed by two-dimensional numerical scanning. A quantitative comparison of the reconstructed results and the original geometries showed an average difference of 0.172 mm and demonstrated the possibility of application to experimental imaging.

Numerical Study on Effective Conditions for the Induction of Apoptotic Temperatures for Various Tumor Aspect Ratios Using a Single Continuous-Wave Laser in Photothermal Therapy Using Gold Nanorods

“…The amount of laser energy absorbed by air was disregarded in this study, because although the laser passes through air during photothermal therapy, the light absorption rate of air is very low [49,50]. The laser was absorbed by tumors containing GNPs and was transferred to the upper air layer at the temperature of 20 °C via conduction.…”

Measurement of Contrast and Spatial Resolution for the Photothermal Imaging Method

“…In order to analyze the image quality of the photothermal imaging method, numerical analysis was conducted on specimens with the simple subsurface structure shown in Figure 4. The numerical analysis model had the boundary conditions presented in Figure 7, and it was conducted on the basis of the model established by Kim et al [3]. Here, the infinite condition means that the physical properties of the adjacent material are infinite [25].…”

“…Sci. 2019, 9, x FOR PEER REVIEW 7 of 15 analysis model had the boundary conditions presented in Figure 7, and it was conducted on the basis of the model established by Kim et al [3]. Here, the infinite condition means that the physical properties of the adjacent material are infinite [25].…”

“…Recently, the photothermal imaging method has been studied as an industrial tomographic tool. It acquires morphological information from the inside of an object by means of the photothermal effect of a temporally modulated heat source [1][2][3][4]. The photothermal effect is a physical phenomenon that occurs when a material absorbs light energy and converts it to thermal energy [5,6].…”