Optics and Photonics Society of Iran

In this paper a new method for measuring the temperature gradient in liquids is introduced which is based on moiré deflectometry. A cell containing liquid is placed on top of a cold plate with temperature  so that the bottom of liquid gets same temperature with the plate. The top of liquid is also isothermal with the environment. The temperature of different points inside the cell is varied with time until getting a stable temperature distribution. The temperature gradient causes a diffraction index gradient that makes the moiré fringes to deflect. The moiré fringes are recorded using a camera and is analyzed using Fourier transforming method. The deflection of moiré fringes is used to get the refractive index distribution inside the cell and then the temperature distribution is derived.