\begin{table}
\begin{tabular}{c c c} \hline \hline  & **Method** & **Limitation** \\ \hline \multirow{4}{*}{**Contact**} & DC heating [9; 10; 11] & Conductive materials only \\ \cline{2-3}  & Pulse heating [12; 13; 14] & Conductive materials only \\ \cline{2-3}  & Laser calorimetry [15] & Large amount of heat loss \\ \cline{2-3}  & \(3\omega\) method & Complexity damage of specimen \\ \hline \multirow{4}{*}{**Non-Contact**} & Photo Acoustic [15] & Low accuracy \\ \cline{2-3}  & Laser Flash [17] & Damage of specimen \& Limitation of shape/size \\ \cline{2-3}  & Photothermal radiometry [15] & Problem of emissivity factor \\ \cline{2-3}  & Photothermal reflection [15] & Standardization of roughness on surface of specimen \\ \cline{2-3}  & Photothermal displacement [15] & Surface treatment of specimen \\ \cline{2-3}  & Photothermal deflection [15] & Increase of S/N \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Various thermal property measurement methods and limitations. Figure 1: Photothermal deflection method types. (**a**) Mirage deflection method. (**b**) Collinear deflection method. In the case of the mirage deflection method, the measurement method for single layer isotropic materials has been established by researchers, including [PERSON] (18), [PERSON] (21,27), and [PERSON] (22,26), and the measurement method for single layer anisotropic materials has been established by [PERSON] et al. [PERSON] _et al._ (29). In the case of the collinear deflection method, studies limited to isotropic single/double layer materials were conducted by [PERSON] et al. [PERSON] _et al._ (20,24) and [PERSON] et al. [PERSON] _et al._ (25,30). Very restricted studies on the photothermal deflection method for anisotropic materials have been conducted by [PERSON] et al. [PERSON] _et al._ (2011), [PERSON] et al. [PERSON] _et al._ (2012), and [PERSON] et al. [PERSON] _et al._ (2013,34). [PERSON] et al. [PERSON] _et al._ (2011) analyzed three-dimensional (3D) heat conduction equations for semi-infinite solid and slab models to describe the propagation of heat waves in anisotropic materials. [PERSON] et al. [PERSON] _et al._ (2012) analyzed the heat conduction equation for 3D models by applying the thermal conductivity with only the component in the principal axis direction to poly (4-BCMU). Based on this, they proposed a relation for the mirage deflection method and showed that the results were in relatively good agreement with the measured experimental data. [PERSON] et al. [PERSON] _et al._ (2013,34) proposed a 3D analysis model for the case where only the thermal conductivity component in the principal axis direction was present based on the mirage deflection method and conducted research on the determination of the thermal diffusivity using the relationship of the anisotropic properties of the thermal conductivity. Through their research, they showed that the analysis method applied to isotropic materials could also be applied to anisotropic materials. In summary, the previous studies on the photothermal deflection method (18-34) were conducted only for the mirage deflection method, which measures the thermal properties of optically thick isotropic/anisotropic materials, but not for the collinear deflection method, which measures the thermal properties of transparent anisotropic materials. Therefore, this study investigates the collinear deflection method for measuring the thermal conductivity of a transparent anisotropic material depending on its crystal orientation. To this end, the temperature distribution of a single layer transparent anisotropic material was derived through numerical analysis using a 3D heat conduction equation. To measure the thermal conductivity of the transparent anisotropic material using the derived temperature distribution, the deflection of the probe beam was analyzed.